diff --git a/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/array_length.ql b/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/array_length.ql
index 3850a63a4657..0d8aa37b8ee9 100644
--- a/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/array_length.ql
+++ b/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/array_length.ql
@@ -2,576 +2,617 @@
 // Database scripts can't import, but this is the definitive copy of the support routines for mapping types to their unaliased equivalent. Ensure this code is in sync between aliases.qll and all copies in individual table .ql files.
 /** A Go type. */
 class Type extends @type {
-    /**
-     * Gets this type with all aliases substituted for their underlying type.
-     *
-     * Note named types are not substituted.
-     */
-    Type getDeepUnaliasedType() { result = this }
-  
-    /**
-     * Gets a basic textual representation of this type.
-     */
-    string toString() { result = "type" }
-  }
-  
-  /** A composite type, that is, not a basic type. */
-  class CompositeType extends @compositetype, Type { }
-  
-  /** An array type. */
-  class ArrayType extends @arraytype, CompositeType {
-    /** Gets the element type of this array type. */
-    Type getElementType() { element_type(this, result) }
-  
-    /** Gets the length of this array type as a string. */
-    string getLengthString() { array_length(this, result) }
-  
-    override ArrayType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType() and
-      result.getLengthString() = this.getLengthString()
-    }
+  /**
+   * Gets this type with all aliases substituted for their underlying type.
+   *
+   * Note named types are not substituted.
+   */
+  Type getDeepUnaliasedType() { result = this }
+
+  /**
+   * Gets a basic textual representation of this type.
+   */
+  string toString() { result = "type" }
+}
+
+/** A composite type, that is, not a basic type. */
+class CompositeType extends @compositetype, Type { }
+
+/** An array type. */
+class ArrayType extends @arraytype, CompositeType {
+  /** Gets the element type of this array type. */
+  Type getElementType() { element_type(this, result) }
+
+  /** Gets the length of this array type as a string. */
+  string getLengthString() { array_length(this, result) }
+
+  override ArrayType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType() and
+    result.getLengthString() = this.getLengthString()
   }
-  
-  /** A slice type. */
-  class SliceType extends @slicetype, CompositeType {
-    /** Gets the element type of this slice type. */
-    Type getElementType() { element_type(this, result) }
-  
-    override SliceType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
+}
+
+/** A slice type. */
+class SliceType extends @slicetype, CompositeType {
+  /** Gets the element type of this slice type. */
+  Type getElementType() { element_type(this, result) }
+
+  override SliceType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  // Improve efficiency of matching a struct to its unaliased equivalent
-  // by unpacking the first 5 fields and tags, allowing a single join
-  // to strongly constrain the available candidates.
-  private predicate hasComponentTypeAndTag(StructType s, int i, string name, Type tp, string tag) {
-    component_types(s, i, name, tp) and component_tags(s, i, tag)
+}
+
+// Improve efficiency of matching a struct to its unaliased equivalent
+// by unpacking the first 5 fields and tags, allowing a single join
+// to strongly constrain the available candidates.
+private predicate hasComponentTypeAndTag(StructType s, int i, string name, Type tp, string tag) {
+  component_types(s, i, name, tp) and component_tags(s, i, tag)
+}
+
+private newtype TOptStructComponent =
+  MkNoComponent() or
+  MkSomeComponent(string name, Type tp, string tag) { hasComponentTypeAndTag(_, _, name, tp, tag) }
+
+private class OptStructComponent extends TOptStructComponent {
+  OptStructComponent getWithDeepUnaliasedType() {
+    this = MkNoComponent() and result = MkNoComponent()
+    or
+    exists(string name, Type tp, string tag |
+      this = MkSomeComponent(name, tp, tag) and
+      result = MkSomeComponent(name, tp.getDeepUnaliasedType(), tag)
+    )
   }
-  
-  private newtype TOptStructComponent =
-    MkNoComponent() or
-    MkSomeComponent(string name, Type tp, string tag) { hasComponentTypeAndTag(_, _, name, tp, tag) }
-  
-  private class OptStructComponent extends TOptStructComponent {
-    OptStructComponent getWithDeepUnaliasedType() {
-      this = MkNoComponent() and result = MkNoComponent()
-      or
-      exists(string name, Type tp, string tag |
-        this = MkSomeComponent(name, tp, tag) and
-        result = MkSomeComponent(name, tp.getDeepUnaliasedType(), tag)
-      )
-    }
-  
-    string toString() { result = "struct component" }
+
+  string toString() { result = "struct component" }
+}
+
+private class StructComponent extends MkSomeComponent {
+  string toString() { result = "struct component" }
+
+  predicate isComponentOf(StructType s, int i) {
+    exists(string name, Type tp, string tag |
+      hasComponentTypeAndTag(s, i, name, tp, tag) and
+      this = MkSomeComponent(name, tp, tag)
+    )
   }
-  
-  private class StructComponent extends MkSomeComponent {
-    string toString() { result = "struct component" }
-  
-    predicate isComponentOf(StructType s, int i) {
-      exists(string name, Type tp, string tag |
-        hasComponentTypeAndTag(s, i, name, tp, tag) and
-        this = MkSomeComponent(name, tp, tag)
-      )
-    }
+}
+
+pragma[nomagic]
+predicate unpackStructType(
+  StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
+  TOptStructComponent c3, TOptStructComponent c4, int nComponents
+) {
+  nComponents = count(int i | component_types(s, i, _, _)) and
+  (
+    if nComponents >= 1
+    then c0 = any(StructComponent sc | sc.isComponentOf(s, 0))
+    else c0 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 2
+    then c1 = any(StructComponent sc | sc.isComponentOf(s, 1))
+    else c1 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 3
+    then c2 = any(StructComponent sc | sc.isComponentOf(s, 2))
+    else c2 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 4
+    then c3 = any(StructComponent sc | sc.isComponentOf(s, 3))
+    else c3 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 5
+    then c4 = any(StructComponent sc | sc.isComponentOf(s, 4))
+    else c4 = MkNoComponent()
+  )
+}
+
+pragma[nomagic]
+predicate unpackAndUnaliasStructType(
+  StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
+  TOptStructComponent c3, TOptStructComponent c4, int nComponents
+) {
+  exists(
+    OptStructComponent c0a, OptStructComponent c1a, OptStructComponent c2a, OptStructComponent c3a,
+    OptStructComponent c4a
+  |
+    unpackStructType(s, c0a, c1a, c2a, c3a, c4a, nComponents) and
+    c0 = c0a.getWithDeepUnaliasedType() and
+    c1 = c1a.getWithDeepUnaliasedType() and
+    c2 = c2a.getWithDeepUnaliasedType() and
+    c3 = c3a.getWithDeepUnaliasedType() and
+    c4 = c4a.getWithDeepUnaliasedType()
+  )
+}
+
+/** A struct type. */
+class StructType extends @structtype, CompositeType {
+  private StructType getDeepUnaliasedTypeCandidate() {
+    exists(
+      OptStructComponent c0, OptStructComponent c1, OptStructComponent c2, OptStructComponent c3,
+      OptStructComponent c4, int nComponents
+    |
+      unpackAndUnaliasStructType(this, c0, c1, c2, c3, c4, nComponents) and
+      unpackStructType(result, c0, c1, c2, c3, c4, nComponents)
+    )
   }
-  
-  pragma[nomagic]
-  predicate unpackStructType(
-    StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
-    TOptStructComponent c3, TOptStructComponent c4, int nComponents
-  ) {
-    nComponents = count(int i | component_types(s, i, _, _)) and
-    (
-      if nComponents >= 1
-      then c0 = any(StructComponent sc | sc.isComponentOf(s, 0))
-      else c0 = MkNoComponent()
-    ) and
-    (
-      if nComponents >= 2
-      then c1 = any(StructComponent sc | sc.isComponentOf(s, 1))
-      else c1 = MkNoComponent()
-    ) and
-    (
-      if nComponents >= 3
-      then c2 = any(StructComponent sc | sc.isComponentOf(s, 2))
-      else c2 = MkNoComponent()
-    ) and
+
+  private predicate isDeepUnaliasedTypeUpTo(StructType unaliased, int i) {
+    // Note we must use component_types not hasOwnField here because component_types may specify
+    // interface-in-struct embedding, but hasOwnField does not return such members.
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 5 and
     (
-      if nComponents >= 4
-      then c3 = any(StructComponent sc | sc.isComponentOf(s, 3))
-      else c3 = MkNoComponent()
+      i = 5 or
+      this.isDeepUnaliasedTypeUpTo(unaliased, i - 1)
     ) and
-    (
-      if nComponents >= 5
-      then c4 = any(StructComponent sc | sc.isComponentOf(s, 4))
-      else c4 = MkNoComponent()
+    exists(string name, Type tp, string tag | hasComponentTypeAndTag(this, i, name, tp, tag) |
+      hasComponentTypeAndTag(unaliased, i, name, tp.getDeepUnaliasedType(), tag)
     )
   }
-  
-  pragma[nomagic]
-  predicate unpackAndUnaliasStructType(
-    StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
-    TOptStructComponent c3, TOptStructComponent c4, int nComponents
-  ) {
-    exists(
-      OptStructComponent c0a, OptStructComponent c1a, OptStructComponent c2a, OptStructComponent c3a,
-      OptStructComponent c4a
-    |
-      unpackStructType(s, c0a, c1a, c2a, c3a, c4a, nComponents) and
-      c0 = c0a.getWithDeepUnaliasedType() and
-      c1 = c1a.getWithDeepUnaliasedType() and
-      c2 = c2a.getWithDeepUnaliasedType() and
-      c3 = c3a.getWithDeepUnaliasedType() and
-      c4 = c4a.getWithDeepUnaliasedType()
+
+  override StructType getDeepUnaliasedType() {
+    result = this.getDeepUnaliasedTypeCandidate() and
+    exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
+      this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
+      or
+      nComponents <= 5
     )
   }
-  
-  /** A struct type. */
-  class StructType extends @structtype, CompositeType {
-    private StructType getDeepUnaliasedTypeCandidate() {
-      exists(
-        OptStructComponent c0, OptStructComponent c1, OptStructComponent c2, OptStructComponent c3,
-        OptStructComponent c4, int nComponents
-      |
-        unpackAndUnaliasStructType(this, c0, c1, c2, c3, c4, nComponents) and
-        unpackStructType(result, c0, c1, c2, c3, c4, nComponents)
-      )
-    }
-  
-    private predicate isDeepUnaliasedTypeUpTo(StructType unaliased, int i) {
-      // Note we must use component_types not hasOwnField here because component_types may specify
-      // interface-in-struct embedding, but hasOwnField does not return such members.
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 5 and
-      (
-        i = 5 or
-        this.isDeepUnaliasedTypeUpTo(unaliased, i - 1)
-      ) and
-      exists(string name, Type tp, string tag | hasComponentTypeAndTag(this, i, name, tp, tag) |
-        hasComponentTypeAndTag(unaliased, i, name, tp.getDeepUnaliasedType(), tag)
-      )
-    }
-  
-    override StructType getDeepUnaliasedType() {
-      result = this.getDeepUnaliasedTypeCandidate() and
-      exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
-        this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
-        or
-        nComponents <= 5
-      )
-    }
+}
+
+/** A pointer type. */
+class PointerType extends @pointertype, CompositeType {
+  /** Gets the base type of this pointer type. */
+  Type getBaseType() { base_type(this, result) }
+
+  override PointerType getDeepUnaliasedType() {
+    result.getBaseType() = this.getBaseType().getDeepUnaliasedType()
   }
-  
-  /** A pointer type. */
-  class PointerType extends @pointertype, CompositeType {
-    /** Gets the base type of this pointer type. */
-    Type getBaseType() { base_type(this, result) }
-  
-    override PointerType getDeepUnaliasedType() {
-      result.getBaseType() = this.getBaseType().getDeepUnaliasedType()
-    }
+}
+
+private predicate isInterfaceComponentWithQualifiedName(
+  InterfaceType intf, int idx, string qualifiedName, Type tp
+) {
+  exists(string name | component_types(intf, idx, name, tp) |
+    interface_private_method_ids(intf, idx, qualifiedName)
+    or
+    not interface_private_method_ids(intf, idx, _) and qualifiedName = name
+  )
+}
+
+private newtype TOptInterfaceComponent =
+  MkNoIComponent() or
+  MkSomeIComponent(string name, Type tp) {
+    isInterfaceComponentWithQualifiedName(any(InterfaceType i), _, name, tp)
   }
-  
-  private newtype TOptInterfaceComponent =
-    MkNoIComponent() or
-    MkSomeIComponent(string name, Type tp) { component_types(any(InterfaceType i), _, name, tp) }
-  
-  private class OptInterfaceComponent extends TOptInterfaceComponent {
-    OptInterfaceComponent getWithDeepUnaliasedType() {
-      this = MkNoIComponent() and result = MkNoIComponent()
-      or
-      exists(string name, Type tp |
-        this = MkSomeIComponent(name, tp) and
-        result = MkSomeIComponent(name, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    string toString() { result = "interface component" }
+
+private class OptInterfaceComponent extends TOptInterfaceComponent {
+  OptInterfaceComponent getWithDeepUnaliasedType() {
+    this = MkNoIComponent() and result = MkNoIComponent()
+    or
+    exists(string name, Type tp |
+      this = MkSomeIComponent(name, tp) and
+      result = MkSomeIComponent(name, tp.getDeepUnaliasedType())
+    )
   }
-  
-  private class InterfaceComponent extends MkSomeIComponent {
-    string toString() { result = "interface component" }
-  
-    predicate isComponentOf(InterfaceType intf, int i) {
-      exists(string name, Type tp |
-        component_types(intf, i, name, tp) and
-        this = MkSomeIComponent(name, tp)
-      )
-    }
+
+  string toString() { result = "interface component" }
+}
+
+private class InterfaceComponent extends MkSomeIComponent {
+  string toString() { result = "interface component" }
+
+  predicate isComponentOf(InterfaceType intf, int i) {
+    exists(string name, Type tp |
+      isInterfaceComponentWithQualifiedName(intf, i, name, tp) and
+      this = MkSomeIComponent(name, tp)
+    )
   }
-  
-  pragma[nomagic]
-  predicate unpackInterfaceType(
-    InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
-    TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
-    TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds
-  ) {
-    nComponents = count(int i | component_types(intf, i, _, _) and i >= 0) and
-    nEmbeds = count(int i | component_types(intf, i, _, _) and i < 0) and
-    (
-      if nComponents >= 1
-      then c0 = any(InterfaceComponent ic | ic.isComponentOf(intf, 0))
-      else c0 = MkNoIComponent()
-    ) and
-    (
-      if nComponents >= 2
-      then c1 = any(InterfaceComponent ic | ic.isComponentOf(intf, 1))
-      else c1 = MkNoIComponent()
-    ) and
+}
+
+pragma[nomagic]
+predicate unpackInterfaceType(
+  InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
+  TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
+  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds,
+  boolean isComparable
+) {
+  nComponents = count(int i | isInterfaceComponentWithQualifiedName(intf, i, _, _) and i >= 0) and
+  nEmbeds = count(int i | isInterfaceComponentWithQualifiedName(intf, i, _, _) and i < 0) and
+  (
+    if intf = any(ComparableType comparable).getBaseType()
+    then isComparable = true
+    else isComparable = false
+  ) and
+  (
+    if nComponents >= 1
+    then c0 = any(InterfaceComponent ic | ic.isComponentOf(intf, 0))
+    else c0 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 2
+    then c1 = any(InterfaceComponent ic | ic.isComponentOf(intf, 1))
+    else c1 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 3
+    then c2 = any(InterfaceComponent ic | ic.isComponentOf(intf, 2))
+    else c2 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 4
+    then c3 = any(InterfaceComponent ic | ic.isComponentOf(intf, 3))
+    else c3 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 5
+    then c4 = any(InterfaceComponent ic | ic.isComponentOf(intf, 4))
+    else c4 = MkNoIComponent()
+  ) and
+  (
+    if nEmbeds >= 1
+    then e1 = any(InterfaceComponent ic | ic.isComponentOf(intf, -1))
+    else e1 = MkNoIComponent()
+  ) and
+  (
+    if nEmbeds >= 2
+    then e2 = any(InterfaceComponent ic | ic.isComponentOf(intf, -2))
+    else e2 = MkNoIComponent()
+  )
+}
+
+pragma[nomagic]
+predicate unpackAndUnaliasInterfaceType(
+  InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
+  TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
+  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds,
+  boolean isComparable
+) {
+  exists(
+    OptInterfaceComponent c0a, OptInterfaceComponent c1a, OptInterfaceComponent c2a,
+    OptInterfaceComponent c3a, OptInterfaceComponent c4a, OptInterfaceComponent e1a,
+    OptInterfaceComponent e2a
+  |
+    unpackInterfaceType(intf, c0a, c1a, c2a, c3a, c4a, e1a, e2a, nComponents, nEmbeds, isComparable) and
+    c0 = c0a.getWithDeepUnaliasedType() and
+    c1 = c1a.getWithDeepUnaliasedType() and
+    c2 = c2a.getWithDeepUnaliasedType() and
+    c3 = c3a.getWithDeepUnaliasedType() and
+    c4 = c4a.getWithDeepUnaliasedType() and
+    e1 = e1a.getWithDeepUnaliasedType() and
+    e2 = e2a.getWithDeepUnaliasedType()
+  )
+}
+
+/** An interface type. */
+class InterfaceType extends @interfacetype, CompositeType {
+  private Type getMethodType(int i, string name) {
+    i >= 0 and isInterfaceComponentWithQualifiedName(this, i, name, result)
+  }
+
+  /**
+   * Holds if `tp` is a directly embedded type with index `index`.
+   *
+   * `tp` (or its underlying type) is either a type set literal type or an
+   * interface type.
+   */
+  private predicate hasDirectlyEmbeddedType(int index, Type tp) {
+    index >= 0 and isInterfaceComponentWithQualifiedName(this, -(index + 1), _, tp)
+  }
+
+  private InterfaceType getDeepUnaliasedTypeCandidate() {
+    exists(
+      OptInterfaceComponent c0, OptInterfaceComponent c1, OptInterfaceComponent c2,
+      OptInterfaceComponent c3, OptInterfaceComponent c4, OptInterfaceComponent e1,
+      OptInterfaceComponent e2, int nComponents, int nEmbeds, boolean isComparable
+    |
+      unpackAndUnaliasInterfaceType(this, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds,
+        isComparable) and
+      unpackInterfaceType(result, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds, isComparable)
+    )
+  }
+
+  private predicate hasDeepUnaliasedComponentTypesUpTo(InterfaceType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 5 and
     (
-      if nComponents >= 3
-      then c2 = any(InterfaceComponent ic | ic.isComponentOf(intf, 2))
-      else c2 = MkNoIComponent()
+      i = 5 or
+      this.hasDeepUnaliasedComponentTypesUpTo(unaliased, i - 1)
     ) and
+    exists(string name |
+      unaliased.getMethodType(i, name) = this.getMethodType(i, name).getDeepUnaliasedType()
+    )
+  }
+
+  private predicate hasDeepUnaliasedEmbeddedTypesUpTo(InterfaceType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 2 and
     (
-      if nComponents >= 4
-      then c3 = any(InterfaceComponent ic | ic.isComponentOf(intf, 3))
-      else c3 = MkNoIComponent()
+      i = 2 or
+      this.hasDeepUnaliasedEmbeddedTypesUpTo(unaliased, i - 1)
     ) and
-    (
-      if nComponents >= 5
-      then c4 = any(InterfaceComponent ic | ic.isComponentOf(intf, 4))
-      else c4 = MkNoIComponent()
+    exists(Type tp | this.hasDirectlyEmbeddedType(i, tp) |
+      unaliased.hasDirectlyEmbeddedType(i, tp.getDeepUnaliasedType())
+    )
+  }
+
+  override InterfaceType getDeepUnaliasedType() {
+    result = this.getDeepUnaliasedTypeCandidate() and
+    exists(int nComponents | nComponents = count(int i | exists(this.getMethodType(i, _))) |
+      this.hasDeepUnaliasedComponentTypesUpTo(result, nComponents - 1)
+      or
+      nComponents <= 5
     ) and
+    exists(int nEmbeds | nEmbeds = count(int i | this.hasDirectlyEmbeddedType(i, _)) |
+      this.hasDeepUnaliasedEmbeddedTypesUpTo(result, nEmbeds - 1)
+      or
+      nEmbeds <= 2
+    )
+  }
+}
+
+pragma[nomagic]
+private predicate unpackTupleType(
+  TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
+) {
+  nComponents = count(int i | component_types(tt, i, _, _)) and
+  (if nComponents >= 1 then c0 = MkSomeType(tt.getComponentType(0)) else c0 = MkNoType()) and
+  (if nComponents >= 2 then c1 = MkSomeType(tt.getComponentType(1)) else c1 = MkNoType()) and
+  (if nComponents >= 3 then c2 = MkSomeType(tt.getComponentType(2)) else c2 = MkNoType())
+}
+
+pragma[nomagic]
+private predicate unpackAndUnaliasTupleType(
+  TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
+) {
+  exists(OptType c0a, OptType c1a, OptType c2a |
+    unpackTupleType(tt, c0a, c1a, c2a, nComponents) and
+    c0 = c0a.getDeepUnaliasedType() and
+    c1 = c1a.getDeepUnaliasedType() and
+    c2 = c2a.getDeepUnaliasedType()
+  )
+}
+
+/** A tuple type. */
+class TupleType extends @tupletype, CompositeType {
+  /** Gets the `i`th component type of this tuple type. */
+  Type getComponentType(int i) { component_types(this, i, _, result) }
+
+  private TupleType getCandidateDeepUnaliasedType() {
+    exists(OptType c0, OptType c1, OptType c2, int nComponents |
+      unpackAndUnaliasTupleType(this, c0, c1, c2, nComponents) and
+      unpackTupleType(result, c0, c1, c2, nComponents)
+    )
+  }
+
+  private predicate isDeepUnaliasedTypeUpTo(TupleType tt, int i) {
+    tt = this.getCandidateDeepUnaliasedType() and
+    i >= 3 and
     (
-      if nEmbeds >= 1
-      then e1 = any(InterfaceComponent ic | ic.isComponentOf(intf, -1))
-      else e1 = MkNoIComponent()
+      i = 3
+      or
+      this.isDeepUnaliasedTypeUpTo(tt, i - 1)
     ) and
-    (
-      if nEmbeds >= 2
-      then e2 = any(InterfaceComponent ic | ic.isComponentOf(intf, -2))
-      else e2 = MkNoIComponent()
+    tt.getComponentType(i) = this.getComponentType(i).getDeepUnaliasedType()
+  }
+
+  override TupleType getDeepUnaliasedType() {
+    result = this.getCandidateDeepUnaliasedType() and
+    exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
+      this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
+      or
+      nComponents <= 3
     )
   }
-  
-  pragma[nomagic]
-  predicate unpackAndUnaliasInterfaceType(
-    InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
-    TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
-    TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds
-  ) {
+}
+
+// Reasonably efficiently map from a signature type to its
+// deep-unaliased equivalent, by using a single join for the leading 5 parameters
+// and/or 3 results.
+private newtype TOptType =
+  MkNoType() or
+  MkSomeType(Type tp)
+
+private class OptType extends TOptType {
+  OptType getDeepUnaliasedType() {
+    exists(Type t | this = MkSomeType(t) | result = MkSomeType(t.getDeepUnaliasedType()))
+    or
+    this = MkNoType() and result = MkNoType()
+  }
+
+  string toString() {
+    exists(Type t | this = MkSomeType(t) | result = t.toString())
+    or
+    this = MkNoType() and result = "no type"
+  }
+}
+
+pragma[nomagic]
+private predicate unpackSignatureType(
+  SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
+  int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
+) {
+  nParams = sig.getNumParameter() and
+  nResults = sig.getNumResult() and
+  (if nParams >= 1 then param0 = MkSomeType(sig.getParameterType(0)) else param0 = MkNoType()) and
+  (if nParams >= 2 then param1 = MkSomeType(sig.getParameterType(1)) else param1 = MkNoType()) and
+  (if nParams >= 3 then param2 = MkSomeType(sig.getParameterType(2)) else param2 = MkNoType()) and
+  (if nParams >= 4 then param3 = MkSomeType(sig.getParameterType(3)) else param3 = MkNoType()) and
+  (if nParams >= 5 then param4 = MkSomeType(sig.getParameterType(4)) else param4 = MkNoType()) and
+  (if nResults >= 1 then result0 = MkSomeType(sig.getResultType(0)) else result0 = MkNoType()) and
+  (if nResults >= 2 then result1 = MkSomeType(sig.getResultType(1)) else result1 = MkNoType()) and
+  (if nResults >= 3 then result2 = MkSomeType(sig.getResultType(2)) else result2 = MkNoType()) and
+  (if sig.isVariadic() then isVariadic = true else isVariadic = false)
+}
+
+pragma[nomagic]
+private predicate unpackAndUnaliasSignatureType(
+  SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
+  int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
+) {
+  exists(
+    OptType param0a, OptType param1a, OptType param2a, OptType param3a, OptType param4a,
+    OptType result0a, OptType result1a, OptType result2a
+  |
+    unpackSignatureType(sig, param0a, param1a, param2a, param3a, param4a, nParams, result0a,
+      result1a, result2a, nResults, isVariadic)
+  |
+    param0 = param0a.getDeepUnaliasedType() and
+    param1 = param1a.getDeepUnaliasedType() and
+    param2 = param2a.getDeepUnaliasedType() and
+    param3 = param3a.getDeepUnaliasedType() and
+    param4 = param4a.getDeepUnaliasedType() and
+    result0 = result0a.getDeepUnaliasedType() and
+    result1 = result1a.getDeepUnaliasedType() and
+    result2 = result2a.getDeepUnaliasedType()
+  )
+}
+
+/** A signature type. */
+class SignatureType extends @signaturetype, CompositeType {
+  /** Gets the `i`th parameter type of this signature type. */
+  Type getParameterType(int i) { i >= 0 and component_types(this, i + 1, _, result) }
+
+  /** Gets the `i`th result type of this signature type. */
+  Type getResultType(int i) { i >= 0 and component_types(this, -(i + 1), _, result) }
+
+  /** Gets the number of parameters specified by this signature. */
+  int getNumParameter() { result = count(int i | exists(this.getParameterType(i))) }
+
+  /** Gets the number of results specified by this signature. */
+  int getNumResult() { result = count(int i | exists(this.getResultType(i))) }
+
+  /** Holds if this signature type is variadic. */
+  predicate isVariadic() { variadic(this) }
+
+  private SignatureType getDeepUnaliasedTypeCandidate() {
     exists(
-      OptInterfaceComponent c0a, OptInterfaceComponent c1a, OptInterfaceComponent c2a,
-      OptInterfaceComponent c3a, OptInterfaceComponent c4a, OptInterfaceComponent e1a,
-      OptInterfaceComponent e2a
+      OptType param0, OptType param1, OptType param2, OptType param3, OptType param4, int nParams,
+      OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
     |
-      unpackInterfaceType(intf, c0a, c1a, c2a, c3a, c4a, e1a, e2a, nComponents, nEmbeds) and
-      c0 = c0a.getWithDeepUnaliasedType() and
-      c1 = c1a.getWithDeepUnaliasedType() and
-      c2 = c2a.getWithDeepUnaliasedType() and
-      c3 = c3a.getWithDeepUnaliasedType() and
-      c4 = c4a.getWithDeepUnaliasedType() and
-      e1 = e1a.getWithDeepUnaliasedType() and
-      e2 = e2a.getWithDeepUnaliasedType()
+      unpackAndUnaliasSignatureType(this, param0, param1, param2, param3, param4, nParams, result0,
+        result1, result2, nResults, isVariadic) and
+      unpackSignatureType(result, param0, param1, param2, param3, param4, nParams, result0, result1,
+        result2, nResults, isVariadic)
     )
   }
-  
-  /** An interface type. */
-  class InterfaceType extends @interfacetype, CompositeType {
-    private InterfaceType getDeepUnaliasedTypeCandidate() {
-      exists(
-        OptInterfaceComponent c0, OptInterfaceComponent c1, OptInterfaceComponent c2,
-        OptInterfaceComponent c3, OptInterfaceComponent c4, OptInterfaceComponent e1,
-        OptInterfaceComponent e2, int nComponents, int nEmbeds
-      |
-        unpackAndUnaliasInterfaceType(this, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds) and
-        unpackInterfaceType(result, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds)
-      )
-    }
-  
-    private predicate hasDeepUnaliasedComponentTypesUpTo(InterfaceType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 5 and
-      (
-        i = 5 or
-        this.hasDeepUnaliasedComponentTypesUpTo(unaliased, i - 1)
-      ) and
-      exists(string name, Type tp | component_types(this, i, name, tp) |
-        component_types(unaliased, i, name, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    private predicate hasDeepUnaliasedEmbeddedTypesUpTo(InterfaceType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 3 and
-      (
-        i = 3 or
-        this.hasDeepUnaliasedEmbeddedTypesUpTo(unaliased, i - 1)
-      ) and
-      exists(string name, Type tp | component_types(this, -i, name, tp) |
-        component_types(unaliased, -i, name, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    override InterfaceType getDeepUnaliasedType() {
-      result = this.getDeepUnaliasedTypeCandidate() and
-      exists(int nComponents |
-        nComponents = count(int i | component_types(this, i, _, _) and i >= 0)
-      |
-        this.hasDeepUnaliasedComponentTypesUpTo(result, nComponents - 1)
-        or
-        nComponents <= 5
-      ) and
-      exists(int nEmbeds | nEmbeds = count(int i | component_types(this, i, _, _) and i < 0) |
-        // Note no -1 here, because the first embedded type is at -1
-        this.hasDeepUnaliasedEmbeddedTypesUpTo(result, nEmbeds)
-        or
-        nEmbeds <= 2
-      )
-    }
-  }
-  
-  pragma[nomagic]
-  private predicate unpackTupleType(
-    TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
-  ) {
-    nComponents = count(int i | component_types(tt, i, _, _)) and
-    (if nComponents >= 1 then c0 = MkSomeType(tt.getComponentType(0)) else c0 = MkNoType()) and
-    (if nComponents >= 2 then c1 = MkSomeType(tt.getComponentType(1)) else c1 = MkNoType()) and
-    (if nComponents >= 3 then c2 = MkSomeType(tt.getComponentType(2)) else c2 = MkNoType())
+
+  // These incremental recursive implementations only apply from parameter 5 or result 3
+  // upwards to avoid constructing large squares of candidates -- the initial parameters
+  // and results are taken care of by the candidate predicate.
+  private predicate hasDeepUnaliasedParameterTypesUpTo(SignatureType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 5 and
+    (i = 5 or this.hasDeepUnaliasedParameterTypesUpTo(unaliased, i - 1)) and
+    unaliased.getParameterType(i) = this.getParameterType(i).getDeepUnaliasedType()
   }
-  
-  pragma[nomagic]
-  private predicate unpackAndUnaliasTupleType(
-    TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
-  ) {
-    exists(OptType c0a, OptType c1a, OptType c2a |
-      unpackTupleType(tt, c0a, c1a, c2a, nComponents) and
-      c0 = c0a.getDeepUnaliasedType() and
-      c1 = c1a.getDeepUnaliasedType() and
-      c2 = c2a.getDeepUnaliasedType()
-    )
+
+  private predicate hasDeepUnaliasedResultTypesUpTo(SignatureType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 3 and
+    (i = 3 or this.hasDeepUnaliasedResultTypesUpTo(unaliased, i - 1)) and
+    unaliased.getResultType(i) = this.getResultType(i).getDeepUnaliasedType()
   }
-  
-  /** A tuple type. */
-  class TupleType extends @tupletype, CompositeType {
-    /** Gets the `i`th component type of this tuple type. */
-    Type getComponentType(int i) { component_types(this, i, _, result) }
-  
-    private TupleType getCandidateDeepUnaliasedType() {
-      exists(OptType c0, OptType c1, OptType c2, int nComponents |
-        unpackAndUnaliasTupleType(this, c0, c1, c2, nComponents) and
-        unpackTupleType(result, c0, c1, c2, nComponents)
-      )
-    }
-  
-    private predicate isDeepUnaliasedTypeUpTo(TupleType tt, int i) {
-      tt = this.getCandidateDeepUnaliasedType() and
-      i >= 3 and
+
+  override SignatureType getDeepUnaliasedType() {
+    result = this.getDeepUnaliasedTypeCandidate() and
+    exists(int nParams, int nResults |
+      this.getNumParameter() = nParams and this.getNumResult() = nResults
+    |
       (
-        i = 3
+        nParams <= 5
         or
-        this.isDeepUnaliasedTypeUpTo(tt, i - 1)
+        this.hasDeepUnaliasedParameterTypesUpTo(result, nParams - 1)
       ) and
-      exists(Type tp | component_types(this, i, _, tp) |
-        component_types(tt, i, _, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    override TupleType getDeepUnaliasedType() {
-      result = this.getCandidateDeepUnaliasedType() and
-      exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
-        this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
+      (
+        nResults <= 3
         or
-        nComponents <= 3
+        this.hasDeepUnaliasedResultTypesUpTo(result, nResults - 1)
       )
-    }
-  }
-  
-  // Reasonably efficiently map from a signature type to its
-  // deep-unaliased equivalent, by using a single join for the leading 5 parameters
-  // and/or 3 results.
-  private newtype TOptType =
-    MkNoType() or
-    MkSomeType(Type tp)
-  
-  private class OptType extends TOptType {
-    OptType getDeepUnaliasedType() {
-      exists(Type t | this = MkSomeType(t) | result = MkSomeType(t.getDeepUnaliasedType()))
-      or
-      this = MkNoType() and result = MkNoType()
-    }
-  
-    string toString() {
-      exists(Type t | this = MkSomeType(t) | result = t.toString())
-      or
-      this = MkNoType() and result = "no type"
-    }
-  }
-  
-  pragma[nomagic]
-  private predicate unpackSignatureType(
-    SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
-    int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
-  ) {
-    nParams = sig.getNumParameter() and
-    nResults = sig.getNumResult() and
-    (if nParams >= 1 then param0 = MkSomeType(sig.getParameterType(0)) else param0 = MkNoType()) and
-    (if nParams >= 2 then param1 = MkSomeType(sig.getParameterType(1)) else param1 = MkNoType()) and
-    (if nParams >= 3 then param2 = MkSomeType(sig.getParameterType(2)) else param2 = MkNoType()) and
-    (if nParams >= 4 then param3 = MkSomeType(sig.getParameterType(3)) else param3 = MkNoType()) and
-    (if nParams >= 5 then param4 = MkSomeType(sig.getParameterType(4)) else param4 = MkNoType()) and
-    (if nResults >= 1 then result0 = MkSomeType(sig.getResultType(0)) else result0 = MkNoType()) and
-    (if nResults >= 2 then result1 = MkSomeType(sig.getResultType(1)) else result1 = MkNoType()) and
-    (if nResults >= 3 then result2 = MkSomeType(sig.getResultType(2)) else result2 = MkNoType()) and
-    (if sig.isVariadic() then isVariadic = true else isVariadic = false)
-  }
-  
-  pragma[nomagic]
-  private predicate unpackAndUnaliasSignatureType(
-    SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
-    int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
-  ) {
-    exists(
-      OptType param0a, OptType param1a, OptType param2a, OptType param3a, OptType param4a,
-      OptType result0a, OptType result1a, OptType result2a
-    |
-      unpackSignatureType(sig, param0a, param1a, param2a, param3a, param4a, nParams, result0a,
-        result1a, result2a, nResults, isVariadic)
-    |
-      param0 = param0a.getDeepUnaliasedType() and
-      param1 = param1a.getDeepUnaliasedType() and
-      param2 = param2a.getDeepUnaliasedType() and
-      param3 = param3a.getDeepUnaliasedType() and
-      param4 = param4a.getDeepUnaliasedType() and
-      result0 = result0a.getDeepUnaliasedType() and
-      result1 = result1a.getDeepUnaliasedType() and
-      result2 = result2a.getDeepUnaliasedType()
     )
   }
-  
-  /** A signature type. */
-  class SignatureType extends @signaturetype, CompositeType {
-    /** Gets the `i`th parameter type of this signature type. */
-    Type getParameterType(int i) { i >= 0 and component_types(this, i + 1, _, result) }
-  
-    /** Gets the `i`th result type of this signature type. */
-    Type getResultType(int i) { i >= 0 and component_types(this, -(i + 1), _, result) }
-  
-    /** Gets the number of parameters specified by this signature. */
-    int getNumParameter() { result = count(int i | exists(this.getParameterType(i))) }
-  
-    /** Gets the number of results specified by this signature. */
-    int getNumResult() { result = count(int i | exists(this.getResultType(i))) }
-  
-    /** Holds if this signature type is variadic. */
-    predicate isVariadic() { variadic(this) }
-  
-    private SignatureType getDeepUnaliasedTypeCandidate() {
-      exists(
-        OptType param0, OptType param1, OptType param2, OptType param3, OptType param4, int nParams,
-        OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
-      |
-        unpackAndUnaliasSignatureType(this, param0, param1, param2, param3, param4, nParams, result0,
-          result1, result2, nResults, isVariadic) and
-        unpackSignatureType(result, param0, param1, param2, param3, param4, nParams, result0, result1,
-          result2, nResults, isVariadic)
-      )
-    }
-  
-    // These incremental recursive implementations only apply from parameter 5 or result 3
-    // upwards to avoid constructing large squares of candidates -- the initial parameters
-    // and results are taken care of by the candidate predicate.
-    private predicate hasDeepUnaliasedParameterTypesUpTo(SignatureType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 5 and
-      (i = 5 or this.hasDeepUnaliasedParameterTypesUpTo(unaliased, i - 1)) and
-      unaliased.getParameterType(i) = this.getParameterType(i).getDeepUnaliasedType()
-    }
-  
-    private predicate hasDeepUnaliasedResultTypesUpTo(SignatureType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 3 and
-      (i = 3 or this.hasDeepUnaliasedResultTypesUpTo(unaliased, i - 1)) and
-      unaliased.getResultType(i) = this.getResultType(i).getDeepUnaliasedType()
-    }
-  
-    override SignatureType getDeepUnaliasedType() {
-      result = this.getDeepUnaliasedTypeCandidate() and
-      exists(int nParams, int nResults |
-        this.getNumParameter() = nParams and this.getNumResult() = nResults
-      |
-        (
-          nParams <= 5
-          or
-          this.hasDeepUnaliasedParameterTypesUpTo(result, nParams - 1)
-        ) and
-        (
-          nResults <= 3
-          or
-          this.hasDeepUnaliasedResultTypesUpTo(result, nResults - 1)
-        )
-      )
-    }
-  }
-  
-  /** A map type. */
-  class MapType extends @maptype, CompositeType {
-    /** Gets the key type of this map type. */
-    Type getKeyType() { key_type(this, result) }
-  
-    /** Gets the value type of this map type. */
-    Type getValueType() { element_type(this, result) }
-  
-    override MapType getDeepUnaliasedType() {
-      result.getKeyType() = this.getKeyType().getDeepUnaliasedType() and
-      result.getValueType() = this.getValueType().getDeepUnaliasedType()
-    }
-  }
-  
-  /** A channel type. */
-  class ChanType extends @chantype, CompositeType {
-    /** Gets the element type of this channel type. */
-    Type getElementType() { element_type(this, result) }
+}
+
+/** A map type. */
+class MapType extends @maptype, CompositeType {
+  /** Gets the key type of this map type. */
+  Type getKeyType() { key_type(this, result) }
+
+  /** Gets the value type of this map type. */
+  Type getValueType() { element_type(this, result) }
+
+  override MapType getDeepUnaliasedType() {
+    result.getKeyType() = this.getKeyType().getDeepUnaliasedType() and
+    result.getValueType() = this.getValueType().getDeepUnaliasedType()
   }
-  
-  /** A channel type that can only send. */
-  class SendChanType extends @sendchantype, ChanType {
-    override SendChanType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
+}
+
+/** A channel type. */
+class ChanType extends @chantype, CompositeType {
+  /** Gets the element type of this channel type. */
+  Type getElementType() { element_type(this, result) }
+}
+
+/** A channel type that can only send. */
+class SendChanType extends @sendchantype, ChanType {
+  override SendChanType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  /** A channel type that can only receive. */
-  class RecvChanType extends @recvchantype, ChanType {
-    override RecvChanType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
+}
+
+/** A channel type that can only receive. */
+class RecvChanType extends @recvchantype, ChanType {
+  override RecvChanType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  /** A channel type that can both send and receive. */
-  class SendRecvChanType extends @sendrcvchantype, ChanType {
-    override SendRecvChanType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
-  }
-  
-  /** An alias type. */
-  class AliasType extends @typealias, CompositeType {
-    /** Gets the aliased type (i.e. that appears on the RHS of the alias definition). */
-    Type getRhs() { alias_rhs(this, result) }
-  
-    override Type getDeepUnaliasedType() { result = unalias(this).getDeepUnaliasedType() }
-  }
-  
-  /**
-   * Gets the non-alias type at the end of the alias chain starting at `t`.
-   *
-   * If `t` is not an alias type then `result` is `t`.
-   */
-  Type unalias(Type t) {
-    not t instanceof AliasType and result = t
-    or
-    result = unalias(t.(AliasType).getRhs())
+}
+
+/** A channel type that can both send and receive. */
+class SendRecvChanType extends @sendrcvchantype, ChanType {
+  override SendRecvChanType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  predicate containsAliases(Type t) { t != t.getDeepUnaliasedType() }
-  // END ALIASES.QLL  
-  
-  from ArrayType at, string length
-  where array_length(at, length)
-  and not containsAliases(at)
-  select at, length
\ No newline at end of file
+}
+
+/** A named type. */
+class NamedType extends @namedtype, CompositeType {
+  Type getBaseType() { underlying_type(this, result) }
+}
+
+/**
+ * The predeclared `comparable` type.
+ */
+class ComparableType extends NamedType {
+  ComparableType() { typename(this, "comparable") }
+}
+
+/** An alias type. */
+class AliasType extends @typealias, CompositeType {
+  /** Gets the aliased type (i.e. that appears on the RHS of the alias definition). */
+  Type getRhs() { alias_rhs(this, result) }
+
+  override Type getDeepUnaliasedType() { result = unalias(this).getDeepUnaliasedType() }
+}
+
+/**
+ * Gets the non-alias type at the end of the alias chain starting at `t`.
+ *
+ * If `t` is not an alias type then `result` is `t`.
+ */
+Type unalias(Type t) {
+  not t instanceof AliasType and result = t
+  or
+  result = unalias(t.(AliasType).getRhs())
+}
+
+predicate containsAliases(Type t) { t != t.getDeepUnaliasedType() }
+// END ALIASES.QLL
+from ArrayType at, string length
+where
+  array_length(at, length) and
+  not containsAliases(at)
+select at, length
diff --git a/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/base_type.ql b/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/base_type.ql
index ca548f02a20d..5f96a8558ff1 100644
--- a/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/base_type.ql
+++ b/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/base_type.ql
@@ -2,576 +2,617 @@
 // Database scripts can't import, but this is the definitive copy of the support routines for mapping types to their unaliased equivalent. Ensure this code is in sync between aliases.qll and all copies in individual table .ql files.
 /** A Go type. */
 class Type extends @type {
-    /**
-     * Gets this type with all aliases substituted for their underlying type.
-     *
-     * Note named types are not substituted.
-     */
-    Type getDeepUnaliasedType() { result = this }
-  
-    /**
-     * Gets a basic textual representation of this type.
-     */
-    string toString() { result = "type" }
-  }
-  
-  /** A composite type, that is, not a basic type. */
-  class CompositeType extends @compositetype, Type { }
-  
-  /** An array type. */
-  class ArrayType extends @arraytype, CompositeType {
-    /** Gets the element type of this array type. */
-    Type getElementType() { element_type(this, result) }
-  
-    /** Gets the length of this array type as a string. */
-    string getLengthString() { array_length(this, result) }
-  
-    override ArrayType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType() and
-      result.getLengthString() = this.getLengthString()
-    }
+  /**
+   * Gets this type with all aliases substituted for their underlying type.
+   *
+   * Note named types are not substituted.
+   */
+  Type getDeepUnaliasedType() { result = this }
+
+  /**
+   * Gets a basic textual representation of this type.
+   */
+  string toString() { result = "type" }
+}
+
+/** A composite type, that is, not a basic type. */
+class CompositeType extends @compositetype, Type { }
+
+/** An array type. */
+class ArrayType extends @arraytype, CompositeType {
+  /** Gets the element type of this array type. */
+  Type getElementType() { element_type(this, result) }
+
+  /** Gets the length of this array type as a string. */
+  string getLengthString() { array_length(this, result) }
+
+  override ArrayType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType() and
+    result.getLengthString() = this.getLengthString()
   }
-  
-  /** A slice type. */
-  class SliceType extends @slicetype, CompositeType {
-    /** Gets the element type of this slice type. */
-    Type getElementType() { element_type(this, result) }
-  
-    override SliceType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
+}
+
+/** A slice type. */
+class SliceType extends @slicetype, CompositeType {
+  /** Gets the element type of this slice type. */
+  Type getElementType() { element_type(this, result) }
+
+  override SliceType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  // Improve efficiency of matching a struct to its unaliased equivalent
-  // by unpacking the first 5 fields and tags, allowing a single join
-  // to strongly constrain the available candidates.
-  private predicate hasComponentTypeAndTag(StructType s, int i, string name, Type tp, string tag) {
-    component_types(s, i, name, tp) and component_tags(s, i, tag)
+}
+
+// Improve efficiency of matching a struct to its unaliased equivalent
+// by unpacking the first 5 fields and tags, allowing a single join
+// to strongly constrain the available candidates.
+private predicate hasComponentTypeAndTag(StructType s, int i, string name, Type tp, string tag) {
+  component_types(s, i, name, tp) and component_tags(s, i, tag)
+}
+
+private newtype TOptStructComponent =
+  MkNoComponent() or
+  MkSomeComponent(string name, Type tp, string tag) { hasComponentTypeAndTag(_, _, name, tp, tag) }
+
+private class OptStructComponent extends TOptStructComponent {
+  OptStructComponent getWithDeepUnaliasedType() {
+    this = MkNoComponent() and result = MkNoComponent()
+    or
+    exists(string name, Type tp, string tag |
+      this = MkSomeComponent(name, tp, tag) and
+      result = MkSomeComponent(name, tp.getDeepUnaliasedType(), tag)
+    )
   }
-  
-  private newtype TOptStructComponent =
-    MkNoComponent() or
-    MkSomeComponent(string name, Type tp, string tag) { hasComponentTypeAndTag(_, _, name, tp, tag) }
-  
-  private class OptStructComponent extends TOptStructComponent {
-    OptStructComponent getWithDeepUnaliasedType() {
-      this = MkNoComponent() and result = MkNoComponent()
-      or
-      exists(string name, Type tp, string tag |
-        this = MkSomeComponent(name, tp, tag) and
-        result = MkSomeComponent(name, tp.getDeepUnaliasedType(), tag)
-      )
-    }
-  
-    string toString() { result = "struct component" }
+
+  string toString() { result = "struct component" }
+}
+
+private class StructComponent extends MkSomeComponent {
+  string toString() { result = "struct component" }
+
+  predicate isComponentOf(StructType s, int i) {
+    exists(string name, Type tp, string tag |
+      hasComponentTypeAndTag(s, i, name, tp, tag) and
+      this = MkSomeComponent(name, tp, tag)
+    )
   }
-  
-  private class StructComponent extends MkSomeComponent {
-    string toString() { result = "struct component" }
-  
-    predicate isComponentOf(StructType s, int i) {
-      exists(string name, Type tp, string tag |
-        hasComponentTypeAndTag(s, i, name, tp, tag) and
-        this = MkSomeComponent(name, tp, tag)
-      )
-    }
+}
+
+pragma[nomagic]
+predicate unpackStructType(
+  StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
+  TOptStructComponent c3, TOptStructComponent c4, int nComponents
+) {
+  nComponents = count(int i | component_types(s, i, _, _)) and
+  (
+    if nComponents >= 1
+    then c0 = any(StructComponent sc | sc.isComponentOf(s, 0))
+    else c0 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 2
+    then c1 = any(StructComponent sc | sc.isComponentOf(s, 1))
+    else c1 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 3
+    then c2 = any(StructComponent sc | sc.isComponentOf(s, 2))
+    else c2 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 4
+    then c3 = any(StructComponent sc | sc.isComponentOf(s, 3))
+    else c3 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 5
+    then c4 = any(StructComponent sc | sc.isComponentOf(s, 4))
+    else c4 = MkNoComponent()
+  )
+}
+
+pragma[nomagic]
+predicate unpackAndUnaliasStructType(
+  StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
+  TOptStructComponent c3, TOptStructComponent c4, int nComponents
+) {
+  exists(
+    OptStructComponent c0a, OptStructComponent c1a, OptStructComponent c2a, OptStructComponent c3a,
+    OptStructComponent c4a
+  |
+    unpackStructType(s, c0a, c1a, c2a, c3a, c4a, nComponents) and
+    c0 = c0a.getWithDeepUnaliasedType() and
+    c1 = c1a.getWithDeepUnaliasedType() and
+    c2 = c2a.getWithDeepUnaliasedType() and
+    c3 = c3a.getWithDeepUnaliasedType() and
+    c4 = c4a.getWithDeepUnaliasedType()
+  )
+}
+
+/** A struct type. */
+class StructType extends @structtype, CompositeType {
+  private StructType getDeepUnaliasedTypeCandidate() {
+    exists(
+      OptStructComponent c0, OptStructComponent c1, OptStructComponent c2, OptStructComponent c3,
+      OptStructComponent c4, int nComponents
+    |
+      unpackAndUnaliasStructType(this, c0, c1, c2, c3, c4, nComponents) and
+      unpackStructType(result, c0, c1, c2, c3, c4, nComponents)
+    )
   }
-  
-  pragma[nomagic]
-  predicate unpackStructType(
-    StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
-    TOptStructComponent c3, TOptStructComponent c4, int nComponents
-  ) {
-    nComponents = count(int i | component_types(s, i, _, _)) and
-    (
-      if nComponents >= 1
-      then c0 = any(StructComponent sc | sc.isComponentOf(s, 0))
-      else c0 = MkNoComponent()
-    ) and
-    (
-      if nComponents >= 2
-      then c1 = any(StructComponent sc | sc.isComponentOf(s, 1))
-      else c1 = MkNoComponent()
-    ) and
-    (
-      if nComponents >= 3
-      then c2 = any(StructComponent sc | sc.isComponentOf(s, 2))
-      else c2 = MkNoComponent()
-    ) and
+
+  private predicate isDeepUnaliasedTypeUpTo(StructType unaliased, int i) {
+    // Note we must use component_types not hasOwnField here because component_types may specify
+    // interface-in-struct embedding, but hasOwnField does not return such members.
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 5 and
     (
-      if nComponents >= 4
-      then c3 = any(StructComponent sc | sc.isComponentOf(s, 3))
-      else c3 = MkNoComponent()
+      i = 5 or
+      this.isDeepUnaliasedTypeUpTo(unaliased, i - 1)
     ) and
-    (
-      if nComponents >= 5
-      then c4 = any(StructComponent sc | sc.isComponentOf(s, 4))
-      else c4 = MkNoComponent()
+    exists(string name, Type tp, string tag | hasComponentTypeAndTag(this, i, name, tp, tag) |
+      hasComponentTypeAndTag(unaliased, i, name, tp.getDeepUnaliasedType(), tag)
     )
   }
-  
-  pragma[nomagic]
-  predicate unpackAndUnaliasStructType(
-    StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
-    TOptStructComponent c3, TOptStructComponent c4, int nComponents
-  ) {
-    exists(
-      OptStructComponent c0a, OptStructComponent c1a, OptStructComponent c2a, OptStructComponent c3a,
-      OptStructComponent c4a
-    |
-      unpackStructType(s, c0a, c1a, c2a, c3a, c4a, nComponents) and
-      c0 = c0a.getWithDeepUnaliasedType() and
-      c1 = c1a.getWithDeepUnaliasedType() and
-      c2 = c2a.getWithDeepUnaliasedType() and
-      c3 = c3a.getWithDeepUnaliasedType() and
-      c4 = c4a.getWithDeepUnaliasedType()
+
+  override StructType getDeepUnaliasedType() {
+    result = this.getDeepUnaliasedTypeCandidate() and
+    exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
+      this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
+      or
+      nComponents <= 5
     )
   }
-  
-  /** A struct type. */
-  class StructType extends @structtype, CompositeType {
-    private StructType getDeepUnaliasedTypeCandidate() {
-      exists(
-        OptStructComponent c0, OptStructComponent c1, OptStructComponent c2, OptStructComponent c3,
-        OptStructComponent c4, int nComponents
-      |
-        unpackAndUnaliasStructType(this, c0, c1, c2, c3, c4, nComponents) and
-        unpackStructType(result, c0, c1, c2, c3, c4, nComponents)
-      )
-    }
-  
-    private predicate isDeepUnaliasedTypeUpTo(StructType unaliased, int i) {
-      // Note we must use component_types not hasOwnField here because component_types may specify
-      // interface-in-struct embedding, but hasOwnField does not return such members.
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 5 and
-      (
-        i = 5 or
-        this.isDeepUnaliasedTypeUpTo(unaliased, i - 1)
-      ) and
-      exists(string name, Type tp, string tag | hasComponentTypeAndTag(this, i, name, tp, tag) |
-        hasComponentTypeAndTag(unaliased, i, name, tp.getDeepUnaliasedType(), tag)
-      )
-    }
-  
-    override StructType getDeepUnaliasedType() {
-      result = this.getDeepUnaliasedTypeCandidate() and
-      exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
-        this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
-        or
-        nComponents <= 5
-      )
-    }
+}
+
+/** A pointer type. */
+class PointerType extends @pointertype, CompositeType {
+  /** Gets the base type of this pointer type. */
+  Type getBaseType() { base_type(this, result) }
+
+  override PointerType getDeepUnaliasedType() {
+    result.getBaseType() = this.getBaseType().getDeepUnaliasedType()
   }
-  
-  /** A pointer type. */
-  class PointerType extends @pointertype, CompositeType {
-    /** Gets the base type of this pointer type. */
-    Type getBaseType() { base_type(this, result) }
-  
-    override PointerType getDeepUnaliasedType() {
-      result.getBaseType() = this.getBaseType().getDeepUnaliasedType()
-    }
+}
+
+private predicate isInterfaceComponentWithQualifiedName(
+  InterfaceType intf, int idx, string qualifiedName, Type tp
+) {
+  exists(string name | component_types(intf, idx, name, tp) |
+    interface_private_method_ids(intf, idx, qualifiedName)
+    or
+    not interface_private_method_ids(intf, idx, _) and qualifiedName = name
+  )
+}
+
+private newtype TOptInterfaceComponent =
+  MkNoIComponent() or
+  MkSomeIComponent(string name, Type tp) {
+    isInterfaceComponentWithQualifiedName(any(InterfaceType i), _, name, tp)
   }
-  
-  private newtype TOptInterfaceComponent =
-    MkNoIComponent() or
-    MkSomeIComponent(string name, Type tp) { component_types(any(InterfaceType i), _, name, tp) }
-  
-  private class OptInterfaceComponent extends TOptInterfaceComponent {
-    OptInterfaceComponent getWithDeepUnaliasedType() {
-      this = MkNoIComponent() and result = MkNoIComponent()
-      or
-      exists(string name, Type tp |
-        this = MkSomeIComponent(name, tp) and
-        result = MkSomeIComponent(name, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    string toString() { result = "interface component" }
+
+private class OptInterfaceComponent extends TOptInterfaceComponent {
+  OptInterfaceComponent getWithDeepUnaliasedType() {
+    this = MkNoIComponent() and result = MkNoIComponent()
+    or
+    exists(string name, Type tp |
+      this = MkSomeIComponent(name, tp) and
+      result = MkSomeIComponent(name, tp.getDeepUnaliasedType())
+    )
   }
-  
-  private class InterfaceComponent extends MkSomeIComponent {
-    string toString() { result = "interface component" }
-  
-    predicate isComponentOf(InterfaceType intf, int i) {
-      exists(string name, Type tp |
-        component_types(intf, i, name, tp) and
-        this = MkSomeIComponent(name, tp)
-      )
-    }
+
+  string toString() { result = "interface component" }
+}
+
+private class InterfaceComponent extends MkSomeIComponent {
+  string toString() { result = "interface component" }
+
+  predicate isComponentOf(InterfaceType intf, int i) {
+    exists(string name, Type tp |
+      isInterfaceComponentWithQualifiedName(intf, i, name, tp) and
+      this = MkSomeIComponent(name, tp)
+    )
   }
-  
-  pragma[nomagic]
-  predicate unpackInterfaceType(
-    InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
-    TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
-    TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds
-  ) {
-    nComponents = count(int i | component_types(intf, i, _, _) and i >= 0) and
-    nEmbeds = count(int i | component_types(intf, i, _, _) and i < 0) and
-    (
-      if nComponents >= 1
-      then c0 = any(InterfaceComponent ic | ic.isComponentOf(intf, 0))
-      else c0 = MkNoIComponent()
-    ) and
-    (
-      if nComponents >= 2
-      then c1 = any(InterfaceComponent ic | ic.isComponentOf(intf, 1))
-      else c1 = MkNoIComponent()
-    ) and
+}
+
+pragma[nomagic]
+predicate unpackInterfaceType(
+  InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
+  TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
+  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds,
+  boolean isComparable
+) {
+  nComponents = count(int i | isInterfaceComponentWithQualifiedName(intf, i, _, _) and i >= 0) and
+  nEmbeds = count(int i | isInterfaceComponentWithQualifiedName(intf, i, _, _) and i < 0) and
+  (
+    if intf = any(ComparableType comparable).getBaseType()
+    then isComparable = true
+    else isComparable = false
+  ) and
+  (
+    if nComponents >= 1
+    then c0 = any(InterfaceComponent ic | ic.isComponentOf(intf, 0))
+    else c0 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 2
+    then c1 = any(InterfaceComponent ic | ic.isComponentOf(intf, 1))
+    else c1 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 3
+    then c2 = any(InterfaceComponent ic | ic.isComponentOf(intf, 2))
+    else c2 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 4
+    then c3 = any(InterfaceComponent ic | ic.isComponentOf(intf, 3))
+    else c3 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 5
+    then c4 = any(InterfaceComponent ic | ic.isComponentOf(intf, 4))
+    else c4 = MkNoIComponent()
+  ) and
+  (
+    if nEmbeds >= 1
+    then e1 = any(InterfaceComponent ic | ic.isComponentOf(intf, -1))
+    else e1 = MkNoIComponent()
+  ) and
+  (
+    if nEmbeds >= 2
+    then e2 = any(InterfaceComponent ic | ic.isComponentOf(intf, -2))
+    else e2 = MkNoIComponent()
+  )
+}
+
+pragma[nomagic]
+predicate unpackAndUnaliasInterfaceType(
+  InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
+  TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
+  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds,
+  boolean isComparable
+) {
+  exists(
+    OptInterfaceComponent c0a, OptInterfaceComponent c1a, OptInterfaceComponent c2a,
+    OptInterfaceComponent c3a, OptInterfaceComponent c4a, OptInterfaceComponent e1a,
+    OptInterfaceComponent e2a
+  |
+    unpackInterfaceType(intf, c0a, c1a, c2a, c3a, c4a, e1a, e2a, nComponents, nEmbeds, isComparable) and
+    c0 = c0a.getWithDeepUnaliasedType() and
+    c1 = c1a.getWithDeepUnaliasedType() and
+    c2 = c2a.getWithDeepUnaliasedType() and
+    c3 = c3a.getWithDeepUnaliasedType() and
+    c4 = c4a.getWithDeepUnaliasedType() and
+    e1 = e1a.getWithDeepUnaliasedType() and
+    e2 = e2a.getWithDeepUnaliasedType()
+  )
+}
+
+/** An interface type. */
+class InterfaceType extends @interfacetype, CompositeType {
+  private Type getMethodType(int i, string name) {
+    i >= 0 and isInterfaceComponentWithQualifiedName(this, i, name, result)
+  }
+
+  /**
+   * Holds if `tp` is a directly embedded type with index `index`.
+   *
+   * `tp` (or its underlying type) is either a type set literal type or an
+   * interface type.
+   */
+  private predicate hasDirectlyEmbeddedType(int index, Type tp) {
+    index >= 0 and isInterfaceComponentWithQualifiedName(this, -(index + 1), _, tp)
+  }
+
+  private InterfaceType getDeepUnaliasedTypeCandidate() {
+    exists(
+      OptInterfaceComponent c0, OptInterfaceComponent c1, OptInterfaceComponent c2,
+      OptInterfaceComponent c3, OptInterfaceComponent c4, OptInterfaceComponent e1,
+      OptInterfaceComponent e2, int nComponents, int nEmbeds, boolean isComparable
+    |
+      unpackAndUnaliasInterfaceType(this, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds,
+        isComparable) and
+      unpackInterfaceType(result, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds, isComparable)
+    )
+  }
+
+  private predicate hasDeepUnaliasedComponentTypesUpTo(InterfaceType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 5 and
     (
-      if nComponents >= 3
-      then c2 = any(InterfaceComponent ic | ic.isComponentOf(intf, 2))
-      else c2 = MkNoIComponent()
+      i = 5 or
+      this.hasDeepUnaliasedComponentTypesUpTo(unaliased, i - 1)
     ) and
+    exists(string name |
+      unaliased.getMethodType(i, name) = this.getMethodType(i, name).getDeepUnaliasedType()
+    )
+  }
+
+  private predicate hasDeepUnaliasedEmbeddedTypesUpTo(InterfaceType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 2 and
     (
-      if nComponents >= 4
-      then c3 = any(InterfaceComponent ic | ic.isComponentOf(intf, 3))
-      else c3 = MkNoIComponent()
+      i = 2 or
+      this.hasDeepUnaliasedEmbeddedTypesUpTo(unaliased, i - 1)
     ) and
-    (
-      if nComponents >= 5
-      then c4 = any(InterfaceComponent ic | ic.isComponentOf(intf, 4))
-      else c4 = MkNoIComponent()
+    exists(Type tp | this.hasDirectlyEmbeddedType(i, tp) |
+      unaliased.hasDirectlyEmbeddedType(i, tp.getDeepUnaliasedType())
+    )
+  }
+
+  override InterfaceType getDeepUnaliasedType() {
+    result = this.getDeepUnaliasedTypeCandidate() and
+    exists(int nComponents | nComponents = count(int i | exists(this.getMethodType(i, _))) |
+      this.hasDeepUnaliasedComponentTypesUpTo(result, nComponents - 1)
+      or
+      nComponents <= 5
     ) and
+    exists(int nEmbeds | nEmbeds = count(int i | this.hasDirectlyEmbeddedType(i, _)) |
+      this.hasDeepUnaliasedEmbeddedTypesUpTo(result, nEmbeds - 1)
+      or
+      nEmbeds <= 2
+    )
+  }
+}
+
+pragma[nomagic]
+private predicate unpackTupleType(
+  TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
+) {
+  nComponents = count(int i | component_types(tt, i, _, _)) and
+  (if nComponents >= 1 then c0 = MkSomeType(tt.getComponentType(0)) else c0 = MkNoType()) and
+  (if nComponents >= 2 then c1 = MkSomeType(tt.getComponentType(1)) else c1 = MkNoType()) and
+  (if nComponents >= 3 then c2 = MkSomeType(tt.getComponentType(2)) else c2 = MkNoType())
+}
+
+pragma[nomagic]
+private predicate unpackAndUnaliasTupleType(
+  TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
+) {
+  exists(OptType c0a, OptType c1a, OptType c2a |
+    unpackTupleType(tt, c0a, c1a, c2a, nComponents) and
+    c0 = c0a.getDeepUnaliasedType() and
+    c1 = c1a.getDeepUnaliasedType() and
+    c2 = c2a.getDeepUnaliasedType()
+  )
+}
+
+/** A tuple type. */
+class TupleType extends @tupletype, CompositeType {
+  /** Gets the `i`th component type of this tuple type. */
+  Type getComponentType(int i) { component_types(this, i, _, result) }
+
+  private TupleType getCandidateDeepUnaliasedType() {
+    exists(OptType c0, OptType c1, OptType c2, int nComponents |
+      unpackAndUnaliasTupleType(this, c0, c1, c2, nComponents) and
+      unpackTupleType(result, c0, c1, c2, nComponents)
+    )
+  }
+
+  private predicate isDeepUnaliasedTypeUpTo(TupleType tt, int i) {
+    tt = this.getCandidateDeepUnaliasedType() and
+    i >= 3 and
     (
-      if nEmbeds >= 1
-      then e1 = any(InterfaceComponent ic | ic.isComponentOf(intf, -1))
-      else e1 = MkNoIComponent()
+      i = 3
+      or
+      this.isDeepUnaliasedTypeUpTo(tt, i - 1)
     ) and
-    (
-      if nEmbeds >= 2
-      then e2 = any(InterfaceComponent ic | ic.isComponentOf(intf, -2))
-      else e2 = MkNoIComponent()
+    tt.getComponentType(i) = this.getComponentType(i).getDeepUnaliasedType()
+  }
+
+  override TupleType getDeepUnaliasedType() {
+    result = this.getCandidateDeepUnaliasedType() and
+    exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
+      this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
+      or
+      nComponents <= 3
     )
   }
-  
-  pragma[nomagic]
-  predicate unpackAndUnaliasInterfaceType(
-    InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
-    TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
-    TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds
-  ) {
+}
+
+// Reasonably efficiently map from a signature type to its
+// deep-unaliased equivalent, by using a single join for the leading 5 parameters
+// and/or 3 results.
+private newtype TOptType =
+  MkNoType() or
+  MkSomeType(Type tp)
+
+private class OptType extends TOptType {
+  OptType getDeepUnaliasedType() {
+    exists(Type t | this = MkSomeType(t) | result = MkSomeType(t.getDeepUnaliasedType()))
+    or
+    this = MkNoType() and result = MkNoType()
+  }
+
+  string toString() {
+    exists(Type t | this = MkSomeType(t) | result = t.toString())
+    or
+    this = MkNoType() and result = "no type"
+  }
+}
+
+pragma[nomagic]
+private predicate unpackSignatureType(
+  SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
+  int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
+) {
+  nParams = sig.getNumParameter() and
+  nResults = sig.getNumResult() and
+  (if nParams >= 1 then param0 = MkSomeType(sig.getParameterType(0)) else param0 = MkNoType()) and
+  (if nParams >= 2 then param1 = MkSomeType(sig.getParameterType(1)) else param1 = MkNoType()) and
+  (if nParams >= 3 then param2 = MkSomeType(sig.getParameterType(2)) else param2 = MkNoType()) and
+  (if nParams >= 4 then param3 = MkSomeType(sig.getParameterType(3)) else param3 = MkNoType()) and
+  (if nParams >= 5 then param4 = MkSomeType(sig.getParameterType(4)) else param4 = MkNoType()) and
+  (if nResults >= 1 then result0 = MkSomeType(sig.getResultType(0)) else result0 = MkNoType()) and
+  (if nResults >= 2 then result1 = MkSomeType(sig.getResultType(1)) else result1 = MkNoType()) and
+  (if nResults >= 3 then result2 = MkSomeType(sig.getResultType(2)) else result2 = MkNoType()) and
+  (if sig.isVariadic() then isVariadic = true else isVariadic = false)
+}
+
+pragma[nomagic]
+private predicate unpackAndUnaliasSignatureType(
+  SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
+  int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
+) {
+  exists(
+    OptType param0a, OptType param1a, OptType param2a, OptType param3a, OptType param4a,
+    OptType result0a, OptType result1a, OptType result2a
+  |
+    unpackSignatureType(sig, param0a, param1a, param2a, param3a, param4a, nParams, result0a,
+      result1a, result2a, nResults, isVariadic)
+  |
+    param0 = param0a.getDeepUnaliasedType() and
+    param1 = param1a.getDeepUnaliasedType() and
+    param2 = param2a.getDeepUnaliasedType() and
+    param3 = param3a.getDeepUnaliasedType() and
+    param4 = param4a.getDeepUnaliasedType() and
+    result0 = result0a.getDeepUnaliasedType() and
+    result1 = result1a.getDeepUnaliasedType() and
+    result2 = result2a.getDeepUnaliasedType()
+  )
+}
+
+/** A signature type. */
+class SignatureType extends @signaturetype, CompositeType {
+  /** Gets the `i`th parameter type of this signature type. */
+  Type getParameterType(int i) { i >= 0 and component_types(this, i + 1, _, result) }
+
+  /** Gets the `i`th result type of this signature type. */
+  Type getResultType(int i) { i >= 0 and component_types(this, -(i + 1), _, result) }
+
+  /** Gets the number of parameters specified by this signature. */
+  int getNumParameter() { result = count(int i | exists(this.getParameterType(i))) }
+
+  /** Gets the number of results specified by this signature. */
+  int getNumResult() { result = count(int i | exists(this.getResultType(i))) }
+
+  /** Holds if this signature type is variadic. */
+  predicate isVariadic() { variadic(this) }
+
+  private SignatureType getDeepUnaliasedTypeCandidate() {
     exists(
-      OptInterfaceComponent c0a, OptInterfaceComponent c1a, OptInterfaceComponent c2a,
-      OptInterfaceComponent c3a, OptInterfaceComponent c4a, OptInterfaceComponent e1a,
-      OptInterfaceComponent e2a
+      OptType param0, OptType param1, OptType param2, OptType param3, OptType param4, int nParams,
+      OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
     |
-      unpackInterfaceType(intf, c0a, c1a, c2a, c3a, c4a, e1a, e2a, nComponents, nEmbeds) and
-      c0 = c0a.getWithDeepUnaliasedType() and
-      c1 = c1a.getWithDeepUnaliasedType() and
-      c2 = c2a.getWithDeepUnaliasedType() and
-      c3 = c3a.getWithDeepUnaliasedType() and
-      c4 = c4a.getWithDeepUnaliasedType() and
-      e1 = e1a.getWithDeepUnaliasedType() and
-      e2 = e2a.getWithDeepUnaliasedType()
+      unpackAndUnaliasSignatureType(this, param0, param1, param2, param3, param4, nParams, result0,
+        result1, result2, nResults, isVariadic) and
+      unpackSignatureType(result, param0, param1, param2, param3, param4, nParams, result0, result1,
+        result2, nResults, isVariadic)
     )
   }
-  
-  /** An interface type. */
-  class InterfaceType extends @interfacetype, CompositeType {
-    private InterfaceType getDeepUnaliasedTypeCandidate() {
-      exists(
-        OptInterfaceComponent c0, OptInterfaceComponent c1, OptInterfaceComponent c2,
-        OptInterfaceComponent c3, OptInterfaceComponent c4, OptInterfaceComponent e1,
-        OptInterfaceComponent e2, int nComponents, int nEmbeds
-      |
-        unpackAndUnaliasInterfaceType(this, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds) and
-        unpackInterfaceType(result, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds)
-      )
-    }
-  
-    private predicate hasDeepUnaliasedComponentTypesUpTo(InterfaceType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 5 and
-      (
-        i = 5 or
-        this.hasDeepUnaliasedComponentTypesUpTo(unaliased, i - 1)
-      ) and
-      exists(string name, Type tp | component_types(this, i, name, tp) |
-        component_types(unaliased, i, name, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    private predicate hasDeepUnaliasedEmbeddedTypesUpTo(InterfaceType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 3 and
-      (
-        i = 3 or
-        this.hasDeepUnaliasedEmbeddedTypesUpTo(unaliased, i - 1)
-      ) and
-      exists(string name, Type tp | component_types(this, -i, name, tp) |
-        component_types(unaliased, -i, name, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    override InterfaceType getDeepUnaliasedType() {
-      result = this.getDeepUnaliasedTypeCandidate() and
-      exists(int nComponents |
-        nComponents = count(int i | component_types(this, i, _, _) and i >= 0)
-      |
-        this.hasDeepUnaliasedComponentTypesUpTo(result, nComponents - 1)
-        or
-        nComponents <= 5
-      ) and
-      exists(int nEmbeds | nEmbeds = count(int i | component_types(this, i, _, _) and i < 0) |
-        // Note no -1 here, because the first embedded type is at -1
-        this.hasDeepUnaliasedEmbeddedTypesUpTo(result, nEmbeds)
-        or
-        nEmbeds <= 2
-      )
-    }
-  }
-  
-  pragma[nomagic]
-  private predicate unpackTupleType(
-    TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
-  ) {
-    nComponents = count(int i | component_types(tt, i, _, _)) and
-    (if nComponents >= 1 then c0 = MkSomeType(tt.getComponentType(0)) else c0 = MkNoType()) and
-    (if nComponents >= 2 then c1 = MkSomeType(tt.getComponentType(1)) else c1 = MkNoType()) and
-    (if nComponents >= 3 then c2 = MkSomeType(tt.getComponentType(2)) else c2 = MkNoType())
+
+  // These incremental recursive implementations only apply from parameter 5 or result 3
+  // upwards to avoid constructing large squares of candidates -- the initial parameters
+  // and results are taken care of by the candidate predicate.
+  private predicate hasDeepUnaliasedParameterTypesUpTo(SignatureType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 5 and
+    (i = 5 or this.hasDeepUnaliasedParameterTypesUpTo(unaliased, i - 1)) and
+    unaliased.getParameterType(i) = this.getParameterType(i).getDeepUnaliasedType()
   }
-  
-  pragma[nomagic]
-  private predicate unpackAndUnaliasTupleType(
-    TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
-  ) {
-    exists(OptType c0a, OptType c1a, OptType c2a |
-      unpackTupleType(tt, c0a, c1a, c2a, nComponents) and
-      c0 = c0a.getDeepUnaliasedType() and
-      c1 = c1a.getDeepUnaliasedType() and
-      c2 = c2a.getDeepUnaliasedType()
-    )
+
+  private predicate hasDeepUnaliasedResultTypesUpTo(SignatureType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 3 and
+    (i = 3 or this.hasDeepUnaliasedResultTypesUpTo(unaliased, i - 1)) and
+    unaliased.getResultType(i) = this.getResultType(i).getDeepUnaliasedType()
   }
-  
-  /** A tuple type. */
-  class TupleType extends @tupletype, CompositeType {
-    /** Gets the `i`th component type of this tuple type. */
-    Type getComponentType(int i) { component_types(this, i, _, result) }
-  
-    private TupleType getCandidateDeepUnaliasedType() {
-      exists(OptType c0, OptType c1, OptType c2, int nComponents |
-        unpackAndUnaliasTupleType(this, c0, c1, c2, nComponents) and
-        unpackTupleType(result, c0, c1, c2, nComponents)
-      )
-    }
-  
-    private predicate isDeepUnaliasedTypeUpTo(TupleType tt, int i) {
-      tt = this.getCandidateDeepUnaliasedType() and
-      i >= 3 and
+
+  override SignatureType getDeepUnaliasedType() {
+    result = this.getDeepUnaliasedTypeCandidate() and
+    exists(int nParams, int nResults |
+      this.getNumParameter() = nParams and this.getNumResult() = nResults
+    |
       (
-        i = 3
+        nParams <= 5
         or
-        this.isDeepUnaliasedTypeUpTo(tt, i - 1)
+        this.hasDeepUnaliasedParameterTypesUpTo(result, nParams - 1)
       ) and
-      exists(Type tp | component_types(this, i, _, tp) |
-        component_types(tt, i, _, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    override TupleType getDeepUnaliasedType() {
-      result = this.getCandidateDeepUnaliasedType() and
-      exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
-        this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
+      (
+        nResults <= 3
         or
-        nComponents <= 3
+        this.hasDeepUnaliasedResultTypesUpTo(result, nResults - 1)
       )
-    }
-  }
-  
-  // Reasonably efficiently map from a signature type to its
-  // deep-unaliased equivalent, by using a single join for the leading 5 parameters
-  // and/or 3 results.
-  private newtype TOptType =
-    MkNoType() or
-    MkSomeType(Type tp)
-  
-  private class OptType extends TOptType {
-    OptType getDeepUnaliasedType() {
-      exists(Type t | this = MkSomeType(t) | result = MkSomeType(t.getDeepUnaliasedType()))
-      or
-      this = MkNoType() and result = MkNoType()
-    }
-  
-    string toString() {
-      exists(Type t | this = MkSomeType(t) | result = t.toString())
-      or
-      this = MkNoType() and result = "no type"
-    }
-  }
-  
-  pragma[nomagic]
-  private predicate unpackSignatureType(
-    SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
-    int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
-  ) {
-    nParams = sig.getNumParameter() and
-    nResults = sig.getNumResult() and
-    (if nParams >= 1 then param0 = MkSomeType(sig.getParameterType(0)) else param0 = MkNoType()) and
-    (if nParams >= 2 then param1 = MkSomeType(sig.getParameterType(1)) else param1 = MkNoType()) and
-    (if nParams >= 3 then param2 = MkSomeType(sig.getParameterType(2)) else param2 = MkNoType()) and
-    (if nParams >= 4 then param3 = MkSomeType(sig.getParameterType(3)) else param3 = MkNoType()) and
-    (if nParams >= 5 then param4 = MkSomeType(sig.getParameterType(4)) else param4 = MkNoType()) and
-    (if nResults >= 1 then result0 = MkSomeType(sig.getResultType(0)) else result0 = MkNoType()) and
-    (if nResults >= 2 then result1 = MkSomeType(sig.getResultType(1)) else result1 = MkNoType()) and
-    (if nResults >= 3 then result2 = MkSomeType(sig.getResultType(2)) else result2 = MkNoType()) and
-    (if sig.isVariadic() then isVariadic = true else isVariadic = false)
-  }
-  
-  pragma[nomagic]
-  private predicate unpackAndUnaliasSignatureType(
-    SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
-    int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
-  ) {
-    exists(
-      OptType param0a, OptType param1a, OptType param2a, OptType param3a, OptType param4a,
-      OptType result0a, OptType result1a, OptType result2a
-    |
-      unpackSignatureType(sig, param0a, param1a, param2a, param3a, param4a, nParams, result0a,
-        result1a, result2a, nResults, isVariadic)
-    |
-      param0 = param0a.getDeepUnaliasedType() and
-      param1 = param1a.getDeepUnaliasedType() and
-      param2 = param2a.getDeepUnaliasedType() and
-      param3 = param3a.getDeepUnaliasedType() and
-      param4 = param4a.getDeepUnaliasedType() and
-      result0 = result0a.getDeepUnaliasedType() and
-      result1 = result1a.getDeepUnaliasedType() and
-      result2 = result2a.getDeepUnaliasedType()
     )
   }
-  
-  /** A signature type. */
-  class SignatureType extends @signaturetype, CompositeType {
-    /** Gets the `i`th parameter type of this signature type. */
-    Type getParameterType(int i) { i >= 0 and component_types(this, i + 1, _, result) }
-  
-    /** Gets the `i`th result type of this signature type. */
-    Type getResultType(int i) { i >= 0 and component_types(this, -(i + 1), _, result) }
-  
-    /** Gets the number of parameters specified by this signature. */
-    int getNumParameter() { result = count(int i | exists(this.getParameterType(i))) }
-  
-    /** Gets the number of results specified by this signature. */
-    int getNumResult() { result = count(int i | exists(this.getResultType(i))) }
-  
-    /** Holds if this signature type is variadic. */
-    predicate isVariadic() { variadic(this) }
-  
-    private SignatureType getDeepUnaliasedTypeCandidate() {
-      exists(
-        OptType param0, OptType param1, OptType param2, OptType param3, OptType param4, int nParams,
-        OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
-      |
-        unpackAndUnaliasSignatureType(this, param0, param1, param2, param3, param4, nParams, result0,
-          result1, result2, nResults, isVariadic) and
-        unpackSignatureType(result, param0, param1, param2, param3, param4, nParams, result0, result1,
-          result2, nResults, isVariadic)
-      )
-    }
-  
-    // These incremental recursive implementations only apply from parameter 5 or result 3
-    // upwards to avoid constructing large squares of candidates -- the initial parameters
-    // and results are taken care of by the candidate predicate.
-    private predicate hasDeepUnaliasedParameterTypesUpTo(SignatureType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 5 and
-      (i = 5 or this.hasDeepUnaliasedParameterTypesUpTo(unaliased, i - 1)) and
-      unaliased.getParameterType(i) = this.getParameterType(i).getDeepUnaliasedType()
-    }
-  
-    private predicate hasDeepUnaliasedResultTypesUpTo(SignatureType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 3 and
-      (i = 3 or this.hasDeepUnaliasedResultTypesUpTo(unaliased, i - 1)) and
-      unaliased.getResultType(i) = this.getResultType(i).getDeepUnaliasedType()
-    }
-  
-    override SignatureType getDeepUnaliasedType() {
-      result = this.getDeepUnaliasedTypeCandidate() and
-      exists(int nParams, int nResults |
-        this.getNumParameter() = nParams and this.getNumResult() = nResults
-      |
-        (
-          nParams <= 5
-          or
-          this.hasDeepUnaliasedParameterTypesUpTo(result, nParams - 1)
-        ) and
-        (
-          nResults <= 3
-          or
-          this.hasDeepUnaliasedResultTypesUpTo(result, nResults - 1)
-        )
-      )
-    }
-  }
-  
-  /** A map type. */
-  class MapType extends @maptype, CompositeType {
-    /** Gets the key type of this map type. */
-    Type getKeyType() { key_type(this, result) }
-  
-    /** Gets the value type of this map type. */
-    Type getValueType() { element_type(this, result) }
-  
-    override MapType getDeepUnaliasedType() {
-      result.getKeyType() = this.getKeyType().getDeepUnaliasedType() and
-      result.getValueType() = this.getValueType().getDeepUnaliasedType()
-    }
-  }
-  
-  /** A channel type. */
-  class ChanType extends @chantype, CompositeType {
-    /** Gets the element type of this channel type. */
-    Type getElementType() { element_type(this, result) }
-  }
-  
-  /** A channel type that can only send. */
-  class SendChanType extends @sendchantype, ChanType {
-    override SendChanType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
-  }
-  
-  /** A channel type that can only receive. */
-  class RecvChanType extends @recvchantype, ChanType {
-    override RecvChanType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
+}
+
+/** A map type. */
+class MapType extends @maptype, CompositeType {
+  /** Gets the key type of this map type. */
+  Type getKeyType() { key_type(this, result) }
+
+  /** Gets the value type of this map type. */
+  Type getValueType() { element_type(this, result) }
+
+  override MapType getDeepUnaliasedType() {
+    result.getKeyType() = this.getKeyType().getDeepUnaliasedType() and
+    result.getValueType() = this.getValueType().getDeepUnaliasedType()
   }
-  
-  /** A channel type that can both send and receive. */
-  class SendRecvChanType extends @sendrcvchantype, ChanType {
-    override SendRecvChanType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
+}
+
+/** A channel type. */
+class ChanType extends @chantype, CompositeType {
+  /** Gets the element type of this channel type. */
+  Type getElementType() { element_type(this, result) }
+}
+
+/** A channel type that can only send. */
+class SendChanType extends @sendchantype, ChanType {
+  override SendChanType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  /** An alias type. */
-  class AliasType extends @typealias, CompositeType {
-    /** Gets the aliased type (i.e. that appears on the RHS of the alias definition). */
-    Type getRhs() { alias_rhs(this, result) }
-  
-    override Type getDeepUnaliasedType() { result = unalias(this).getDeepUnaliasedType() }
+}
+
+/** A channel type that can only receive. */
+class RecvChanType extends @recvchantype, ChanType {
+  override RecvChanType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  /**
-   * Gets the non-alias type at the end of the alias chain starting at `t`.
-   *
-   * If `t` is not an alias type then `result` is `t`.
-   */
-  Type unalias(Type t) {
-    not t instanceof AliasType and result = t
-    or
-    result = unalias(t.(AliasType).getRhs())
+}
+
+/** A channel type that can both send and receive. */
+class SendRecvChanType extends @sendrcvchantype, ChanType {
+  override SendRecvChanType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  predicate containsAliases(Type t) { t != t.getDeepUnaliasedType() }
-  // END ALIASES.QLL  
-
-  from PointerType pt, Type base
-  where base_type(pt, base)
-  and not containsAliases(pt)
-  select pt, base
\ No newline at end of file
+}
+
+/** A named type. */
+class NamedType extends @namedtype, CompositeType {
+  Type getBaseType() { underlying_type(this, result) }
+}
+
+/**
+ * The predeclared `comparable` type.
+ */
+class ComparableType extends NamedType {
+  ComparableType() { typename(this, "comparable") }
+}
+
+/** An alias type. */
+class AliasType extends @typealias, CompositeType {
+  /** Gets the aliased type (i.e. that appears on the RHS of the alias definition). */
+  Type getRhs() { alias_rhs(this, result) }
+
+  override Type getDeepUnaliasedType() { result = unalias(this).getDeepUnaliasedType() }
+}
+
+/**
+ * Gets the non-alias type at the end of the alias chain starting at `t`.
+ *
+ * If `t` is not an alias type then `result` is `t`.
+ */
+Type unalias(Type t) {
+  not t instanceof AliasType and result = t
+  or
+  result = unalias(t.(AliasType).getRhs())
+}
+
+predicate containsAliases(Type t) { t != t.getDeepUnaliasedType() }
+// END ALIASES.QLL
+from PointerType pt, Type base
+where
+  base_type(pt, base) and
+  not containsAliases(pt)
+select pt, base
diff --git a/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/component_types.ql b/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/component_types.ql
index 2f0dd0e5bd39..f17ed42901a5 100644
--- a/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/component_types.ql
+++ b/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/component_types.ql
@@ -2,577 +2,617 @@
 // Database scripts can't import, but this is the definitive copy of the support routines for mapping types to their unaliased equivalent. Ensure this code is in sync between aliases.qll and all copies in individual table .ql files.
 /** A Go type. */
 class Type extends @type {
-    /**
-     * Gets this type with all aliases substituted for their underlying type.
-     *
-     * Note named types are not substituted.
-     */
-    Type getDeepUnaliasedType() { result = this }
-  
-    /**
-     * Gets a basic textual representation of this type.
-     */
-    string toString() { result = "type" }
-  }
-  
-  /** A composite type, that is, not a basic type. */
-  class CompositeType extends @compositetype, Type { }
-  
-  /** An array type. */
-  class ArrayType extends @arraytype, CompositeType {
-    /** Gets the element type of this array type. */
-    Type getElementType() { element_type(this, result) }
-  
-    /** Gets the length of this array type as a string. */
-    string getLengthString() { array_length(this, result) }
-  
-    override ArrayType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType() and
-      result.getLengthString() = this.getLengthString()
-    }
+  /**
+   * Gets this type with all aliases substituted for their underlying type.
+   *
+   * Note named types are not substituted.
+   */
+  Type getDeepUnaliasedType() { result = this }
+
+  /**
+   * Gets a basic textual representation of this type.
+   */
+  string toString() { result = "type" }
+}
+
+/** A composite type, that is, not a basic type. */
+class CompositeType extends @compositetype, Type { }
+
+/** An array type. */
+class ArrayType extends @arraytype, CompositeType {
+  /** Gets the element type of this array type. */
+  Type getElementType() { element_type(this, result) }
+
+  /** Gets the length of this array type as a string. */
+  string getLengthString() { array_length(this, result) }
+
+  override ArrayType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType() and
+    result.getLengthString() = this.getLengthString()
   }
-  
-  /** A slice type. */
-  class SliceType extends @slicetype, CompositeType {
-    /** Gets the element type of this slice type. */
-    Type getElementType() { element_type(this, result) }
-  
-    override SliceType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
+}
+
+/** A slice type. */
+class SliceType extends @slicetype, CompositeType {
+  /** Gets the element type of this slice type. */
+  Type getElementType() { element_type(this, result) }
+
+  override SliceType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  // Improve efficiency of matching a struct to its unaliased equivalent
-  // by unpacking the first 5 fields and tags, allowing a single join
-  // to strongly constrain the available candidates.
-  private predicate hasComponentTypeAndTag(StructType s, int i, string name, Type tp, string tag) {
-    component_types(s, i, name, tp) and component_tags(s, i, tag)
+}
+
+// Improve efficiency of matching a struct to its unaliased equivalent
+// by unpacking the first 5 fields and tags, allowing a single join
+// to strongly constrain the available candidates.
+private predicate hasComponentTypeAndTag(StructType s, int i, string name, Type tp, string tag) {
+  component_types(s, i, name, tp) and component_tags(s, i, tag)
+}
+
+private newtype TOptStructComponent =
+  MkNoComponent() or
+  MkSomeComponent(string name, Type tp, string tag) { hasComponentTypeAndTag(_, _, name, tp, tag) }
+
+private class OptStructComponent extends TOptStructComponent {
+  OptStructComponent getWithDeepUnaliasedType() {
+    this = MkNoComponent() and result = MkNoComponent()
+    or
+    exists(string name, Type tp, string tag |
+      this = MkSomeComponent(name, tp, tag) and
+      result = MkSomeComponent(name, tp.getDeepUnaliasedType(), tag)
+    )
   }
-  
-  private newtype TOptStructComponent =
-    MkNoComponent() or
-    MkSomeComponent(string name, Type tp, string tag) { hasComponentTypeAndTag(_, _, name, tp, tag) }
-  
-  private class OptStructComponent extends TOptStructComponent {
-    OptStructComponent getWithDeepUnaliasedType() {
-      this = MkNoComponent() and result = MkNoComponent()
-      or
-      exists(string name, Type tp, string tag |
-        this = MkSomeComponent(name, tp, tag) and
-        result = MkSomeComponent(name, tp.getDeepUnaliasedType(), tag)
-      )
-    }
-  
-    string toString() { result = "struct component" }
+
+  string toString() { result = "struct component" }
+}
+
+private class StructComponent extends MkSomeComponent {
+  string toString() { result = "struct component" }
+
+  predicate isComponentOf(StructType s, int i) {
+    exists(string name, Type tp, string tag |
+      hasComponentTypeAndTag(s, i, name, tp, tag) and
+      this = MkSomeComponent(name, tp, tag)
+    )
   }
-  
-  private class StructComponent extends MkSomeComponent {
-    string toString() { result = "struct component" }
-  
-    predicate isComponentOf(StructType s, int i) {
-      exists(string name, Type tp, string tag |
-        hasComponentTypeAndTag(s, i, name, tp, tag) and
-        this = MkSomeComponent(name, tp, tag)
-      )
-    }
+}
+
+pragma[nomagic]
+predicate unpackStructType(
+  StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
+  TOptStructComponent c3, TOptStructComponent c4, int nComponents
+) {
+  nComponents = count(int i | component_types(s, i, _, _)) and
+  (
+    if nComponents >= 1
+    then c0 = any(StructComponent sc | sc.isComponentOf(s, 0))
+    else c0 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 2
+    then c1 = any(StructComponent sc | sc.isComponentOf(s, 1))
+    else c1 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 3
+    then c2 = any(StructComponent sc | sc.isComponentOf(s, 2))
+    else c2 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 4
+    then c3 = any(StructComponent sc | sc.isComponentOf(s, 3))
+    else c3 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 5
+    then c4 = any(StructComponent sc | sc.isComponentOf(s, 4))
+    else c4 = MkNoComponent()
+  )
+}
+
+pragma[nomagic]
+predicate unpackAndUnaliasStructType(
+  StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
+  TOptStructComponent c3, TOptStructComponent c4, int nComponents
+) {
+  exists(
+    OptStructComponent c0a, OptStructComponent c1a, OptStructComponent c2a, OptStructComponent c3a,
+    OptStructComponent c4a
+  |
+    unpackStructType(s, c0a, c1a, c2a, c3a, c4a, nComponents) and
+    c0 = c0a.getWithDeepUnaliasedType() and
+    c1 = c1a.getWithDeepUnaliasedType() and
+    c2 = c2a.getWithDeepUnaliasedType() and
+    c3 = c3a.getWithDeepUnaliasedType() and
+    c4 = c4a.getWithDeepUnaliasedType()
+  )
+}
+
+/** A struct type. */
+class StructType extends @structtype, CompositeType {
+  private StructType getDeepUnaliasedTypeCandidate() {
+    exists(
+      OptStructComponent c0, OptStructComponent c1, OptStructComponent c2, OptStructComponent c3,
+      OptStructComponent c4, int nComponents
+    |
+      unpackAndUnaliasStructType(this, c0, c1, c2, c3, c4, nComponents) and
+      unpackStructType(result, c0, c1, c2, c3, c4, nComponents)
+    )
   }
-  
-  pragma[nomagic]
-  predicate unpackStructType(
-    StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
-    TOptStructComponent c3, TOptStructComponent c4, int nComponents
-  ) {
-    nComponents = count(int i | component_types(s, i, _, _)) and
-    (
-      if nComponents >= 1
-      then c0 = any(StructComponent sc | sc.isComponentOf(s, 0))
-      else c0 = MkNoComponent()
-    ) and
-    (
-      if nComponents >= 2
-      then c1 = any(StructComponent sc | sc.isComponentOf(s, 1))
-      else c1 = MkNoComponent()
-    ) and
-    (
-      if nComponents >= 3
-      then c2 = any(StructComponent sc | sc.isComponentOf(s, 2))
-      else c2 = MkNoComponent()
-    ) and
+
+  private predicate isDeepUnaliasedTypeUpTo(StructType unaliased, int i) {
+    // Note we must use component_types not hasOwnField here because component_types may specify
+    // interface-in-struct embedding, but hasOwnField does not return such members.
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 5 and
     (
-      if nComponents >= 4
-      then c3 = any(StructComponent sc | sc.isComponentOf(s, 3))
-      else c3 = MkNoComponent()
+      i = 5 or
+      this.isDeepUnaliasedTypeUpTo(unaliased, i - 1)
     ) and
-    (
-      if nComponents >= 5
-      then c4 = any(StructComponent sc | sc.isComponentOf(s, 4))
-      else c4 = MkNoComponent()
+    exists(string name, Type tp, string tag | hasComponentTypeAndTag(this, i, name, tp, tag) |
+      hasComponentTypeAndTag(unaliased, i, name, tp.getDeepUnaliasedType(), tag)
     )
   }
-  
-  pragma[nomagic]
-  predicate unpackAndUnaliasStructType(
-    StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
-    TOptStructComponent c3, TOptStructComponent c4, int nComponents
-  ) {
-    exists(
-      OptStructComponent c0a, OptStructComponent c1a, OptStructComponent c2a, OptStructComponent c3a,
-      OptStructComponent c4a
-    |
-      unpackStructType(s, c0a, c1a, c2a, c3a, c4a, nComponents) and
-      c0 = c0a.getWithDeepUnaliasedType() and
-      c1 = c1a.getWithDeepUnaliasedType() and
-      c2 = c2a.getWithDeepUnaliasedType() and
-      c3 = c3a.getWithDeepUnaliasedType() and
-      c4 = c4a.getWithDeepUnaliasedType()
+
+  override StructType getDeepUnaliasedType() {
+    result = this.getDeepUnaliasedTypeCandidate() and
+    exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
+      this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
+      or
+      nComponents <= 5
     )
   }
-  
-  /** A struct type. */
-  class StructType extends @structtype, CompositeType {
-    private StructType getDeepUnaliasedTypeCandidate() {
-      exists(
-        OptStructComponent c0, OptStructComponent c1, OptStructComponent c2, OptStructComponent c3,
-        OptStructComponent c4, int nComponents
-      |
-        unpackAndUnaliasStructType(this, c0, c1, c2, c3, c4, nComponents) and
-        unpackStructType(result, c0, c1, c2, c3, c4, nComponents)
-      )
-    }
-  
-    private predicate isDeepUnaliasedTypeUpTo(StructType unaliased, int i) {
-      // Note we must use component_types not hasOwnField here because component_types may specify
-      // interface-in-struct embedding, but hasOwnField does not return such members.
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 5 and
-      (
-        i = 5 or
-        this.isDeepUnaliasedTypeUpTo(unaliased, i - 1)
-      ) and
-      exists(string name, Type tp, string tag | hasComponentTypeAndTag(this, i, name, tp, tag) |
-        hasComponentTypeAndTag(unaliased, i, name, tp.getDeepUnaliasedType(), tag)
-      )
-    }
-  
-    override StructType getDeepUnaliasedType() {
-      result = this.getDeepUnaliasedTypeCandidate() and
-      exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
-        this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
-        or
-        nComponents <= 5
-      )
-    }
+}
+
+/** A pointer type. */
+class PointerType extends @pointertype, CompositeType {
+  /** Gets the base type of this pointer type. */
+  Type getBaseType() { base_type(this, result) }
+
+  override PointerType getDeepUnaliasedType() {
+    result.getBaseType() = this.getBaseType().getDeepUnaliasedType()
   }
-  
-  /** A pointer type. */
-  class PointerType extends @pointertype, CompositeType {
-    /** Gets the base type of this pointer type. */
-    Type getBaseType() { base_type(this, result) }
-  
-    override PointerType getDeepUnaliasedType() {
-      result.getBaseType() = this.getBaseType().getDeepUnaliasedType()
-    }
+}
+
+private predicate isInterfaceComponentWithQualifiedName(
+  InterfaceType intf, int idx, string qualifiedName, Type tp
+) {
+  exists(string name | component_types(intf, idx, name, tp) |
+    interface_private_method_ids(intf, idx, qualifiedName)
+    or
+    not interface_private_method_ids(intf, idx, _) and qualifiedName = name
+  )
+}
+
+private newtype TOptInterfaceComponent =
+  MkNoIComponent() or
+  MkSomeIComponent(string name, Type tp) {
+    isInterfaceComponentWithQualifiedName(any(InterfaceType i), _, name, tp)
   }
-  
-  private newtype TOptInterfaceComponent =
-    MkNoIComponent() or
-    MkSomeIComponent(string name, Type tp) { component_types(any(InterfaceType i), _, name, tp) }
-  
-  private class OptInterfaceComponent extends TOptInterfaceComponent {
-    OptInterfaceComponent getWithDeepUnaliasedType() {
-      this = MkNoIComponent() and result = MkNoIComponent()
-      or
-      exists(string name, Type tp |
-        this = MkSomeIComponent(name, tp) and
-        result = MkSomeIComponent(name, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    string toString() { result = "interface component" }
+
+private class OptInterfaceComponent extends TOptInterfaceComponent {
+  OptInterfaceComponent getWithDeepUnaliasedType() {
+    this = MkNoIComponent() and result = MkNoIComponent()
+    or
+    exists(string name, Type tp |
+      this = MkSomeIComponent(name, tp) and
+      result = MkSomeIComponent(name, tp.getDeepUnaliasedType())
+    )
   }
-  
-  private class InterfaceComponent extends MkSomeIComponent {
-    string toString() { result = "interface component" }
-  
-    predicate isComponentOf(InterfaceType intf, int i) {
-      exists(string name, Type tp |
-        component_types(intf, i, name, tp) and
-        this = MkSomeIComponent(name, tp)
-      )
-    }
+
+  string toString() { result = "interface component" }
+}
+
+private class InterfaceComponent extends MkSomeIComponent {
+  string toString() { result = "interface component" }
+
+  predicate isComponentOf(InterfaceType intf, int i) {
+    exists(string name, Type tp |
+      isInterfaceComponentWithQualifiedName(intf, i, name, tp) and
+      this = MkSomeIComponent(name, tp)
+    )
   }
-  
-  pragma[nomagic]
-  predicate unpackInterfaceType(
-    InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
-    TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
-    TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds
-  ) {
-    nComponents = count(int i | component_types(intf, i, _, _) and i >= 0) and
-    nEmbeds = count(int i | component_types(intf, i, _, _) and i < 0) and
-    (
-      if nComponents >= 1
-      then c0 = any(InterfaceComponent ic | ic.isComponentOf(intf, 0))
-      else c0 = MkNoIComponent()
-    ) and
-    (
-      if nComponents >= 2
-      then c1 = any(InterfaceComponent ic | ic.isComponentOf(intf, 1))
-      else c1 = MkNoIComponent()
-    ) and
+}
+
+pragma[nomagic]
+predicate unpackInterfaceType(
+  InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
+  TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
+  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds,
+  boolean isComparable
+) {
+  nComponents = count(int i | isInterfaceComponentWithQualifiedName(intf, i, _, _) and i >= 0) and
+  nEmbeds = count(int i | isInterfaceComponentWithQualifiedName(intf, i, _, _) and i < 0) and
+  (
+    if intf = any(ComparableType comparable).getBaseType()
+    then isComparable = true
+    else isComparable = false
+  ) and
+  (
+    if nComponents >= 1
+    then c0 = any(InterfaceComponent ic | ic.isComponentOf(intf, 0))
+    else c0 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 2
+    then c1 = any(InterfaceComponent ic | ic.isComponentOf(intf, 1))
+    else c1 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 3
+    then c2 = any(InterfaceComponent ic | ic.isComponentOf(intf, 2))
+    else c2 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 4
+    then c3 = any(InterfaceComponent ic | ic.isComponentOf(intf, 3))
+    else c3 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 5
+    then c4 = any(InterfaceComponent ic | ic.isComponentOf(intf, 4))
+    else c4 = MkNoIComponent()
+  ) and
+  (
+    if nEmbeds >= 1
+    then e1 = any(InterfaceComponent ic | ic.isComponentOf(intf, -1))
+    else e1 = MkNoIComponent()
+  ) and
+  (
+    if nEmbeds >= 2
+    then e2 = any(InterfaceComponent ic | ic.isComponentOf(intf, -2))
+    else e2 = MkNoIComponent()
+  )
+}
+
+pragma[nomagic]
+predicate unpackAndUnaliasInterfaceType(
+  InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
+  TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
+  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds,
+  boolean isComparable
+) {
+  exists(
+    OptInterfaceComponent c0a, OptInterfaceComponent c1a, OptInterfaceComponent c2a,
+    OptInterfaceComponent c3a, OptInterfaceComponent c4a, OptInterfaceComponent e1a,
+    OptInterfaceComponent e2a
+  |
+    unpackInterfaceType(intf, c0a, c1a, c2a, c3a, c4a, e1a, e2a, nComponents, nEmbeds, isComparable) and
+    c0 = c0a.getWithDeepUnaliasedType() and
+    c1 = c1a.getWithDeepUnaliasedType() and
+    c2 = c2a.getWithDeepUnaliasedType() and
+    c3 = c3a.getWithDeepUnaliasedType() and
+    c4 = c4a.getWithDeepUnaliasedType() and
+    e1 = e1a.getWithDeepUnaliasedType() and
+    e2 = e2a.getWithDeepUnaliasedType()
+  )
+}
+
+/** An interface type. */
+class InterfaceType extends @interfacetype, CompositeType {
+  private Type getMethodType(int i, string name) {
+    i >= 0 and isInterfaceComponentWithQualifiedName(this, i, name, result)
+  }
+
+  /**
+   * Holds if `tp` is a directly embedded type with index `index`.
+   *
+   * `tp` (or its underlying type) is either a type set literal type or an
+   * interface type.
+   */
+  private predicate hasDirectlyEmbeddedType(int index, Type tp) {
+    index >= 0 and isInterfaceComponentWithQualifiedName(this, -(index + 1), _, tp)
+  }
+
+  private InterfaceType getDeepUnaliasedTypeCandidate() {
+    exists(
+      OptInterfaceComponent c0, OptInterfaceComponent c1, OptInterfaceComponent c2,
+      OptInterfaceComponent c3, OptInterfaceComponent c4, OptInterfaceComponent e1,
+      OptInterfaceComponent e2, int nComponents, int nEmbeds, boolean isComparable
+    |
+      unpackAndUnaliasInterfaceType(this, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds,
+        isComparable) and
+      unpackInterfaceType(result, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds, isComparable)
+    )
+  }
+
+  private predicate hasDeepUnaliasedComponentTypesUpTo(InterfaceType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 5 and
     (
-      if nComponents >= 3
-      then c2 = any(InterfaceComponent ic | ic.isComponentOf(intf, 2))
-      else c2 = MkNoIComponent()
+      i = 5 or
+      this.hasDeepUnaliasedComponentTypesUpTo(unaliased, i - 1)
     ) and
+    exists(string name |
+      unaliased.getMethodType(i, name) = this.getMethodType(i, name).getDeepUnaliasedType()
+    )
+  }
+
+  private predicate hasDeepUnaliasedEmbeddedTypesUpTo(InterfaceType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 2 and
     (
-      if nComponents >= 4
-      then c3 = any(InterfaceComponent ic | ic.isComponentOf(intf, 3))
-      else c3 = MkNoIComponent()
+      i = 2 or
+      this.hasDeepUnaliasedEmbeddedTypesUpTo(unaliased, i - 1)
     ) and
-    (
-      if nComponents >= 5
-      then c4 = any(InterfaceComponent ic | ic.isComponentOf(intf, 4))
-      else c4 = MkNoIComponent()
+    exists(Type tp | this.hasDirectlyEmbeddedType(i, tp) |
+      unaliased.hasDirectlyEmbeddedType(i, tp.getDeepUnaliasedType())
+    )
+  }
+
+  override InterfaceType getDeepUnaliasedType() {
+    result = this.getDeepUnaliasedTypeCandidate() and
+    exists(int nComponents | nComponents = count(int i | exists(this.getMethodType(i, _))) |
+      this.hasDeepUnaliasedComponentTypesUpTo(result, nComponents - 1)
+      or
+      nComponents <= 5
     ) and
+    exists(int nEmbeds | nEmbeds = count(int i | this.hasDirectlyEmbeddedType(i, _)) |
+      this.hasDeepUnaliasedEmbeddedTypesUpTo(result, nEmbeds - 1)
+      or
+      nEmbeds <= 2
+    )
+  }
+}
+
+pragma[nomagic]
+private predicate unpackTupleType(
+  TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
+) {
+  nComponents = count(int i | component_types(tt, i, _, _)) and
+  (if nComponents >= 1 then c0 = MkSomeType(tt.getComponentType(0)) else c0 = MkNoType()) and
+  (if nComponents >= 2 then c1 = MkSomeType(tt.getComponentType(1)) else c1 = MkNoType()) and
+  (if nComponents >= 3 then c2 = MkSomeType(tt.getComponentType(2)) else c2 = MkNoType())
+}
+
+pragma[nomagic]
+private predicate unpackAndUnaliasTupleType(
+  TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
+) {
+  exists(OptType c0a, OptType c1a, OptType c2a |
+    unpackTupleType(tt, c0a, c1a, c2a, nComponents) and
+    c0 = c0a.getDeepUnaliasedType() and
+    c1 = c1a.getDeepUnaliasedType() and
+    c2 = c2a.getDeepUnaliasedType()
+  )
+}
+
+/** A tuple type. */
+class TupleType extends @tupletype, CompositeType {
+  /** Gets the `i`th component type of this tuple type. */
+  Type getComponentType(int i) { component_types(this, i, _, result) }
+
+  private TupleType getCandidateDeepUnaliasedType() {
+    exists(OptType c0, OptType c1, OptType c2, int nComponents |
+      unpackAndUnaliasTupleType(this, c0, c1, c2, nComponents) and
+      unpackTupleType(result, c0, c1, c2, nComponents)
+    )
+  }
+
+  private predicate isDeepUnaliasedTypeUpTo(TupleType tt, int i) {
+    tt = this.getCandidateDeepUnaliasedType() and
+    i >= 3 and
     (
-      if nEmbeds >= 1
-      then e1 = any(InterfaceComponent ic | ic.isComponentOf(intf, -1))
-      else e1 = MkNoIComponent()
+      i = 3
+      or
+      this.isDeepUnaliasedTypeUpTo(tt, i - 1)
     ) and
-    (
-      if nEmbeds >= 2
-      then e2 = any(InterfaceComponent ic | ic.isComponentOf(intf, -2))
-      else e2 = MkNoIComponent()
+    tt.getComponentType(i) = this.getComponentType(i).getDeepUnaliasedType()
+  }
+
+  override TupleType getDeepUnaliasedType() {
+    result = this.getCandidateDeepUnaliasedType() and
+    exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
+      this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
+      or
+      nComponents <= 3
     )
   }
-  
-  pragma[nomagic]
-  predicate unpackAndUnaliasInterfaceType(
-    InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
-    TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
-    TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds
-  ) {
+}
+
+// Reasonably efficiently map from a signature type to its
+// deep-unaliased equivalent, by using a single join for the leading 5 parameters
+// and/or 3 results.
+private newtype TOptType =
+  MkNoType() or
+  MkSomeType(Type tp)
+
+private class OptType extends TOptType {
+  OptType getDeepUnaliasedType() {
+    exists(Type t | this = MkSomeType(t) | result = MkSomeType(t.getDeepUnaliasedType()))
+    or
+    this = MkNoType() and result = MkNoType()
+  }
+
+  string toString() {
+    exists(Type t | this = MkSomeType(t) | result = t.toString())
+    or
+    this = MkNoType() and result = "no type"
+  }
+}
+
+pragma[nomagic]
+private predicate unpackSignatureType(
+  SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
+  int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
+) {
+  nParams = sig.getNumParameter() and
+  nResults = sig.getNumResult() and
+  (if nParams >= 1 then param0 = MkSomeType(sig.getParameterType(0)) else param0 = MkNoType()) and
+  (if nParams >= 2 then param1 = MkSomeType(sig.getParameterType(1)) else param1 = MkNoType()) and
+  (if nParams >= 3 then param2 = MkSomeType(sig.getParameterType(2)) else param2 = MkNoType()) and
+  (if nParams >= 4 then param3 = MkSomeType(sig.getParameterType(3)) else param3 = MkNoType()) and
+  (if nParams >= 5 then param4 = MkSomeType(sig.getParameterType(4)) else param4 = MkNoType()) and
+  (if nResults >= 1 then result0 = MkSomeType(sig.getResultType(0)) else result0 = MkNoType()) and
+  (if nResults >= 2 then result1 = MkSomeType(sig.getResultType(1)) else result1 = MkNoType()) and
+  (if nResults >= 3 then result2 = MkSomeType(sig.getResultType(2)) else result2 = MkNoType()) and
+  (if sig.isVariadic() then isVariadic = true else isVariadic = false)
+}
+
+pragma[nomagic]
+private predicate unpackAndUnaliasSignatureType(
+  SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
+  int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
+) {
+  exists(
+    OptType param0a, OptType param1a, OptType param2a, OptType param3a, OptType param4a,
+    OptType result0a, OptType result1a, OptType result2a
+  |
+    unpackSignatureType(sig, param0a, param1a, param2a, param3a, param4a, nParams, result0a,
+      result1a, result2a, nResults, isVariadic)
+  |
+    param0 = param0a.getDeepUnaliasedType() and
+    param1 = param1a.getDeepUnaliasedType() and
+    param2 = param2a.getDeepUnaliasedType() and
+    param3 = param3a.getDeepUnaliasedType() and
+    param4 = param4a.getDeepUnaliasedType() and
+    result0 = result0a.getDeepUnaliasedType() and
+    result1 = result1a.getDeepUnaliasedType() and
+    result2 = result2a.getDeepUnaliasedType()
+  )
+}
+
+/** A signature type. */
+class SignatureType extends @signaturetype, CompositeType {
+  /** Gets the `i`th parameter type of this signature type. */
+  Type getParameterType(int i) { i >= 0 and component_types(this, i + 1, _, result) }
+
+  /** Gets the `i`th result type of this signature type. */
+  Type getResultType(int i) { i >= 0 and component_types(this, -(i + 1), _, result) }
+
+  /** Gets the number of parameters specified by this signature. */
+  int getNumParameter() { result = count(int i | exists(this.getParameterType(i))) }
+
+  /** Gets the number of results specified by this signature. */
+  int getNumResult() { result = count(int i | exists(this.getResultType(i))) }
+
+  /** Holds if this signature type is variadic. */
+  predicate isVariadic() { variadic(this) }
+
+  private SignatureType getDeepUnaliasedTypeCandidate() {
     exists(
-      OptInterfaceComponent c0a, OptInterfaceComponent c1a, OptInterfaceComponent c2a,
-      OptInterfaceComponent c3a, OptInterfaceComponent c4a, OptInterfaceComponent e1a,
-      OptInterfaceComponent e2a
+      OptType param0, OptType param1, OptType param2, OptType param3, OptType param4, int nParams,
+      OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
     |
-      unpackInterfaceType(intf, c0a, c1a, c2a, c3a, c4a, e1a, e2a, nComponents, nEmbeds) and
-      c0 = c0a.getWithDeepUnaliasedType() and
-      c1 = c1a.getWithDeepUnaliasedType() and
-      c2 = c2a.getWithDeepUnaliasedType() and
-      c3 = c3a.getWithDeepUnaliasedType() and
-      c4 = c4a.getWithDeepUnaliasedType() and
-      e1 = e1a.getWithDeepUnaliasedType() and
-      e2 = e2a.getWithDeepUnaliasedType()
+      unpackAndUnaliasSignatureType(this, param0, param1, param2, param3, param4, nParams, result0,
+        result1, result2, nResults, isVariadic) and
+      unpackSignatureType(result, param0, param1, param2, param3, param4, nParams, result0, result1,
+        result2, nResults, isVariadic)
     )
   }
-  
-  /** An interface type. */
-  class InterfaceType extends @interfacetype, CompositeType {
-    private InterfaceType getDeepUnaliasedTypeCandidate() {
-      exists(
-        OptInterfaceComponent c0, OptInterfaceComponent c1, OptInterfaceComponent c2,
-        OptInterfaceComponent c3, OptInterfaceComponent c4, OptInterfaceComponent e1,
-        OptInterfaceComponent e2, int nComponents, int nEmbeds
-      |
-        unpackAndUnaliasInterfaceType(this, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds) and
-        unpackInterfaceType(result, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds)
-      )
-    }
-  
-    private predicate hasDeepUnaliasedComponentTypesUpTo(InterfaceType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 5 and
-      (
-        i = 5 or
-        this.hasDeepUnaliasedComponentTypesUpTo(unaliased, i - 1)
-      ) and
-      exists(string name, Type tp | component_types(this, i, name, tp) |
-        component_types(unaliased, i, name, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    private predicate hasDeepUnaliasedEmbeddedTypesUpTo(InterfaceType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 3 and
-      (
-        i = 3 or
-        this.hasDeepUnaliasedEmbeddedTypesUpTo(unaliased, i - 1)
-      ) and
-      exists(string name, Type tp | component_types(this, -i, name, tp) |
-        component_types(unaliased, -i, name, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    override InterfaceType getDeepUnaliasedType() {
-      result = this.getDeepUnaliasedTypeCandidate() and
-      exists(int nComponents |
-        nComponents = count(int i | component_types(this, i, _, _) and i >= 0)
-      |
-        this.hasDeepUnaliasedComponentTypesUpTo(result, nComponents - 1)
-        or
-        nComponents <= 5
-      ) and
-      exists(int nEmbeds | nEmbeds = count(int i | component_types(this, i, _, _) and i < 0) |
-        // Note no -1 here, because the first embedded type is at -1
-        this.hasDeepUnaliasedEmbeddedTypesUpTo(result, nEmbeds)
-        or
-        nEmbeds <= 2
-      )
-    }
-  }
-  
-  pragma[nomagic]
-  private predicate unpackTupleType(
-    TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
-  ) {
-    nComponents = count(int i | component_types(tt, i, _, _)) and
-    (if nComponents >= 1 then c0 = MkSomeType(tt.getComponentType(0)) else c0 = MkNoType()) and
-    (if nComponents >= 2 then c1 = MkSomeType(tt.getComponentType(1)) else c1 = MkNoType()) and
-    (if nComponents >= 3 then c2 = MkSomeType(tt.getComponentType(2)) else c2 = MkNoType())
+
+  // These incremental recursive implementations only apply from parameter 5 or result 3
+  // upwards to avoid constructing large squares of candidates -- the initial parameters
+  // and results are taken care of by the candidate predicate.
+  private predicate hasDeepUnaliasedParameterTypesUpTo(SignatureType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 5 and
+    (i = 5 or this.hasDeepUnaliasedParameterTypesUpTo(unaliased, i - 1)) and
+    unaliased.getParameterType(i) = this.getParameterType(i).getDeepUnaliasedType()
   }
-  
-  pragma[nomagic]
-  private predicate unpackAndUnaliasTupleType(
-    TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
-  ) {
-    exists(OptType c0a, OptType c1a, OptType c2a |
-      unpackTupleType(tt, c0a, c1a, c2a, nComponents) and
-      c0 = c0a.getDeepUnaliasedType() and
-      c1 = c1a.getDeepUnaliasedType() and
-      c2 = c2a.getDeepUnaliasedType()
-    )
+
+  private predicate hasDeepUnaliasedResultTypesUpTo(SignatureType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 3 and
+    (i = 3 or this.hasDeepUnaliasedResultTypesUpTo(unaliased, i - 1)) and
+    unaliased.getResultType(i) = this.getResultType(i).getDeepUnaliasedType()
   }
-  
-  /** A tuple type. */
-  class TupleType extends @tupletype, CompositeType {
-    /** Gets the `i`th component type of this tuple type. */
-    Type getComponentType(int i) { component_types(this, i, _, result) }
-  
-    private TupleType getCandidateDeepUnaliasedType() {
-      exists(OptType c0, OptType c1, OptType c2, int nComponents |
-        unpackAndUnaliasTupleType(this, c0, c1, c2, nComponents) and
-        unpackTupleType(result, c0, c1, c2, nComponents)
-      )
-    }
-  
-    private predicate isDeepUnaliasedTypeUpTo(TupleType tt, int i) {
-      tt = this.getCandidateDeepUnaliasedType() and
-      i >= 3 and
+
+  override SignatureType getDeepUnaliasedType() {
+    result = this.getDeepUnaliasedTypeCandidate() and
+    exists(int nParams, int nResults |
+      this.getNumParameter() = nParams and this.getNumResult() = nResults
+    |
       (
-        i = 3
+        nParams <= 5
         or
-        this.isDeepUnaliasedTypeUpTo(tt, i - 1)
+        this.hasDeepUnaliasedParameterTypesUpTo(result, nParams - 1)
       ) and
-      exists(Type tp | component_types(this, i, _, tp) |
-        component_types(tt, i, _, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    override TupleType getDeepUnaliasedType() {
-      result = this.getCandidateDeepUnaliasedType() and
-      exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
-        this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
+      (
+        nResults <= 3
         or
-        nComponents <= 3
+        this.hasDeepUnaliasedResultTypesUpTo(result, nResults - 1)
       )
-    }
-  }
-  
-  // Reasonably efficiently map from a signature type to its
-  // deep-unaliased equivalent, by using a single join for the leading 5 parameters
-  // and/or 3 results.
-  private newtype TOptType =
-    MkNoType() or
-    MkSomeType(Type tp)
-  
-  private class OptType extends TOptType {
-    OptType getDeepUnaliasedType() {
-      exists(Type t | this = MkSomeType(t) | result = MkSomeType(t.getDeepUnaliasedType()))
-      or
-      this = MkNoType() and result = MkNoType()
-    }
-  
-    string toString() {
-      exists(Type t | this = MkSomeType(t) | result = t.toString())
-      or
-      this = MkNoType() and result = "no type"
-    }
-  }
-  
-  pragma[nomagic]
-  private predicate unpackSignatureType(
-    SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
-    int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
-  ) {
-    nParams = sig.getNumParameter() and
-    nResults = sig.getNumResult() and
-    (if nParams >= 1 then param0 = MkSomeType(sig.getParameterType(0)) else param0 = MkNoType()) and
-    (if nParams >= 2 then param1 = MkSomeType(sig.getParameterType(1)) else param1 = MkNoType()) and
-    (if nParams >= 3 then param2 = MkSomeType(sig.getParameterType(2)) else param2 = MkNoType()) and
-    (if nParams >= 4 then param3 = MkSomeType(sig.getParameterType(3)) else param3 = MkNoType()) and
-    (if nParams >= 5 then param4 = MkSomeType(sig.getParameterType(4)) else param4 = MkNoType()) and
-    (if nResults >= 1 then result0 = MkSomeType(sig.getResultType(0)) else result0 = MkNoType()) and
-    (if nResults >= 2 then result1 = MkSomeType(sig.getResultType(1)) else result1 = MkNoType()) and
-    (if nResults >= 3 then result2 = MkSomeType(sig.getResultType(2)) else result2 = MkNoType()) and
-    (if sig.isVariadic() then isVariadic = true else isVariadic = false)
-  }
-  
-  pragma[nomagic]
-  private predicate unpackAndUnaliasSignatureType(
-    SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
-    int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
-  ) {
-    exists(
-      OptType param0a, OptType param1a, OptType param2a, OptType param3a, OptType param4a,
-      OptType result0a, OptType result1a, OptType result2a
-    |
-      unpackSignatureType(sig, param0a, param1a, param2a, param3a, param4a, nParams, result0a,
-        result1a, result2a, nResults, isVariadic)
-    |
-      param0 = param0a.getDeepUnaliasedType() and
-      param1 = param1a.getDeepUnaliasedType() and
-      param2 = param2a.getDeepUnaliasedType() and
-      param3 = param3a.getDeepUnaliasedType() and
-      param4 = param4a.getDeepUnaliasedType() and
-      result0 = result0a.getDeepUnaliasedType() and
-      result1 = result1a.getDeepUnaliasedType() and
-      result2 = result2a.getDeepUnaliasedType()
     )
   }
-  
-  /** A signature type. */
-  class SignatureType extends @signaturetype, CompositeType {
-    /** Gets the `i`th parameter type of this signature type. */
-    Type getParameterType(int i) { i >= 0 and component_types(this, i + 1, _, result) }
-  
-    /** Gets the `i`th result type of this signature type. */
-    Type getResultType(int i) { i >= 0 and component_types(this, -(i + 1), _, result) }
-  
-    /** Gets the number of parameters specified by this signature. */
-    int getNumParameter() { result = count(int i | exists(this.getParameterType(i))) }
-  
-    /** Gets the number of results specified by this signature. */
-    int getNumResult() { result = count(int i | exists(this.getResultType(i))) }
-  
-    /** Holds if this signature type is variadic. */
-    predicate isVariadic() { variadic(this) }
-  
-    private SignatureType getDeepUnaliasedTypeCandidate() {
-      exists(
-        OptType param0, OptType param1, OptType param2, OptType param3, OptType param4, int nParams,
-        OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
-      |
-        unpackAndUnaliasSignatureType(this, param0, param1, param2, param3, param4, nParams, result0,
-          result1, result2, nResults, isVariadic) and
-        unpackSignatureType(result, param0, param1, param2, param3, param4, nParams, result0, result1,
-          result2, nResults, isVariadic)
-      )
-    }
-  
-    // These incremental recursive implementations only apply from parameter 5 or result 3
-    // upwards to avoid constructing large squares of candidates -- the initial parameters
-    // and results are taken care of by the candidate predicate.
-    private predicate hasDeepUnaliasedParameterTypesUpTo(SignatureType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 5 and
-      (i = 5 or this.hasDeepUnaliasedParameterTypesUpTo(unaliased, i - 1)) and
-      unaliased.getParameterType(i) = this.getParameterType(i).getDeepUnaliasedType()
-    }
-  
-    private predicate hasDeepUnaliasedResultTypesUpTo(SignatureType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 3 and
-      (i = 3 or this.hasDeepUnaliasedResultTypesUpTo(unaliased, i - 1)) and
-      unaliased.getResultType(i) = this.getResultType(i).getDeepUnaliasedType()
-    }
-  
-    override SignatureType getDeepUnaliasedType() {
-      result = this.getDeepUnaliasedTypeCandidate() and
-      exists(int nParams, int nResults |
-        this.getNumParameter() = nParams and this.getNumResult() = nResults
-      |
-        (
-          nParams <= 5
-          or
-          this.hasDeepUnaliasedParameterTypesUpTo(result, nParams - 1)
-        ) and
-        (
-          nResults <= 3
-          or
-          this.hasDeepUnaliasedResultTypesUpTo(result, nResults - 1)
-        )
-      )
-    }
-  }
-  
-  /** A map type. */
-  class MapType extends @maptype, CompositeType {
-    /** Gets the key type of this map type. */
-    Type getKeyType() { key_type(this, result) }
-  
-    /** Gets the value type of this map type. */
-    Type getValueType() { element_type(this, result) }
-  
-    override MapType getDeepUnaliasedType() {
-      result.getKeyType() = this.getKeyType().getDeepUnaliasedType() and
-      result.getValueType() = this.getValueType().getDeepUnaliasedType()
-    }
-  }
-  
-  /** A channel type. */
-  class ChanType extends @chantype, CompositeType {
-    /** Gets the element type of this channel type. */
-    Type getElementType() { element_type(this, result) }
-  }
-  
-  /** A channel type that can only send. */
-  class SendChanType extends @sendchantype, ChanType {
-    override SendChanType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
-  }
-  
-  /** A channel type that can only receive. */
-  class RecvChanType extends @recvchantype, ChanType {
-    override RecvChanType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
+}
+
+/** A map type. */
+class MapType extends @maptype, CompositeType {
+  /** Gets the key type of this map type. */
+  Type getKeyType() { key_type(this, result) }
+
+  /** Gets the value type of this map type. */
+  Type getValueType() { element_type(this, result) }
+
+  override MapType getDeepUnaliasedType() {
+    result.getKeyType() = this.getKeyType().getDeepUnaliasedType() and
+    result.getValueType() = this.getValueType().getDeepUnaliasedType()
   }
-  
-  /** A channel type that can both send and receive. */
-  class SendRecvChanType extends @sendrcvchantype, ChanType {
-    override SendRecvChanType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
+}
+
+/** A channel type. */
+class ChanType extends @chantype, CompositeType {
+  /** Gets the element type of this channel type. */
+  Type getElementType() { element_type(this, result) }
+}
+
+/** A channel type that can only send. */
+class SendChanType extends @sendchantype, ChanType {
+  override SendChanType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  /** An alias type. */
-  class AliasType extends @typealias, CompositeType {
-    /** Gets the aliased type (i.e. that appears on the RHS of the alias definition). */
-    Type getRhs() { alias_rhs(this, result) }
-  
-    override Type getDeepUnaliasedType() { result = unalias(this).getDeepUnaliasedType() }
+}
+
+/** A channel type that can only receive. */
+class RecvChanType extends @recvchantype, ChanType {
+  override RecvChanType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  /**
-   * Gets the non-alias type at the end of the alias chain starting at `t`.
-   *
-   * If `t` is not an alias type then `result` is `t`.
-   */
-  Type unalias(Type t) {
-    not t instanceof AliasType and result = t
-    or
-    result = unalias(t.(AliasType).getRhs())
+}
+
+/** A channel type that can both send and receive. */
+class SendRecvChanType extends @sendrcvchantype, ChanType {
+  override SendRecvChanType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  predicate containsAliases(Type t) { t != t.getDeepUnaliasedType() }
-  // END ALIASES.QLL
-  
-
-  from CompositeType ct, int i, string name, Type tp
-  where component_types(ct, i, name, tp)
-  and not containsAliases(ct)
-  select ct, i, name, tp
\ No newline at end of file
+}
+
+/** A named type. */
+class NamedType extends @namedtype, CompositeType {
+  Type getBaseType() { underlying_type(this, result) }
+}
+
+/**
+ * The predeclared `comparable` type.
+ */
+class ComparableType extends NamedType {
+  ComparableType() { typename(this, "comparable") }
+}
+
+/** An alias type. */
+class AliasType extends @typealias, CompositeType {
+  /** Gets the aliased type (i.e. that appears on the RHS of the alias definition). */
+  Type getRhs() { alias_rhs(this, result) }
+
+  override Type getDeepUnaliasedType() { result = unalias(this).getDeepUnaliasedType() }
+}
+
+/**
+ * Gets the non-alias type at the end of the alias chain starting at `t`.
+ *
+ * If `t` is not an alias type then `result` is `t`.
+ */
+Type unalias(Type t) {
+  not t instanceof AliasType and result = t
+  or
+  result = unalias(t.(AliasType).getRhs())
+}
+
+predicate containsAliases(Type t) { t != t.getDeepUnaliasedType() }
+// END ALIASES.QLL
+from CompositeType ct, int i, string name, Type tp
+where
+  component_types(ct, i, name, tp) and
+  not containsAliases(ct)
+select ct, i, name, tp
diff --git a/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/element_type.ql b/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/element_type.ql
index 32b9d6bef107..8f9ad3912aba 100644
--- a/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/element_type.ql
+++ b/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/element_type.ql
@@ -2,577 +2,617 @@
 // Database scripts can't import, but this is the definitive copy of the support routines for mapping types to their unaliased equivalent. Ensure this code is in sync between aliases.qll and all copies in individual table .ql files.
 /** A Go type. */
 class Type extends @type {
-    /**
-     * Gets this type with all aliases substituted for their underlying type.
-     *
-     * Note named types are not substituted.
-     */
-    Type getDeepUnaliasedType() { result = this }
-  
-    /**
-     * Gets a basic textual representation of this type.
-     */
-    string toString() { result = "type" }
-  }
-  
-  /** A composite type, that is, not a basic type. */
-  class CompositeType extends @compositetype, Type { }
-  
-  /** An array type. */
-  class ArrayType extends @arraytype, CompositeType {
-    /** Gets the element type of this array type. */
-    Type getElementType() { element_type(this, result) }
-  
-    /** Gets the length of this array type as a string. */
-    string getLengthString() { array_length(this, result) }
-  
-    override ArrayType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType() and
-      result.getLengthString() = this.getLengthString()
-    }
+  /**
+   * Gets this type with all aliases substituted for their underlying type.
+   *
+   * Note named types are not substituted.
+   */
+  Type getDeepUnaliasedType() { result = this }
+
+  /**
+   * Gets a basic textual representation of this type.
+   */
+  string toString() { result = "type" }
+}
+
+/** A composite type, that is, not a basic type. */
+class CompositeType extends @compositetype, Type { }
+
+/** An array type. */
+class ArrayType extends @arraytype, CompositeType {
+  /** Gets the element type of this array type. */
+  Type getElementType() { element_type(this, result) }
+
+  /** Gets the length of this array type as a string. */
+  string getLengthString() { array_length(this, result) }
+
+  override ArrayType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType() and
+    result.getLengthString() = this.getLengthString()
   }
-  
-  /** A slice type. */
-  class SliceType extends @slicetype, CompositeType {
-    /** Gets the element type of this slice type. */
-    Type getElementType() { element_type(this, result) }
-  
-    override SliceType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
+}
+
+/** A slice type. */
+class SliceType extends @slicetype, CompositeType {
+  /** Gets the element type of this slice type. */
+  Type getElementType() { element_type(this, result) }
+
+  override SliceType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  // Improve efficiency of matching a struct to its unaliased equivalent
-  // by unpacking the first 5 fields and tags, allowing a single join
-  // to strongly constrain the available candidates.
-  private predicate hasComponentTypeAndTag(StructType s, int i, string name, Type tp, string tag) {
-    component_types(s, i, name, tp) and component_tags(s, i, tag)
+}
+
+// Improve efficiency of matching a struct to its unaliased equivalent
+// by unpacking the first 5 fields and tags, allowing a single join
+// to strongly constrain the available candidates.
+private predicate hasComponentTypeAndTag(StructType s, int i, string name, Type tp, string tag) {
+  component_types(s, i, name, tp) and component_tags(s, i, tag)
+}
+
+private newtype TOptStructComponent =
+  MkNoComponent() or
+  MkSomeComponent(string name, Type tp, string tag) { hasComponentTypeAndTag(_, _, name, tp, tag) }
+
+private class OptStructComponent extends TOptStructComponent {
+  OptStructComponent getWithDeepUnaliasedType() {
+    this = MkNoComponent() and result = MkNoComponent()
+    or
+    exists(string name, Type tp, string tag |
+      this = MkSomeComponent(name, tp, tag) and
+      result = MkSomeComponent(name, tp.getDeepUnaliasedType(), tag)
+    )
   }
-  
-  private newtype TOptStructComponent =
-    MkNoComponent() or
-    MkSomeComponent(string name, Type tp, string tag) { hasComponentTypeAndTag(_, _, name, tp, tag) }
-  
-  private class OptStructComponent extends TOptStructComponent {
-    OptStructComponent getWithDeepUnaliasedType() {
-      this = MkNoComponent() and result = MkNoComponent()
-      or
-      exists(string name, Type tp, string tag |
-        this = MkSomeComponent(name, tp, tag) and
-        result = MkSomeComponent(name, tp.getDeepUnaliasedType(), tag)
-      )
-    }
-  
-    string toString() { result = "struct component" }
+
+  string toString() { result = "struct component" }
+}
+
+private class StructComponent extends MkSomeComponent {
+  string toString() { result = "struct component" }
+
+  predicate isComponentOf(StructType s, int i) {
+    exists(string name, Type tp, string tag |
+      hasComponentTypeAndTag(s, i, name, tp, tag) and
+      this = MkSomeComponent(name, tp, tag)
+    )
   }
-  
-  private class StructComponent extends MkSomeComponent {
-    string toString() { result = "struct component" }
-  
-    predicate isComponentOf(StructType s, int i) {
-      exists(string name, Type tp, string tag |
-        hasComponentTypeAndTag(s, i, name, tp, tag) and
-        this = MkSomeComponent(name, tp, tag)
-      )
-    }
+}
+
+pragma[nomagic]
+predicate unpackStructType(
+  StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
+  TOptStructComponent c3, TOptStructComponent c4, int nComponents
+) {
+  nComponents = count(int i | component_types(s, i, _, _)) and
+  (
+    if nComponents >= 1
+    then c0 = any(StructComponent sc | sc.isComponentOf(s, 0))
+    else c0 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 2
+    then c1 = any(StructComponent sc | sc.isComponentOf(s, 1))
+    else c1 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 3
+    then c2 = any(StructComponent sc | sc.isComponentOf(s, 2))
+    else c2 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 4
+    then c3 = any(StructComponent sc | sc.isComponentOf(s, 3))
+    else c3 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 5
+    then c4 = any(StructComponent sc | sc.isComponentOf(s, 4))
+    else c4 = MkNoComponent()
+  )
+}
+
+pragma[nomagic]
+predicate unpackAndUnaliasStructType(
+  StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
+  TOptStructComponent c3, TOptStructComponent c4, int nComponents
+) {
+  exists(
+    OptStructComponent c0a, OptStructComponent c1a, OptStructComponent c2a, OptStructComponent c3a,
+    OptStructComponent c4a
+  |
+    unpackStructType(s, c0a, c1a, c2a, c3a, c4a, nComponents) and
+    c0 = c0a.getWithDeepUnaliasedType() and
+    c1 = c1a.getWithDeepUnaliasedType() and
+    c2 = c2a.getWithDeepUnaliasedType() and
+    c3 = c3a.getWithDeepUnaliasedType() and
+    c4 = c4a.getWithDeepUnaliasedType()
+  )
+}
+
+/** A struct type. */
+class StructType extends @structtype, CompositeType {
+  private StructType getDeepUnaliasedTypeCandidate() {
+    exists(
+      OptStructComponent c0, OptStructComponent c1, OptStructComponent c2, OptStructComponent c3,
+      OptStructComponent c4, int nComponents
+    |
+      unpackAndUnaliasStructType(this, c0, c1, c2, c3, c4, nComponents) and
+      unpackStructType(result, c0, c1, c2, c3, c4, nComponents)
+    )
   }
-  
-  pragma[nomagic]
-  predicate unpackStructType(
-    StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
-    TOptStructComponent c3, TOptStructComponent c4, int nComponents
-  ) {
-    nComponents = count(int i | component_types(s, i, _, _)) and
-    (
-      if nComponents >= 1
-      then c0 = any(StructComponent sc | sc.isComponentOf(s, 0))
-      else c0 = MkNoComponent()
-    ) and
-    (
-      if nComponents >= 2
-      then c1 = any(StructComponent sc | sc.isComponentOf(s, 1))
-      else c1 = MkNoComponent()
-    ) and
-    (
-      if nComponents >= 3
-      then c2 = any(StructComponent sc | sc.isComponentOf(s, 2))
-      else c2 = MkNoComponent()
-    ) and
+
+  private predicate isDeepUnaliasedTypeUpTo(StructType unaliased, int i) {
+    // Note we must use component_types not hasOwnField here because component_types may specify
+    // interface-in-struct embedding, but hasOwnField does not return such members.
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 5 and
     (
-      if nComponents >= 4
-      then c3 = any(StructComponent sc | sc.isComponentOf(s, 3))
-      else c3 = MkNoComponent()
+      i = 5 or
+      this.isDeepUnaliasedTypeUpTo(unaliased, i - 1)
     ) and
-    (
-      if nComponents >= 5
-      then c4 = any(StructComponent sc | sc.isComponentOf(s, 4))
-      else c4 = MkNoComponent()
+    exists(string name, Type tp, string tag | hasComponentTypeAndTag(this, i, name, tp, tag) |
+      hasComponentTypeAndTag(unaliased, i, name, tp.getDeepUnaliasedType(), tag)
     )
   }
-  
-  pragma[nomagic]
-  predicate unpackAndUnaliasStructType(
-    StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
-    TOptStructComponent c3, TOptStructComponent c4, int nComponents
-  ) {
-    exists(
-      OptStructComponent c0a, OptStructComponent c1a, OptStructComponent c2a, OptStructComponent c3a,
-      OptStructComponent c4a
-    |
-      unpackStructType(s, c0a, c1a, c2a, c3a, c4a, nComponents) and
-      c0 = c0a.getWithDeepUnaliasedType() and
-      c1 = c1a.getWithDeepUnaliasedType() and
-      c2 = c2a.getWithDeepUnaliasedType() and
-      c3 = c3a.getWithDeepUnaliasedType() and
-      c4 = c4a.getWithDeepUnaliasedType()
+
+  override StructType getDeepUnaliasedType() {
+    result = this.getDeepUnaliasedTypeCandidate() and
+    exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
+      this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
+      or
+      nComponents <= 5
     )
   }
-  
-  /** A struct type. */
-  class StructType extends @structtype, CompositeType {
-    private StructType getDeepUnaliasedTypeCandidate() {
-      exists(
-        OptStructComponent c0, OptStructComponent c1, OptStructComponent c2, OptStructComponent c3,
-        OptStructComponent c4, int nComponents
-      |
-        unpackAndUnaliasStructType(this, c0, c1, c2, c3, c4, nComponents) and
-        unpackStructType(result, c0, c1, c2, c3, c4, nComponents)
-      )
-    }
-  
-    private predicate isDeepUnaliasedTypeUpTo(StructType unaliased, int i) {
-      // Note we must use component_types not hasOwnField here because component_types may specify
-      // interface-in-struct embedding, but hasOwnField does not return such members.
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 5 and
-      (
-        i = 5 or
-        this.isDeepUnaliasedTypeUpTo(unaliased, i - 1)
-      ) and
-      exists(string name, Type tp, string tag | hasComponentTypeAndTag(this, i, name, tp, tag) |
-        hasComponentTypeAndTag(unaliased, i, name, tp.getDeepUnaliasedType(), tag)
-      )
-    }
-  
-    override StructType getDeepUnaliasedType() {
-      result = this.getDeepUnaliasedTypeCandidate() and
-      exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
-        this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
-        or
-        nComponents <= 5
-      )
-    }
+}
+
+/** A pointer type. */
+class PointerType extends @pointertype, CompositeType {
+  /** Gets the base type of this pointer type. */
+  Type getBaseType() { base_type(this, result) }
+
+  override PointerType getDeepUnaliasedType() {
+    result.getBaseType() = this.getBaseType().getDeepUnaliasedType()
   }
-  
-  /** A pointer type. */
-  class PointerType extends @pointertype, CompositeType {
-    /** Gets the base type of this pointer type. */
-    Type getBaseType() { base_type(this, result) }
-  
-    override PointerType getDeepUnaliasedType() {
-      result.getBaseType() = this.getBaseType().getDeepUnaliasedType()
-    }
+}
+
+private predicate isInterfaceComponentWithQualifiedName(
+  InterfaceType intf, int idx, string qualifiedName, Type tp
+) {
+  exists(string name | component_types(intf, idx, name, tp) |
+    interface_private_method_ids(intf, idx, qualifiedName)
+    or
+    not interface_private_method_ids(intf, idx, _) and qualifiedName = name
+  )
+}
+
+private newtype TOptInterfaceComponent =
+  MkNoIComponent() or
+  MkSomeIComponent(string name, Type tp) {
+    isInterfaceComponentWithQualifiedName(any(InterfaceType i), _, name, tp)
   }
-  
-  private newtype TOptInterfaceComponent =
-    MkNoIComponent() or
-    MkSomeIComponent(string name, Type tp) { component_types(any(InterfaceType i), _, name, tp) }
-  
-  private class OptInterfaceComponent extends TOptInterfaceComponent {
-    OptInterfaceComponent getWithDeepUnaliasedType() {
-      this = MkNoIComponent() and result = MkNoIComponent()
-      or
-      exists(string name, Type tp |
-        this = MkSomeIComponent(name, tp) and
-        result = MkSomeIComponent(name, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    string toString() { result = "interface component" }
+
+private class OptInterfaceComponent extends TOptInterfaceComponent {
+  OptInterfaceComponent getWithDeepUnaliasedType() {
+    this = MkNoIComponent() and result = MkNoIComponent()
+    or
+    exists(string name, Type tp |
+      this = MkSomeIComponent(name, tp) and
+      result = MkSomeIComponent(name, tp.getDeepUnaliasedType())
+    )
   }
-  
-  private class InterfaceComponent extends MkSomeIComponent {
-    string toString() { result = "interface component" }
-  
-    predicate isComponentOf(InterfaceType intf, int i) {
-      exists(string name, Type tp |
-        component_types(intf, i, name, tp) and
-        this = MkSomeIComponent(name, tp)
-      )
-    }
+
+  string toString() { result = "interface component" }
+}
+
+private class InterfaceComponent extends MkSomeIComponent {
+  string toString() { result = "interface component" }
+
+  predicate isComponentOf(InterfaceType intf, int i) {
+    exists(string name, Type tp |
+      isInterfaceComponentWithQualifiedName(intf, i, name, tp) and
+      this = MkSomeIComponent(name, tp)
+    )
   }
-  
-  pragma[nomagic]
-  predicate unpackInterfaceType(
-    InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
-    TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
-    TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds
-  ) {
-    nComponents = count(int i | component_types(intf, i, _, _) and i >= 0) and
-    nEmbeds = count(int i | component_types(intf, i, _, _) and i < 0) and
-    (
-      if nComponents >= 1
-      then c0 = any(InterfaceComponent ic | ic.isComponentOf(intf, 0))
-      else c0 = MkNoIComponent()
-    ) and
-    (
-      if nComponents >= 2
-      then c1 = any(InterfaceComponent ic | ic.isComponentOf(intf, 1))
-      else c1 = MkNoIComponent()
-    ) and
+}
+
+pragma[nomagic]
+predicate unpackInterfaceType(
+  InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
+  TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
+  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds,
+  boolean isComparable
+) {
+  nComponents = count(int i | isInterfaceComponentWithQualifiedName(intf, i, _, _) and i >= 0) and
+  nEmbeds = count(int i | isInterfaceComponentWithQualifiedName(intf, i, _, _) and i < 0) and
+  (
+    if intf = any(ComparableType comparable).getBaseType()
+    then isComparable = true
+    else isComparable = false
+  ) and
+  (
+    if nComponents >= 1
+    then c0 = any(InterfaceComponent ic | ic.isComponentOf(intf, 0))
+    else c0 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 2
+    then c1 = any(InterfaceComponent ic | ic.isComponentOf(intf, 1))
+    else c1 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 3
+    then c2 = any(InterfaceComponent ic | ic.isComponentOf(intf, 2))
+    else c2 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 4
+    then c3 = any(InterfaceComponent ic | ic.isComponentOf(intf, 3))
+    else c3 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 5
+    then c4 = any(InterfaceComponent ic | ic.isComponentOf(intf, 4))
+    else c4 = MkNoIComponent()
+  ) and
+  (
+    if nEmbeds >= 1
+    then e1 = any(InterfaceComponent ic | ic.isComponentOf(intf, -1))
+    else e1 = MkNoIComponent()
+  ) and
+  (
+    if nEmbeds >= 2
+    then e2 = any(InterfaceComponent ic | ic.isComponentOf(intf, -2))
+    else e2 = MkNoIComponent()
+  )
+}
+
+pragma[nomagic]
+predicate unpackAndUnaliasInterfaceType(
+  InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
+  TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
+  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds,
+  boolean isComparable
+) {
+  exists(
+    OptInterfaceComponent c0a, OptInterfaceComponent c1a, OptInterfaceComponent c2a,
+    OptInterfaceComponent c3a, OptInterfaceComponent c4a, OptInterfaceComponent e1a,
+    OptInterfaceComponent e2a
+  |
+    unpackInterfaceType(intf, c0a, c1a, c2a, c3a, c4a, e1a, e2a, nComponents, nEmbeds, isComparable) and
+    c0 = c0a.getWithDeepUnaliasedType() and
+    c1 = c1a.getWithDeepUnaliasedType() and
+    c2 = c2a.getWithDeepUnaliasedType() and
+    c3 = c3a.getWithDeepUnaliasedType() and
+    c4 = c4a.getWithDeepUnaliasedType() and
+    e1 = e1a.getWithDeepUnaliasedType() and
+    e2 = e2a.getWithDeepUnaliasedType()
+  )
+}
+
+/** An interface type. */
+class InterfaceType extends @interfacetype, CompositeType {
+  private Type getMethodType(int i, string name) {
+    i >= 0 and isInterfaceComponentWithQualifiedName(this, i, name, result)
+  }
+
+  /**
+   * Holds if `tp` is a directly embedded type with index `index`.
+   *
+   * `tp` (or its underlying type) is either a type set literal type or an
+   * interface type.
+   */
+  private predicate hasDirectlyEmbeddedType(int index, Type tp) {
+    index >= 0 and isInterfaceComponentWithQualifiedName(this, -(index + 1), _, tp)
+  }
+
+  private InterfaceType getDeepUnaliasedTypeCandidate() {
+    exists(
+      OptInterfaceComponent c0, OptInterfaceComponent c1, OptInterfaceComponent c2,
+      OptInterfaceComponent c3, OptInterfaceComponent c4, OptInterfaceComponent e1,
+      OptInterfaceComponent e2, int nComponents, int nEmbeds, boolean isComparable
+    |
+      unpackAndUnaliasInterfaceType(this, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds,
+        isComparable) and
+      unpackInterfaceType(result, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds, isComparable)
+    )
+  }
+
+  private predicate hasDeepUnaliasedComponentTypesUpTo(InterfaceType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 5 and
     (
-      if nComponents >= 3
-      then c2 = any(InterfaceComponent ic | ic.isComponentOf(intf, 2))
-      else c2 = MkNoIComponent()
+      i = 5 or
+      this.hasDeepUnaliasedComponentTypesUpTo(unaliased, i - 1)
     ) and
+    exists(string name |
+      unaliased.getMethodType(i, name) = this.getMethodType(i, name).getDeepUnaliasedType()
+    )
+  }
+
+  private predicate hasDeepUnaliasedEmbeddedTypesUpTo(InterfaceType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 2 and
     (
-      if nComponents >= 4
-      then c3 = any(InterfaceComponent ic | ic.isComponentOf(intf, 3))
-      else c3 = MkNoIComponent()
+      i = 2 or
+      this.hasDeepUnaliasedEmbeddedTypesUpTo(unaliased, i - 1)
     ) and
-    (
-      if nComponents >= 5
-      then c4 = any(InterfaceComponent ic | ic.isComponentOf(intf, 4))
-      else c4 = MkNoIComponent()
+    exists(Type tp | this.hasDirectlyEmbeddedType(i, tp) |
+      unaliased.hasDirectlyEmbeddedType(i, tp.getDeepUnaliasedType())
+    )
+  }
+
+  override InterfaceType getDeepUnaliasedType() {
+    result = this.getDeepUnaliasedTypeCandidate() and
+    exists(int nComponents | nComponents = count(int i | exists(this.getMethodType(i, _))) |
+      this.hasDeepUnaliasedComponentTypesUpTo(result, nComponents - 1)
+      or
+      nComponents <= 5
     ) and
+    exists(int nEmbeds | nEmbeds = count(int i | this.hasDirectlyEmbeddedType(i, _)) |
+      this.hasDeepUnaliasedEmbeddedTypesUpTo(result, nEmbeds - 1)
+      or
+      nEmbeds <= 2
+    )
+  }
+}
+
+pragma[nomagic]
+private predicate unpackTupleType(
+  TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
+) {
+  nComponents = count(int i | component_types(tt, i, _, _)) and
+  (if nComponents >= 1 then c0 = MkSomeType(tt.getComponentType(0)) else c0 = MkNoType()) and
+  (if nComponents >= 2 then c1 = MkSomeType(tt.getComponentType(1)) else c1 = MkNoType()) and
+  (if nComponents >= 3 then c2 = MkSomeType(tt.getComponentType(2)) else c2 = MkNoType())
+}
+
+pragma[nomagic]
+private predicate unpackAndUnaliasTupleType(
+  TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
+) {
+  exists(OptType c0a, OptType c1a, OptType c2a |
+    unpackTupleType(tt, c0a, c1a, c2a, nComponents) and
+    c0 = c0a.getDeepUnaliasedType() and
+    c1 = c1a.getDeepUnaliasedType() and
+    c2 = c2a.getDeepUnaliasedType()
+  )
+}
+
+/** A tuple type. */
+class TupleType extends @tupletype, CompositeType {
+  /** Gets the `i`th component type of this tuple type. */
+  Type getComponentType(int i) { component_types(this, i, _, result) }
+
+  private TupleType getCandidateDeepUnaliasedType() {
+    exists(OptType c0, OptType c1, OptType c2, int nComponents |
+      unpackAndUnaliasTupleType(this, c0, c1, c2, nComponents) and
+      unpackTupleType(result, c0, c1, c2, nComponents)
+    )
+  }
+
+  private predicate isDeepUnaliasedTypeUpTo(TupleType tt, int i) {
+    tt = this.getCandidateDeepUnaliasedType() and
+    i >= 3 and
     (
-      if nEmbeds >= 1
-      then e1 = any(InterfaceComponent ic | ic.isComponentOf(intf, -1))
-      else e1 = MkNoIComponent()
+      i = 3
+      or
+      this.isDeepUnaliasedTypeUpTo(tt, i - 1)
     ) and
-    (
-      if nEmbeds >= 2
-      then e2 = any(InterfaceComponent ic | ic.isComponentOf(intf, -2))
-      else e2 = MkNoIComponent()
+    tt.getComponentType(i) = this.getComponentType(i).getDeepUnaliasedType()
+  }
+
+  override TupleType getDeepUnaliasedType() {
+    result = this.getCandidateDeepUnaliasedType() and
+    exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
+      this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
+      or
+      nComponents <= 3
     )
   }
-  
-  pragma[nomagic]
-  predicate unpackAndUnaliasInterfaceType(
-    InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
-    TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
-    TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds
-  ) {
+}
+
+// Reasonably efficiently map from a signature type to its
+// deep-unaliased equivalent, by using a single join for the leading 5 parameters
+// and/or 3 results.
+private newtype TOptType =
+  MkNoType() or
+  MkSomeType(Type tp)
+
+private class OptType extends TOptType {
+  OptType getDeepUnaliasedType() {
+    exists(Type t | this = MkSomeType(t) | result = MkSomeType(t.getDeepUnaliasedType()))
+    or
+    this = MkNoType() and result = MkNoType()
+  }
+
+  string toString() {
+    exists(Type t | this = MkSomeType(t) | result = t.toString())
+    or
+    this = MkNoType() and result = "no type"
+  }
+}
+
+pragma[nomagic]
+private predicate unpackSignatureType(
+  SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
+  int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
+) {
+  nParams = sig.getNumParameter() and
+  nResults = sig.getNumResult() and
+  (if nParams >= 1 then param0 = MkSomeType(sig.getParameterType(0)) else param0 = MkNoType()) and
+  (if nParams >= 2 then param1 = MkSomeType(sig.getParameterType(1)) else param1 = MkNoType()) and
+  (if nParams >= 3 then param2 = MkSomeType(sig.getParameterType(2)) else param2 = MkNoType()) and
+  (if nParams >= 4 then param3 = MkSomeType(sig.getParameterType(3)) else param3 = MkNoType()) and
+  (if nParams >= 5 then param4 = MkSomeType(sig.getParameterType(4)) else param4 = MkNoType()) and
+  (if nResults >= 1 then result0 = MkSomeType(sig.getResultType(0)) else result0 = MkNoType()) and
+  (if nResults >= 2 then result1 = MkSomeType(sig.getResultType(1)) else result1 = MkNoType()) and
+  (if nResults >= 3 then result2 = MkSomeType(sig.getResultType(2)) else result2 = MkNoType()) and
+  (if sig.isVariadic() then isVariadic = true else isVariadic = false)
+}
+
+pragma[nomagic]
+private predicate unpackAndUnaliasSignatureType(
+  SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
+  int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
+) {
+  exists(
+    OptType param0a, OptType param1a, OptType param2a, OptType param3a, OptType param4a,
+    OptType result0a, OptType result1a, OptType result2a
+  |
+    unpackSignatureType(sig, param0a, param1a, param2a, param3a, param4a, nParams, result0a,
+      result1a, result2a, nResults, isVariadic)
+  |
+    param0 = param0a.getDeepUnaliasedType() and
+    param1 = param1a.getDeepUnaliasedType() and
+    param2 = param2a.getDeepUnaliasedType() and
+    param3 = param3a.getDeepUnaliasedType() and
+    param4 = param4a.getDeepUnaliasedType() and
+    result0 = result0a.getDeepUnaliasedType() and
+    result1 = result1a.getDeepUnaliasedType() and
+    result2 = result2a.getDeepUnaliasedType()
+  )
+}
+
+/** A signature type. */
+class SignatureType extends @signaturetype, CompositeType {
+  /** Gets the `i`th parameter type of this signature type. */
+  Type getParameterType(int i) { i >= 0 and component_types(this, i + 1, _, result) }
+
+  /** Gets the `i`th result type of this signature type. */
+  Type getResultType(int i) { i >= 0 and component_types(this, -(i + 1), _, result) }
+
+  /** Gets the number of parameters specified by this signature. */
+  int getNumParameter() { result = count(int i | exists(this.getParameterType(i))) }
+
+  /** Gets the number of results specified by this signature. */
+  int getNumResult() { result = count(int i | exists(this.getResultType(i))) }
+
+  /** Holds if this signature type is variadic. */
+  predicate isVariadic() { variadic(this) }
+
+  private SignatureType getDeepUnaliasedTypeCandidate() {
     exists(
-      OptInterfaceComponent c0a, OptInterfaceComponent c1a, OptInterfaceComponent c2a,
-      OptInterfaceComponent c3a, OptInterfaceComponent c4a, OptInterfaceComponent e1a,
-      OptInterfaceComponent e2a
+      OptType param0, OptType param1, OptType param2, OptType param3, OptType param4, int nParams,
+      OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
     |
-      unpackInterfaceType(intf, c0a, c1a, c2a, c3a, c4a, e1a, e2a, nComponents, nEmbeds) and
-      c0 = c0a.getWithDeepUnaliasedType() and
-      c1 = c1a.getWithDeepUnaliasedType() and
-      c2 = c2a.getWithDeepUnaliasedType() and
-      c3 = c3a.getWithDeepUnaliasedType() and
-      c4 = c4a.getWithDeepUnaliasedType() and
-      e1 = e1a.getWithDeepUnaliasedType() and
-      e2 = e2a.getWithDeepUnaliasedType()
+      unpackAndUnaliasSignatureType(this, param0, param1, param2, param3, param4, nParams, result0,
+        result1, result2, nResults, isVariadic) and
+      unpackSignatureType(result, param0, param1, param2, param3, param4, nParams, result0, result1,
+        result2, nResults, isVariadic)
     )
   }
-  
-  /** An interface type. */
-  class InterfaceType extends @interfacetype, CompositeType {
-    private InterfaceType getDeepUnaliasedTypeCandidate() {
-      exists(
-        OptInterfaceComponent c0, OptInterfaceComponent c1, OptInterfaceComponent c2,
-        OptInterfaceComponent c3, OptInterfaceComponent c4, OptInterfaceComponent e1,
-        OptInterfaceComponent e2, int nComponents, int nEmbeds
-      |
-        unpackAndUnaliasInterfaceType(this, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds) and
-        unpackInterfaceType(result, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds)
-      )
-    }
-  
-    private predicate hasDeepUnaliasedComponentTypesUpTo(InterfaceType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 5 and
-      (
-        i = 5 or
-        this.hasDeepUnaliasedComponentTypesUpTo(unaliased, i - 1)
-      ) and
-      exists(string name, Type tp | component_types(this, i, name, tp) |
-        component_types(unaliased, i, name, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    private predicate hasDeepUnaliasedEmbeddedTypesUpTo(InterfaceType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 3 and
-      (
-        i = 3 or
-        this.hasDeepUnaliasedEmbeddedTypesUpTo(unaliased, i - 1)
-      ) and
-      exists(string name, Type tp | component_types(this, -i, name, tp) |
-        component_types(unaliased, -i, name, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    override InterfaceType getDeepUnaliasedType() {
-      result = this.getDeepUnaliasedTypeCandidate() and
-      exists(int nComponents |
-        nComponents = count(int i | component_types(this, i, _, _) and i >= 0)
-      |
-        this.hasDeepUnaliasedComponentTypesUpTo(result, nComponents - 1)
-        or
-        nComponents <= 5
-      ) and
-      exists(int nEmbeds | nEmbeds = count(int i | component_types(this, i, _, _) and i < 0) |
-        // Note no -1 here, because the first embedded type is at -1
-        this.hasDeepUnaliasedEmbeddedTypesUpTo(result, nEmbeds)
-        or
-        nEmbeds <= 2
-      )
-    }
-  }
-  
-  pragma[nomagic]
-  private predicate unpackTupleType(
-    TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
-  ) {
-    nComponents = count(int i | component_types(tt, i, _, _)) and
-    (if nComponents >= 1 then c0 = MkSomeType(tt.getComponentType(0)) else c0 = MkNoType()) and
-    (if nComponents >= 2 then c1 = MkSomeType(tt.getComponentType(1)) else c1 = MkNoType()) and
-    (if nComponents >= 3 then c2 = MkSomeType(tt.getComponentType(2)) else c2 = MkNoType())
+
+  // These incremental recursive implementations only apply from parameter 5 or result 3
+  // upwards to avoid constructing large squares of candidates -- the initial parameters
+  // and results are taken care of by the candidate predicate.
+  private predicate hasDeepUnaliasedParameterTypesUpTo(SignatureType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 5 and
+    (i = 5 or this.hasDeepUnaliasedParameterTypesUpTo(unaliased, i - 1)) and
+    unaliased.getParameterType(i) = this.getParameterType(i).getDeepUnaliasedType()
   }
-  
-  pragma[nomagic]
-  private predicate unpackAndUnaliasTupleType(
-    TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
-  ) {
-    exists(OptType c0a, OptType c1a, OptType c2a |
-      unpackTupleType(tt, c0a, c1a, c2a, nComponents) and
-      c0 = c0a.getDeepUnaliasedType() and
-      c1 = c1a.getDeepUnaliasedType() and
-      c2 = c2a.getDeepUnaliasedType()
-    )
+
+  private predicate hasDeepUnaliasedResultTypesUpTo(SignatureType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 3 and
+    (i = 3 or this.hasDeepUnaliasedResultTypesUpTo(unaliased, i - 1)) and
+    unaliased.getResultType(i) = this.getResultType(i).getDeepUnaliasedType()
   }
-  
-  /** A tuple type. */
-  class TupleType extends @tupletype, CompositeType {
-    /** Gets the `i`th component type of this tuple type. */
-    Type getComponentType(int i) { component_types(this, i, _, result) }
-  
-    private TupleType getCandidateDeepUnaliasedType() {
-      exists(OptType c0, OptType c1, OptType c2, int nComponents |
-        unpackAndUnaliasTupleType(this, c0, c1, c2, nComponents) and
-        unpackTupleType(result, c0, c1, c2, nComponents)
-      )
-    }
-  
-    private predicate isDeepUnaliasedTypeUpTo(TupleType tt, int i) {
-      tt = this.getCandidateDeepUnaliasedType() and
-      i >= 3 and
+
+  override SignatureType getDeepUnaliasedType() {
+    result = this.getDeepUnaliasedTypeCandidate() and
+    exists(int nParams, int nResults |
+      this.getNumParameter() = nParams and this.getNumResult() = nResults
+    |
       (
-        i = 3
+        nParams <= 5
         or
-        this.isDeepUnaliasedTypeUpTo(tt, i - 1)
+        this.hasDeepUnaliasedParameterTypesUpTo(result, nParams - 1)
       ) and
-      exists(Type tp | component_types(this, i, _, tp) |
-        component_types(tt, i, _, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    override TupleType getDeepUnaliasedType() {
-      result = this.getCandidateDeepUnaliasedType() and
-      exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
-        this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
+      (
+        nResults <= 3
         or
-        nComponents <= 3
+        this.hasDeepUnaliasedResultTypesUpTo(result, nResults - 1)
       )
-    }
-  }
-  
-  // Reasonably efficiently map from a signature type to its
-  // deep-unaliased equivalent, by using a single join for the leading 5 parameters
-  // and/or 3 results.
-  private newtype TOptType =
-    MkNoType() or
-    MkSomeType(Type tp)
-  
-  private class OptType extends TOptType {
-    OptType getDeepUnaliasedType() {
-      exists(Type t | this = MkSomeType(t) | result = MkSomeType(t.getDeepUnaliasedType()))
-      or
-      this = MkNoType() and result = MkNoType()
-    }
-  
-    string toString() {
-      exists(Type t | this = MkSomeType(t) | result = t.toString())
-      or
-      this = MkNoType() and result = "no type"
-    }
-  }
-  
-  pragma[nomagic]
-  private predicate unpackSignatureType(
-    SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
-    int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
-  ) {
-    nParams = sig.getNumParameter() and
-    nResults = sig.getNumResult() and
-    (if nParams >= 1 then param0 = MkSomeType(sig.getParameterType(0)) else param0 = MkNoType()) and
-    (if nParams >= 2 then param1 = MkSomeType(sig.getParameterType(1)) else param1 = MkNoType()) and
-    (if nParams >= 3 then param2 = MkSomeType(sig.getParameterType(2)) else param2 = MkNoType()) and
-    (if nParams >= 4 then param3 = MkSomeType(sig.getParameterType(3)) else param3 = MkNoType()) and
-    (if nParams >= 5 then param4 = MkSomeType(sig.getParameterType(4)) else param4 = MkNoType()) and
-    (if nResults >= 1 then result0 = MkSomeType(sig.getResultType(0)) else result0 = MkNoType()) and
-    (if nResults >= 2 then result1 = MkSomeType(sig.getResultType(1)) else result1 = MkNoType()) and
-    (if nResults >= 3 then result2 = MkSomeType(sig.getResultType(2)) else result2 = MkNoType()) and
-    (if sig.isVariadic() then isVariadic = true else isVariadic = false)
-  }
-  
-  pragma[nomagic]
-  private predicate unpackAndUnaliasSignatureType(
-    SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
-    int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
-  ) {
-    exists(
-      OptType param0a, OptType param1a, OptType param2a, OptType param3a, OptType param4a,
-      OptType result0a, OptType result1a, OptType result2a
-    |
-      unpackSignatureType(sig, param0a, param1a, param2a, param3a, param4a, nParams, result0a,
-        result1a, result2a, nResults, isVariadic)
-    |
-      param0 = param0a.getDeepUnaliasedType() and
-      param1 = param1a.getDeepUnaliasedType() and
-      param2 = param2a.getDeepUnaliasedType() and
-      param3 = param3a.getDeepUnaliasedType() and
-      param4 = param4a.getDeepUnaliasedType() and
-      result0 = result0a.getDeepUnaliasedType() and
-      result1 = result1a.getDeepUnaliasedType() and
-      result2 = result2a.getDeepUnaliasedType()
     )
   }
-  
-  /** A signature type. */
-  class SignatureType extends @signaturetype, CompositeType {
-    /** Gets the `i`th parameter type of this signature type. */
-    Type getParameterType(int i) { i >= 0 and component_types(this, i + 1, _, result) }
-  
-    /** Gets the `i`th result type of this signature type. */
-    Type getResultType(int i) { i >= 0 and component_types(this, -(i + 1), _, result) }
-  
-    /** Gets the number of parameters specified by this signature. */
-    int getNumParameter() { result = count(int i | exists(this.getParameterType(i))) }
-  
-    /** Gets the number of results specified by this signature. */
-    int getNumResult() { result = count(int i | exists(this.getResultType(i))) }
-  
-    /** Holds if this signature type is variadic. */
-    predicate isVariadic() { variadic(this) }
-  
-    private SignatureType getDeepUnaliasedTypeCandidate() {
-      exists(
-        OptType param0, OptType param1, OptType param2, OptType param3, OptType param4, int nParams,
-        OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
-      |
-        unpackAndUnaliasSignatureType(this, param0, param1, param2, param3, param4, nParams, result0,
-          result1, result2, nResults, isVariadic) and
-        unpackSignatureType(result, param0, param1, param2, param3, param4, nParams, result0, result1,
-          result2, nResults, isVariadic)
-      )
-    }
-  
-    // These incremental recursive implementations only apply from parameter 5 or result 3
-    // upwards to avoid constructing large squares of candidates -- the initial parameters
-    // and results are taken care of by the candidate predicate.
-    private predicate hasDeepUnaliasedParameterTypesUpTo(SignatureType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 5 and
-      (i = 5 or this.hasDeepUnaliasedParameterTypesUpTo(unaliased, i - 1)) and
-      unaliased.getParameterType(i) = this.getParameterType(i).getDeepUnaliasedType()
-    }
-  
-    private predicate hasDeepUnaliasedResultTypesUpTo(SignatureType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 3 and
-      (i = 3 or this.hasDeepUnaliasedResultTypesUpTo(unaliased, i - 1)) and
-      unaliased.getResultType(i) = this.getResultType(i).getDeepUnaliasedType()
-    }
-  
-    override SignatureType getDeepUnaliasedType() {
-      result = this.getDeepUnaliasedTypeCandidate() and
-      exists(int nParams, int nResults |
-        this.getNumParameter() = nParams and this.getNumResult() = nResults
-      |
-        (
-          nParams <= 5
-          or
-          this.hasDeepUnaliasedParameterTypesUpTo(result, nParams - 1)
-        ) and
-        (
-          nResults <= 3
-          or
-          this.hasDeepUnaliasedResultTypesUpTo(result, nResults - 1)
-        )
-      )
-    }
-  }
-  
-  /** A map type. */
-  class MapType extends @maptype, CompositeType {
-    /** Gets the key type of this map type. */
-    Type getKeyType() { key_type(this, result) }
-  
-    /** Gets the value type of this map type. */
-    Type getValueType() { element_type(this, result) }
-  
-    override MapType getDeepUnaliasedType() {
-      result.getKeyType() = this.getKeyType().getDeepUnaliasedType() and
-      result.getValueType() = this.getValueType().getDeepUnaliasedType()
-    }
-  }
-  
-  /** A channel type. */
-  class ChanType extends @chantype, CompositeType {
-    /** Gets the element type of this channel type. */
-    Type getElementType() { element_type(this, result) }
-  }
-  
-  /** A channel type that can only send. */
-  class SendChanType extends @sendchantype, ChanType {
-    override SendChanType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
-  }
-  
-  /** A channel type that can only receive. */
-  class RecvChanType extends @recvchantype, ChanType {
-    override RecvChanType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
+}
+
+/** A map type. */
+class MapType extends @maptype, CompositeType {
+  /** Gets the key type of this map type. */
+  Type getKeyType() { key_type(this, result) }
+
+  /** Gets the value type of this map type. */
+  Type getValueType() { element_type(this, result) }
+
+  override MapType getDeepUnaliasedType() {
+    result.getKeyType() = this.getKeyType().getDeepUnaliasedType() and
+    result.getValueType() = this.getValueType().getDeepUnaliasedType()
   }
-  
-  /** A channel type that can both send and receive. */
-  class SendRecvChanType extends @sendrcvchantype, ChanType {
-    override SendRecvChanType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
+}
+
+/** A channel type. */
+class ChanType extends @chantype, CompositeType {
+  /** Gets the element type of this channel type. */
+  Type getElementType() { element_type(this, result) }
+}
+
+/** A channel type that can only send. */
+class SendChanType extends @sendchantype, ChanType {
+  override SendChanType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  /** An alias type. */
-  class AliasType extends @typealias, CompositeType {
-    /** Gets the aliased type (i.e. that appears on the RHS of the alias definition). */
-    Type getRhs() { alias_rhs(this, result) }
-  
-    override Type getDeepUnaliasedType() { result = unalias(this).getDeepUnaliasedType() }
+}
+
+/** A channel type that can only receive. */
+class RecvChanType extends @recvchantype, ChanType {
+  override RecvChanType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  /**
-   * Gets the non-alias type at the end of the alias chain starting at `t`.
-   *
-   * If `t` is not an alias type then `result` is `t`.
-   */
-  Type unalias(Type t) {
-    not t instanceof AliasType and result = t
-    or
-    result = unalias(t.(AliasType).getRhs())
+}
+
+/** A channel type that can both send and receive. */
+class SendRecvChanType extends @sendrcvchantype, ChanType {
+  override SendRecvChanType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  predicate containsAliases(Type t) { t != t.getDeepUnaliasedType() }
-  // END ALIASES.QLL
-  
-
-  from CompositeType ct, Type et
-  where element_type(ct, et)
-  and not containsAliases(ct)
-  select ct, et
\ No newline at end of file
+}
+
+/** A named type. */
+class NamedType extends @namedtype, CompositeType {
+  Type getBaseType() { underlying_type(this, result) }
+}
+
+/**
+ * The predeclared `comparable` type.
+ */
+class ComparableType extends NamedType {
+  ComparableType() { typename(this, "comparable") }
+}
+
+/** An alias type. */
+class AliasType extends @typealias, CompositeType {
+  /** Gets the aliased type (i.e. that appears on the RHS of the alias definition). */
+  Type getRhs() { alias_rhs(this, result) }
+
+  override Type getDeepUnaliasedType() { result = unalias(this).getDeepUnaliasedType() }
+}
+
+/**
+ * Gets the non-alias type at the end of the alias chain starting at `t`.
+ *
+ * If `t` is not an alias type then `result` is `t`.
+ */
+Type unalias(Type t) {
+  not t instanceof AliasType and result = t
+  or
+  result = unalias(t.(AliasType).getRhs())
+}
+
+predicate containsAliases(Type t) { t != t.getDeepUnaliasedType() }
+// END ALIASES.QLL
+from CompositeType ct, Type et
+where
+  element_type(ct, et) and
+  not containsAliases(ct)
+select ct, et
diff --git a/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/key_type.ql b/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/key_type.ql
index 8d1fe2f1ae5f..36748ad1825b 100644
--- a/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/key_type.ql
+++ b/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/key_type.ql
@@ -2,577 +2,617 @@
 // Database scripts can't import, but this is the definitive copy of the support routines for mapping types to their unaliased equivalent. Ensure this code is in sync between aliases.qll and all copies in individual table .ql files.
 /** A Go type. */
 class Type extends @type {
-    /**
-     * Gets this type with all aliases substituted for their underlying type.
-     *
-     * Note named types are not substituted.
-     */
-    Type getDeepUnaliasedType() { result = this }
-  
-    /**
-     * Gets a basic textual representation of this type.
-     */
-    string toString() { result = "type" }
-  }
-  
-  /** A composite type, that is, not a basic type. */
-  class CompositeType extends @compositetype, Type { }
-  
-  /** An array type. */
-  class ArrayType extends @arraytype, CompositeType {
-    /** Gets the element type of this array type. */
-    Type getElementType() { element_type(this, result) }
-  
-    /** Gets the length of this array type as a string. */
-    string getLengthString() { array_length(this, result) }
-  
-    override ArrayType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType() and
-      result.getLengthString() = this.getLengthString()
-    }
+  /**
+   * Gets this type with all aliases substituted for their underlying type.
+   *
+   * Note named types are not substituted.
+   */
+  Type getDeepUnaliasedType() { result = this }
+
+  /**
+   * Gets a basic textual representation of this type.
+   */
+  string toString() { result = "type" }
+}
+
+/** A composite type, that is, not a basic type. */
+class CompositeType extends @compositetype, Type { }
+
+/** An array type. */
+class ArrayType extends @arraytype, CompositeType {
+  /** Gets the element type of this array type. */
+  Type getElementType() { element_type(this, result) }
+
+  /** Gets the length of this array type as a string. */
+  string getLengthString() { array_length(this, result) }
+
+  override ArrayType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType() and
+    result.getLengthString() = this.getLengthString()
   }
-  
-  /** A slice type. */
-  class SliceType extends @slicetype, CompositeType {
-    /** Gets the element type of this slice type. */
-    Type getElementType() { element_type(this, result) }
-  
-    override SliceType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
+}
+
+/** A slice type. */
+class SliceType extends @slicetype, CompositeType {
+  /** Gets the element type of this slice type. */
+  Type getElementType() { element_type(this, result) }
+
+  override SliceType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  // Improve efficiency of matching a struct to its unaliased equivalent
-  // by unpacking the first 5 fields and tags, allowing a single join
-  // to strongly constrain the available candidates.
-  private predicate hasComponentTypeAndTag(StructType s, int i, string name, Type tp, string tag) {
-    component_types(s, i, name, tp) and component_tags(s, i, tag)
+}
+
+// Improve efficiency of matching a struct to its unaliased equivalent
+// by unpacking the first 5 fields and tags, allowing a single join
+// to strongly constrain the available candidates.
+private predicate hasComponentTypeAndTag(StructType s, int i, string name, Type tp, string tag) {
+  component_types(s, i, name, tp) and component_tags(s, i, tag)
+}
+
+private newtype TOptStructComponent =
+  MkNoComponent() or
+  MkSomeComponent(string name, Type tp, string tag) { hasComponentTypeAndTag(_, _, name, tp, tag) }
+
+private class OptStructComponent extends TOptStructComponent {
+  OptStructComponent getWithDeepUnaliasedType() {
+    this = MkNoComponent() and result = MkNoComponent()
+    or
+    exists(string name, Type tp, string tag |
+      this = MkSomeComponent(name, tp, tag) and
+      result = MkSomeComponent(name, tp.getDeepUnaliasedType(), tag)
+    )
   }
-  
-  private newtype TOptStructComponent =
-    MkNoComponent() or
-    MkSomeComponent(string name, Type tp, string tag) { hasComponentTypeAndTag(_, _, name, tp, tag) }
-  
-  private class OptStructComponent extends TOptStructComponent {
-    OptStructComponent getWithDeepUnaliasedType() {
-      this = MkNoComponent() and result = MkNoComponent()
-      or
-      exists(string name, Type tp, string tag |
-        this = MkSomeComponent(name, tp, tag) and
-        result = MkSomeComponent(name, tp.getDeepUnaliasedType(), tag)
-      )
-    }
-  
-    string toString() { result = "struct component" }
+
+  string toString() { result = "struct component" }
+}
+
+private class StructComponent extends MkSomeComponent {
+  string toString() { result = "struct component" }
+
+  predicate isComponentOf(StructType s, int i) {
+    exists(string name, Type tp, string tag |
+      hasComponentTypeAndTag(s, i, name, tp, tag) and
+      this = MkSomeComponent(name, tp, tag)
+    )
   }
-  
-  private class StructComponent extends MkSomeComponent {
-    string toString() { result = "struct component" }
-  
-    predicate isComponentOf(StructType s, int i) {
-      exists(string name, Type tp, string tag |
-        hasComponentTypeAndTag(s, i, name, tp, tag) and
-        this = MkSomeComponent(name, tp, tag)
-      )
-    }
+}
+
+pragma[nomagic]
+predicate unpackStructType(
+  StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
+  TOptStructComponent c3, TOptStructComponent c4, int nComponents
+) {
+  nComponents = count(int i | component_types(s, i, _, _)) and
+  (
+    if nComponents >= 1
+    then c0 = any(StructComponent sc | sc.isComponentOf(s, 0))
+    else c0 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 2
+    then c1 = any(StructComponent sc | sc.isComponentOf(s, 1))
+    else c1 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 3
+    then c2 = any(StructComponent sc | sc.isComponentOf(s, 2))
+    else c2 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 4
+    then c3 = any(StructComponent sc | sc.isComponentOf(s, 3))
+    else c3 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 5
+    then c4 = any(StructComponent sc | sc.isComponentOf(s, 4))
+    else c4 = MkNoComponent()
+  )
+}
+
+pragma[nomagic]
+predicate unpackAndUnaliasStructType(
+  StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
+  TOptStructComponent c3, TOptStructComponent c4, int nComponents
+) {
+  exists(
+    OptStructComponent c0a, OptStructComponent c1a, OptStructComponent c2a, OptStructComponent c3a,
+    OptStructComponent c4a
+  |
+    unpackStructType(s, c0a, c1a, c2a, c3a, c4a, nComponents) and
+    c0 = c0a.getWithDeepUnaliasedType() and
+    c1 = c1a.getWithDeepUnaliasedType() and
+    c2 = c2a.getWithDeepUnaliasedType() and
+    c3 = c3a.getWithDeepUnaliasedType() and
+    c4 = c4a.getWithDeepUnaliasedType()
+  )
+}
+
+/** A struct type. */
+class StructType extends @structtype, CompositeType {
+  private StructType getDeepUnaliasedTypeCandidate() {
+    exists(
+      OptStructComponent c0, OptStructComponent c1, OptStructComponent c2, OptStructComponent c3,
+      OptStructComponent c4, int nComponents
+    |
+      unpackAndUnaliasStructType(this, c0, c1, c2, c3, c4, nComponents) and
+      unpackStructType(result, c0, c1, c2, c3, c4, nComponents)
+    )
   }
-  
-  pragma[nomagic]
-  predicate unpackStructType(
-    StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
-    TOptStructComponent c3, TOptStructComponent c4, int nComponents
-  ) {
-    nComponents = count(int i | component_types(s, i, _, _)) and
-    (
-      if nComponents >= 1
-      then c0 = any(StructComponent sc | sc.isComponentOf(s, 0))
-      else c0 = MkNoComponent()
-    ) and
-    (
-      if nComponents >= 2
-      then c1 = any(StructComponent sc | sc.isComponentOf(s, 1))
-      else c1 = MkNoComponent()
-    ) and
-    (
-      if nComponents >= 3
-      then c2 = any(StructComponent sc | sc.isComponentOf(s, 2))
-      else c2 = MkNoComponent()
-    ) and
+
+  private predicate isDeepUnaliasedTypeUpTo(StructType unaliased, int i) {
+    // Note we must use component_types not hasOwnField here because component_types may specify
+    // interface-in-struct embedding, but hasOwnField does not return such members.
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 5 and
     (
-      if nComponents >= 4
-      then c3 = any(StructComponent sc | sc.isComponentOf(s, 3))
-      else c3 = MkNoComponent()
+      i = 5 or
+      this.isDeepUnaliasedTypeUpTo(unaliased, i - 1)
     ) and
-    (
-      if nComponents >= 5
-      then c4 = any(StructComponent sc | sc.isComponentOf(s, 4))
-      else c4 = MkNoComponent()
+    exists(string name, Type tp, string tag | hasComponentTypeAndTag(this, i, name, tp, tag) |
+      hasComponentTypeAndTag(unaliased, i, name, tp.getDeepUnaliasedType(), tag)
     )
   }
-  
-  pragma[nomagic]
-  predicate unpackAndUnaliasStructType(
-    StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
-    TOptStructComponent c3, TOptStructComponent c4, int nComponents
-  ) {
-    exists(
-      OptStructComponent c0a, OptStructComponent c1a, OptStructComponent c2a, OptStructComponent c3a,
-      OptStructComponent c4a
-    |
-      unpackStructType(s, c0a, c1a, c2a, c3a, c4a, nComponents) and
-      c0 = c0a.getWithDeepUnaliasedType() and
-      c1 = c1a.getWithDeepUnaliasedType() and
-      c2 = c2a.getWithDeepUnaliasedType() and
-      c3 = c3a.getWithDeepUnaliasedType() and
-      c4 = c4a.getWithDeepUnaliasedType()
+
+  override StructType getDeepUnaliasedType() {
+    result = this.getDeepUnaliasedTypeCandidate() and
+    exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
+      this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
+      or
+      nComponents <= 5
     )
   }
-  
-  /** A struct type. */
-  class StructType extends @structtype, CompositeType {
-    private StructType getDeepUnaliasedTypeCandidate() {
-      exists(
-        OptStructComponent c0, OptStructComponent c1, OptStructComponent c2, OptStructComponent c3,
-        OptStructComponent c4, int nComponents
-      |
-        unpackAndUnaliasStructType(this, c0, c1, c2, c3, c4, nComponents) and
-        unpackStructType(result, c0, c1, c2, c3, c4, nComponents)
-      )
-    }
-  
-    private predicate isDeepUnaliasedTypeUpTo(StructType unaliased, int i) {
-      // Note we must use component_types not hasOwnField here because component_types may specify
-      // interface-in-struct embedding, but hasOwnField does not return such members.
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 5 and
-      (
-        i = 5 or
-        this.isDeepUnaliasedTypeUpTo(unaliased, i - 1)
-      ) and
-      exists(string name, Type tp, string tag | hasComponentTypeAndTag(this, i, name, tp, tag) |
-        hasComponentTypeAndTag(unaliased, i, name, tp.getDeepUnaliasedType(), tag)
-      )
-    }
-  
-    override StructType getDeepUnaliasedType() {
-      result = this.getDeepUnaliasedTypeCandidate() and
-      exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
-        this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
-        or
-        nComponents <= 5
-      )
-    }
+}
+
+/** A pointer type. */
+class PointerType extends @pointertype, CompositeType {
+  /** Gets the base type of this pointer type. */
+  Type getBaseType() { base_type(this, result) }
+
+  override PointerType getDeepUnaliasedType() {
+    result.getBaseType() = this.getBaseType().getDeepUnaliasedType()
   }
-  
-  /** A pointer type. */
-  class PointerType extends @pointertype, CompositeType {
-    /** Gets the base type of this pointer type. */
-    Type getBaseType() { base_type(this, result) }
-  
-    override PointerType getDeepUnaliasedType() {
-      result.getBaseType() = this.getBaseType().getDeepUnaliasedType()
-    }
+}
+
+private predicate isInterfaceComponentWithQualifiedName(
+  InterfaceType intf, int idx, string qualifiedName, Type tp
+) {
+  exists(string name | component_types(intf, idx, name, tp) |
+    interface_private_method_ids(intf, idx, qualifiedName)
+    or
+    not interface_private_method_ids(intf, idx, _) and qualifiedName = name
+  )
+}
+
+private newtype TOptInterfaceComponent =
+  MkNoIComponent() or
+  MkSomeIComponent(string name, Type tp) {
+    isInterfaceComponentWithQualifiedName(any(InterfaceType i), _, name, tp)
   }
-  
-  private newtype TOptInterfaceComponent =
-    MkNoIComponent() or
-    MkSomeIComponent(string name, Type tp) { component_types(any(InterfaceType i), _, name, tp) }
-  
-  private class OptInterfaceComponent extends TOptInterfaceComponent {
-    OptInterfaceComponent getWithDeepUnaliasedType() {
-      this = MkNoIComponent() and result = MkNoIComponent()
-      or
-      exists(string name, Type tp |
-        this = MkSomeIComponent(name, tp) and
-        result = MkSomeIComponent(name, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    string toString() { result = "interface component" }
+
+private class OptInterfaceComponent extends TOptInterfaceComponent {
+  OptInterfaceComponent getWithDeepUnaliasedType() {
+    this = MkNoIComponent() and result = MkNoIComponent()
+    or
+    exists(string name, Type tp |
+      this = MkSomeIComponent(name, tp) and
+      result = MkSomeIComponent(name, tp.getDeepUnaliasedType())
+    )
   }
-  
-  private class InterfaceComponent extends MkSomeIComponent {
-    string toString() { result = "interface component" }
-  
-    predicate isComponentOf(InterfaceType intf, int i) {
-      exists(string name, Type tp |
-        component_types(intf, i, name, tp) and
-        this = MkSomeIComponent(name, tp)
-      )
-    }
+
+  string toString() { result = "interface component" }
+}
+
+private class InterfaceComponent extends MkSomeIComponent {
+  string toString() { result = "interface component" }
+
+  predicate isComponentOf(InterfaceType intf, int i) {
+    exists(string name, Type tp |
+      isInterfaceComponentWithQualifiedName(intf, i, name, tp) and
+      this = MkSomeIComponent(name, tp)
+    )
   }
-  
-  pragma[nomagic]
-  predicate unpackInterfaceType(
-    InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
-    TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
-    TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds
-  ) {
-    nComponents = count(int i | component_types(intf, i, _, _) and i >= 0) and
-    nEmbeds = count(int i | component_types(intf, i, _, _) and i < 0) and
-    (
-      if nComponents >= 1
-      then c0 = any(InterfaceComponent ic | ic.isComponentOf(intf, 0))
-      else c0 = MkNoIComponent()
-    ) and
-    (
-      if nComponents >= 2
-      then c1 = any(InterfaceComponent ic | ic.isComponentOf(intf, 1))
-      else c1 = MkNoIComponent()
-    ) and
+}
+
+pragma[nomagic]
+predicate unpackInterfaceType(
+  InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
+  TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
+  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds,
+  boolean isComparable
+) {
+  nComponents = count(int i | isInterfaceComponentWithQualifiedName(intf, i, _, _) and i >= 0) and
+  nEmbeds = count(int i | isInterfaceComponentWithQualifiedName(intf, i, _, _) and i < 0) and
+  (
+    if intf = any(ComparableType comparable).getBaseType()
+    then isComparable = true
+    else isComparable = false
+  ) and
+  (
+    if nComponents >= 1
+    then c0 = any(InterfaceComponent ic | ic.isComponentOf(intf, 0))
+    else c0 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 2
+    then c1 = any(InterfaceComponent ic | ic.isComponentOf(intf, 1))
+    else c1 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 3
+    then c2 = any(InterfaceComponent ic | ic.isComponentOf(intf, 2))
+    else c2 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 4
+    then c3 = any(InterfaceComponent ic | ic.isComponentOf(intf, 3))
+    else c3 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 5
+    then c4 = any(InterfaceComponent ic | ic.isComponentOf(intf, 4))
+    else c4 = MkNoIComponent()
+  ) and
+  (
+    if nEmbeds >= 1
+    then e1 = any(InterfaceComponent ic | ic.isComponentOf(intf, -1))
+    else e1 = MkNoIComponent()
+  ) and
+  (
+    if nEmbeds >= 2
+    then e2 = any(InterfaceComponent ic | ic.isComponentOf(intf, -2))
+    else e2 = MkNoIComponent()
+  )
+}
+
+pragma[nomagic]
+predicate unpackAndUnaliasInterfaceType(
+  InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
+  TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
+  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds,
+  boolean isComparable
+) {
+  exists(
+    OptInterfaceComponent c0a, OptInterfaceComponent c1a, OptInterfaceComponent c2a,
+    OptInterfaceComponent c3a, OptInterfaceComponent c4a, OptInterfaceComponent e1a,
+    OptInterfaceComponent e2a
+  |
+    unpackInterfaceType(intf, c0a, c1a, c2a, c3a, c4a, e1a, e2a, nComponents, nEmbeds, isComparable) and
+    c0 = c0a.getWithDeepUnaliasedType() and
+    c1 = c1a.getWithDeepUnaliasedType() and
+    c2 = c2a.getWithDeepUnaliasedType() and
+    c3 = c3a.getWithDeepUnaliasedType() and
+    c4 = c4a.getWithDeepUnaliasedType() and
+    e1 = e1a.getWithDeepUnaliasedType() and
+    e2 = e2a.getWithDeepUnaliasedType()
+  )
+}
+
+/** An interface type. */
+class InterfaceType extends @interfacetype, CompositeType {
+  private Type getMethodType(int i, string name) {
+    i >= 0 and isInterfaceComponentWithQualifiedName(this, i, name, result)
+  }
+
+  /**
+   * Holds if `tp` is a directly embedded type with index `index`.
+   *
+   * `tp` (or its underlying type) is either a type set literal type or an
+   * interface type.
+   */
+  private predicate hasDirectlyEmbeddedType(int index, Type tp) {
+    index >= 0 and isInterfaceComponentWithQualifiedName(this, -(index + 1), _, tp)
+  }
+
+  private InterfaceType getDeepUnaliasedTypeCandidate() {
+    exists(
+      OptInterfaceComponent c0, OptInterfaceComponent c1, OptInterfaceComponent c2,
+      OptInterfaceComponent c3, OptInterfaceComponent c4, OptInterfaceComponent e1,
+      OptInterfaceComponent e2, int nComponents, int nEmbeds, boolean isComparable
+    |
+      unpackAndUnaliasInterfaceType(this, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds,
+        isComparable) and
+      unpackInterfaceType(result, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds, isComparable)
+    )
+  }
+
+  private predicate hasDeepUnaliasedComponentTypesUpTo(InterfaceType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 5 and
     (
-      if nComponents >= 3
-      then c2 = any(InterfaceComponent ic | ic.isComponentOf(intf, 2))
-      else c2 = MkNoIComponent()
+      i = 5 or
+      this.hasDeepUnaliasedComponentTypesUpTo(unaliased, i - 1)
     ) and
+    exists(string name |
+      unaliased.getMethodType(i, name) = this.getMethodType(i, name).getDeepUnaliasedType()
+    )
+  }
+
+  private predicate hasDeepUnaliasedEmbeddedTypesUpTo(InterfaceType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 2 and
     (
-      if nComponents >= 4
-      then c3 = any(InterfaceComponent ic | ic.isComponentOf(intf, 3))
-      else c3 = MkNoIComponent()
+      i = 2 or
+      this.hasDeepUnaliasedEmbeddedTypesUpTo(unaliased, i - 1)
     ) and
-    (
-      if nComponents >= 5
-      then c4 = any(InterfaceComponent ic | ic.isComponentOf(intf, 4))
-      else c4 = MkNoIComponent()
+    exists(Type tp | this.hasDirectlyEmbeddedType(i, tp) |
+      unaliased.hasDirectlyEmbeddedType(i, tp.getDeepUnaliasedType())
+    )
+  }
+
+  override InterfaceType getDeepUnaliasedType() {
+    result = this.getDeepUnaliasedTypeCandidate() and
+    exists(int nComponents | nComponents = count(int i | exists(this.getMethodType(i, _))) |
+      this.hasDeepUnaliasedComponentTypesUpTo(result, nComponents - 1)
+      or
+      nComponents <= 5
     ) and
+    exists(int nEmbeds | nEmbeds = count(int i | this.hasDirectlyEmbeddedType(i, _)) |
+      this.hasDeepUnaliasedEmbeddedTypesUpTo(result, nEmbeds - 1)
+      or
+      nEmbeds <= 2
+    )
+  }
+}
+
+pragma[nomagic]
+private predicate unpackTupleType(
+  TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
+) {
+  nComponents = count(int i | component_types(tt, i, _, _)) and
+  (if nComponents >= 1 then c0 = MkSomeType(tt.getComponentType(0)) else c0 = MkNoType()) and
+  (if nComponents >= 2 then c1 = MkSomeType(tt.getComponentType(1)) else c1 = MkNoType()) and
+  (if nComponents >= 3 then c2 = MkSomeType(tt.getComponentType(2)) else c2 = MkNoType())
+}
+
+pragma[nomagic]
+private predicate unpackAndUnaliasTupleType(
+  TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
+) {
+  exists(OptType c0a, OptType c1a, OptType c2a |
+    unpackTupleType(tt, c0a, c1a, c2a, nComponents) and
+    c0 = c0a.getDeepUnaliasedType() and
+    c1 = c1a.getDeepUnaliasedType() and
+    c2 = c2a.getDeepUnaliasedType()
+  )
+}
+
+/** A tuple type. */
+class TupleType extends @tupletype, CompositeType {
+  /** Gets the `i`th component type of this tuple type. */
+  Type getComponentType(int i) { component_types(this, i, _, result) }
+
+  private TupleType getCandidateDeepUnaliasedType() {
+    exists(OptType c0, OptType c1, OptType c2, int nComponents |
+      unpackAndUnaliasTupleType(this, c0, c1, c2, nComponents) and
+      unpackTupleType(result, c0, c1, c2, nComponents)
+    )
+  }
+
+  private predicate isDeepUnaliasedTypeUpTo(TupleType tt, int i) {
+    tt = this.getCandidateDeepUnaliasedType() and
+    i >= 3 and
     (
-      if nEmbeds >= 1
-      then e1 = any(InterfaceComponent ic | ic.isComponentOf(intf, -1))
-      else e1 = MkNoIComponent()
+      i = 3
+      or
+      this.isDeepUnaliasedTypeUpTo(tt, i - 1)
     ) and
-    (
-      if nEmbeds >= 2
-      then e2 = any(InterfaceComponent ic | ic.isComponentOf(intf, -2))
-      else e2 = MkNoIComponent()
+    tt.getComponentType(i) = this.getComponentType(i).getDeepUnaliasedType()
+  }
+
+  override TupleType getDeepUnaliasedType() {
+    result = this.getCandidateDeepUnaliasedType() and
+    exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
+      this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
+      or
+      nComponents <= 3
     )
   }
-  
-  pragma[nomagic]
-  predicate unpackAndUnaliasInterfaceType(
-    InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
-    TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
-    TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds
-  ) {
+}
+
+// Reasonably efficiently map from a signature type to its
+// deep-unaliased equivalent, by using a single join for the leading 5 parameters
+// and/or 3 results.
+private newtype TOptType =
+  MkNoType() or
+  MkSomeType(Type tp)
+
+private class OptType extends TOptType {
+  OptType getDeepUnaliasedType() {
+    exists(Type t | this = MkSomeType(t) | result = MkSomeType(t.getDeepUnaliasedType()))
+    or
+    this = MkNoType() and result = MkNoType()
+  }
+
+  string toString() {
+    exists(Type t | this = MkSomeType(t) | result = t.toString())
+    or
+    this = MkNoType() and result = "no type"
+  }
+}
+
+pragma[nomagic]
+private predicate unpackSignatureType(
+  SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
+  int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
+) {
+  nParams = sig.getNumParameter() and
+  nResults = sig.getNumResult() and
+  (if nParams >= 1 then param0 = MkSomeType(sig.getParameterType(0)) else param0 = MkNoType()) and
+  (if nParams >= 2 then param1 = MkSomeType(sig.getParameterType(1)) else param1 = MkNoType()) and
+  (if nParams >= 3 then param2 = MkSomeType(sig.getParameterType(2)) else param2 = MkNoType()) and
+  (if nParams >= 4 then param3 = MkSomeType(sig.getParameterType(3)) else param3 = MkNoType()) and
+  (if nParams >= 5 then param4 = MkSomeType(sig.getParameterType(4)) else param4 = MkNoType()) and
+  (if nResults >= 1 then result0 = MkSomeType(sig.getResultType(0)) else result0 = MkNoType()) and
+  (if nResults >= 2 then result1 = MkSomeType(sig.getResultType(1)) else result1 = MkNoType()) and
+  (if nResults >= 3 then result2 = MkSomeType(sig.getResultType(2)) else result2 = MkNoType()) and
+  (if sig.isVariadic() then isVariadic = true else isVariadic = false)
+}
+
+pragma[nomagic]
+private predicate unpackAndUnaliasSignatureType(
+  SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
+  int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
+) {
+  exists(
+    OptType param0a, OptType param1a, OptType param2a, OptType param3a, OptType param4a,
+    OptType result0a, OptType result1a, OptType result2a
+  |
+    unpackSignatureType(sig, param0a, param1a, param2a, param3a, param4a, nParams, result0a,
+      result1a, result2a, nResults, isVariadic)
+  |
+    param0 = param0a.getDeepUnaliasedType() and
+    param1 = param1a.getDeepUnaliasedType() and
+    param2 = param2a.getDeepUnaliasedType() and
+    param3 = param3a.getDeepUnaliasedType() and
+    param4 = param4a.getDeepUnaliasedType() and
+    result0 = result0a.getDeepUnaliasedType() and
+    result1 = result1a.getDeepUnaliasedType() and
+    result2 = result2a.getDeepUnaliasedType()
+  )
+}
+
+/** A signature type. */
+class SignatureType extends @signaturetype, CompositeType {
+  /** Gets the `i`th parameter type of this signature type. */
+  Type getParameterType(int i) { i >= 0 and component_types(this, i + 1, _, result) }
+
+  /** Gets the `i`th result type of this signature type. */
+  Type getResultType(int i) { i >= 0 and component_types(this, -(i + 1), _, result) }
+
+  /** Gets the number of parameters specified by this signature. */
+  int getNumParameter() { result = count(int i | exists(this.getParameterType(i))) }
+
+  /** Gets the number of results specified by this signature. */
+  int getNumResult() { result = count(int i | exists(this.getResultType(i))) }
+
+  /** Holds if this signature type is variadic. */
+  predicate isVariadic() { variadic(this) }
+
+  private SignatureType getDeepUnaliasedTypeCandidate() {
     exists(
-      OptInterfaceComponent c0a, OptInterfaceComponent c1a, OptInterfaceComponent c2a,
-      OptInterfaceComponent c3a, OptInterfaceComponent c4a, OptInterfaceComponent e1a,
-      OptInterfaceComponent e2a
+      OptType param0, OptType param1, OptType param2, OptType param3, OptType param4, int nParams,
+      OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
     |
-      unpackInterfaceType(intf, c0a, c1a, c2a, c3a, c4a, e1a, e2a, nComponents, nEmbeds) and
-      c0 = c0a.getWithDeepUnaliasedType() and
-      c1 = c1a.getWithDeepUnaliasedType() and
-      c2 = c2a.getWithDeepUnaliasedType() and
-      c3 = c3a.getWithDeepUnaliasedType() and
-      c4 = c4a.getWithDeepUnaliasedType() and
-      e1 = e1a.getWithDeepUnaliasedType() and
-      e2 = e2a.getWithDeepUnaliasedType()
+      unpackAndUnaliasSignatureType(this, param0, param1, param2, param3, param4, nParams, result0,
+        result1, result2, nResults, isVariadic) and
+      unpackSignatureType(result, param0, param1, param2, param3, param4, nParams, result0, result1,
+        result2, nResults, isVariadic)
     )
   }
-  
-  /** An interface type. */
-  class InterfaceType extends @interfacetype, CompositeType {
-    private InterfaceType getDeepUnaliasedTypeCandidate() {
-      exists(
-        OptInterfaceComponent c0, OptInterfaceComponent c1, OptInterfaceComponent c2,
-        OptInterfaceComponent c3, OptInterfaceComponent c4, OptInterfaceComponent e1,
-        OptInterfaceComponent e2, int nComponents, int nEmbeds
-      |
-        unpackAndUnaliasInterfaceType(this, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds) and
-        unpackInterfaceType(result, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds)
-      )
-    }
-  
-    private predicate hasDeepUnaliasedComponentTypesUpTo(InterfaceType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 5 and
-      (
-        i = 5 or
-        this.hasDeepUnaliasedComponentTypesUpTo(unaliased, i - 1)
-      ) and
-      exists(string name, Type tp | component_types(this, i, name, tp) |
-        component_types(unaliased, i, name, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    private predicate hasDeepUnaliasedEmbeddedTypesUpTo(InterfaceType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 3 and
-      (
-        i = 3 or
-        this.hasDeepUnaliasedEmbeddedTypesUpTo(unaliased, i - 1)
-      ) and
-      exists(string name, Type tp | component_types(this, -i, name, tp) |
-        component_types(unaliased, -i, name, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    override InterfaceType getDeepUnaliasedType() {
-      result = this.getDeepUnaliasedTypeCandidate() and
-      exists(int nComponents |
-        nComponents = count(int i | component_types(this, i, _, _) and i >= 0)
-      |
-        this.hasDeepUnaliasedComponentTypesUpTo(result, nComponents - 1)
-        or
-        nComponents <= 5
-      ) and
-      exists(int nEmbeds | nEmbeds = count(int i | component_types(this, i, _, _) and i < 0) |
-        // Note no -1 here, because the first embedded type is at -1
-        this.hasDeepUnaliasedEmbeddedTypesUpTo(result, nEmbeds)
-        or
-        nEmbeds <= 2
-      )
-    }
-  }
-  
-  pragma[nomagic]
-  private predicate unpackTupleType(
-    TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
-  ) {
-    nComponents = count(int i | component_types(tt, i, _, _)) and
-    (if nComponents >= 1 then c0 = MkSomeType(tt.getComponentType(0)) else c0 = MkNoType()) and
-    (if nComponents >= 2 then c1 = MkSomeType(tt.getComponentType(1)) else c1 = MkNoType()) and
-    (if nComponents >= 3 then c2 = MkSomeType(tt.getComponentType(2)) else c2 = MkNoType())
+
+  // These incremental recursive implementations only apply from parameter 5 or result 3
+  // upwards to avoid constructing large squares of candidates -- the initial parameters
+  // and results are taken care of by the candidate predicate.
+  private predicate hasDeepUnaliasedParameterTypesUpTo(SignatureType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 5 and
+    (i = 5 or this.hasDeepUnaliasedParameterTypesUpTo(unaliased, i - 1)) and
+    unaliased.getParameterType(i) = this.getParameterType(i).getDeepUnaliasedType()
   }
-  
-  pragma[nomagic]
-  private predicate unpackAndUnaliasTupleType(
-    TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
-  ) {
-    exists(OptType c0a, OptType c1a, OptType c2a |
-      unpackTupleType(tt, c0a, c1a, c2a, nComponents) and
-      c0 = c0a.getDeepUnaliasedType() and
-      c1 = c1a.getDeepUnaliasedType() and
-      c2 = c2a.getDeepUnaliasedType()
-    )
+
+  private predicate hasDeepUnaliasedResultTypesUpTo(SignatureType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 3 and
+    (i = 3 or this.hasDeepUnaliasedResultTypesUpTo(unaliased, i - 1)) and
+    unaliased.getResultType(i) = this.getResultType(i).getDeepUnaliasedType()
   }
-  
-  /** A tuple type. */
-  class TupleType extends @tupletype, CompositeType {
-    /** Gets the `i`th component type of this tuple type. */
-    Type getComponentType(int i) { component_types(this, i, _, result) }
-  
-    private TupleType getCandidateDeepUnaliasedType() {
-      exists(OptType c0, OptType c1, OptType c2, int nComponents |
-        unpackAndUnaliasTupleType(this, c0, c1, c2, nComponents) and
-        unpackTupleType(result, c0, c1, c2, nComponents)
-      )
-    }
-  
-    private predicate isDeepUnaliasedTypeUpTo(TupleType tt, int i) {
-      tt = this.getCandidateDeepUnaliasedType() and
-      i >= 3 and
+
+  override SignatureType getDeepUnaliasedType() {
+    result = this.getDeepUnaliasedTypeCandidate() and
+    exists(int nParams, int nResults |
+      this.getNumParameter() = nParams and this.getNumResult() = nResults
+    |
       (
-        i = 3
+        nParams <= 5
         or
-        this.isDeepUnaliasedTypeUpTo(tt, i - 1)
+        this.hasDeepUnaliasedParameterTypesUpTo(result, nParams - 1)
       ) and
-      exists(Type tp | component_types(this, i, _, tp) |
-        component_types(tt, i, _, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    override TupleType getDeepUnaliasedType() {
-      result = this.getCandidateDeepUnaliasedType() and
-      exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
-        this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
+      (
+        nResults <= 3
         or
-        nComponents <= 3
+        this.hasDeepUnaliasedResultTypesUpTo(result, nResults - 1)
       )
-    }
-  }
-  
-  // Reasonably efficiently map from a signature type to its
-  // deep-unaliased equivalent, by using a single join for the leading 5 parameters
-  // and/or 3 results.
-  private newtype TOptType =
-    MkNoType() or
-    MkSomeType(Type tp)
-  
-  private class OptType extends TOptType {
-    OptType getDeepUnaliasedType() {
-      exists(Type t | this = MkSomeType(t) | result = MkSomeType(t.getDeepUnaliasedType()))
-      or
-      this = MkNoType() and result = MkNoType()
-    }
-  
-    string toString() {
-      exists(Type t | this = MkSomeType(t) | result = t.toString())
-      or
-      this = MkNoType() and result = "no type"
-    }
-  }
-  
-  pragma[nomagic]
-  private predicate unpackSignatureType(
-    SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
-    int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
-  ) {
-    nParams = sig.getNumParameter() and
-    nResults = sig.getNumResult() and
-    (if nParams >= 1 then param0 = MkSomeType(sig.getParameterType(0)) else param0 = MkNoType()) and
-    (if nParams >= 2 then param1 = MkSomeType(sig.getParameterType(1)) else param1 = MkNoType()) and
-    (if nParams >= 3 then param2 = MkSomeType(sig.getParameterType(2)) else param2 = MkNoType()) and
-    (if nParams >= 4 then param3 = MkSomeType(sig.getParameterType(3)) else param3 = MkNoType()) and
-    (if nParams >= 5 then param4 = MkSomeType(sig.getParameterType(4)) else param4 = MkNoType()) and
-    (if nResults >= 1 then result0 = MkSomeType(sig.getResultType(0)) else result0 = MkNoType()) and
-    (if nResults >= 2 then result1 = MkSomeType(sig.getResultType(1)) else result1 = MkNoType()) and
-    (if nResults >= 3 then result2 = MkSomeType(sig.getResultType(2)) else result2 = MkNoType()) and
-    (if sig.isVariadic() then isVariadic = true else isVariadic = false)
-  }
-  
-  pragma[nomagic]
-  private predicate unpackAndUnaliasSignatureType(
-    SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
-    int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
-  ) {
-    exists(
-      OptType param0a, OptType param1a, OptType param2a, OptType param3a, OptType param4a,
-      OptType result0a, OptType result1a, OptType result2a
-    |
-      unpackSignatureType(sig, param0a, param1a, param2a, param3a, param4a, nParams, result0a,
-        result1a, result2a, nResults, isVariadic)
-    |
-      param0 = param0a.getDeepUnaliasedType() and
-      param1 = param1a.getDeepUnaliasedType() and
-      param2 = param2a.getDeepUnaliasedType() and
-      param3 = param3a.getDeepUnaliasedType() and
-      param4 = param4a.getDeepUnaliasedType() and
-      result0 = result0a.getDeepUnaliasedType() and
-      result1 = result1a.getDeepUnaliasedType() and
-      result2 = result2a.getDeepUnaliasedType()
     )
   }
-  
-  /** A signature type. */
-  class SignatureType extends @signaturetype, CompositeType {
-    /** Gets the `i`th parameter type of this signature type. */
-    Type getParameterType(int i) { i >= 0 and component_types(this, i + 1, _, result) }
-  
-    /** Gets the `i`th result type of this signature type. */
-    Type getResultType(int i) { i >= 0 and component_types(this, -(i + 1), _, result) }
-  
-    /** Gets the number of parameters specified by this signature. */
-    int getNumParameter() { result = count(int i | exists(this.getParameterType(i))) }
-  
-    /** Gets the number of results specified by this signature. */
-    int getNumResult() { result = count(int i | exists(this.getResultType(i))) }
-  
-    /** Holds if this signature type is variadic. */
-    predicate isVariadic() { variadic(this) }
-  
-    private SignatureType getDeepUnaliasedTypeCandidate() {
-      exists(
-        OptType param0, OptType param1, OptType param2, OptType param3, OptType param4, int nParams,
-        OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
-      |
-        unpackAndUnaliasSignatureType(this, param0, param1, param2, param3, param4, nParams, result0,
-          result1, result2, nResults, isVariadic) and
-        unpackSignatureType(result, param0, param1, param2, param3, param4, nParams, result0, result1,
-          result2, nResults, isVariadic)
-      )
-    }
-  
-    // These incremental recursive implementations only apply from parameter 5 or result 3
-    // upwards to avoid constructing large squares of candidates -- the initial parameters
-    // and results are taken care of by the candidate predicate.
-    private predicate hasDeepUnaliasedParameterTypesUpTo(SignatureType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 5 and
-      (i = 5 or this.hasDeepUnaliasedParameterTypesUpTo(unaliased, i - 1)) and
-      unaliased.getParameterType(i) = this.getParameterType(i).getDeepUnaliasedType()
-    }
-  
-    private predicate hasDeepUnaliasedResultTypesUpTo(SignatureType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 3 and
-      (i = 3 or this.hasDeepUnaliasedResultTypesUpTo(unaliased, i - 1)) and
-      unaliased.getResultType(i) = this.getResultType(i).getDeepUnaliasedType()
-    }
-  
-    override SignatureType getDeepUnaliasedType() {
-      result = this.getDeepUnaliasedTypeCandidate() and
-      exists(int nParams, int nResults |
-        this.getNumParameter() = nParams and this.getNumResult() = nResults
-      |
-        (
-          nParams <= 5
-          or
-          this.hasDeepUnaliasedParameterTypesUpTo(result, nParams - 1)
-        ) and
-        (
-          nResults <= 3
-          or
-          this.hasDeepUnaliasedResultTypesUpTo(result, nResults - 1)
-        )
-      )
-    }
-  }
-  
-  /** A map type. */
-  class MapType extends @maptype, CompositeType {
-    /** Gets the key type of this map type. */
-    Type getKeyType() { key_type(this, result) }
-  
-    /** Gets the value type of this map type. */
-    Type getValueType() { element_type(this, result) }
-  
-    override MapType getDeepUnaliasedType() {
-      result.getKeyType() = this.getKeyType().getDeepUnaliasedType() and
-      result.getValueType() = this.getValueType().getDeepUnaliasedType()
-    }
-  }
-  
-  /** A channel type. */
-  class ChanType extends @chantype, CompositeType {
-    /** Gets the element type of this channel type. */
-    Type getElementType() { element_type(this, result) }
-  }
-  
-  /** A channel type that can only send. */
-  class SendChanType extends @sendchantype, ChanType {
-    override SendChanType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
-  }
-  
-  /** A channel type that can only receive. */
-  class RecvChanType extends @recvchantype, ChanType {
-    override RecvChanType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
+}
+
+/** A map type. */
+class MapType extends @maptype, CompositeType {
+  /** Gets the key type of this map type. */
+  Type getKeyType() { key_type(this, result) }
+
+  /** Gets the value type of this map type. */
+  Type getValueType() { element_type(this, result) }
+
+  override MapType getDeepUnaliasedType() {
+    result.getKeyType() = this.getKeyType().getDeepUnaliasedType() and
+    result.getValueType() = this.getValueType().getDeepUnaliasedType()
   }
-  
-  /** A channel type that can both send and receive. */
-  class SendRecvChanType extends @sendrcvchantype, ChanType {
-    override SendRecvChanType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
+}
+
+/** A channel type. */
+class ChanType extends @chantype, CompositeType {
+  /** Gets the element type of this channel type. */
+  Type getElementType() { element_type(this, result) }
+}
+
+/** A channel type that can only send. */
+class SendChanType extends @sendchantype, ChanType {
+  override SendChanType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  /** An alias type. */
-  class AliasType extends @typealias, CompositeType {
-    /** Gets the aliased type (i.e. that appears on the RHS of the alias definition). */
-    Type getRhs() { alias_rhs(this, result) }
-  
-    override Type getDeepUnaliasedType() { result = unalias(this).getDeepUnaliasedType() }
+}
+
+/** A channel type that can only receive. */
+class RecvChanType extends @recvchantype, ChanType {
+  override RecvChanType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  /**
-   * Gets the non-alias type at the end of the alias chain starting at `t`.
-   *
-   * If `t` is not an alias type then `result` is `t`.
-   */
-  Type unalias(Type t) {
-    not t instanceof AliasType and result = t
-    or
-    result = unalias(t.(AliasType).getRhs())
+}
+
+/** A channel type that can both send and receive. */
+class SendRecvChanType extends @sendrcvchantype, ChanType {
+  override SendRecvChanType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  predicate containsAliases(Type t) { t != t.getDeepUnaliasedType() }
-  // END ALIASES.QLL
-  
-
-  from MapType mt, Type kt
-  where key_type(mt, kt)
-  and not containsAliases(mt)
-  select mt, kt
\ No newline at end of file
+}
+
+/** A named type. */
+class NamedType extends @namedtype, CompositeType {
+  Type getBaseType() { underlying_type(this, result) }
+}
+
+/**
+ * The predeclared `comparable` type.
+ */
+class ComparableType extends NamedType {
+  ComparableType() { typename(this, "comparable") }
+}
+
+/** An alias type. */
+class AliasType extends @typealias, CompositeType {
+  /** Gets the aliased type (i.e. that appears on the RHS of the alias definition). */
+  Type getRhs() { alias_rhs(this, result) }
+
+  override Type getDeepUnaliasedType() { result = unalias(this).getDeepUnaliasedType() }
+}
+
+/**
+ * Gets the non-alias type at the end of the alias chain starting at `t`.
+ *
+ * If `t` is not an alias type then `result` is `t`.
+ */
+Type unalias(Type t) {
+  not t instanceof AliasType and result = t
+  or
+  result = unalias(t.(AliasType).getRhs())
+}
+
+predicate containsAliases(Type t) { t != t.getDeepUnaliasedType() }
+// END ALIASES.QLL
+from MapType mt, Type kt
+where
+  key_type(mt, kt) and
+  not containsAliases(mt)
+select mt, kt
diff --git a/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/objecttypes.ql b/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/objecttypes.ql
index 0fd7fb2d99ad..584eda347c41 100644
--- a/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/objecttypes.ql
+++ b/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/objecttypes.ql
@@ -2,578 +2,617 @@
 // Database scripts can't import, but this is the definitive copy of the support routines for mapping types to their unaliased equivalent. Ensure this code is in sync between aliases.qll and all copies in individual table .ql files.
 /** A Go type. */
 class Type extends @type {
-    /**
-     * Gets this type with all aliases substituted for their underlying type.
-     *
-     * Note named types are not substituted.
-     */
-    Type getDeepUnaliasedType() { result = this }
-  
-    /**
-     * Gets a basic textual representation of this type.
-     */
-    string toString() { result = "type" }
-  }
-  
-  /** A composite type, that is, not a basic type. */
-  class CompositeType extends @compositetype, Type { }
-  
-  /** An array type. */
-  class ArrayType extends @arraytype, CompositeType {
-    /** Gets the element type of this array type. */
-    Type getElementType() { element_type(this, result) }
-  
-    /** Gets the length of this array type as a string. */
-    string getLengthString() { array_length(this, result) }
-  
-    override ArrayType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType() and
-      result.getLengthString() = this.getLengthString()
-    }
+  /**
+   * Gets this type with all aliases substituted for their underlying type.
+   *
+   * Note named types are not substituted.
+   */
+  Type getDeepUnaliasedType() { result = this }
+
+  /**
+   * Gets a basic textual representation of this type.
+   */
+  string toString() { result = "type" }
+}
+
+/** A composite type, that is, not a basic type. */
+class CompositeType extends @compositetype, Type { }
+
+/** An array type. */
+class ArrayType extends @arraytype, CompositeType {
+  /** Gets the element type of this array type. */
+  Type getElementType() { element_type(this, result) }
+
+  /** Gets the length of this array type as a string. */
+  string getLengthString() { array_length(this, result) }
+
+  override ArrayType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType() and
+    result.getLengthString() = this.getLengthString()
   }
-  
-  /** A slice type. */
-  class SliceType extends @slicetype, CompositeType {
-    /** Gets the element type of this slice type. */
-    Type getElementType() { element_type(this, result) }
-  
-    override SliceType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
+}
+
+/** A slice type. */
+class SliceType extends @slicetype, CompositeType {
+  /** Gets the element type of this slice type. */
+  Type getElementType() { element_type(this, result) }
+
+  override SliceType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  // Improve efficiency of matching a struct to its unaliased equivalent
-  // by unpacking the first 5 fields and tags, allowing a single join
-  // to strongly constrain the available candidates.
-  private predicate hasComponentTypeAndTag(StructType s, int i, string name, Type tp, string tag) {
-    component_types(s, i, name, tp) and component_tags(s, i, tag)
+}
+
+// Improve efficiency of matching a struct to its unaliased equivalent
+// by unpacking the first 5 fields and tags, allowing a single join
+// to strongly constrain the available candidates.
+private predicate hasComponentTypeAndTag(StructType s, int i, string name, Type tp, string tag) {
+  component_types(s, i, name, tp) and component_tags(s, i, tag)
+}
+
+private newtype TOptStructComponent =
+  MkNoComponent() or
+  MkSomeComponent(string name, Type tp, string tag) { hasComponentTypeAndTag(_, _, name, tp, tag) }
+
+private class OptStructComponent extends TOptStructComponent {
+  OptStructComponent getWithDeepUnaliasedType() {
+    this = MkNoComponent() and result = MkNoComponent()
+    or
+    exists(string name, Type tp, string tag |
+      this = MkSomeComponent(name, tp, tag) and
+      result = MkSomeComponent(name, tp.getDeepUnaliasedType(), tag)
+    )
   }
-  
-  private newtype TOptStructComponent =
-    MkNoComponent() or
-    MkSomeComponent(string name, Type tp, string tag) { hasComponentTypeAndTag(_, _, name, tp, tag) }
-  
-  private class OptStructComponent extends TOptStructComponent {
-    OptStructComponent getWithDeepUnaliasedType() {
-      this = MkNoComponent() and result = MkNoComponent()
-      or
-      exists(string name, Type tp, string tag |
-        this = MkSomeComponent(name, tp, tag) and
-        result = MkSomeComponent(name, tp.getDeepUnaliasedType(), tag)
-      )
-    }
-  
-    string toString() { result = "struct component" }
+
+  string toString() { result = "struct component" }
+}
+
+private class StructComponent extends MkSomeComponent {
+  string toString() { result = "struct component" }
+
+  predicate isComponentOf(StructType s, int i) {
+    exists(string name, Type tp, string tag |
+      hasComponentTypeAndTag(s, i, name, tp, tag) and
+      this = MkSomeComponent(name, tp, tag)
+    )
   }
-  
-  private class StructComponent extends MkSomeComponent {
-    string toString() { result = "struct component" }
-  
-    predicate isComponentOf(StructType s, int i) {
-      exists(string name, Type tp, string tag |
-        hasComponentTypeAndTag(s, i, name, tp, tag) and
-        this = MkSomeComponent(name, tp, tag)
-      )
-    }
+}
+
+pragma[nomagic]
+predicate unpackStructType(
+  StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
+  TOptStructComponent c3, TOptStructComponent c4, int nComponents
+) {
+  nComponents = count(int i | component_types(s, i, _, _)) and
+  (
+    if nComponents >= 1
+    then c0 = any(StructComponent sc | sc.isComponentOf(s, 0))
+    else c0 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 2
+    then c1 = any(StructComponent sc | sc.isComponentOf(s, 1))
+    else c1 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 3
+    then c2 = any(StructComponent sc | sc.isComponentOf(s, 2))
+    else c2 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 4
+    then c3 = any(StructComponent sc | sc.isComponentOf(s, 3))
+    else c3 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 5
+    then c4 = any(StructComponent sc | sc.isComponentOf(s, 4))
+    else c4 = MkNoComponent()
+  )
+}
+
+pragma[nomagic]
+predicate unpackAndUnaliasStructType(
+  StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
+  TOptStructComponent c3, TOptStructComponent c4, int nComponents
+) {
+  exists(
+    OptStructComponent c0a, OptStructComponent c1a, OptStructComponent c2a, OptStructComponent c3a,
+    OptStructComponent c4a
+  |
+    unpackStructType(s, c0a, c1a, c2a, c3a, c4a, nComponents) and
+    c0 = c0a.getWithDeepUnaliasedType() and
+    c1 = c1a.getWithDeepUnaliasedType() and
+    c2 = c2a.getWithDeepUnaliasedType() and
+    c3 = c3a.getWithDeepUnaliasedType() and
+    c4 = c4a.getWithDeepUnaliasedType()
+  )
+}
+
+/** A struct type. */
+class StructType extends @structtype, CompositeType {
+  private StructType getDeepUnaliasedTypeCandidate() {
+    exists(
+      OptStructComponent c0, OptStructComponent c1, OptStructComponent c2, OptStructComponent c3,
+      OptStructComponent c4, int nComponents
+    |
+      unpackAndUnaliasStructType(this, c0, c1, c2, c3, c4, nComponents) and
+      unpackStructType(result, c0, c1, c2, c3, c4, nComponents)
+    )
   }
-  
-  pragma[nomagic]
-  predicate unpackStructType(
-    StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
-    TOptStructComponent c3, TOptStructComponent c4, int nComponents
-  ) {
-    nComponents = count(int i | component_types(s, i, _, _)) and
-    (
-      if nComponents >= 1
-      then c0 = any(StructComponent sc | sc.isComponentOf(s, 0))
-      else c0 = MkNoComponent()
-    ) and
-    (
-      if nComponents >= 2
-      then c1 = any(StructComponent sc | sc.isComponentOf(s, 1))
-      else c1 = MkNoComponent()
-    ) and
-    (
-      if nComponents >= 3
-      then c2 = any(StructComponent sc | sc.isComponentOf(s, 2))
-      else c2 = MkNoComponent()
-    ) and
+
+  private predicate isDeepUnaliasedTypeUpTo(StructType unaliased, int i) {
+    // Note we must use component_types not hasOwnField here because component_types may specify
+    // interface-in-struct embedding, but hasOwnField does not return such members.
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 5 and
     (
-      if nComponents >= 4
-      then c3 = any(StructComponent sc | sc.isComponentOf(s, 3))
-      else c3 = MkNoComponent()
+      i = 5 or
+      this.isDeepUnaliasedTypeUpTo(unaliased, i - 1)
     ) and
-    (
-      if nComponents >= 5
-      then c4 = any(StructComponent sc | sc.isComponentOf(s, 4))
-      else c4 = MkNoComponent()
+    exists(string name, Type tp, string tag | hasComponentTypeAndTag(this, i, name, tp, tag) |
+      hasComponentTypeAndTag(unaliased, i, name, tp.getDeepUnaliasedType(), tag)
     )
   }
-  
-  pragma[nomagic]
-  predicate unpackAndUnaliasStructType(
-    StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
-    TOptStructComponent c3, TOptStructComponent c4, int nComponents
-  ) {
-    exists(
-      OptStructComponent c0a, OptStructComponent c1a, OptStructComponent c2a, OptStructComponent c3a,
-      OptStructComponent c4a
-    |
-      unpackStructType(s, c0a, c1a, c2a, c3a, c4a, nComponents) and
-      c0 = c0a.getWithDeepUnaliasedType() and
-      c1 = c1a.getWithDeepUnaliasedType() and
-      c2 = c2a.getWithDeepUnaliasedType() and
-      c3 = c3a.getWithDeepUnaliasedType() and
-      c4 = c4a.getWithDeepUnaliasedType()
+
+  override StructType getDeepUnaliasedType() {
+    result = this.getDeepUnaliasedTypeCandidate() and
+    exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
+      this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
+      or
+      nComponents <= 5
     )
   }
-  
-  /** A struct type. */
-  class StructType extends @structtype, CompositeType {
-    private StructType getDeepUnaliasedTypeCandidate() {
-      exists(
-        OptStructComponent c0, OptStructComponent c1, OptStructComponent c2, OptStructComponent c3,
-        OptStructComponent c4, int nComponents
-      |
-        unpackAndUnaliasStructType(this, c0, c1, c2, c3, c4, nComponents) and
-        unpackStructType(result, c0, c1, c2, c3, c4, nComponents)
-      )
-    }
-  
-    private predicate isDeepUnaliasedTypeUpTo(StructType unaliased, int i) {
-      // Note we must use component_types not hasOwnField here because component_types may specify
-      // interface-in-struct embedding, but hasOwnField does not return such members.
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 5 and
-      (
-        i = 5 or
-        this.isDeepUnaliasedTypeUpTo(unaliased, i - 1)
-      ) and
-      exists(string name, Type tp, string tag | hasComponentTypeAndTag(this, i, name, tp, tag) |
-        hasComponentTypeAndTag(unaliased, i, name, tp.getDeepUnaliasedType(), tag)
-      )
-    }
-  
-    override StructType getDeepUnaliasedType() {
-      result = this.getDeepUnaliasedTypeCandidate() and
-      exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
-        this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
-        or
-        nComponents <= 5
-      )
-    }
+}
+
+/** A pointer type. */
+class PointerType extends @pointertype, CompositeType {
+  /** Gets the base type of this pointer type. */
+  Type getBaseType() { base_type(this, result) }
+
+  override PointerType getDeepUnaliasedType() {
+    result.getBaseType() = this.getBaseType().getDeepUnaliasedType()
   }
-  
-  /** A pointer type. */
-  class PointerType extends @pointertype, CompositeType {
-    /** Gets the base type of this pointer type. */
-    Type getBaseType() { base_type(this, result) }
-  
-    override PointerType getDeepUnaliasedType() {
-      result.getBaseType() = this.getBaseType().getDeepUnaliasedType()
-    }
+}
+
+private predicate isInterfaceComponentWithQualifiedName(
+  InterfaceType intf, int idx, string qualifiedName, Type tp
+) {
+  exists(string name | component_types(intf, idx, name, tp) |
+    interface_private_method_ids(intf, idx, qualifiedName)
+    or
+    not interface_private_method_ids(intf, idx, _) and qualifiedName = name
+  )
+}
+
+private newtype TOptInterfaceComponent =
+  MkNoIComponent() or
+  MkSomeIComponent(string name, Type tp) {
+    isInterfaceComponentWithQualifiedName(any(InterfaceType i), _, name, tp)
   }
-  
-  private newtype TOptInterfaceComponent =
-    MkNoIComponent() or
-    MkSomeIComponent(string name, Type tp) { component_types(any(InterfaceType i), _, name, tp) }
-  
-  private class OptInterfaceComponent extends TOptInterfaceComponent {
-    OptInterfaceComponent getWithDeepUnaliasedType() {
-      this = MkNoIComponent() and result = MkNoIComponent()
-      or
-      exists(string name, Type tp |
-        this = MkSomeIComponent(name, tp) and
-        result = MkSomeIComponent(name, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    string toString() { result = "interface component" }
+
+private class OptInterfaceComponent extends TOptInterfaceComponent {
+  OptInterfaceComponent getWithDeepUnaliasedType() {
+    this = MkNoIComponent() and result = MkNoIComponent()
+    or
+    exists(string name, Type tp |
+      this = MkSomeIComponent(name, tp) and
+      result = MkSomeIComponent(name, tp.getDeepUnaliasedType())
+    )
   }
-  
-  private class InterfaceComponent extends MkSomeIComponent {
-    string toString() { result = "interface component" }
-  
-    predicate isComponentOf(InterfaceType intf, int i) {
-      exists(string name, Type tp |
-        component_types(intf, i, name, tp) and
-        this = MkSomeIComponent(name, tp)
-      )
-    }
+
+  string toString() { result = "interface component" }
+}
+
+private class InterfaceComponent extends MkSomeIComponent {
+  string toString() { result = "interface component" }
+
+  predicate isComponentOf(InterfaceType intf, int i) {
+    exists(string name, Type tp |
+      isInterfaceComponentWithQualifiedName(intf, i, name, tp) and
+      this = MkSomeIComponent(name, tp)
+    )
   }
-  
-  pragma[nomagic]
-  predicate unpackInterfaceType(
-    InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
-    TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
-    TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds
-  ) {
-    nComponents = count(int i | component_types(intf, i, _, _) and i >= 0) and
-    nEmbeds = count(int i | component_types(intf, i, _, _) and i < 0) and
-    (
-      if nComponents >= 1
-      then c0 = any(InterfaceComponent ic | ic.isComponentOf(intf, 0))
-      else c0 = MkNoIComponent()
-    ) and
-    (
-      if nComponents >= 2
-      then c1 = any(InterfaceComponent ic | ic.isComponentOf(intf, 1))
-      else c1 = MkNoIComponent()
-    ) and
+}
+
+pragma[nomagic]
+predicate unpackInterfaceType(
+  InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
+  TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
+  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds,
+  boolean isComparable
+) {
+  nComponents = count(int i | isInterfaceComponentWithQualifiedName(intf, i, _, _) and i >= 0) and
+  nEmbeds = count(int i | isInterfaceComponentWithQualifiedName(intf, i, _, _) and i < 0) and
+  (
+    if intf = any(ComparableType comparable).getBaseType()
+    then isComparable = true
+    else isComparable = false
+  ) and
+  (
+    if nComponents >= 1
+    then c0 = any(InterfaceComponent ic | ic.isComponentOf(intf, 0))
+    else c0 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 2
+    then c1 = any(InterfaceComponent ic | ic.isComponentOf(intf, 1))
+    else c1 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 3
+    then c2 = any(InterfaceComponent ic | ic.isComponentOf(intf, 2))
+    else c2 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 4
+    then c3 = any(InterfaceComponent ic | ic.isComponentOf(intf, 3))
+    else c3 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 5
+    then c4 = any(InterfaceComponent ic | ic.isComponentOf(intf, 4))
+    else c4 = MkNoIComponent()
+  ) and
+  (
+    if nEmbeds >= 1
+    then e1 = any(InterfaceComponent ic | ic.isComponentOf(intf, -1))
+    else e1 = MkNoIComponent()
+  ) and
+  (
+    if nEmbeds >= 2
+    then e2 = any(InterfaceComponent ic | ic.isComponentOf(intf, -2))
+    else e2 = MkNoIComponent()
+  )
+}
+
+pragma[nomagic]
+predicate unpackAndUnaliasInterfaceType(
+  InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
+  TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
+  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds,
+  boolean isComparable
+) {
+  exists(
+    OptInterfaceComponent c0a, OptInterfaceComponent c1a, OptInterfaceComponent c2a,
+    OptInterfaceComponent c3a, OptInterfaceComponent c4a, OptInterfaceComponent e1a,
+    OptInterfaceComponent e2a
+  |
+    unpackInterfaceType(intf, c0a, c1a, c2a, c3a, c4a, e1a, e2a, nComponents, nEmbeds, isComparable) and
+    c0 = c0a.getWithDeepUnaliasedType() and
+    c1 = c1a.getWithDeepUnaliasedType() and
+    c2 = c2a.getWithDeepUnaliasedType() and
+    c3 = c3a.getWithDeepUnaliasedType() and
+    c4 = c4a.getWithDeepUnaliasedType() and
+    e1 = e1a.getWithDeepUnaliasedType() and
+    e2 = e2a.getWithDeepUnaliasedType()
+  )
+}
+
+/** An interface type. */
+class InterfaceType extends @interfacetype, CompositeType {
+  private Type getMethodType(int i, string name) {
+    i >= 0 and isInterfaceComponentWithQualifiedName(this, i, name, result)
+  }
+
+  /**
+   * Holds if `tp` is a directly embedded type with index `index`.
+   *
+   * `tp` (or its underlying type) is either a type set literal type or an
+   * interface type.
+   */
+  private predicate hasDirectlyEmbeddedType(int index, Type tp) {
+    index >= 0 and isInterfaceComponentWithQualifiedName(this, -(index + 1), _, tp)
+  }
+
+  private InterfaceType getDeepUnaliasedTypeCandidate() {
+    exists(
+      OptInterfaceComponent c0, OptInterfaceComponent c1, OptInterfaceComponent c2,
+      OptInterfaceComponent c3, OptInterfaceComponent c4, OptInterfaceComponent e1,
+      OptInterfaceComponent e2, int nComponents, int nEmbeds, boolean isComparable
+    |
+      unpackAndUnaliasInterfaceType(this, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds,
+        isComparable) and
+      unpackInterfaceType(result, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds, isComparable)
+    )
+  }
+
+  private predicate hasDeepUnaliasedComponentTypesUpTo(InterfaceType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 5 and
     (
-      if nComponents >= 3
-      then c2 = any(InterfaceComponent ic | ic.isComponentOf(intf, 2))
-      else c2 = MkNoIComponent()
+      i = 5 or
+      this.hasDeepUnaliasedComponentTypesUpTo(unaliased, i - 1)
     ) and
+    exists(string name |
+      unaliased.getMethodType(i, name) = this.getMethodType(i, name).getDeepUnaliasedType()
+    )
+  }
+
+  private predicate hasDeepUnaliasedEmbeddedTypesUpTo(InterfaceType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 2 and
     (
-      if nComponents >= 4
-      then c3 = any(InterfaceComponent ic | ic.isComponentOf(intf, 3))
-      else c3 = MkNoIComponent()
+      i = 2 or
+      this.hasDeepUnaliasedEmbeddedTypesUpTo(unaliased, i - 1)
     ) and
-    (
-      if nComponents >= 5
-      then c4 = any(InterfaceComponent ic | ic.isComponentOf(intf, 4))
-      else c4 = MkNoIComponent()
+    exists(Type tp | this.hasDirectlyEmbeddedType(i, tp) |
+      unaliased.hasDirectlyEmbeddedType(i, tp.getDeepUnaliasedType())
+    )
+  }
+
+  override InterfaceType getDeepUnaliasedType() {
+    result = this.getDeepUnaliasedTypeCandidate() and
+    exists(int nComponents | nComponents = count(int i | exists(this.getMethodType(i, _))) |
+      this.hasDeepUnaliasedComponentTypesUpTo(result, nComponents - 1)
+      or
+      nComponents <= 5
     ) and
+    exists(int nEmbeds | nEmbeds = count(int i | this.hasDirectlyEmbeddedType(i, _)) |
+      this.hasDeepUnaliasedEmbeddedTypesUpTo(result, nEmbeds - 1)
+      or
+      nEmbeds <= 2
+    )
+  }
+}
+
+pragma[nomagic]
+private predicate unpackTupleType(
+  TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
+) {
+  nComponents = count(int i | component_types(tt, i, _, _)) and
+  (if nComponents >= 1 then c0 = MkSomeType(tt.getComponentType(0)) else c0 = MkNoType()) and
+  (if nComponents >= 2 then c1 = MkSomeType(tt.getComponentType(1)) else c1 = MkNoType()) and
+  (if nComponents >= 3 then c2 = MkSomeType(tt.getComponentType(2)) else c2 = MkNoType())
+}
+
+pragma[nomagic]
+private predicate unpackAndUnaliasTupleType(
+  TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
+) {
+  exists(OptType c0a, OptType c1a, OptType c2a |
+    unpackTupleType(tt, c0a, c1a, c2a, nComponents) and
+    c0 = c0a.getDeepUnaliasedType() and
+    c1 = c1a.getDeepUnaliasedType() and
+    c2 = c2a.getDeepUnaliasedType()
+  )
+}
+
+/** A tuple type. */
+class TupleType extends @tupletype, CompositeType {
+  /** Gets the `i`th component type of this tuple type. */
+  Type getComponentType(int i) { component_types(this, i, _, result) }
+
+  private TupleType getCandidateDeepUnaliasedType() {
+    exists(OptType c0, OptType c1, OptType c2, int nComponents |
+      unpackAndUnaliasTupleType(this, c0, c1, c2, nComponents) and
+      unpackTupleType(result, c0, c1, c2, nComponents)
+    )
+  }
+
+  private predicate isDeepUnaliasedTypeUpTo(TupleType tt, int i) {
+    tt = this.getCandidateDeepUnaliasedType() and
+    i >= 3 and
     (
-      if nEmbeds >= 1
-      then e1 = any(InterfaceComponent ic | ic.isComponentOf(intf, -1))
-      else e1 = MkNoIComponent()
+      i = 3
+      or
+      this.isDeepUnaliasedTypeUpTo(tt, i - 1)
     ) and
-    (
-      if nEmbeds >= 2
-      then e2 = any(InterfaceComponent ic | ic.isComponentOf(intf, -2))
-      else e2 = MkNoIComponent()
+    tt.getComponentType(i) = this.getComponentType(i).getDeepUnaliasedType()
+  }
+
+  override TupleType getDeepUnaliasedType() {
+    result = this.getCandidateDeepUnaliasedType() and
+    exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
+      this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
+      or
+      nComponents <= 3
     )
   }
-  
-  pragma[nomagic]
-  predicate unpackAndUnaliasInterfaceType(
-    InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
-    TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
-    TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds
-  ) {
+}
+
+// Reasonably efficiently map from a signature type to its
+// deep-unaliased equivalent, by using a single join for the leading 5 parameters
+// and/or 3 results.
+private newtype TOptType =
+  MkNoType() or
+  MkSomeType(Type tp)
+
+private class OptType extends TOptType {
+  OptType getDeepUnaliasedType() {
+    exists(Type t | this = MkSomeType(t) | result = MkSomeType(t.getDeepUnaliasedType()))
+    or
+    this = MkNoType() and result = MkNoType()
+  }
+
+  string toString() {
+    exists(Type t | this = MkSomeType(t) | result = t.toString())
+    or
+    this = MkNoType() and result = "no type"
+  }
+}
+
+pragma[nomagic]
+private predicate unpackSignatureType(
+  SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
+  int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
+) {
+  nParams = sig.getNumParameter() and
+  nResults = sig.getNumResult() and
+  (if nParams >= 1 then param0 = MkSomeType(sig.getParameterType(0)) else param0 = MkNoType()) and
+  (if nParams >= 2 then param1 = MkSomeType(sig.getParameterType(1)) else param1 = MkNoType()) and
+  (if nParams >= 3 then param2 = MkSomeType(sig.getParameterType(2)) else param2 = MkNoType()) and
+  (if nParams >= 4 then param3 = MkSomeType(sig.getParameterType(3)) else param3 = MkNoType()) and
+  (if nParams >= 5 then param4 = MkSomeType(sig.getParameterType(4)) else param4 = MkNoType()) and
+  (if nResults >= 1 then result0 = MkSomeType(sig.getResultType(0)) else result0 = MkNoType()) and
+  (if nResults >= 2 then result1 = MkSomeType(sig.getResultType(1)) else result1 = MkNoType()) and
+  (if nResults >= 3 then result2 = MkSomeType(sig.getResultType(2)) else result2 = MkNoType()) and
+  (if sig.isVariadic() then isVariadic = true else isVariadic = false)
+}
+
+pragma[nomagic]
+private predicate unpackAndUnaliasSignatureType(
+  SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
+  int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
+) {
+  exists(
+    OptType param0a, OptType param1a, OptType param2a, OptType param3a, OptType param4a,
+    OptType result0a, OptType result1a, OptType result2a
+  |
+    unpackSignatureType(sig, param0a, param1a, param2a, param3a, param4a, nParams, result0a,
+      result1a, result2a, nResults, isVariadic)
+  |
+    param0 = param0a.getDeepUnaliasedType() and
+    param1 = param1a.getDeepUnaliasedType() and
+    param2 = param2a.getDeepUnaliasedType() and
+    param3 = param3a.getDeepUnaliasedType() and
+    param4 = param4a.getDeepUnaliasedType() and
+    result0 = result0a.getDeepUnaliasedType() and
+    result1 = result1a.getDeepUnaliasedType() and
+    result2 = result2a.getDeepUnaliasedType()
+  )
+}
+
+/** A signature type. */
+class SignatureType extends @signaturetype, CompositeType {
+  /** Gets the `i`th parameter type of this signature type. */
+  Type getParameterType(int i) { i >= 0 and component_types(this, i + 1, _, result) }
+
+  /** Gets the `i`th result type of this signature type. */
+  Type getResultType(int i) { i >= 0 and component_types(this, -(i + 1), _, result) }
+
+  /** Gets the number of parameters specified by this signature. */
+  int getNumParameter() { result = count(int i | exists(this.getParameterType(i))) }
+
+  /** Gets the number of results specified by this signature. */
+  int getNumResult() { result = count(int i | exists(this.getResultType(i))) }
+
+  /** Holds if this signature type is variadic. */
+  predicate isVariadic() { variadic(this) }
+
+  private SignatureType getDeepUnaliasedTypeCandidate() {
     exists(
-      OptInterfaceComponent c0a, OptInterfaceComponent c1a, OptInterfaceComponent c2a,
-      OptInterfaceComponent c3a, OptInterfaceComponent c4a, OptInterfaceComponent e1a,
-      OptInterfaceComponent e2a
+      OptType param0, OptType param1, OptType param2, OptType param3, OptType param4, int nParams,
+      OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
     |
-      unpackInterfaceType(intf, c0a, c1a, c2a, c3a, c4a, e1a, e2a, nComponents, nEmbeds) and
-      c0 = c0a.getWithDeepUnaliasedType() and
-      c1 = c1a.getWithDeepUnaliasedType() and
-      c2 = c2a.getWithDeepUnaliasedType() and
-      c3 = c3a.getWithDeepUnaliasedType() and
-      c4 = c4a.getWithDeepUnaliasedType() and
-      e1 = e1a.getWithDeepUnaliasedType() and
-      e2 = e2a.getWithDeepUnaliasedType()
+      unpackAndUnaliasSignatureType(this, param0, param1, param2, param3, param4, nParams, result0,
+        result1, result2, nResults, isVariadic) and
+      unpackSignatureType(result, param0, param1, param2, param3, param4, nParams, result0, result1,
+        result2, nResults, isVariadic)
     )
   }
-  
-  /** An interface type. */
-  class InterfaceType extends @interfacetype, CompositeType {
-    private InterfaceType getDeepUnaliasedTypeCandidate() {
-      exists(
-        OptInterfaceComponent c0, OptInterfaceComponent c1, OptInterfaceComponent c2,
-        OptInterfaceComponent c3, OptInterfaceComponent c4, OptInterfaceComponent e1,
-        OptInterfaceComponent e2, int nComponents, int nEmbeds
-      |
-        unpackAndUnaliasInterfaceType(this, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds) and
-        unpackInterfaceType(result, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds)
-      )
-    }
-  
-    private predicate hasDeepUnaliasedComponentTypesUpTo(InterfaceType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 5 and
-      (
-        i = 5 or
-        this.hasDeepUnaliasedComponentTypesUpTo(unaliased, i - 1)
-      ) and
-      exists(string name, Type tp | component_types(this, i, name, tp) |
-        component_types(unaliased, i, name, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    private predicate hasDeepUnaliasedEmbeddedTypesUpTo(InterfaceType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 3 and
-      (
-        i = 3 or
-        this.hasDeepUnaliasedEmbeddedTypesUpTo(unaliased, i - 1)
-      ) and
-      exists(string name, Type tp | component_types(this, -i, name, tp) |
-        component_types(unaliased, -i, name, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    override InterfaceType getDeepUnaliasedType() {
-      result = this.getDeepUnaliasedTypeCandidate() and
-      exists(int nComponents |
-        nComponents = count(int i | component_types(this, i, _, _) and i >= 0)
-      |
-        this.hasDeepUnaliasedComponentTypesUpTo(result, nComponents - 1)
-        or
-        nComponents <= 5
-      ) and
-      exists(int nEmbeds | nEmbeds = count(int i | component_types(this, i, _, _) and i < 0) |
-        // Note no -1 here, because the first embedded type is at -1
-        this.hasDeepUnaliasedEmbeddedTypesUpTo(result, nEmbeds)
-        or
-        nEmbeds <= 2
-      )
-    }
-  }
-  
-  pragma[nomagic]
-  private predicate unpackTupleType(
-    TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
-  ) {
-    nComponents = count(int i | component_types(tt, i, _, _)) and
-    (if nComponents >= 1 then c0 = MkSomeType(tt.getComponentType(0)) else c0 = MkNoType()) and
-    (if nComponents >= 2 then c1 = MkSomeType(tt.getComponentType(1)) else c1 = MkNoType()) and
-    (if nComponents >= 3 then c2 = MkSomeType(tt.getComponentType(2)) else c2 = MkNoType())
+
+  // These incremental recursive implementations only apply from parameter 5 or result 3
+  // upwards to avoid constructing large squares of candidates -- the initial parameters
+  // and results are taken care of by the candidate predicate.
+  private predicate hasDeepUnaliasedParameterTypesUpTo(SignatureType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 5 and
+    (i = 5 or this.hasDeepUnaliasedParameterTypesUpTo(unaliased, i - 1)) and
+    unaliased.getParameterType(i) = this.getParameterType(i).getDeepUnaliasedType()
   }
-  
-  pragma[nomagic]
-  private predicate unpackAndUnaliasTupleType(
-    TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
-  ) {
-    exists(OptType c0a, OptType c1a, OptType c2a |
-      unpackTupleType(tt, c0a, c1a, c2a, nComponents) and
-      c0 = c0a.getDeepUnaliasedType() and
-      c1 = c1a.getDeepUnaliasedType() and
-      c2 = c2a.getDeepUnaliasedType()
-    )
+
+  private predicate hasDeepUnaliasedResultTypesUpTo(SignatureType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 3 and
+    (i = 3 or this.hasDeepUnaliasedResultTypesUpTo(unaliased, i - 1)) and
+    unaliased.getResultType(i) = this.getResultType(i).getDeepUnaliasedType()
   }
-  
-  /** A tuple type. */
-  class TupleType extends @tupletype, CompositeType {
-    /** Gets the `i`th component type of this tuple type. */
-    Type getComponentType(int i) { component_types(this, i, _, result) }
-  
-    private TupleType getCandidateDeepUnaliasedType() {
-      exists(OptType c0, OptType c1, OptType c2, int nComponents |
-        unpackAndUnaliasTupleType(this, c0, c1, c2, nComponents) and
-        unpackTupleType(result, c0, c1, c2, nComponents)
-      )
-    }
-  
-    private predicate isDeepUnaliasedTypeUpTo(TupleType tt, int i) {
-      tt = this.getCandidateDeepUnaliasedType() and
-      i >= 3 and
+
+  override SignatureType getDeepUnaliasedType() {
+    result = this.getDeepUnaliasedTypeCandidate() and
+    exists(int nParams, int nResults |
+      this.getNumParameter() = nParams and this.getNumResult() = nResults
+    |
       (
-        i = 3
+        nParams <= 5
         or
-        this.isDeepUnaliasedTypeUpTo(tt, i - 1)
+        this.hasDeepUnaliasedParameterTypesUpTo(result, nParams - 1)
       ) and
-      exists(Type tp | component_types(this, i, _, tp) |
-        component_types(tt, i, _, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    override TupleType getDeepUnaliasedType() {
-      result = this.getCandidateDeepUnaliasedType() and
-      exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
-        this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
+      (
+        nResults <= 3
         or
-        nComponents <= 3
+        this.hasDeepUnaliasedResultTypesUpTo(result, nResults - 1)
       )
-    }
-  }
-  
-  // Reasonably efficiently map from a signature type to its
-  // deep-unaliased equivalent, by using a single join for the leading 5 parameters
-  // and/or 3 results.
-  private newtype TOptType =
-    MkNoType() or
-    MkSomeType(Type tp)
-  
-  private class OptType extends TOptType {
-    OptType getDeepUnaliasedType() {
-      exists(Type t | this = MkSomeType(t) | result = MkSomeType(t.getDeepUnaliasedType()))
-      or
-      this = MkNoType() and result = MkNoType()
-    }
-  
-    string toString() {
-      exists(Type t | this = MkSomeType(t) | result = t.toString())
-      or
-      this = MkNoType() and result = "no type"
-    }
-  }
-  
-  pragma[nomagic]
-  private predicate unpackSignatureType(
-    SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
-    int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
-  ) {
-    nParams = sig.getNumParameter() and
-    nResults = sig.getNumResult() and
-    (if nParams >= 1 then param0 = MkSomeType(sig.getParameterType(0)) else param0 = MkNoType()) and
-    (if nParams >= 2 then param1 = MkSomeType(sig.getParameterType(1)) else param1 = MkNoType()) and
-    (if nParams >= 3 then param2 = MkSomeType(sig.getParameterType(2)) else param2 = MkNoType()) and
-    (if nParams >= 4 then param3 = MkSomeType(sig.getParameterType(3)) else param3 = MkNoType()) and
-    (if nParams >= 5 then param4 = MkSomeType(sig.getParameterType(4)) else param4 = MkNoType()) and
-    (if nResults >= 1 then result0 = MkSomeType(sig.getResultType(0)) else result0 = MkNoType()) and
-    (if nResults >= 2 then result1 = MkSomeType(sig.getResultType(1)) else result1 = MkNoType()) and
-    (if nResults >= 3 then result2 = MkSomeType(sig.getResultType(2)) else result2 = MkNoType()) and
-    (if sig.isVariadic() then isVariadic = true else isVariadic = false)
-  }
-  
-  pragma[nomagic]
-  private predicate unpackAndUnaliasSignatureType(
-    SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
-    int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
-  ) {
-    exists(
-      OptType param0a, OptType param1a, OptType param2a, OptType param3a, OptType param4a,
-      OptType result0a, OptType result1a, OptType result2a
-    |
-      unpackSignatureType(sig, param0a, param1a, param2a, param3a, param4a, nParams, result0a,
-        result1a, result2a, nResults, isVariadic)
-    |
-      param0 = param0a.getDeepUnaliasedType() and
-      param1 = param1a.getDeepUnaliasedType() and
-      param2 = param2a.getDeepUnaliasedType() and
-      param3 = param3a.getDeepUnaliasedType() and
-      param4 = param4a.getDeepUnaliasedType() and
-      result0 = result0a.getDeepUnaliasedType() and
-      result1 = result1a.getDeepUnaliasedType() and
-      result2 = result2a.getDeepUnaliasedType()
     )
   }
-  
-  /** A signature type. */
-  class SignatureType extends @signaturetype, CompositeType {
-    /** Gets the `i`th parameter type of this signature type. */
-    Type getParameterType(int i) { i >= 0 and component_types(this, i + 1, _, result) }
-  
-    /** Gets the `i`th result type of this signature type. */
-    Type getResultType(int i) { i >= 0 and component_types(this, -(i + 1), _, result) }
-  
-    /** Gets the number of parameters specified by this signature. */
-    int getNumParameter() { result = count(int i | exists(this.getParameterType(i))) }
-  
-    /** Gets the number of results specified by this signature. */
-    int getNumResult() { result = count(int i | exists(this.getResultType(i))) }
-  
-    /** Holds if this signature type is variadic. */
-    predicate isVariadic() { variadic(this) }
-  
-    private SignatureType getDeepUnaliasedTypeCandidate() {
-      exists(
-        OptType param0, OptType param1, OptType param2, OptType param3, OptType param4, int nParams,
-        OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
-      |
-        unpackAndUnaliasSignatureType(this, param0, param1, param2, param3, param4, nParams, result0,
-          result1, result2, nResults, isVariadic) and
-        unpackSignatureType(result, param0, param1, param2, param3, param4, nParams, result0, result1,
-          result2, nResults, isVariadic)
-      )
-    }
-  
-    // These incremental recursive implementations only apply from parameter 5 or result 3
-    // upwards to avoid constructing large squares of candidates -- the initial parameters
-    // and results are taken care of by the candidate predicate.
-    private predicate hasDeepUnaliasedParameterTypesUpTo(SignatureType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 5 and
-      (i = 5 or this.hasDeepUnaliasedParameterTypesUpTo(unaliased, i - 1)) and
-      unaliased.getParameterType(i) = this.getParameterType(i).getDeepUnaliasedType()
-    }
-  
-    private predicate hasDeepUnaliasedResultTypesUpTo(SignatureType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 3 and
-      (i = 3 or this.hasDeepUnaliasedResultTypesUpTo(unaliased, i - 1)) and
-      unaliased.getResultType(i) = this.getResultType(i).getDeepUnaliasedType()
-    }
-  
-    override SignatureType getDeepUnaliasedType() {
-      result = this.getDeepUnaliasedTypeCandidate() and
-      exists(int nParams, int nResults |
-        this.getNumParameter() = nParams and this.getNumResult() = nResults
-      |
-        (
-          nParams <= 5
-          or
-          this.hasDeepUnaliasedParameterTypesUpTo(result, nParams - 1)
-        ) and
-        (
-          nResults <= 3
-          or
-          this.hasDeepUnaliasedResultTypesUpTo(result, nResults - 1)
-        )
-      )
-    }
-  }
-  
-  /** A map type. */
-  class MapType extends @maptype, CompositeType {
-    /** Gets the key type of this map type. */
-    Type getKeyType() { key_type(this, result) }
-  
-    /** Gets the value type of this map type. */
-    Type getValueType() { element_type(this, result) }
-  
-    override MapType getDeepUnaliasedType() {
-      result.getKeyType() = this.getKeyType().getDeepUnaliasedType() and
-      result.getValueType() = this.getValueType().getDeepUnaliasedType()
-    }
-  }
-  
-  /** A channel type. */
-  class ChanType extends @chantype, CompositeType {
-    /** Gets the element type of this channel type. */
-    Type getElementType() { element_type(this, result) }
-  }
-  
-  /** A channel type that can only send. */
-  class SendChanType extends @sendchantype, ChanType {
-    override SendChanType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
-  }
-  
-  /** A channel type that can only receive. */
-  class RecvChanType extends @recvchantype, ChanType {
-    override RecvChanType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
+}
+
+/** A map type. */
+class MapType extends @maptype, CompositeType {
+  /** Gets the key type of this map type. */
+  Type getKeyType() { key_type(this, result) }
+
+  /** Gets the value type of this map type. */
+  Type getValueType() { element_type(this, result) }
+
+  override MapType getDeepUnaliasedType() {
+    result.getKeyType() = this.getKeyType().getDeepUnaliasedType() and
+    result.getValueType() = this.getValueType().getDeepUnaliasedType()
   }
-  
-  /** A channel type that can both send and receive. */
-  class SendRecvChanType extends @sendrcvchantype, ChanType {
-    override SendRecvChanType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
+}
+
+/** A channel type. */
+class ChanType extends @chantype, CompositeType {
+  /** Gets the element type of this channel type. */
+  Type getElementType() { element_type(this, result) }
+}
+
+/** A channel type that can only send. */
+class SendChanType extends @sendchantype, ChanType {
+  override SendChanType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  /** An alias type. */
-  class AliasType extends @typealias, CompositeType {
-    /** Gets the aliased type (i.e. that appears on the RHS of the alias definition). */
-    Type getRhs() { alias_rhs(this, result) }
-  
-    override Type getDeepUnaliasedType() { result = unalias(this).getDeepUnaliasedType() }
+}
+
+/** A channel type that can only receive. */
+class RecvChanType extends @recvchantype, ChanType {
+  override RecvChanType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  /**
-   * Gets the non-alias type at the end of the alias chain starting at `t`.
-   *
-   * If `t` is not an alias type then `result` is `t`.
-   */
-  Type unalias(Type t) {
-    not t instanceof AliasType and result = t
-    or
-    result = unalias(t.(AliasType).getRhs())
+}
+
+/** A channel type that can both send and receive. */
+class SendRecvChanType extends @sendrcvchantype, ChanType {
+  override SendRecvChanType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  predicate containsAliases(Type t) { t != t.getDeepUnaliasedType() }
-  // END ALIASES.QLL
-  
+}
+
+/** A named type. */
+class NamedType extends @namedtype, CompositeType {
+  Type getBaseType() { underlying_type(this, result) }
+}
+
+/**
+ * The predeclared `comparable` type.
+ */
+class ComparableType extends NamedType {
+  ComparableType() { typename(this, "comparable") }
+}
+
+/** An alias type. */
+class AliasType extends @typealias, CompositeType {
+  /** Gets the aliased type (i.e. that appears on the RHS of the alias definition). */
+  Type getRhs() { alias_rhs(this, result) }
+
+  override Type getDeepUnaliasedType() { result = unalias(this).getDeepUnaliasedType() }
+}
+
+/**
+ * Gets the non-alias type at the end of the alias chain starting at `t`.
+ *
+ * If `t` is not an alias type then `result` is `t`.
+ */
+Type unalias(Type t) {
+  not t instanceof AliasType and result = t
+  or
+  result = unalias(t.(AliasType).getRhs())
+}
 
+predicate containsAliases(Type t) { t != t.getDeepUnaliasedType() }
+// END ALIASES.QLL
 class Object extends @object {
-    string toString() { result = "object" }
+  string toString() { result = "object" }
 }
 
 from Object o, Type t
diff --git a/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/old.dbscheme b/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/old.dbscheme
index 40dfd9635451..629b145fac46 100644
--- a/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/old.dbscheme
+++ b/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/old.dbscheme
@@ -212,6 +212,9 @@ component_types(int parent: @compositetype ref, int index: int ref, string name:
 #keyset[parent, index]
 component_tags(int parent: @compositetype ref, int index: int ref, string tag: string ref);
 
+#keyset[interface, index]
+interface_private_method_ids(int interface: @interfacetype ref, int index: int ref, string id: string ref);
+
 array_length(unique int tp: @arraytype ref, string len: string ref);
 
 type_objects(unique int tp: @type ref, int object: @object ref);
diff --git a/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/type_objects.ql b/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/type_objects.ql
index a4c783022b42..cf4c0f587e9f 100644
--- a/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/type_objects.ql
+++ b/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/type_objects.ql
@@ -174,9 +174,21 @@ class PointerType extends @pointertype, CompositeType {
   }
 }
 
+private predicate isInterfaceComponentWithQualifiedName(
+  InterfaceType intf, int idx, string qualifiedName, Type tp
+) {
+  exists(string name | component_types(intf, idx, name, tp) |
+    interface_private_method_ids(intf, idx, qualifiedName)
+    or
+    not interface_private_method_ids(intf, idx, _) and qualifiedName = name
+  )
+}
+
 private newtype TOptInterfaceComponent =
   MkNoIComponent() or
-  MkSomeIComponent(string name, Type tp) { component_types(any(InterfaceType i), _, name, tp) }
+  MkSomeIComponent(string name, Type tp) {
+    isInterfaceComponentWithQualifiedName(any(InterfaceType i), _, name, tp)
+  }
 
 private class OptInterfaceComponent extends TOptInterfaceComponent {
   OptInterfaceComponent getWithDeepUnaliasedType() {
@@ -196,7 +208,7 @@ private class InterfaceComponent extends MkSomeIComponent {
 
   predicate isComponentOf(InterfaceType intf, int i) {
     exists(string name, Type tp |
-      component_types(intf, i, name, tp) and
+      isInterfaceComponentWithQualifiedName(intf, i, name, tp) and
       this = MkSomeIComponent(name, tp)
     )
   }
@@ -206,10 +218,16 @@ pragma[nomagic]
 predicate unpackInterfaceType(
   InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
   TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
-  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds
+  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds,
+  boolean isComparable
 ) {
-  nComponents = count(int i | component_types(intf, i, _, _) and i >= 0) and
-  nEmbeds = count(int i | component_types(intf, i, _, _) and i < 0) and
+  nComponents = count(int i | isInterfaceComponentWithQualifiedName(intf, i, _, _) and i >= 0) and
+  nEmbeds = count(int i | isInterfaceComponentWithQualifiedName(intf, i, _, _) and i < 0) and
+  (
+    if intf = any(ComparableType comparable).getBaseType()
+    then isComparable = true
+    else isComparable = false
+  ) and
   (
     if nComponents >= 1
     then c0 = any(InterfaceComponent ic | ic.isComponentOf(intf, 0))
@@ -251,14 +269,15 @@ pragma[nomagic]
 predicate unpackAndUnaliasInterfaceType(
   InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
   TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
-  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds
+  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds,
+  boolean isComparable
 ) {
   exists(
     OptInterfaceComponent c0a, OptInterfaceComponent c1a, OptInterfaceComponent c2a,
     OptInterfaceComponent c3a, OptInterfaceComponent c4a, OptInterfaceComponent e1a,
     OptInterfaceComponent e2a
   |
-    unpackInterfaceType(intf, c0a, c1a, c2a, c3a, c4a, e1a, e2a, nComponents, nEmbeds) and
+    unpackInterfaceType(intf, c0a, c1a, c2a, c3a, c4a, e1a, e2a, nComponents, nEmbeds, isComparable) and
     c0 = c0a.getWithDeepUnaliasedType() and
     c1 = c1a.getWithDeepUnaliasedType() and
     c2 = c2a.getWithDeepUnaliasedType() and
@@ -271,14 +290,29 @@ predicate unpackAndUnaliasInterfaceType(
 
 /** An interface type. */
 class InterfaceType extends @interfacetype, CompositeType {
+  private Type getMethodType(int i, string name) {
+    i >= 0 and isInterfaceComponentWithQualifiedName(this, i, name, result)
+  }
+
+  /**
+   * Holds if `tp` is a directly embedded type with index `index`.
+   *
+   * `tp` (or its underlying type) is either a type set literal type or an
+   * interface type.
+   */
+  private predicate hasDirectlyEmbeddedType(int index, Type tp) {
+    index >= 0 and isInterfaceComponentWithQualifiedName(this, -(index + 1), _, tp)
+  }
+
   private InterfaceType getDeepUnaliasedTypeCandidate() {
     exists(
       OptInterfaceComponent c0, OptInterfaceComponent c1, OptInterfaceComponent c2,
       OptInterfaceComponent c3, OptInterfaceComponent c4, OptInterfaceComponent e1,
-      OptInterfaceComponent e2, int nComponents, int nEmbeds
+      OptInterfaceComponent e2, int nComponents, int nEmbeds, boolean isComparable
     |
-      unpackAndUnaliasInterfaceType(this, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds) and
-      unpackInterfaceType(result, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds)
+      unpackAndUnaliasInterfaceType(this, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds,
+        isComparable) and
+      unpackInterfaceType(result, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds, isComparable)
     )
   }
 
@@ -289,35 +323,32 @@ class InterfaceType extends @interfacetype, CompositeType {
       i = 5 or
       this.hasDeepUnaliasedComponentTypesUpTo(unaliased, i - 1)
     ) and
-    exists(string name, Type tp | component_types(this, i, name, tp) |
-      component_types(unaliased, i, name, tp.getDeepUnaliasedType())
+    exists(string name |
+      unaliased.getMethodType(i, name) = this.getMethodType(i, name).getDeepUnaliasedType()
     )
   }
 
   private predicate hasDeepUnaliasedEmbeddedTypesUpTo(InterfaceType unaliased, int i) {
     unaliased = this.getDeepUnaliasedTypeCandidate() and
-    i >= 3 and
+    i >= 2 and
     (
-      i = 3 or
+      i = 2 or
       this.hasDeepUnaliasedEmbeddedTypesUpTo(unaliased, i - 1)
     ) and
-    exists(string name, Type tp | component_types(this, -i, name, tp) |
-      component_types(unaliased, -i, name, tp.getDeepUnaliasedType())
+    exists(Type tp | this.hasDirectlyEmbeddedType(i, tp) |
+      unaliased.hasDirectlyEmbeddedType(i, tp.getDeepUnaliasedType())
     )
   }
 
   override InterfaceType getDeepUnaliasedType() {
     result = this.getDeepUnaliasedTypeCandidate() and
-    exists(int nComponents |
-      nComponents = count(int i | component_types(this, i, _, _) and i >= 0)
-    |
+    exists(int nComponents | nComponents = count(int i | exists(this.getMethodType(i, _))) |
       this.hasDeepUnaliasedComponentTypesUpTo(result, nComponents - 1)
       or
       nComponents <= 5
     ) and
-    exists(int nEmbeds | nEmbeds = count(int i | component_types(this, i, _, _) and i < 0) |
-      // Note no -1 here, because the first embedded type is at -1
-      this.hasDeepUnaliasedEmbeddedTypesUpTo(result, nEmbeds)
+    exists(int nEmbeds | nEmbeds = count(int i | this.hasDirectlyEmbeddedType(i, _)) |
+      this.hasDeepUnaliasedEmbeddedTypesUpTo(result, nEmbeds - 1)
       or
       nEmbeds <= 2
     )
@@ -366,9 +397,7 @@ class TupleType extends @tupletype, CompositeType {
       or
       this.isDeepUnaliasedTypeUpTo(tt, i - 1)
     ) and
-    exists(Type tp | component_types(this, i, _, tp) |
-      component_types(tt, i, _, tp.getDeepUnaliasedType())
-    )
+    tt.getComponentType(i) = this.getComponentType(i).getDeepUnaliasedType()
   }
 
   override TupleType getDeepUnaliasedType() {
@@ -549,6 +578,18 @@ class SendRecvChanType extends @sendrcvchantype, ChanType {
   }
 }
 
+/** A named type. */
+class NamedType extends @namedtype, CompositeType {
+  Type getBaseType() { underlying_type(this, result) }
+}
+
+/**
+ * The predeclared `comparable` type.
+ */
+class ComparableType extends NamedType {
+  ComparableType() { typename(this, "comparable") }
+}
+
 /** An alias type. */
 class AliasType extends @typealias, CompositeType {
   /** Gets the aliased type (i.e. that appears on the RHS of the alias definition). */
@@ -570,8 +611,6 @@ Type unalias(Type t) {
 
 predicate containsAliases(Type t) { t != t.getDeepUnaliasedType() }
 // END ALIASES.QLL
-
-
 class Object extends @object {
   string toString() { result = "object" }
 }
@@ -582,6 +621,6 @@ class Object extends @object {
 // type_objects(unique int tp: @type ref, int object: @object ref);
 from Type type, Object object
 where
-  type_objects(type, object)
-  and not containsAliases(type)
+  type_objects(type, object) and
+  not containsAliases(type)
 select type, object
diff --git a/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/type_of.ql b/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/type_of.ql
index 1390b1b1b5d4..511d32d5a7e0 100644
--- a/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/type_of.ql
+++ b/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/type_of.ql
@@ -2,580 +2,619 @@
 // Database scripts can't import, but this is the definitive copy of the support routines for mapping types to their unaliased equivalent. Ensure this code is in sync between aliases.qll and all copies in individual table .ql files.
 /** A Go type. */
 class Type extends @type {
-    /**
-     * Gets this type with all aliases substituted for their underlying type.
-     *
-     * Note named types are not substituted.
-     */
-    Type getDeepUnaliasedType() { result = this }
-  
-    /**
-     * Gets a basic textual representation of this type.
-     */
-    string toString() { result = "type" }
-  }
-  
-  /** A composite type, that is, not a basic type. */
-  class CompositeType extends @compositetype, Type { }
-  
-  /** An array type. */
-  class ArrayType extends @arraytype, CompositeType {
-    /** Gets the element type of this array type. */
-    Type getElementType() { element_type(this, result) }
-  
-    /** Gets the length of this array type as a string. */
-    string getLengthString() { array_length(this, result) }
-  
-    override ArrayType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType() and
-      result.getLengthString() = this.getLengthString()
-    }
+  /**
+   * Gets this type with all aliases substituted for their underlying type.
+   *
+   * Note named types are not substituted.
+   */
+  Type getDeepUnaliasedType() { result = this }
+
+  /**
+   * Gets a basic textual representation of this type.
+   */
+  string toString() { result = "type" }
+}
+
+/** A composite type, that is, not a basic type. */
+class CompositeType extends @compositetype, Type { }
+
+/** An array type. */
+class ArrayType extends @arraytype, CompositeType {
+  /** Gets the element type of this array type. */
+  Type getElementType() { element_type(this, result) }
+
+  /** Gets the length of this array type as a string. */
+  string getLengthString() { array_length(this, result) }
+
+  override ArrayType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType() and
+    result.getLengthString() = this.getLengthString()
   }
-  
-  /** A slice type. */
-  class SliceType extends @slicetype, CompositeType {
-    /** Gets the element type of this slice type. */
-    Type getElementType() { element_type(this, result) }
-  
-    override SliceType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
+}
+
+/** A slice type. */
+class SliceType extends @slicetype, CompositeType {
+  /** Gets the element type of this slice type. */
+  Type getElementType() { element_type(this, result) }
+
+  override SliceType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  // Improve efficiency of matching a struct to its unaliased equivalent
-  // by unpacking the first 5 fields and tags, allowing a single join
-  // to strongly constrain the available candidates.
-  private predicate hasComponentTypeAndTag(StructType s, int i, string name, Type tp, string tag) {
-    component_types(s, i, name, tp) and component_tags(s, i, tag)
+}
+
+// Improve efficiency of matching a struct to its unaliased equivalent
+// by unpacking the first 5 fields and tags, allowing a single join
+// to strongly constrain the available candidates.
+private predicate hasComponentTypeAndTag(StructType s, int i, string name, Type tp, string tag) {
+  component_types(s, i, name, tp) and component_tags(s, i, tag)
+}
+
+private newtype TOptStructComponent =
+  MkNoComponent() or
+  MkSomeComponent(string name, Type tp, string tag) { hasComponentTypeAndTag(_, _, name, tp, tag) }
+
+private class OptStructComponent extends TOptStructComponent {
+  OptStructComponent getWithDeepUnaliasedType() {
+    this = MkNoComponent() and result = MkNoComponent()
+    or
+    exists(string name, Type tp, string tag |
+      this = MkSomeComponent(name, tp, tag) and
+      result = MkSomeComponent(name, tp.getDeepUnaliasedType(), tag)
+    )
   }
-  
-  private newtype TOptStructComponent =
-    MkNoComponent() or
-    MkSomeComponent(string name, Type tp, string tag) { hasComponentTypeAndTag(_, _, name, tp, tag) }
-  
-  private class OptStructComponent extends TOptStructComponent {
-    OptStructComponent getWithDeepUnaliasedType() {
-      this = MkNoComponent() and result = MkNoComponent()
-      or
-      exists(string name, Type tp, string tag |
-        this = MkSomeComponent(name, tp, tag) and
-        result = MkSomeComponent(name, tp.getDeepUnaliasedType(), tag)
-      )
-    }
-  
-    string toString() { result = "struct component" }
+
+  string toString() { result = "struct component" }
+}
+
+private class StructComponent extends MkSomeComponent {
+  string toString() { result = "struct component" }
+
+  predicate isComponentOf(StructType s, int i) {
+    exists(string name, Type tp, string tag |
+      hasComponentTypeAndTag(s, i, name, tp, tag) and
+      this = MkSomeComponent(name, tp, tag)
+    )
   }
-  
-  private class StructComponent extends MkSomeComponent {
-    string toString() { result = "struct component" }
-  
-    predicate isComponentOf(StructType s, int i) {
-      exists(string name, Type tp, string tag |
-        hasComponentTypeAndTag(s, i, name, tp, tag) and
-        this = MkSomeComponent(name, tp, tag)
-      )
-    }
+}
+
+pragma[nomagic]
+predicate unpackStructType(
+  StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
+  TOptStructComponent c3, TOptStructComponent c4, int nComponents
+) {
+  nComponents = count(int i | component_types(s, i, _, _)) and
+  (
+    if nComponents >= 1
+    then c0 = any(StructComponent sc | sc.isComponentOf(s, 0))
+    else c0 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 2
+    then c1 = any(StructComponent sc | sc.isComponentOf(s, 1))
+    else c1 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 3
+    then c2 = any(StructComponent sc | sc.isComponentOf(s, 2))
+    else c2 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 4
+    then c3 = any(StructComponent sc | sc.isComponentOf(s, 3))
+    else c3 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 5
+    then c4 = any(StructComponent sc | sc.isComponentOf(s, 4))
+    else c4 = MkNoComponent()
+  )
+}
+
+pragma[nomagic]
+predicate unpackAndUnaliasStructType(
+  StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
+  TOptStructComponent c3, TOptStructComponent c4, int nComponents
+) {
+  exists(
+    OptStructComponent c0a, OptStructComponent c1a, OptStructComponent c2a, OptStructComponent c3a,
+    OptStructComponent c4a
+  |
+    unpackStructType(s, c0a, c1a, c2a, c3a, c4a, nComponents) and
+    c0 = c0a.getWithDeepUnaliasedType() and
+    c1 = c1a.getWithDeepUnaliasedType() and
+    c2 = c2a.getWithDeepUnaliasedType() and
+    c3 = c3a.getWithDeepUnaliasedType() and
+    c4 = c4a.getWithDeepUnaliasedType()
+  )
+}
+
+/** A struct type. */
+class StructType extends @structtype, CompositeType {
+  private StructType getDeepUnaliasedTypeCandidate() {
+    exists(
+      OptStructComponent c0, OptStructComponent c1, OptStructComponent c2, OptStructComponent c3,
+      OptStructComponent c4, int nComponents
+    |
+      unpackAndUnaliasStructType(this, c0, c1, c2, c3, c4, nComponents) and
+      unpackStructType(result, c0, c1, c2, c3, c4, nComponents)
+    )
   }
-  
-  pragma[nomagic]
-  predicate unpackStructType(
-    StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
-    TOptStructComponent c3, TOptStructComponent c4, int nComponents
-  ) {
-    nComponents = count(int i | component_types(s, i, _, _)) and
-    (
-      if nComponents >= 1
-      then c0 = any(StructComponent sc | sc.isComponentOf(s, 0))
-      else c0 = MkNoComponent()
-    ) and
-    (
-      if nComponents >= 2
-      then c1 = any(StructComponent sc | sc.isComponentOf(s, 1))
-      else c1 = MkNoComponent()
-    ) and
-    (
-      if nComponents >= 3
-      then c2 = any(StructComponent sc | sc.isComponentOf(s, 2))
-      else c2 = MkNoComponent()
-    ) and
+
+  private predicate isDeepUnaliasedTypeUpTo(StructType unaliased, int i) {
+    // Note we must use component_types not hasOwnField here because component_types may specify
+    // interface-in-struct embedding, but hasOwnField does not return such members.
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 5 and
     (
-      if nComponents >= 4
-      then c3 = any(StructComponent sc | sc.isComponentOf(s, 3))
-      else c3 = MkNoComponent()
+      i = 5 or
+      this.isDeepUnaliasedTypeUpTo(unaliased, i - 1)
     ) and
-    (
-      if nComponents >= 5
-      then c4 = any(StructComponent sc | sc.isComponentOf(s, 4))
-      else c4 = MkNoComponent()
+    exists(string name, Type tp, string tag | hasComponentTypeAndTag(this, i, name, tp, tag) |
+      hasComponentTypeAndTag(unaliased, i, name, tp.getDeepUnaliasedType(), tag)
     )
   }
-  
-  pragma[nomagic]
-  predicate unpackAndUnaliasStructType(
-    StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
-    TOptStructComponent c3, TOptStructComponent c4, int nComponents
-  ) {
-    exists(
-      OptStructComponent c0a, OptStructComponent c1a, OptStructComponent c2a, OptStructComponent c3a,
-      OptStructComponent c4a
-    |
-      unpackStructType(s, c0a, c1a, c2a, c3a, c4a, nComponents) and
-      c0 = c0a.getWithDeepUnaliasedType() and
-      c1 = c1a.getWithDeepUnaliasedType() and
-      c2 = c2a.getWithDeepUnaliasedType() and
-      c3 = c3a.getWithDeepUnaliasedType() and
-      c4 = c4a.getWithDeepUnaliasedType()
+
+  override StructType getDeepUnaliasedType() {
+    result = this.getDeepUnaliasedTypeCandidate() and
+    exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
+      this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
+      or
+      nComponents <= 5
     )
   }
-  
-  /** A struct type. */
-  class StructType extends @structtype, CompositeType {
-    private StructType getDeepUnaliasedTypeCandidate() {
-      exists(
-        OptStructComponent c0, OptStructComponent c1, OptStructComponent c2, OptStructComponent c3,
-        OptStructComponent c4, int nComponents
-      |
-        unpackAndUnaliasStructType(this, c0, c1, c2, c3, c4, nComponents) and
-        unpackStructType(result, c0, c1, c2, c3, c4, nComponents)
-      )
-    }
-  
-    private predicate isDeepUnaliasedTypeUpTo(StructType unaliased, int i) {
-      // Note we must use component_types not hasOwnField here because component_types may specify
-      // interface-in-struct embedding, but hasOwnField does not return such members.
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 5 and
-      (
-        i = 5 or
-        this.isDeepUnaliasedTypeUpTo(unaliased, i - 1)
-      ) and
-      exists(string name, Type tp, string tag | hasComponentTypeAndTag(this, i, name, tp, tag) |
-        hasComponentTypeAndTag(unaliased, i, name, tp.getDeepUnaliasedType(), tag)
-      )
-    }
-  
-    override StructType getDeepUnaliasedType() {
-      result = this.getDeepUnaliasedTypeCandidate() and
-      exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
-        this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
-        or
-        nComponents <= 5
-      )
-    }
+}
+
+/** A pointer type. */
+class PointerType extends @pointertype, CompositeType {
+  /** Gets the base type of this pointer type. */
+  Type getBaseType() { base_type(this, result) }
+
+  override PointerType getDeepUnaliasedType() {
+    result.getBaseType() = this.getBaseType().getDeepUnaliasedType()
   }
-  
-  /** A pointer type. */
-  class PointerType extends @pointertype, CompositeType {
-    /** Gets the base type of this pointer type. */
-    Type getBaseType() { base_type(this, result) }
-  
-    override PointerType getDeepUnaliasedType() {
-      result.getBaseType() = this.getBaseType().getDeepUnaliasedType()
-    }
+}
+
+private predicate isInterfaceComponentWithQualifiedName(
+  InterfaceType intf, int idx, string qualifiedName, Type tp
+) {
+  exists(string name | component_types(intf, idx, name, tp) |
+    interface_private_method_ids(intf, idx, qualifiedName)
+    or
+    not interface_private_method_ids(intf, idx, _) and qualifiedName = name
+  )
+}
+
+private newtype TOptInterfaceComponent =
+  MkNoIComponent() or
+  MkSomeIComponent(string name, Type tp) {
+    isInterfaceComponentWithQualifiedName(any(InterfaceType i), _, name, tp)
   }
-  
-  private newtype TOptInterfaceComponent =
-    MkNoIComponent() or
-    MkSomeIComponent(string name, Type tp) { component_types(any(InterfaceType i), _, name, tp) }
-  
-  private class OptInterfaceComponent extends TOptInterfaceComponent {
-    OptInterfaceComponent getWithDeepUnaliasedType() {
-      this = MkNoIComponent() and result = MkNoIComponent()
-      or
-      exists(string name, Type tp |
-        this = MkSomeIComponent(name, tp) and
-        result = MkSomeIComponent(name, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    string toString() { result = "interface component" }
+
+private class OptInterfaceComponent extends TOptInterfaceComponent {
+  OptInterfaceComponent getWithDeepUnaliasedType() {
+    this = MkNoIComponent() and result = MkNoIComponent()
+    or
+    exists(string name, Type tp |
+      this = MkSomeIComponent(name, tp) and
+      result = MkSomeIComponent(name, tp.getDeepUnaliasedType())
+    )
   }
-  
-  private class InterfaceComponent extends MkSomeIComponent {
-    string toString() { result = "interface component" }
-  
-    predicate isComponentOf(InterfaceType intf, int i) {
-      exists(string name, Type tp |
-        component_types(intf, i, name, tp) and
-        this = MkSomeIComponent(name, tp)
-      )
-    }
+
+  string toString() { result = "interface component" }
+}
+
+private class InterfaceComponent extends MkSomeIComponent {
+  string toString() { result = "interface component" }
+
+  predicate isComponentOf(InterfaceType intf, int i) {
+    exists(string name, Type tp |
+      isInterfaceComponentWithQualifiedName(intf, i, name, tp) and
+      this = MkSomeIComponent(name, tp)
+    )
   }
-  
-  pragma[nomagic]
-  predicate unpackInterfaceType(
-    InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
-    TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
-    TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds
-  ) {
-    nComponents = count(int i | component_types(intf, i, _, _) and i >= 0) and
-    nEmbeds = count(int i | component_types(intf, i, _, _) and i < 0) and
-    (
-      if nComponents >= 1
-      then c0 = any(InterfaceComponent ic | ic.isComponentOf(intf, 0))
-      else c0 = MkNoIComponent()
-    ) and
-    (
-      if nComponents >= 2
-      then c1 = any(InterfaceComponent ic | ic.isComponentOf(intf, 1))
-      else c1 = MkNoIComponent()
-    ) and
+}
+
+pragma[nomagic]
+predicate unpackInterfaceType(
+  InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
+  TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
+  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds,
+  boolean isComparable
+) {
+  nComponents = count(int i | isInterfaceComponentWithQualifiedName(intf, i, _, _) and i >= 0) and
+  nEmbeds = count(int i | isInterfaceComponentWithQualifiedName(intf, i, _, _) and i < 0) and
+  (
+    if intf = any(ComparableType comparable).getBaseType()
+    then isComparable = true
+    else isComparable = false
+  ) and
+  (
+    if nComponents >= 1
+    then c0 = any(InterfaceComponent ic | ic.isComponentOf(intf, 0))
+    else c0 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 2
+    then c1 = any(InterfaceComponent ic | ic.isComponentOf(intf, 1))
+    else c1 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 3
+    then c2 = any(InterfaceComponent ic | ic.isComponentOf(intf, 2))
+    else c2 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 4
+    then c3 = any(InterfaceComponent ic | ic.isComponentOf(intf, 3))
+    else c3 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 5
+    then c4 = any(InterfaceComponent ic | ic.isComponentOf(intf, 4))
+    else c4 = MkNoIComponent()
+  ) and
+  (
+    if nEmbeds >= 1
+    then e1 = any(InterfaceComponent ic | ic.isComponentOf(intf, -1))
+    else e1 = MkNoIComponent()
+  ) and
+  (
+    if nEmbeds >= 2
+    then e2 = any(InterfaceComponent ic | ic.isComponentOf(intf, -2))
+    else e2 = MkNoIComponent()
+  )
+}
+
+pragma[nomagic]
+predicate unpackAndUnaliasInterfaceType(
+  InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
+  TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
+  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds,
+  boolean isComparable
+) {
+  exists(
+    OptInterfaceComponent c0a, OptInterfaceComponent c1a, OptInterfaceComponent c2a,
+    OptInterfaceComponent c3a, OptInterfaceComponent c4a, OptInterfaceComponent e1a,
+    OptInterfaceComponent e2a
+  |
+    unpackInterfaceType(intf, c0a, c1a, c2a, c3a, c4a, e1a, e2a, nComponents, nEmbeds, isComparable) and
+    c0 = c0a.getWithDeepUnaliasedType() and
+    c1 = c1a.getWithDeepUnaliasedType() and
+    c2 = c2a.getWithDeepUnaliasedType() and
+    c3 = c3a.getWithDeepUnaliasedType() and
+    c4 = c4a.getWithDeepUnaliasedType() and
+    e1 = e1a.getWithDeepUnaliasedType() and
+    e2 = e2a.getWithDeepUnaliasedType()
+  )
+}
+
+/** An interface type. */
+class InterfaceType extends @interfacetype, CompositeType {
+  private Type getMethodType(int i, string name) {
+    i >= 0 and isInterfaceComponentWithQualifiedName(this, i, name, result)
+  }
+
+  /**
+   * Holds if `tp` is a directly embedded type with index `index`.
+   *
+   * `tp` (or its underlying type) is either a type set literal type or an
+   * interface type.
+   */
+  private predicate hasDirectlyEmbeddedType(int index, Type tp) {
+    index >= 0 and isInterfaceComponentWithQualifiedName(this, -(index + 1), _, tp)
+  }
+
+  private InterfaceType getDeepUnaliasedTypeCandidate() {
+    exists(
+      OptInterfaceComponent c0, OptInterfaceComponent c1, OptInterfaceComponent c2,
+      OptInterfaceComponent c3, OptInterfaceComponent c4, OptInterfaceComponent e1,
+      OptInterfaceComponent e2, int nComponents, int nEmbeds, boolean isComparable
+    |
+      unpackAndUnaliasInterfaceType(this, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds,
+        isComparable) and
+      unpackInterfaceType(result, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds, isComparable)
+    )
+  }
+
+  private predicate hasDeepUnaliasedComponentTypesUpTo(InterfaceType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 5 and
     (
-      if nComponents >= 3
-      then c2 = any(InterfaceComponent ic | ic.isComponentOf(intf, 2))
-      else c2 = MkNoIComponent()
+      i = 5 or
+      this.hasDeepUnaliasedComponentTypesUpTo(unaliased, i - 1)
     ) and
+    exists(string name |
+      unaliased.getMethodType(i, name) = this.getMethodType(i, name).getDeepUnaliasedType()
+    )
+  }
+
+  private predicate hasDeepUnaliasedEmbeddedTypesUpTo(InterfaceType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 2 and
     (
-      if nComponents >= 4
-      then c3 = any(InterfaceComponent ic | ic.isComponentOf(intf, 3))
-      else c3 = MkNoIComponent()
+      i = 2 or
+      this.hasDeepUnaliasedEmbeddedTypesUpTo(unaliased, i - 1)
     ) and
-    (
-      if nComponents >= 5
-      then c4 = any(InterfaceComponent ic | ic.isComponentOf(intf, 4))
-      else c4 = MkNoIComponent()
+    exists(Type tp | this.hasDirectlyEmbeddedType(i, tp) |
+      unaliased.hasDirectlyEmbeddedType(i, tp.getDeepUnaliasedType())
+    )
+  }
+
+  override InterfaceType getDeepUnaliasedType() {
+    result = this.getDeepUnaliasedTypeCandidate() and
+    exists(int nComponents | nComponents = count(int i | exists(this.getMethodType(i, _))) |
+      this.hasDeepUnaliasedComponentTypesUpTo(result, nComponents - 1)
+      or
+      nComponents <= 5
     ) and
+    exists(int nEmbeds | nEmbeds = count(int i | this.hasDirectlyEmbeddedType(i, _)) |
+      this.hasDeepUnaliasedEmbeddedTypesUpTo(result, nEmbeds - 1)
+      or
+      nEmbeds <= 2
+    )
+  }
+}
+
+pragma[nomagic]
+private predicate unpackTupleType(
+  TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
+) {
+  nComponents = count(int i | component_types(tt, i, _, _)) and
+  (if nComponents >= 1 then c0 = MkSomeType(tt.getComponentType(0)) else c0 = MkNoType()) and
+  (if nComponents >= 2 then c1 = MkSomeType(tt.getComponentType(1)) else c1 = MkNoType()) and
+  (if nComponents >= 3 then c2 = MkSomeType(tt.getComponentType(2)) else c2 = MkNoType())
+}
+
+pragma[nomagic]
+private predicate unpackAndUnaliasTupleType(
+  TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
+) {
+  exists(OptType c0a, OptType c1a, OptType c2a |
+    unpackTupleType(tt, c0a, c1a, c2a, nComponents) and
+    c0 = c0a.getDeepUnaliasedType() and
+    c1 = c1a.getDeepUnaliasedType() and
+    c2 = c2a.getDeepUnaliasedType()
+  )
+}
+
+/** A tuple type. */
+class TupleType extends @tupletype, CompositeType {
+  /** Gets the `i`th component type of this tuple type. */
+  Type getComponentType(int i) { component_types(this, i, _, result) }
+
+  private TupleType getCandidateDeepUnaliasedType() {
+    exists(OptType c0, OptType c1, OptType c2, int nComponents |
+      unpackAndUnaliasTupleType(this, c0, c1, c2, nComponents) and
+      unpackTupleType(result, c0, c1, c2, nComponents)
+    )
+  }
+
+  private predicate isDeepUnaliasedTypeUpTo(TupleType tt, int i) {
+    tt = this.getCandidateDeepUnaliasedType() and
+    i >= 3 and
     (
-      if nEmbeds >= 1
-      then e1 = any(InterfaceComponent ic | ic.isComponentOf(intf, -1))
-      else e1 = MkNoIComponent()
+      i = 3
+      or
+      this.isDeepUnaliasedTypeUpTo(tt, i - 1)
     ) and
-    (
-      if nEmbeds >= 2
-      then e2 = any(InterfaceComponent ic | ic.isComponentOf(intf, -2))
-      else e2 = MkNoIComponent()
+    tt.getComponentType(i) = this.getComponentType(i).getDeepUnaliasedType()
+  }
+
+  override TupleType getDeepUnaliasedType() {
+    result = this.getCandidateDeepUnaliasedType() and
+    exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
+      this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
+      or
+      nComponents <= 3
     )
   }
-  
-  pragma[nomagic]
-  predicate unpackAndUnaliasInterfaceType(
-    InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
-    TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
-    TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds
-  ) {
+}
+
+// Reasonably efficiently map from a signature type to its
+// deep-unaliased equivalent, by using a single join for the leading 5 parameters
+// and/or 3 results.
+private newtype TOptType =
+  MkNoType() or
+  MkSomeType(Type tp)
+
+private class OptType extends TOptType {
+  OptType getDeepUnaliasedType() {
+    exists(Type t | this = MkSomeType(t) | result = MkSomeType(t.getDeepUnaliasedType()))
+    or
+    this = MkNoType() and result = MkNoType()
+  }
+
+  string toString() {
+    exists(Type t | this = MkSomeType(t) | result = t.toString())
+    or
+    this = MkNoType() and result = "no type"
+  }
+}
+
+pragma[nomagic]
+private predicate unpackSignatureType(
+  SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
+  int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
+) {
+  nParams = sig.getNumParameter() and
+  nResults = sig.getNumResult() and
+  (if nParams >= 1 then param0 = MkSomeType(sig.getParameterType(0)) else param0 = MkNoType()) and
+  (if nParams >= 2 then param1 = MkSomeType(sig.getParameterType(1)) else param1 = MkNoType()) and
+  (if nParams >= 3 then param2 = MkSomeType(sig.getParameterType(2)) else param2 = MkNoType()) and
+  (if nParams >= 4 then param3 = MkSomeType(sig.getParameterType(3)) else param3 = MkNoType()) and
+  (if nParams >= 5 then param4 = MkSomeType(sig.getParameterType(4)) else param4 = MkNoType()) and
+  (if nResults >= 1 then result0 = MkSomeType(sig.getResultType(0)) else result0 = MkNoType()) and
+  (if nResults >= 2 then result1 = MkSomeType(sig.getResultType(1)) else result1 = MkNoType()) and
+  (if nResults >= 3 then result2 = MkSomeType(sig.getResultType(2)) else result2 = MkNoType()) and
+  (if sig.isVariadic() then isVariadic = true else isVariadic = false)
+}
+
+pragma[nomagic]
+private predicate unpackAndUnaliasSignatureType(
+  SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
+  int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
+) {
+  exists(
+    OptType param0a, OptType param1a, OptType param2a, OptType param3a, OptType param4a,
+    OptType result0a, OptType result1a, OptType result2a
+  |
+    unpackSignatureType(sig, param0a, param1a, param2a, param3a, param4a, nParams, result0a,
+      result1a, result2a, nResults, isVariadic)
+  |
+    param0 = param0a.getDeepUnaliasedType() and
+    param1 = param1a.getDeepUnaliasedType() and
+    param2 = param2a.getDeepUnaliasedType() and
+    param3 = param3a.getDeepUnaliasedType() and
+    param4 = param4a.getDeepUnaliasedType() and
+    result0 = result0a.getDeepUnaliasedType() and
+    result1 = result1a.getDeepUnaliasedType() and
+    result2 = result2a.getDeepUnaliasedType()
+  )
+}
+
+/** A signature type. */
+class SignatureType extends @signaturetype, CompositeType {
+  /** Gets the `i`th parameter type of this signature type. */
+  Type getParameterType(int i) { i >= 0 and component_types(this, i + 1, _, result) }
+
+  /** Gets the `i`th result type of this signature type. */
+  Type getResultType(int i) { i >= 0 and component_types(this, -(i + 1), _, result) }
+
+  /** Gets the number of parameters specified by this signature. */
+  int getNumParameter() { result = count(int i | exists(this.getParameterType(i))) }
+
+  /** Gets the number of results specified by this signature. */
+  int getNumResult() { result = count(int i | exists(this.getResultType(i))) }
+
+  /** Holds if this signature type is variadic. */
+  predicate isVariadic() { variadic(this) }
+
+  private SignatureType getDeepUnaliasedTypeCandidate() {
     exists(
-      OptInterfaceComponent c0a, OptInterfaceComponent c1a, OptInterfaceComponent c2a,
-      OptInterfaceComponent c3a, OptInterfaceComponent c4a, OptInterfaceComponent e1a,
-      OptInterfaceComponent e2a
+      OptType param0, OptType param1, OptType param2, OptType param3, OptType param4, int nParams,
+      OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
     |
-      unpackInterfaceType(intf, c0a, c1a, c2a, c3a, c4a, e1a, e2a, nComponents, nEmbeds) and
-      c0 = c0a.getWithDeepUnaliasedType() and
-      c1 = c1a.getWithDeepUnaliasedType() and
-      c2 = c2a.getWithDeepUnaliasedType() and
-      c3 = c3a.getWithDeepUnaliasedType() and
-      c4 = c4a.getWithDeepUnaliasedType() and
-      e1 = e1a.getWithDeepUnaliasedType() and
-      e2 = e2a.getWithDeepUnaliasedType()
+      unpackAndUnaliasSignatureType(this, param0, param1, param2, param3, param4, nParams, result0,
+        result1, result2, nResults, isVariadic) and
+      unpackSignatureType(result, param0, param1, param2, param3, param4, nParams, result0, result1,
+        result2, nResults, isVariadic)
     )
   }
-  
-  /** An interface type. */
-  class InterfaceType extends @interfacetype, CompositeType {
-    private InterfaceType getDeepUnaliasedTypeCandidate() {
-      exists(
-        OptInterfaceComponent c0, OptInterfaceComponent c1, OptInterfaceComponent c2,
-        OptInterfaceComponent c3, OptInterfaceComponent c4, OptInterfaceComponent e1,
-        OptInterfaceComponent e2, int nComponents, int nEmbeds
-      |
-        unpackAndUnaliasInterfaceType(this, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds) and
-        unpackInterfaceType(result, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds)
-      )
-    }
-  
-    private predicate hasDeepUnaliasedComponentTypesUpTo(InterfaceType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 5 and
-      (
-        i = 5 or
-        this.hasDeepUnaliasedComponentTypesUpTo(unaliased, i - 1)
-      ) and
-      exists(string name, Type tp | component_types(this, i, name, tp) |
-        component_types(unaliased, i, name, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    private predicate hasDeepUnaliasedEmbeddedTypesUpTo(InterfaceType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 3 and
-      (
-        i = 3 or
-        this.hasDeepUnaliasedEmbeddedTypesUpTo(unaliased, i - 1)
-      ) and
-      exists(string name, Type tp | component_types(this, -i, name, tp) |
-        component_types(unaliased, -i, name, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    override InterfaceType getDeepUnaliasedType() {
-      result = this.getDeepUnaliasedTypeCandidate() and
-      exists(int nComponents |
-        nComponents = count(int i | component_types(this, i, _, _) and i >= 0)
-      |
-        this.hasDeepUnaliasedComponentTypesUpTo(result, nComponents - 1)
-        or
-        nComponents <= 5
-      ) and
-      exists(int nEmbeds | nEmbeds = count(int i | component_types(this, i, _, _) and i < 0) |
-        // Note no -1 here, because the first embedded type is at -1
-        this.hasDeepUnaliasedEmbeddedTypesUpTo(result, nEmbeds)
-        or
-        nEmbeds <= 2
-      )
-    }
-  }
-  
-  pragma[nomagic]
-  private predicate unpackTupleType(
-    TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
-  ) {
-    nComponents = count(int i | component_types(tt, i, _, _)) and
-    (if nComponents >= 1 then c0 = MkSomeType(tt.getComponentType(0)) else c0 = MkNoType()) and
-    (if nComponents >= 2 then c1 = MkSomeType(tt.getComponentType(1)) else c1 = MkNoType()) and
-    (if nComponents >= 3 then c2 = MkSomeType(tt.getComponentType(2)) else c2 = MkNoType())
+
+  // These incremental recursive implementations only apply from parameter 5 or result 3
+  // upwards to avoid constructing large squares of candidates -- the initial parameters
+  // and results are taken care of by the candidate predicate.
+  private predicate hasDeepUnaliasedParameterTypesUpTo(SignatureType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 5 and
+    (i = 5 or this.hasDeepUnaliasedParameterTypesUpTo(unaliased, i - 1)) and
+    unaliased.getParameterType(i) = this.getParameterType(i).getDeepUnaliasedType()
   }
-  
-  pragma[nomagic]
-  private predicate unpackAndUnaliasTupleType(
-    TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
-  ) {
-    exists(OptType c0a, OptType c1a, OptType c2a |
-      unpackTupleType(tt, c0a, c1a, c2a, nComponents) and
-      c0 = c0a.getDeepUnaliasedType() and
-      c1 = c1a.getDeepUnaliasedType() and
-      c2 = c2a.getDeepUnaliasedType()
-    )
+
+  private predicate hasDeepUnaliasedResultTypesUpTo(SignatureType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 3 and
+    (i = 3 or this.hasDeepUnaliasedResultTypesUpTo(unaliased, i - 1)) and
+    unaliased.getResultType(i) = this.getResultType(i).getDeepUnaliasedType()
   }
-  
-  /** A tuple type. */
-  class TupleType extends @tupletype, CompositeType {
-    /** Gets the `i`th component type of this tuple type. */
-    Type getComponentType(int i) { component_types(this, i, _, result) }
-  
-    private TupleType getCandidateDeepUnaliasedType() {
-      exists(OptType c0, OptType c1, OptType c2, int nComponents |
-        unpackAndUnaliasTupleType(this, c0, c1, c2, nComponents) and
-        unpackTupleType(result, c0, c1, c2, nComponents)
-      )
-    }
-  
-    private predicate isDeepUnaliasedTypeUpTo(TupleType tt, int i) {
-      tt = this.getCandidateDeepUnaliasedType() and
-      i >= 3 and
+
+  override SignatureType getDeepUnaliasedType() {
+    result = this.getDeepUnaliasedTypeCandidate() and
+    exists(int nParams, int nResults |
+      this.getNumParameter() = nParams and this.getNumResult() = nResults
+    |
       (
-        i = 3
+        nParams <= 5
         or
-        this.isDeepUnaliasedTypeUpTo(tt, i - 1)
+        this.hasDeepUnaliasedParameterTypesUpTo(result, nParams - 1)
       ) and
-      exists(Type tp | component_types(this, i, _, tp) |
-        component_types(tt, i, _, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    override TupleType getDeepUnaliasedType() {
-      result = this.getCandidateDeepUnaliasedType() and
-      exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
-        this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
+      (
+        nResults <= 3
         or
-        nComponents <= 3
+        this.hasDeepUnaliasedResultTypesUpTo(result, nResults - 1)
       )
-    }
-  }
-  
-  // Reasonably efficiently map from a signature type to its
-  // deep-unaliased equivalent, by using a single join for the leading 5 parameters
-  // and/or 3 results.
-  private newtype TOptType =
-    MkNoType() or
-    MkSomeType(Type tp)
-  
-  private class OptType extends TOptType {
-    OptType getDeepUnaliasedType() {
-      exists(Type t | this = MkSomeType(t) | result = MkSomeType(t.getDeepUnaliasedType()))
-      or
-      this = MkNoType() and result = MkNoType()
-    }
-  
-    string toString() {
-      exists(Type t | this = MkSomeType(t) | result = t.toString())
-      or
-      this = MkNoType() and result = "no type"
-    }
-  }
-  
-  pragma[nomagic]
-  private predicate unpackSignatureType(
-    SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
-    int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
-  ) {
-    nParams = sig.getNumParameter() and
-    nResults = sig.getNumResult() and
-    (if nParams >= 1 then param0 = MkSomeType(sig.getParameterType(0)) else param0 = MkNoType()) and
-    (if nParams >= 2 then param1 = MkSomeType(sig.getParameterType(1)) else param1 = MkNoType()) and
-    (if nParams >= 3 then param2 = MkSomeType(sig.getParameterType(2)) else param2 = MkNoType()) and
-    (if nParams >= 4 then param3 = MkSomeType(sig.getParameterType(3)) else param3 = MkNoType()) and
-    (if nParams >= 5 then param4 = MkSomeType(sig.getParameterType(4)) else param4 = MkNoType()) and
-    (if nResults >= 1 then result0 = MkSomeType(sig.getResultType(0)) else result0 = MkNoType()) and
-    (if nResults >= 2 then result1 = MkSomeType(sig.getResultType(1)) else result1 = MkNoType()) and
-    (if nResults >= 3 then result2 = MkSomeType(sig.getResultType(2)) else result2 = MkNoType()) and
-    (if sig.isVariadic() then isVariadic = true else isVariadic = false)
-  }
-  
-  pragma[nomagic]
-  private predicate unpackAndUnaliasSignatureType(
-    SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
-    int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
-  ) {
-    exists(
-      OptType param0a, OptType param1a, OptType param2a, OptType param3a, OptType param4a,
-      OptType result0a, OptType result1a, OptType result2a
-    |
-      unpackSignatureType(sig, param0a, param1a, param2a, param3a, param4a, nParams, result0a,
-        result1a, result2a, nResults, isVariadic)
-    |
-      param0 = param0a.getDeepUnaliasedType() and
-      param1 = param1a.getDeepUnaliasedType() and
-      param2 = param2a.getDeepUnaliasedType() and
-      param3 = param3a.getDeepUnaliasedType() and
-      param4 = param4a.getDeepUnaliasedType() and
-      result0 = result0a.getDeepUnaliasedType() and
-      result1 = result1a.getDeepUnaliasedType() and
-      result2 = result2a.getDeepUnaliasedType()
     )
   }
-  
-  /** A signature type. */
-  class SignatureType extends @signaturetype, CompositeType {
-    /** Gets the `i`th parameter type of this signature type. */
-    Type getParameterType(int i) { i >= 0 and component_types(this, i + 1, _, result) }
-  
-    /** Gets the `i`th result type of this signature type. */
-    Type getResultType(int i) { i >= 0 and component_types(this, -(i + 1), _, result) }
-  
-    /** Gets the number of parameters specified by this signature. */
-    int getNumParameter() { result = count(int i | exists(this.getParameterType(i))) }
-  
-    /** Gets the number of results specified by this signature. */
-    int getNumResult() { result = count(int i | exists(this.getResultType(i))) }
-  
-    /** Holds if this signature type is variadic. */
-    predicate isVariadic() { variadic(this) }
-  
-    private SignatureType getDeepUnaliasedTypeCandidate() {
-      exists(
-        OptType param0, OptType param1, OptType param2, OptType param3, OptType param4, int nParams,
-        OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
-      |
-        unpackAndUnaliasSignatureType(this, param0, param1, param2, param3, param4, nParams, result0,
-          result1, result2, nResults, isVariadic) and
-        unpackSignatureType(result, param0, param1, param2, param3, param4, nParams, result0, result1,
-          result2, nResults, isVariadic)
-      )
-    }
-  
-    // These incremental recursive implementations only apply from parameter 5 or result 3
-    // upwards to avoid constructing large squares of candidates -- the initial parameters
-    // and results are taken care of by the candidate predicate.
-    private predicate hasDeepUnaliasedParameterTypesUpTo(SignatureType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 5 and
-      (i = 5 or this.hasDeepUnaliasedParameterTypesUpTo(unaliased, i - 1)) and
-      unaliased.getParameterType(i) = this.getParameterType(i).getDeepUnaliasedType()
-    }
-  
-    private predicate hasDeepUnaliasedResultTypesUpTo(SignatureType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 3 and
-      (i = 3 or this.hasDeepUnaliasedResultTypesUpTo(unaliased, i - 1)) and
-      unaliased.getResultType(i) = this.getResultType(i).getDeepUnaliasedType()
-    }
-  
-    override SignatureType getDeepUnaliasedType() {
-      result = this.getDeepUnaliasedTypeCandidate() and
-      exists(int nParams, int nResults |
-        this.getNumParameter() = nParams and this.getNumResult() = nResults
-      |
-        (
-          nParams <= 5
-          or
-          this.hasDeepUnaliasedParameterTypesUpTo(result, nParams - 1)
-        ) and
-        (
-          nResults <= 3
-          or
-          this.hasDeepUnaliasedResultTypesUpTo(result, nResults - 1)
-        )
-      )
-    }
-  }
-  
-  /** A map type. */
-  class MapType extends @maptype, CompositeType {
-    /** Gets the key type of this map type. */
-    Type getKeyType() { key_type(this, result) }
-  
-    /** Gets the value type of this map type. */
-    Type getValueType() { element_type(this, result) }
-  
-    override MapType getDeepUnaliasedType() {
-      result.getKeyType() = this.getKeyType().getDeepUnaliasedType() and
-      result.getValueType() = this.getValueType().getDeepUnaliasedType()
-    }
-  }
-  
-  /** A channel type. */
-  class ChanType extends @chantype, CompositeType {
-    /** Gets the element type of this channel type. */
-    Type getElementType() { element_type(this, result) }
-  }
-  
-  /** A channel type that can only send. */
-  class SendChanType extends @sendchantype, ChanType {
-    override SendChanType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
-  }
-  
-  /** A channel type that can only receive. */
-  class RecvChanType extends @recvchantype, ChanType {
-    override RecvChanType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
+}
+
+/** A map type. */
+class MapType extends @maptype, CompositeType {
+  /** Gets the key type of this map type. */
+  Type getKeyType() { key_type(this, result) }
+
+  /** Gets the value type of this map type. */
+  Type getValueType() { element_type(this, result) }
+
+  override MapType getDeepUnaliasedType() {
+    result.getKeyType() = this.getKeyType().getDeepUnaliasedType() and
+    result.getValueType() = this.getValueType().getDeepUnaliasedType()
   }
-  
-  /** A channel type that can both send and receive. */
-  class SendRecvChanType extends @sendrcvchantype, ChanType {
-    override SendRecvChanType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
+}
+
+/** A channel type. */
+class ChanType extends @chantype, CompositeType {
+  /** Gets the element type of this channel type. */
+  Type getElementType() { element_type(this, result) }
+}
+
+/** A channel type that can only send. */
+class SendChanType extends @sendchantype, ChanType {
+  override SendChanType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  /** An alias type. */
-  class AliasType extends @typealias, CompositeType {
-    /** Gets the aliased type (i.e. that appears on the RHS of the alias definition). */
-    Type getRhs() { alias_rhs(this, result) }
-  
-    override Type getDeepUnaliasedType() { result = unalias(this).getDeepUnaliasedType() }
+}
+
+/** A channel type that can only receive. */
+class RecvChanType extends @recvchantype, ChanType {
+  override RecvChanType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  /**
-   * Gets the non-alias type at the end of the alias chain starting at `t`.
-   *
-   * If `t` is not an alias type then `result` is `t`.
-   */
-  Type unalias(Type t) {
-    not t instanceof AliasType and result = t
-    or
-    result = unalias(t.(AliasType).getRhs())
+}
+
+/** A channel type that can both send and receive. */
+class SendRecvChanType extends @sendrcvchantype, ChanType {
+  override SendRecvChanType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  predicate containsAliases(Type t) { t != t.getDeepUnaliasedType() }
-  // END ALIASES.QLL
-  
+}
+
+/** A named type. */
+class NamedType extends @namedtype, CompositeType {
+  Type getBaseType() { underlying_type(this, result) }
+}
+
+/**
+ * The predeclared `comparable` type.
+ */
+class ComparableType extends NamedType {
+  ComparableType() { typename(this, "comparable") }
+}
+
+/** An alias type. */
+class AliasType extends @typealias, CompositeType {
+  /** Gets the aliased type (i.e. that appears on the RHS of the alias definition). */
+  Type getRhs() { alias_rhs(this, result) }
+
+  override Type getDeepUnaliasedType() { result = unalias(this).getDeepUnaliasedType() }
+}
+
+/**
+ * Gets the non-alias type at the end of the alias chain starting at `t`.
+ *
+ * If `t` is not an alias type then `result` is `t`.
+ */
+Type unalias(Type t) {
+  not t instanceof AliasType and result = t
+  or
+  result = unalias(t.(AliasType).getRhs())
+}
 
+predicate containsAliases(Type t) { t != t.getDeepUnaliasedType() }
+// END ALIASES.QLL
 class Expr extends @expr {
-    string toString() { result = "expr" }
+  string toString() { result = "expr" }
 }
 
-  from Expr e, Type t
-  where type_of(e, t)
-  select e, t.getDeepUnaliasedType()
\ No newline at end of file
+from Expr e, Type t
+where type_of(e, t)
+select e, t.getDeepUnaliasedType()
diff --git a/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/typename.ql b/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/typename.ql
index 451297d10e4d..520a0d9e2f6e 100644
--- a/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/typename.ql
+++ b/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/typename.ql
@@ -174,9 +174,21 @@ class PointerType extends @pointertype, CompositeType {
   }
 }
 
+private predicate isInterfaceComponentWithQualifiedName(
+  InterfaceType intf, int idx, string qualifiedName, Type tp
+) {
+  exists(string name | component_types(intf, idx, name, tp) |
+    interface_private_method_ids(intf, idx, qualifiedName)
+    or
+    not interface_private_method_ids(intf, idx, _) and qualifiedName = name
+  )
+}
+
 private newtype TOptInterfaceComponent =
   MkNoIComponent() or
-  MkSomeIComponent(string name, Type tp) { component_types(any(InterfaceType i), _, name, tp) }
+  MkSomeIComponent(string name, Type tp) {
+    isInterfaceComponentWithQualifiedName(any(InterfaceType i), _, name, tp)
+  }
 
 private class OptInterfaceComponent extends TOptInterfaceComponent {
   OptInterfaceComponent getWithDeepUnaliasedType() {
@@ -196,7 +208,7 @@ private class InterfaceComponent extends MkSomeIComponent {
 
   predicate isComponentOf(InterfaceType intf, int i) {
     exists(string name, Type tp |
-      component_types(intf, i, name, tp) and
+      isInterfaceComponentWithQualifiedName(intf, i, name, tp) and
       this = MkSomeIComponent(name, tp)
     )
   }
@@ -206,10 +218,16 @@ pragma[nomagic]
 predicate unpackInterfaceType(
   InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
   TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
-  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds
+  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds,
+  boolean isComparable
 ) {
-  nComponents = count(int i | component_types(intf, i, _, _) and i >= 0) and
-  nEmbeds = count(int i | component_types(intf, i, _, _) and i < 0) and
+  nComponents = count(int i | isInterfaceComponentWithQualifiedName(intf, i, _, _) and i >= 0) and
+  nEmbeds = count(int i | isInterfaceComponentWithQualifiedName(intf, i, _, _) and i < 0) and
+  (
+    if intf = any(ComparableType comparable).getBaseType()
+    then isComparable = true
+    else isComparable = false
+  ) and
   (
     if nComponents >= 1
     then c0 = any(InterfaceComponent ic | ic.isComponentOf(intf, 0))
@@ -251,14 +269,15 @@ pragma[nomagic]
 predicate unpackAndUnaliasInterfaceType(
   InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
   TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
-  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds
+  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds,
+  boolean isComparable
 ) {
   exists(
     OptInterfaceComponent c0a, OptInterfaceComponent c1a, OptInterfaceComponent c2a,
     OptInterfaceComponent c3a, OptInterfaceComponent c4a, OptInterfaceComponent e1a,
     OptInterfaceComponent e2a
   |
-    unpackInterfaceType(intf, c0a, c1a, c2a, c3a, c4a, e1a, e2a, nComponents, nEmbeds) and
+    unpackInterfaceType(intf, c0a, c1a, c2a, c3a, c4a, e1a, e2a, nComponents, nEmbeds, isComparable) and
     c0 = c0a.getWithDeepUnaliasedType() and
     c1 = c1a.getWithDeepUnaliasedType() and
     c2 = c2a.getWithDeepUnaliasedType() and
@@ -271,14 +290,29 @@ predicate unpackAndUnaliasInterfaceType(
 
 /** An interface type. */
 class InterfaceType extends @interfacetype, CompositeType {
+  private Type getMethodType(int i, string name) {
+    i >= 0 and isInterfaceComponentWithQualifiedName(this, i, name, result)
+  }
+
+  /**
+   * Holds if `tp` is a directly embedded type with index `index`.
+   *
+   * `tp` (or its underlying type) is either a type set literal type or an
+   * interface type.
+   */
+  private predicate hasDirectlyEmbeddedType(int index, Type tp) {
+    index >= 0 and isInterfaceComponentWithQualifiedName(this, -(index + 1), _, tp)
+  }
+
   private InterfaceType getDeepUnaliasedTypeCandidate() {
     exists(
       OptInterfaceComponent c0, OptInterfaceComponent c1, OptInterfaceComponent c2,
       OptInterfaceComponent c3, OptInterfaceComponent c4, OptInterfaceComponent e1,
-      OptInterfaceComponent e2, int nComponents, int nEmbeds
+      OptInterfaceComponent e2, int nComponents, int nEmbeds, boolean isComparable
     |
-      unpackAndUnaliasInterfaceType(this, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds) and
-      unpackInterfaceType(result, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds)
+      unpackAndUnaliasInterfaceType(this, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds,
+        isComparable) and
+      unpackInterfaceType(result, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds, isComparable)
     )
   }
 
@@ -289,35 +323,32 @@ class InterfaceType extends @interfacetype, CompositeType {
       i = 5 or
       this.hasDeepUnaliasedComponentTypesUpTo(unaliased, i - 1)
     ) and
-    exists(string name, Type tp | component_types(this, i, name, tp) |
-      component_types(unaliased, i, name, tp.getDeepUnaliasedType())
+    exists(string name |
+      unaliased.getMethodType(i, name) = this.getMethodType(i, name).getDeepUnaliasedType()
     )
   }
 
   private predicate hasDeepUnaliasedEmbeddedTypesUpTo(InterfaceType unaliased, int i) {
     unaliased = this.getDeepUnaliasedTypeCandidate() and
-    i >= 3 and
+    i >= 2 and
     (
-      i = 3 or
+      i = 2 or
       this.hasDeepUnaliasedEmbeddedTypesUpTo(unaliased, i - 1)
     ) and
-    exists(string name, Type tp | component_types(this, -i, name, tp) |
-      component_types(unaliased, -i, name, tp.getDeepUnaliasedType())
+    exists(Type tp | this.hasDirectlyEmbeddedType(i, tp) |
+      unaliased.hasDirectlyEmbeddedType(i, tp.getDeepUnaliasedType())
     )
   }
 
   override InterfaceType getDeepUnaliasedType() {
     result = this.getDeepUnaliasedTypeCandidate() and
-    exists(int nComponents |
-      nComponents = count(int i | component_types(this, i, _, _) and i >= 0)
-    |
+    exists(int nComponents | nComponents = count(int i | exists(this.getMethodType(i, _))) |
       this.hasDeepUnaliasedComponentTypesUpTo(result, nComponents - 1)
       or
       nComponents <= 5
     ) and
-    exists(int nEmbeds | nEmbeds = count(int i | component_types(this, i, _, _) and i < 0) |
-      // Note no -1 here, because the first embedded type is at -1
-      this.hasDeepUnaliasedEmbeddedTypesUpTo(result, nEmbeds)
+    exists(int nEmbeds | nEmbeds = count(int i | this.hasDirectlyEmbeddedType(i, _)) |
+      this.hasDeepUnaliasedEmbeddedTypesUpTo(result, nEmbeds - 1)
       or
       nEmbeds <= 2
     )
@@ -366,9 +397,7 @@ class TupleType extends @tupletype, CompositeType {
       or
       this.isDeepUnaliasedTypeUpTo(tt, i - 1)
     ) and
-    exists(Type tp | component_types(this, i, _, tp) |
-      component_types(tt, i, _, tp.getDeepUnaliasedType())
-    )
+    tt.getComponentType(i) = this.getComponentType(i).getDeepUnaliasedType()
   }
 
   override TupleType getDeepUnaliasedType() {
@@ -549,6 +578,18 @@ class SendRecvChanType extends @sendrcvchantype, ChanType {
   }
 }
 
+/** A named type. */
+class NamedType extends @namedtype, CompositeType {
+  Type getBaseType() { underlying_type(this, result) }
+}
+
+/**
+ * The predeclared `comparable` type.
+ */
+class ComparableType extends NamedType {
+  ComparableType() { typename(this, "comparable") }
+}
+
 /** An alias type. */
 class AliasType extends @typealias, CompositeType {
   /** Gets the aliased type (i.e. that appears on the RHS of the alias definition). */
@@ -570,8 +611,6 @@ Type unalias(Type t) {
 
 predicate containsAliases(Type t) { t != t.getDeepUnaliasedType() }
 // END ALIASES.QLL
-
-
 // The schema for types and typename are:
 //
 // types(unique int id: @type, int kind: int ref);
diff --git a/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/types.ql b/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/types.ql
index 77371c92c960..50f9d5e32bb3 100644
--- a/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/types.ql
+++ b/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/types.ql
@@ -174,9 +174,21 @@ class PointerType extends @pointertype, CompositeType {
   }
 }
 
+private predicate isInterfaceComponentWithQualifiedName(
+  InterfaceType intf, int idx, string qualifiedName, Type tp
+) {
+  exists(string name | component_types(intf, idx, name, tp) |
+    interface_private_method_ids(intf, idx, qualifiedName)
+    or
+    not interface_private_method_ids(intf, idx, _) and qualifiedName = name
+  )
+}
+
 private newtype TOptInterfaceComponent =
   MkNoIComponent() or
-  MkSomeIComponent(string name, Type tp) { component_types(any(InterfaceType i), _, name, tp) }
+  MkSomeIComponent(string name, Type tp) {
+    isInterfaceComponentWithQualifiedName(any(InterfaceType i), _, name, tp)
+  }
 
 private class OptInterfaceComponent extends TOptInterfaceComponent {
   OptInterfaceComponent getWithDeepUnaliasedType() {
@@ -196,7 +208,7 @@ private class InterfaceComponent extends MkSomeIComponent {
 
   predicate isComponentOf(InterfaceType intf, int i) {
     exists(string name, Type tp |
-      component_types(intf, i, name, tp) and
+      isInterfaceComponentWithQualifiedName(intf, i, name, tp) and
       this = MkSomeIComponent(name, tp)
     )
   }
@@ -206,10 +218,16 @@ pragma[nomagic]
 predicate unpackInterfaceType(
   InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
   TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
-  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds
+  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds,
+  boolean isComparable
 ) {
-  nComponents = count(int i | component_types(intf, i, _, _) and i >= 0) and
-  nEmbeds = count(int i | component_types(intf, i, _, _) and i < 0) and
+  nComponents = count(int i | isInterfaceComponentWithQualifiedName(intf, i, _, _) and i >= 0) and
+  nEmbeds = count(int i | isInterfaceComponentWithQualifiedName(intf, i, _, _) and i < 0) and
+  (
+    if intf = any(ComparableType comparable).getBaseType()
+    then isComparable = true
+    else isComparable = false
+  ) and
   (
     if nComponents >= 1
     then c0 = any(InterfaceComponent ic | ic.isComponentOf(intf, 0))
@@ -251,14 +269,15 @@ pragma[nomagic]
 predicate unpackAndUnaliasInterfaceType(
   InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
   TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
-  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds
+  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds,
+  boolean isComparable
 ) {
   exists(
     OptInterfaceComponent c0a, OptInterfaceComponent c1a, OptInterfaceComponent c2a,
     OptInterfaceComponent c3a, OptInterfaceComponent c4a, OptInterfaceComponent e1a,
     OptInterfaceComponent e2a
   |
-    unpackInterfaceType(intf, c0a, c1a, c2a, c3a, c4a, e1a, e2a, nComponents, nEmbeds) and
+    unpackInterfaceType(intf, c0a, c1a, c2a, c3a, c4a, e1a, e2a, nComponents, nEmbeds, isComparable) and
     c0 = c0a.getWithDeepUnaliasedType() and
     c1 = c1a.getWithDeepUnaliasedType() and
     c2 = c2a.getWithDeepUnaliasedType() and
@@ -271,14 +290,29 @@ predicate unpackAndUnaliasInterfaceType(
 
 /** An interface type. */
 class InterfaceType extends @interfacetype, CompositeType {
+  private Type getMethodType(int i, string name) {
+    i >= 0 and isInterfaceComponentWithQualifiedName(this, i, name, result)
+  }
+
+  /**
+   * Holds if `tp` is a directly embedded type with index `index`.
+   *
+   * `tp` (or its underlying type) is either a type set literal type or an
+   * interface type.
+   */
+  private predicate hasDirectlyEmbeddedType(int index, Type tp) {
+    index >= 0 and isInterfaceComponentWithQualifiedName(this, -(index + 1), _, tp)
+  }
+
   private InterfaceType getDeepUnaliasedTypeCandidate() {
     exists(
       OptInterfaceComponent c0, OptInterfaceComponent c1, OptInterfaceComponent c2,
       OptInterfaceComponent c3, OptInterfaceComponent c4, OptInterfaceComponent e1,
-      OptInterfaceComponent e2, int nComponents, int nEmbeds
+      OptInterfaceComponent e2, int nComponents, int nEmbeds, boolean isComparable
     |
-      unpackAndUnaliasInterfaceType(this, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds) and
-      unpackInterfaceType(result, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds)
+      unpackAndUnaliasInterfaceType(this, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds,
+        isComparable) and
+      unpackInterfaceType(result, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds, isComparable)
     )
   }
 
@@ -289,35 +323,32 @@ class InterfaceType extends @interfacetype, CompositeType {
       i = 5 or
       this.hasDeepUnaliasedComponentTypesUpTo(unaliased, i - 1)
     ) and
-    exists(string name, Type tp | component_types(this, i, name, tp) |
-      component_types(unaliased, i, name, tp.getDeepUnaliasedType())
+    exists(string name |
+      unaliased.getMethodType(i, name) = this.getMethodType(i, name).getDeepUnaliasedType()
     )
   }
 
   private predicate hasDeepUnaliasedEmbeddedTypesUpTo(InterfaceType unaliased, int i) {
     unaliased = this.getDeepUnaliasedTypeCandidate() and
-    i >= 3 and
+    i >= 2 and
     (
-      i = 3 or
+      i = 2 or
       this.hasDeepUnaliasedEmbeddedTypesUpTo(unaliased, i - 1)
     ) and
-    exists(string name, Type tp | component_types(this, -i, name, tp) |
-      component_types(unaliased, -i, name, tp.getDeepUnaliasedType())
+    exists(Type tp | this.hasDirectlyEmbeddedType(i, tp) |
+      unaliased.hasDirectlyEmbeddedType(i, tp.getDeepUnaliasedType())
     )
   }
 
   override InterfaceType getDeepUnaliasedType() {
     result = this.getDeepUnaliasedTypeCandidate() and
-    exists(int nComponents |
-      nComponents = count(int i | component_types(this, i, _, _) and i >= 0)
-    |
+    exists(int nComponents | nComponents = count(int i | exists(this.getMethodType(i, _))) |
       this.hasDeepUnaliasedComponentTypesUpTo(result, nComponents - 1)
       or
       nComponents <= 5
     ) and
-    exists(int nEmbeds | nEmbeds = count(int i | component_types(this, i, _, _) and i < 0) |
-      // Note no -1 here, because the first embedded type is at -1
-      this.hasDeepUnaliasedEmbeddedTypesUpTo(result, nEmbeds)
+    exists(int nEmbeds | nEmbeds = count(int i | this.hasDirectlyEmbeddedType(i, _)) |
+      this.hasDeepUnaliasedEmbeddedTypesUpTo(result, nEmbeds - 1)
       or
       nEmbeds <= 2
     )
@@ -366,9 +397,7 @@ class TupleType extends @tupletype, CompositeType {
       or
       this.isDeepUnaliasedTypeUpTo(tt, i - 1)
     ) and
-    exists(Type tp | component_types(this, i, _, tp) |
-      component_types(tt, i, _, tp.getDeepUnaliasedType())
-    )
+    tt.getComponentType(i) = this.getComponentType(i).getDeepUnaliasedType()
   }
 
   override TupleType getDeepUnaliasedType() {
@@ -549,6 +578,18 @@ class SendRecvChanType extends @sendrcvchantype, ChanType {
   }
 }
 
+/** A named type. */
+class NamedType extends @namedtype, CompositeType {
+  Type getBaseType() { underlying_type(this, result) }
+}
+
+/**
+ * The predeclared `comparable` type.
+ */
+class ComparableType extends NamedType {
+  ComparableType() { typename(this, "comparable") }
+}
+
 /** An alias type. */
 class AliasType extends @typealias, CompositeType {
   /** Gets the aliased type (i.e. that appears on the RHS of the alias definition). */
@@ -570,8 +611,6 @@ Type unalias(Type t) {
 
 predicate containsAliases(Type t) { t != t.getDeepUnaliasedType() }
 // END ALIASES.QLL
-
-
 // The schema for types is:
 //
 // types(unique int id: @type, int kind: int ref);
diff --git a/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/underlying_type.ql b/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/underlying_type.ql
index 0ee705b45eec..bb857e8ad221 100644
--- a/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/underlying_type.ql
+++ b/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/underlying_type.ql
@@ -2,578 +2,616 @@
 // Database scripts can't import, but this is the definitive copy of the support routines for mapping types to their unaliased equivalent. Ensure this code is in sync between aliases.qll and all copies in individual table .ql files.
 /** A Go type. */
 class Type extends @type {
-    /**
-     * Gets this type with all aliases substituted for their underlying type.
-     *
-     * Note named types are not substituted.
-     */
-    Type getDeepUnaliasedType() { result = this }
-  
-    /**
-     * Gets a basic textual representation of this type.
-     */
-    string toString() { result = "type" }
-  }
-  
-  /** A composite type, that is, not a basic type. */
-  class CompositeType extends @compositetype, Type { }
-  
-  /** An array type. */
-  class ArrayType extends @arraytype, CompositeType {
-    /** Gets the element type of this array type. */
-    Type getElementType() { element_type(this, result) }
-  
-    /** Gets the length of this array type as a string. */
-    string getLengthString() { array_length(this, result) }
-  
-    override ArrayType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType() and
-      result.getLengthString() = this.getLengthString()
-    }
+  /**
+   * Gets this type with all aliases substituted for their underlying type.
+   *
+   * Note named types are not substituted.
+   */
+  Type getDeepUnaliasedType() { result = this }
+
+  /**
+   * Gets a basic textual representation of this type.
+   */
+  string toString() { result = "type" }
+}
+
+/** A composite type, that is, not a basic type. */
+class CompositeType extends @compositetype, Type { }
+
+/** An array type. */
+class ArrayType extends @arraytype, CompositeType {
+  /** Gets the element type of this array type. */
+  Type getElementType() { element_type(this, result) }
+
+  /** Gets the length of this array type as a string. */
+  string getLengthString() { array_length(this, result) }
+
+  override ArrayType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType() and
+    result.getLengthString() = this.getLengthString()
   }
-  
-  /** A slice type. */
-  class SliceType extends @slicetype, CompositeType {
-    /** Gets the element type of this slice type. */
-    Type getElementType() { element_type(this, result) }
-  
-    override SliceType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
+}
+
+/** A slice type. */
+class SliceType extends @slicetype, CompositeType {
+  /** Gets the element type of this slice type. */
+  Type getElementType() { element_type(this, result) }
+
+  override SliceType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  // Improve efficiency of matching a struct to its unaliased equivalent
-  // by unpacking the first 5 fields and tags, allowing a single join
-  // to strongly constrain the available candidates.
-  private predicate hasComponentTypeAndTag(StructType s, int i, string name, Type tp, string tag) {
-    component_types(s, i, name, tp) and component_tags(s, i, tag)
+}
+
+// Improve efficiency of matching a struct to its unaliased equivalent
+// by unpacking the first 5 fields and tags, allowing a single join
+// to strongly constrain the available candidates.
+private predicate hasComponentTypeAndTag(StructType s, int i, string name, Type tp, string tag) {
+  component_types(s, i, name, tp) and component_tags(s, i, tag)
+}
+
+private newtype TOptStructComponent =
+  MkNoComponent() or
+  MkSomeComponent(string name, Type tp, string tag) { hasComponentTypeAndTag(_, _, name, tp, tag) }
+
+private class OptStructComponent extends TOptStructComponent {
+  OptStructComponent getWithDeepUnaliasedType() {
+    this = MkNoComponent() and result = MkNoComponent()
+    or
+    exists(string name, Type tp, string tag |
+      this = MkSomeComponent(name, tp, tag) and
+      result = MkSomeComponent(name, tp.getDeepUnaliasedType(), tag)
+    )
   }
-  
-  private newtype TOptStructComponent =
-    MkNoComponent() or
-    MkSomeComponent(string name, Type tp, string tag) { hasComponentTypeAndTag(_, _, name, tp, tag) }
-  
-  private class OptStructComponent extends TOptStructComponent {
-    OptStructComponent getWithDeepUnaliasedType() {
-      this = MkNoComponent() and result = MkNoComponent()
-      or
-      exists(string name, Type tp, string tag |
-        this = MkSomeComponent(name, tp, tag) and
-        result = MkSomeComponent(name, tp.getDeepUnaliasedType(), tag)
-      )
-    }
-  
-    string toString() { result = "struct component" }
+
+  string toString() { result = "struct component" }
+}
+
+private class StructComponent extends MkSomeComponent {
+  string toString() { result = "struct component" }
+
+  predicate isComponentOf(StructType s, int i) {
+    exists(string name, Type tp, string tag |
+      hasComponentTypeAndTag(s, i, name, tp, tag) and
+      this = MkSomeComponent(name, tp, tag)
+    )
   }
-  
-  private class StructComponent extends MkSomeComponent {
-    string toString() { result = "struct component" }
-  
-    predicate isComponentOf(StructType s, int i) {
-      exists(string name, Type tp, string tag |
-        hasComponentTypeAndTag(s, i, name, tp, tag) and
-        this = MkSomeComponent(name, tp, tag)
-      )
-    }
+}
+
+pragma[nomagic]
+predicate unpackStructType(
+  StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
+  TOptStructComponent c3, TOptStructComponent c4, int nComponents
+) {
+  nComponents = count(int i | component_types(s, i, _, _)) and
+  (
+    if nComponents >= 1
+    then c0 = any(StructComponent sc | sc.isComponentOf(s, 0))
+    else c0 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 2
+    then c1 = any(StructComponent sc | sc.isComponentOf(s, 1))
+    else c1 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 3
+    then c2 = any(StructComponent sc | sc.isComponentOf(s, 2))
+    else c2 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 4
+    then c3 = any(StructComponent sc | sc.isComponentOf(s, 3))
+    else c3 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 5
+    then c4 = any(StructComponent sc | sc.isComponentOf(s, 4))
+    else c4 = MkNoComponent()
+  )
+}
+
+pragma[nomagic]
+predicate unpackAndUnaliasStructType(
+  StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
+  TOptStructComponent c3, TOptStructComponent c4, int nComponents
+) {
+  exists(
+    OptStructComponent c0a, OptStructComponent c1a, OptStructComponent c2a, OptStructComponent c3a,
+    OptStructComponent c4a
+  |
+    unpackStructType(s, c0a, c1a, c2a, c3a, c4a, nComponents) and
+    c0 = c0a.getWithDeepUnaliasedType() and
+    c1 = c1a.getWithDeepUnaliasedType() and
+    c2 = c2a.getWithDeepUnaliasedType() and
+    c3 = c3a.getWithDeepUnaliasedType() and
+    c4 = c4a.getWithDeepUnaliasedType()
+  )
+}
+
+/** A struct type. */
+class StructType extends @structtype, CompositeType {
+  private StructType getDeepUnaliasedTypeCandidate() {
+    exists(
+      OptStructComponent c0, OptStructComponent c1, OptStructComponent c2, OptStructComponent c3,
+      OptStructComponent c4, int nComponents
+    |
+      unpackAndUnaliasStructType(this, c0, c1, c2, c3, c4, nComponents) and
+      unpackStructType(result, c0, c1, c2, c3, c4, nComponents)
+    )
   }
-  
-  pragma[nomagic]
-  predicate unpackStructType(
-    StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
-    TOptStructComponent c3, TOptStructComponent c4, int nComponents
-  ) {
-    nComponents = count(int i | component_types(s, i, _, _)) and
-    (
-      if nComponents >= 1
-      then c0 = any(StructComponent sc | sc.isComponentOf(s, 0))
-      else c0 = MkNoComponent()
-    ) and
-    (
-      if nComponents >= 2
-      then c1 = any(StructComponent sc | sc.isComponentOf(s, 1))
-      else c1 = MkNoComponent()
-    ) and
-    (
-      if nComponents >= 3
-      then c2 = any(StructComponent sc | sc.isComponentOf(s, 2))
-      else c2 = MkNoComponent()
-    ) and
+
+  private predicate isDeepUnaliasedTypeUpTo(StructType unaliased, int i) {
+    // Note we must use component_types not hasOwnField here because component_types may specify
+    // interface-in-struct embedding, but hasOwnField does not return such members.
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 5 and
     (
-      if nComponents >= 4
-      then c3 = any(StructComponent sc | sc.isComponentOf(s, 3))
-      else c3 = MkNoComponent()
+      i = 5 or
+      this.isDeepUnaliasedTypeUpTo(unaliased, i - 1)
     ) and
-    (
-      if nComponents >= 5
-      then c4 = any(StructComponent sc | sc.isComponentOf(s, 4))
-      else c4 = MkNoComponent()
+    exists(string name, Type tp, string tag | hasComponentTypeAndTag(this, i, name, tp, tag) |
+      hasComponentTypeAndTag(unaliased, i, name, tp.getDeepUnaliasedType(), tag)
     )
   }
-  
-  pragma[nomagic]
-  predicate unpackAndUnaliasStructType(
-    StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
-    TOptStructComponent c3, TOptStructComponent c4, int nComponents
-  ) {
-    exists(
-      OptStructComponent c0a, OptStructComponent c1a, OptStructComponent c2a, OptStructComponent c3a,
-      OptStructComponent c4a
-    |
-      unpackStructType(s, c0a, c1a, c2a, c3a, c4a, nComponents) and
-      c0 = c0a.getWithDeepUnaliasedType() and
-      c1 = c1a.getWithDeepUnaliasedType() and
-      c2 = c2a.getWithDeepUnaliasedType() and
-      c3 = c3a.getWithDeepUnaliasedType() and
-      c4 = c4a.getWithDeepUnaliasedType()
+
+  override StructType getDeepUnaliasedType() {
+    result = this.getDeepUnaliasedTypeCandidate() and
+    exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
+      this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
+      or
+      nComponents <= 5
     )
   }
-  
-  /** A struct type. */
-  class StructType extends @structtype, CompositeType {
-    private StructType getDeepUnaliasedTypeCandidate() {
-      exists(
-        OptStructComponent c0, OptStructComponent c1, OptStructComponent c2, OptStructComponent c3,
-        OptStructComponent c4, int nComponents
-      |
-        unpackAndUnaliasStructType(this, c0, c1, c2, c3, c4, nComponents) and
-        unpackStructType(result, c0, c1, c2, c3, c4, nComponents)
-      )
-    }
-  
-    private predicate isDeepUnaliasedTypeUpTo(StructType unaliased, int i) {
-      // Note we must use component_types not hasOwnField here because component_types may specify
-      // interface-in-struct embedding, but hasOwnField does not return such members.
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 5 and
-      (
-        i = 5 or
-        this.isDeepUnaliasedTypeUpTo(unaliased, i - 1)
-      ) and
-      exists(string name, Type tp, string tag | hasComponentTypeAndTag(this, i, name, tp, tag) |
-        hasComponentTypeAndTag(unaliased, i, name, tp.getDeepUnaliasedType(), tag)
-      )
-    }
-  
-    override StructType getDeepUnaliasedType() {
-      result = this.getDeepUnaliasedTypeCandidate() and
-      exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
-        this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
-        or
-        nComponents <= 5
-      )
-    }
+}
+
+/** A pointer type. */
+class PointerType extends @pointertype, CompositeType {
+  /** Gets the base type of this pointer type. */
+  Type getBaseType() { base_type(this, result) }
+
+  override PointerType getDeepUnaliasedType() {
+    result.getBaseType() = this.getBaseType().getDeepUnaliasedType()
   }
-  
-  /** A pointer type. */
-  class PointerType extends @pointertype, CompositeType {
-    /** Gets the base type of this pointer type. */
-    Type getBaseType() { base_type(this, result) }
-  
-    override PointerType getDeepUnaliasedType() {
-      result.getBaseType() = this.getBaseType().getDeepUnaliasedType()
-    }
+}
+
+private predicate isInterfaceComponentWithQualifiedName(
+  InterfaceType intf, int idx, string qualifiedName, Type tp
+) {
+  exists(string name | component_types(intf, idx, name, tp) |
+    interface_private_method_ids(intf, idx, qualifiedName)
+    or
+    not interface_private_method_ids(intf, idx, _) and qualifiedName = name
+  )
+}
+
+private newtype TOptInterfaceComponent =
+  MkNoIComponent() or
+  MkSomeIComponent(string name, Type tp) {
+    isInterfaceComponentWithQualifiedName(any(InterfaceType i), _, name, tp)
   }
-  
-  private newtype TOptInterfaceComponent =
-    MkNoIComponent() or
-    MkSomeIComponent(string name, Type tp) { component_types(any(InterfaceType i), _, name, tp) }
-  
-  private class OptInterfaceComponent extends TOptInterfaceComponent {
-    OptInterfaceComponent getWithDeepUnaliasedType() {
-      this = MkNoIComponent() and result = MkNoIComponent()
-      or
-      exists(string name, Type tp |
-        this = MkSomeIComponent(name, tp) and
-        result = MkSomeIComponent(name, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    string toString() { result = "interface component" }
+
+private class OptInterfaceComponent extends TOptInterfaceComponent {
+  OptInterfaceComponent getWithDeepUnaliasedType() {
+    this = MkNoIComponent() and result = MkNoIComponent()
+    or
+    exists(string name, Type tp |
+      this = MkSomeIComponent(name, tp) and
+      result = MkSomeIComponent(name, tp.getDeepUnaliasedType())
+    )
   }
-  
-  private class InterfaceComponent extends MkSomeIComponent {
-    string toString() { result = "interface component" }
-  
-    predicate isComponentOf(InterfaceType intf, int i) {
-      exists(string name, Type tp |
-        component_types(intf, i, name, tp) and
-        this = MkSomeIComponent(name, tp)
-      )
-    }
+
+  string toString() { result = "interface component" }
+}
+
+private class InterfaceComponent extends MkSomeIComponent {
+  string toString() { result = "interface component" }
+
+  predicate isComponentOf(InterfaceType intf, int i) {
+    exists(string name, Type tp |
+      isInterfaceComponentWithQualifiedName(intf, i, name, tp) and
+      this = MkSomeIComponent(name, tp)
+    )
   }
-  
-  pragma[nomagic]
-  predicate unpackInterfaceType(
-    InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
-    TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
-    TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds
-  ) {
-    nComponents = count(int i | component_types(intf, i, _, _) and i >= 0) and
-    nEmbeds = count(int i | component_types(intf, i, _, _) and i < 0) and
-    (
-      if nComponents >= 1
-      then c0 = any(InterfaceComponent ic | ic.isComponentOf(intf, 0))
-      else c0 = MkNoIComponent()
-    ) and
-    (
-      if nComponents >= 2
-      then c1 = any(InterfaceComponent ic | ic.isComponentOf(intf, 1))
-      else c1 = MkNoIComponent()
-    ) and
+}
+
+pragma[nomagic]
+predicate unpackInterfaceType(
+  InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
+  TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
+  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds,
+  boolean isComparable
+) {
+  nComponents = count(int i | isInterfaceComponentWithQualifiedName(intf, i, _, _) and i >= 0) and
+  nEmbeds = count(int i | isInterfaceComponentWithQualifiedName(intf, i, _, _) and i < 0) and
+  (
+    if intf = any(ComparableType comparable).getBaseType()
+    then isComparable = true
+    else isComparable = false
+  ) and
+  (
+    if nComponents >= 1
+    then c0 = any(InterfaceComponent ic | ic.isComponentOf(intf, 0))
+    else c0 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 2
+    then c1 = any(InterfaceComponent ic | ic.isComponentOf(intf, 1))
+    else c1 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 3
+    then c2 = any(InterfaceComponent ic | ic.isComponentOf(intf, 2))
+    else c2 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 4
+    then c3 = any(InterfaceComponent ic | ic.isComponentOf(intf, 3))
+    else c3 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 5
+    then c4 = any(InterfaceComponent ic | ic.isComponentOf(intf, 4))
+    else c4 = MkNoIComponent()
+  ) and
+  (
+    if nEmbeds >= 1
+    then e1 = any(InterfaceComponent ic | ic.isComponentOf(intf, -1))
+    else e1 = MkNoIComponent()
+  ) and
+  (
+    if nEmbeds >= 2
+    then e2 = any(InterfaceComponent ic | ic.isComponentOf(intf, -2))
+    else e2 = MkNoIComponent()
+  )
+}
+
+pragma[nomagic]
+predicate unpackAndUnaliasInterfaceType(
+  InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
+  TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
+  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds,
+  boolean isComparable
+) {
+  exists(
+    OptInterfaceComponent c0a, OptInterfaceComponent c1a, OptInterfaceComponent c2a,
+    OptInterfaceComponent c3a, OptInterfaceComponent c4a, OptInterfaceComponent e1a,
+    OptInterfaceComponent e2a
+  |
+    unpackInterfaceType(intf, c0a, c1a, c2a, c3a, c4a, e1a, e2a, nComponents, nEmbeds, isComparable) and
+    c0 = c0a.getWithDeepUnaliasedType() and
+    c1 = c1a.getWithDeepUnaliasedType() and
+    c2 = c2a.getWithDeepUnaliasedType() and
+    c3 = c3a.getWithDeepUnaliasedType() and
+    c4 = c4a.getWithDeepUnaliasedType() and
+    e1 = e1a.getWithDeepUnaliasedType() and
+    e2 = e2a.getWithDeepUnaliasedType()
+  )
+}
+
+/** An interface type. */
+class InterfaceType extends @interfacetype, CompositeType {
+  private Type getMethodType(int i, string name) {
+    i >= 0 and isInterfaceComponentWithQualifiedName(this, i, name, result)
+  }
+
+  /**
+   * Holds if `tp` is a directly embedded type with index `index`.
+   *
+   * `tp` (or its underlying type) is either a type set literal type or an
+   * interface type.
+   */
+  private predicate hasDirectlyEmbeddedType(int index, Type tp) {
+    index >= 0 and isInterfaceComponentWithQualifiedName(this, -(index + 1), _, tp)
+  }
+
+  private InterfaceType getDeepUnaliasedTypeCandidate() {
+    exists(
+      OptInterfaceComponent c0, OptInterfaceComponent c1, OptInterfaceComponent c2,
+      OptInterfaceComponent c3, OptInterfaceComponent c4, OptInterfaceComponent e1,
+      OptInterfaceComponent e2, int nComponents, int nEmbeds, boolean isComparable
+    |
+      unpackAndUnaliasInterfaceType(this, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds,
+        isComparable) and
+      unpackInterfaceType(result, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds, isComparable)
+    )
+  }
+
+  private predicate hasDeepUnaliasedComponentTypesUpTo(InterfaceType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 5 and
     (
-      if nComponents >= 3
-      then c2 = any(InterfaceComponent ic | ic.isComponentOf(intf, 2))
-      else c2 = MkNoIComponent()
+      i = 5 or
+      this.hasDeepUnaliasedComponentTypesUpTo(unaliased, i - 1)
     ) and
+    exists(string name |
+      unaliased.getMethodType(i, name) = this.getMethodType(i, name).getDeepUnaliasedType()
+    )
+  }
+
+  private predicate hasDeepUnaliasedEmbeddedTypesUpTo(InterfaceType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 2 and
     (
-      if nComponents >= 4
-      then c3 = any(InterfaceComponent ic | ic.isComponentOf(intf, 3))
-      else c3 = MkNoIComponent()
+      i = 2 or
+      this.hasDeepUnaliasedEmbeddedTypesUpTo(unaliased, i - 1)
     ) and
-    (
-      if nComponents >= 5
-      then c4 = any(InterfaceComponent ic | ic.isComponentOf(intf, 4))
-      else c4 = MkNoIComponent()
+    exists(Type tp | this.hasDirectlyEmbeddedType(i, tp) |
+      unaliased.hasDirectlyEmbeddedType(i, tp.getDeepUnaliasedType())
+    )
+  }
+
+  override InterfaceType getDeepUnaliasedType() {
+    result = this.getDeepUnaliasedTypeCandidate() and
+    exists(int nComponents | nComponents = count(int i | exists(this.getMethodType(i, _))) |
+      this.hasDeepUnaliasedComponentTypesUpTo(result, nComponents - 1)
+      or
+      nComponents <= 5
     ) and
+    exists(int nEmbeds | nEmbeds = count(int i | this.hasDirectlyEmbeddedType(i, _)) |
+      this.hasDeepUnaliasedEmbeddedTypesUpTo(result, nEmbeds - 1)
+      or
+      nEmbeds <= 2
+    )
+  }
+}
+
+pragma[nomagic]
+private predicate unpackTupleType(
+  TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
+) {
+  nComponents = count(int i | component_types(tt, i, _, _)) and
+  (if nComponents >= 1 then c0 = MkSomeType(tt.getComponentType(0)) else c0 = MkNoType()) and
+  (if nComponents >= 2 then c1 = MkSomeType(tt.getComponentType(1)) else c1 = MkNoType()) and
+  (if nComponents >= 3 then c2 = MkSomeType(tt.getComponentType(2)) else c2 = MkNoType())
+}
+
+pragma[nomagic]
+private predicate unpackAndUnaliasTupleType(
+  TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
+) {
+  exists(OptType c0a, OptType c1a, OptType c2a |
+    unpackTupleType(tt, c0a, c1a, c2a, nComponents) and
+    c0 = c0a.getDeepUnaliasedType() and
+    c1 = c1a.getDeepUnaliasedType() and
+    c2 = c2a.getDeepUnaliasedType()
+  )
+}
+
+/** A tuple type. */
+class TupleType extends @tupletype, CompositeType {
+  /** Gets the `i`th component type of this tuple type. */
+  Type getComponentType(int i) { component_types(this, i, _, result) }
+
+  private TupleType getCandidateDeepUnaliasedType() {
+    exists(OptType c0, OptType c1, OptType c2, int nComponents |
+      unpackAndUnaliasTupleType(this, c0, c1, c2, nComponents) and
+      unpackTupleType(result, c0, c1, c2, nComponents)
+    )
+  }
+
+  private predicate isDeepUnaliasedTypeUpTo(TupleType tt, int i) {
+    tt = this.getCandidateDeepUnaliasedType() and
+    i >= 3 and
     (
-      if nEmbeds >= 1
-      then e1 = any(InterfaceComponent ic | ic.isComponentOf(intf, -1))
-      else e1 = MkNoIComponent()
+      i = 3
+      or
+      this.isDeepUnaliasedTypeUpTo(tt, i - 1)
     ) and
-    (
-      if nEmbeds >= 2
-      then e2 = any(InterfaceComponent ic | ic.isComponentOf(intf, -2))
-      else e2 = MkNoIComponent()
+    tt.getComponentType(i) = this.getComponentType(i).getDeepUnaliasedType()
+  }
+
+  override TupleType getDeepUnaliasedType() {
+    result = this.getCandidateDeepUnaliasedType() and
+    exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
+      this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
+      or
+      nComponents <= 3
     )
   }
-  
-  pragma[nomagic]
-  predicate unpackAndUnaliasInterfaceType(
-    InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
-    TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
-    TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds
-  ) {
+}
+
+// Reasonably efficiently map from a signature type to its
+// deep-unaliased equivalent, by using a single join for the leading 5 parameters
+// and/or 3 results.
+private newtype TOptType =
+  MkNoType() or
+  MkSomeType(Type tp)
+
+private class OptType extends TOptType {
+  OptType getDeepUnaliasedType() {
+    exists(Type t | this = MkSomeType(t) | result = MkSomeType(t.getDeepUnaliasedType()))
+    or
+    this = MkNoType() and result = MkNoType()
+  }
+
+  string toString() {
+    exists(Type t | this = MkSomeType(t) | result = t.toString())
+    or
+    this = MkNoType() and result = "no type"
+  }
+}
+
+pragma[nomagic]
+private predicate unpackSignatureType(
+  SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
+  int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
+) {
+  nParams = sig.getNumParameter() and
+  nResults = sig.getNumResult() and
+  (if nParams >= 1 then param0 = MkSomeType(sig.getParameterType(0)) else param0 = MkNoType()) and
+  (if nParams >= 2 then param1 = MkSomeType(sig.getParameterType(1)) else param1 = MkNoType()) and
+  (if nParams >= 3 then param2 = MkSomeType(sig.getParameterType(2)) else param2 = MkNoType()) and
+  (if nParams >= 4 then param3 = MkSomeType(sig.getParameterType(3)) else param3 = MkNoType()) and
+  (if nParams >= 5 then param4 = MkSomeType(sig.getParameterType(4)) else param4 = MkNoType()) and
+  (if nResults >= 1 then result0 = MkSomeType(sig.getResultType(0)) else result0 = MkNoType()) and
+  (if nResults >= 2 then result1 = MkSomeType(sig.getResultType(1)) else result1 = MkNoType()) and
+  (if nResults >= 3 then result2 = MkSomeType(sig.getResultType(2)) else result2 = MkNoType()) and
+  (if sig.isVariadic() then isVariadic = true else isVariadic = false)
+}
+
+pragma[nomagic]
+private predicate unpackAndUnaliasSignatureType(
+  SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
+  int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
+) {
+  exists(
+    OptType param0a, OptType param1a, OptType param2a, OptType param3a, OptType param4a,
+    OptType result0a, OptType result1a, OptType result2a
+  |
+    unpackSignatureType(sig, param0a, param1a, param2a, param3a, param4a, nParams, result0a,
+      result1a, result2a, nResults, isVariadic)
+  |
+    param0 = param0a.getDeepUnaliasedType() and
+    param1 = param1a.getDeepUnaliasedType() and
+    param2 = param2a.getDeepUnaliasedType() and
+    param3 = param3a.getDeepUnaliasedType() and
+    param4 = param4a.getDeepUnaliasedType() and
+    result0 = result0a.getDeepUnaliasedType() and
+    result1 = result1a.getDeepUnaliasedType() and
+    result2 = result2a.getDeepUnaliasedType()
+  )
+}
+
+/** A signature type. */
+class SignatureType extends @signaturetype, CompositeType {
+  /** Gets the `i`th parameter type of this signature type. */
+  Type getParameterType(int i) { i >= 0 and component_types(this, i + 1, _, result) }
+
+  /** Gets the `i`th result type of this signature type. */
+  Type getResultType(int i) { i >= 0 and component_types(this, -(i + 1), _, result) }
+
+  /** Gets the number of parameters specified by this signature. */
+  int getNumParameter() { result = count(int i | exists(this.getParameterType(i))) }
+
+  /** Gets the number of results specified by this signature. */
+  int getNumResult() { result = count(int i | exists(this.getResultType(i))) }
+
+  /** Holds if this signature type is variadic. */
+  predicate isVariadic() { variadic(this) }
+
+  private SignatureType getDeepUnaliasedTypeCandidate() {
     exists(
-      OptInterfaceComponent c0a, OptInterfaceComponent c1a, OptInterfaceComponent c2a,
-      OptInterfaceComponent c3a, OptInterfaceComponent c4a, OptInterfaceComponent e1a,
-      OptInterfaceComponent e2a
+      OptType param0, OptType param1, OptType param2, OptType param3, OptType param4, int nParams,
+      OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
     |
-      unpackInterfaceType(intf, c0a, c1a, c2a, c3a, c4a, e1a, e2a, nComponents, nEmbeds) and
-      c0 = c0a.getWithDeepUnaliasedType() and
-      c1 = c1a.getWithDeepUnaliasedType() and
-      c2 = c2a.getWithDeepUnaliasedType() and
-      c3 = c3a.getWithDeepUnaliasedType() and
-      c4 = c4a.getWithDeepUnaliasedType() and
-      e1 = e1a.getWithDeepUnaliasedType() and
-      e2 = e2a.getWithDeepUnaliasedType()
+      unpackAndUnaliasSignatureType(this, param0, param1, param2, param3, param4, nParams, result0,
+        result1, result2, nResults, isVariadic) and
+      unpackSignatureType(result, param0, param1, param2, param3, param4, nParams, result0, result1,
+        result2, nResults, isVariadic)
     )
   }
-  
-  /** An interface type. */
-  class InterfaceType extends @interfacetype, CompositeType {
-    private InterfaceType getDeepUnaliasedTypeCandidate() {
-      exists(
-        OptInterfaceComponent c0, OptInterfaceComponent c1, OptInterfaceComponent c2,
-        OptInterfaceComponent c3, OptInterfaceComponent c4, OptInterfaceComponent e1,
-        OptInterfaceComponent e2, int nComponents, int nEmbeds
-      |
-        unpackAndUnaliasInterfaceType(this, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds) and
-        unpackInterfaceType(result, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds)
-      )
-    }
-  
-    private predicate hasDeepUnaliasedComponentTypesUpTo(InterfaceType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 5 and
-      (
-        i = 5 or
-        this.hasDeepUnaliasedComponentTypesUpTo(unaliased, i - 1)
-      ) and
-      exists(string name, Type tp | component_types(this, i, name, tp) |
-        component_types(unaliased, i, name, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    private predicate hasDeepUnaliasedEmbeddedTypesUpTo(InterfaceType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 3 and
-      (
-        i = 3 or
-        this.hasDeepUnaliasedEmbeddedTypesUpTo(unaliased, i - 1)
-      ) and
-      exists(string name, Type tp | component_types(this, -i, name, tp) |
-        component_types(unaliased, -i, name, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    override InterfaceType getDeepUnaliasedType() {
-      result = this.getDeepUnaliasedTypeCandidate() and
-      exists(int nComponents |
-        nComponents = count(int i | component_types(this, i, _, _) and i >= 0)
-      |
-        this.hasDeepUnaliasedComponentTypesUpTo(result, nComponents - 1)
-        or
-        nComponents <= 5
-      ) and
-      exists(int nEmbeds | nEmbeds = count(int i | component_types(this, i, _, _) and i < 0) |
-        // Note no -1 here, because the first embedded type is at -1
-        this.hasDeepUnaliasedEmbeddedTypesUpTo(result, nEmbeds)
-        or
-        nEmbeds <= 2
-      )
-    }
-  }
-  
-  pragma[nomagic]
-  private predicate unpackTupleType(
-    TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
-  ) {
-    nComponents = count(int i | component_types(tt, i, _, _)) and
-    (if nComponents >= 1 then c0 = MkSomeType(tt.getComponentType(0)) else c0 = MkNoType()) and
-    (if nComponents >= 2 then c1 = MkSomeType(tt.getComponentType(1)) else c1 = MkNoType()) and
-    (if nComponents >= 3 then c2 = MkSomeType(tt.getComponentType(2)) else c2 = MkNoType())
+
+  // These incremental recursive implementations only apply from parameter 5 or result 3
+  // upwards to avoid constructing large squares of candidates -- the initial parameters
+  // and results are taken care of by the candidate predicate.
+  private predicate hasDeepUnaliasedParameterTypesUpTo(SignatureType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 5 and
+    (i = 5 or this.hasDeepUnaliasedParameterTypesUpTo(unaliased, i - 1)) and
+    unaliased.getParameterType(i) = this.getParameterType(i).getDeepUnaliasedType()
   }
-  
-  pragma[nomagic]
-  private predicate unpackAndUnaliasTupleType(
-    TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
-  ) {
-    exists(OptType c0a, OptType c1a, OptType c2a |
-      unpackTupleType(tt, c0a, c1a, c2a, nComponents) and
-      c0 = c0a.getDeepUnaliasedType() and
-      c1 = c1a.getDeepUnaliasedType() and
-      c2 = c2a.getDeepUnaliasedType()
-    )
+
+  private predicate hasDeepUnaliasedResultTypesUpTo(SignatureType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 3 and
+    (i = 3 or this.hasDeepUnaliasedResultTypesUpTo(unaliased, i - 1)) and
+    unaliased.getResultType(i) = this.getResultType(i).getDeepUnaliasedType()
   }
-  
-  /** A tuple type. */
-  class TupleType extends @tupletype, CompositeType {
-    /** Gets the `i`th component type of this tuple type. */
-    Type getComponentType(int i) { component_types(this, i, _, result) }
-  
-    private TupleType getCandidateDeepUnaliasedType() {
-      exists(OptType c0, OptType c1, OptType c2, int nComponents |
-        unpackAndUnaliasTupleType(this, c0, c1, c2, nComponents) and
-        unpackTupleType(result, c0, c1, c2, nComponents)
-      )
-    }
-  
-    private predicate isDeepUnaliasedTypeUpTo(TupleType tt, int i) {
-      tt = this.getCandidateDeepUnaliasedType() and
-      i >= 3 and
+
+  override SignatureType getDeepUnaliasedType() {
+    result = this.getDeepUnaliasedTypeCandidate() and
+    exists(int nParams, int nResults |
+      this.getNumParameter() = nParams and this.getNumResult() = nResults
+    |
       (
-        i = 3
+        nParams <= 5
         or
-        this.isDeepUnaliasedTypeUpTo(tt, i - 1)
+        this.hasDeepUnaliasedParameterTypesUpTo(result, nParams - 1)
       ) and
-      exists(Type tp | component_types(this, i, _, tp) |
-        component_types(tt, i, _, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    override TupleType getDeepUnaliasedType() {
-      result = this.getCandidateDeepUnaliasedType() and
-      exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
-        this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
+      (
+        nResults <= 3
         or
-        nComponents <= 3
+        this.hasDeepUnaliasedResultTypesUpTo(result, nResults - 1)
       )
-    }
-  }
-  
-  // Reasonably efficiently map from a signature type to its
-  // deep-unaliased equivalent, by using a single join for the leading 5 parameters
-  // and/or 3 results.
-  private newtype TOptType =
-    MkNoType() or
-    MkSomeType(Type tp)
-  
-  private class OptType extends TOptType {
-    OptType getDeepUnaliasedType() {
-      exists(Type t | this = MkSomeType(t) | result = MkSomeType(t.getDeepUnaliasedType()))
-      or
-      this = MkNoType() and result = MkNoType()
-    }
-  
-    string toString() {
-      exists(Type t | this = MkSomeType(t) | result = t.toString())
-      or
-      this = MkNoType() and result = "no type"
-    }
-  }
-  
-  pragma[nomagic]
-  private predicate unpackSignatureType(
-    SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
-    int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
-  ) {
-    nParams = sig.getNumParameter() and
-    nResults = sig.getNumResult() and
-    (if nParams >= 1 then param0 = MkSomeType(sig.getParameterType(0)) else param0 = MkNoType()) and
-    (if nParams >= 2 then param1 = MkSomeType(sig.getParameterType(1)) else param1 = MkNoType()) and
-    (if nParams >= 3 then param2 = MkSomeType(sig.getParameterType(2)) else param2 = MkNoType()) and
-    (if nParams >= 4 then param3 = MkSomeType(sig.getParameterType(3)) else param3 = MkNoType()) and
-    (if nParams >= 5 then param4 = MkSomeType(sig.getParameterType(4)) else param4 = MkNoType()) and
-    (if nResults >= 1 then result0 = MkSomeType(sig.getResultType(0)) else result0 = MkNoType()) and
-    (if nResults >= 2 then result1 = MkSomeType(sig.getResultType(1)) else result1 = MkNoType()) and
-    (if nResults >= 3 then result2 = MkSomeType(sig.getResultType(2)) else result2 = MkNoType()) and
-    (if sig.isVariadic() then isVariadic = true else isVariadic = false)
-  }
-  
-  pragma[nomagic]
-  private predicate unpackAndUnaliasSignatureType(
-    SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
-    int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
-  ) {
-    exists(
-      OptType param0a, OptType param1a, OptType param2a, OptType param3a, OptType param4a,
-      OptType result0a, OptType result1a, OptType result2a
-    |
-      unpackSignatureType(sig, param0a, param1a, param2a, param3a, param4a, nParams, result0a,
-        result1a, result2a, nResults, isVariadic)
-    |
-      param0 = param0a.getDeepUnaliasedType() and
-      param1 = param1a.getDeepUnaliasedType() and
-      param2 = param2a.getDeepUnaliasedType() and
-      param3 = param3a.getDeepUnaliasedType() and
-      param4 = param4a.getDeepUnaliasedType() and
-      result0 = result0a.getDeepUnaliasedType() and
-      result1 = result1a.getDeepUnaliasedType() and
-      result2 = result2a.getDeepUnaliasedType()
     )
   }
-  
-  /** A signature type. */
-  class SignatureType extends @signaturetype, CompositeType {
-    /** Gets the `i`th parameter type of this signature type. */
-    Type getParameterType(int i) { i >= 0 and component_types(this, i + 1, _, result) }
-  
-    /** Gets the `i`th result type of this signature type. */
-    Type getResultType(int i) { i >= 0 and component_types(this, -(i + 1), _, result) }
-  
-    /** Gets the number of parameters specified by this signature. */
-    int getNumParameter() { result = count(int i | exists(this.getParameterType(i))) }
-  
-    /** Gets the number of results specified by this signature. */
-    int getNumResult() { result = count(int i | exists(this.getResultType(i))) }
-  
-    /** Holds if this signature type is variadic. */
-    predicate isVariadic() { variadic(this) }
-  
-    private SignatureType getDeepUnaliasedTypeCandidate() {
-      exists(
-        OptType param0, OptType param1, OptType param2, OptType param3, OptType param4, int nParams,
-        OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
-      |
-        unpackAndUnaliasSignatureType(this, param0, param1, param2, param3, param4, nParams, result0,
-          result1, result2, nResults, isVariadic) and
-        unpackSignatureType(result, param0, param1, param2, param3, param4, nParams, result0, result1,
-          result2, nResults, isVariadic)
-      )
-    }
-  
-    // These incremental recursive implementations only apply from parameter 5 or result 3
-    // upwards to avoid constructing large squares of candidates -- the initial parameters
-    // and results are taken care of by the candidate predicate.
-    private predicate hasDeepUnaliasedParameterTypesUpTo(SignatureType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 5 and
-      (i = 5 or this.hasDeepUnaliasedParameterTypesUpTo(unaliased, i - 1)) and
-      unaliased.getParameterType(i) = this.getParameterType(i).getDeepUnaliasedType()
-    }
-  
-    private predicate hasDeepUnaliasedResultTypesUpTo(SignatureType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 3 and
-      (i = 3 or this.hasDeepUnaliasedResultTypesUpTo(unaliased, i - 1)) and
-      unaliased.getResultType(i) = this.getResultType(i).getDeepUnaliasedType()
-    }
-  
-    override SignatureType getDeepUnaliasedType() {
-      result = this.getDeepUnaliasedTypeCandidate() and
-      exists(int nParams, int nResults |
-        this.getNumParameter() = nParams and this.getNumResult() = nResults
-      |
-        (
-          nParams <= 5
-          or
-          this.hasDeepUnaliasedParameterTypesUpTo(result, nParams - 1)
-        ) and
-        (
-          nResults <= 3
-          or
-          this.hasDeepUnaliasedResultTypesUpTo(result, nResults - 1)
-        )
-      )
-    }
-  }
-  
-  /** A map type. */
-  class MapType extends @maptype, CompositeType {
-    /** Gets the key type of this map type. */
-    Type getKeyType() { key_type(this, result) }
-  
-    /** Gets the value type of this map type. */
-    Type getValueType() { element_type(this, result) }
-  
-    override MapType getDeepUnaliasedType() {
-      result.getKeyType() = this.getKeyType().getDeepUnaliasedType() and
-      result.getValueType() = this.getValueType().getDeepUnaliasedType()
-    }
-  }
-  
-  /** A channel type. */
-  class ChanType extends @chantype, CompositeType {
-    /** Gets the element type of this channel type. */
-    Type getElementType() { element_type(this, result) }
-  }
-  
-  /** A channel type that can only send. */
-  class SendChanType extends @sendchantype, ChanType {
-    override SendChanType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
-  }
-  
-  /** A channel type that can only receive. */
-  class RecvChanType extends @recvchantype, ChanType {
-    override RecvChanType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
+}
+
+/** A map type. */
+class MapType extends @maptype, CompositeType {
+  /** Gets the key type of this map type. */
+  Type getKeyType() { key_type(this, result) }
+
+  /** Gets the value type of this map type. */
+  Type getValueType() { element_type(this, result) }
+
+  override MapType getDeepUnaliasedType() {
+    result.getKeyType() = this.getKeyType().getDeepUnaliasedType() and
+    result.getValueType() = this.getValueType().getDeepUnaliasedType()
   }
-  
-  /** A channel type that can both send and receive. */
-  class SendRecvChanType extends @sendrcvchantype, ChanType {
-    override SendRecvChanType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
+}
+
+/** A channel type. */
+class ChanType extends @chantype, CompositeType {
+  /** Gets the element type of this channel type. */
+  Type getElementType() { element_type(this, result) }
+}
+
+/** A channel type that can only send. */
+class SendChanType extends @sendchantype, ChanType {
+  override SendChanType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  /** An alias type. */
-  class AliasType extends @typealias, CompositeType {
-    /** Gets the aliased type (i.e. that appears on the RHS of the alias definition). */
-    Type getRhs() { alias_rhs(this, result) }
-  
-    override Type getDeepUnaliasedType() { result = unalias(this).getDeepUnaliasedType() }
+}
+
+/** A channel type that can only receive. */
+class RecvChanType extends @recvchantype, ChanType {
+  override RecvChanType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  /**
-   * Gets the non-alias type at the end of the alias chain starting at `t`.
-   *
-   * If `t` is not an alias type then `result` is `t`.
-   */
-  Type unalias(Type t) {
-    not t instanceof AliasType and result = t
-    or
-    result = unalias(t.(AliasType).getRhs())
+}
+
+/** A channel type that can both send and receive. */
+class SendRecvChanType extends @sendrcvchantype, ChanType {
+  override SendRecvChanType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  predicate containsAliases(Type t) { t != t.getDeepUnaliasedType() }
-  // END ALIASES.QLL
-  
+}
+
+/** A named type. */
+class NamedType extends @namedtype, CompositeType {
+  Type getBaseType() { underlying_type(this, result) }
+}
+
+/**
+ * The predeclared `comparable` type.
+ */
+class ComparableType extends NamedType {
+  ComparableType() { typename(this, "comparable") }
+}
+
+/** An alias type. */
+class AliasType extends @typealias, CompositeType {
+  /** Gets the aliased type (i.e. that appears on the RHS of the alias definition). */
+  Type getRhs() { alias_rhs(this, result) }
+
+  override Type getDeepUnaliasedType() { result = unalias(this).getDeepUnaliasedType() }
+}
+
+/**
+ * Gets the non-alias type at the end of the alias chain starting at `t`.
+ *
+ * If `t` is not an alias type then `result` is `t`.
+ */
+Type unalias(Type t) {
+  not t instanceof AliasType and result = t
+  or
+  result = unalias(t.(AliasType).getRhs())
+}
 
-class NamedType extends @namedtype, Type {}
+predicate containsAliases(Type t) { t != t.getDeepUnaliasedType() }
+// END ALIASES.QLL
 
-  from NamedType nt, Type ut
-  where underlying_type(nt, ut)
-  select nt, ut.getDeepUnaliasedType()
\ No newline at end of file
+from NamedType nt, Type ut
+where underlying_type(nt, ut)
+select nt, ut.getDeepUnaliasedType()
diff --git a/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/variadic.ql b/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/variadic.ql
index 4d93c94afd02..f926a7725acc 100644
--- a/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/variadic.ql
+++ b/go/downgrades/629b145fac466483e5eb38e1fd752f82cbb89196/variadic.ql
@@ -2,576 +2,617 @@
 // Database scripts can't import, but this is the definitive copy of the support routines for mapping types to their unaliased equivalent. Ensure this code is in sync between aliases.qll and all copies in individual table .ql files.
 /** A Go type. */
 class Type extends @type {
-    /**
-     * Gets this type with all aliases substituted for their underlying type.
-     *
-     * Note named types are not substituted.
-     */
-    Type getDeepUnaliasedType() { result = this }
-  
-    /**
-     * Gets a basic textual representation of this type.
-     */
-    string toString() { result = "type" }
-  }
-  
-  /** A composite type, that is, not a basic type. */
-  class CompositeType extends @compositetype, Type { }
-  
-  /** An array type. */
-  class ArrayType extends @arraytype, CompositeType {
-    /** Gets the element type of this array type. */
-    Type getElementType() { element_type(this, result) }
-  
-    /** Gets the length of this array type as a string. */
-    string getLengthString() { array_length(this, result) }
-  
-    override ArrayType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType() and
-      result.getLengthString() = this.getLengthString()
-    }
+  /**
+   * Gets this type with all aliases substituted for their underlying type.
+   *
+   * Note named types are not substituted.
+   */
+  Type getDeepUnaliasedType() { result = this }
+
+  /**
+   * Gets a basic textual representation of this type.
+   */
+  string toString() { result = "type" }
+}
+
+/** A composite type, that is, not a basic type. */
+class CompositeType extends @compositetype, Type { }
+
+/** An array type. */
+class ArrayType extends @arraytype, CompositeType {
+  /** Gets the element type of this array type. */
+  Type getElementType() { element_type(this, result) }
+
+  /** Gets the length of this array type as a string. */
+  string getLengthString() { array_length(this, result) }
+
+  override ArrayType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType() and
+    result.getLengthString() = this.getLengthString()
   }
-  
-  /** A slice type. */
-  class SliceType extends @slicetype, CompositeType {
-    /** Gets the element type of this slice type. */
-    Type getElementType() { element_type(this, result) }
-  
-    override SliceType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
+}
+
+/** A slice type. */
+class SliceType extends @slicetype, CompositeType {
+  /** Gets the element type of this slice type. */
+  Type getElementType() { element_type(this, result) }
+
+  override SliceType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  // Improve efficiency of matching a struct to its unaliased equivalent
-  // by unpacking the first 5 fields and tags, allowing a single join
-  // to strongly constrain the available candidates.
-  private predicate hasComponentTypeAndTag(StructType s, int i, string name, Type tp, string tag) {
-    component_types(s, i, name, tp) and component_tags(s, i, tag)
+}
+
+// Improve efficiency of matching a struct to its unaliased equivalent
+// by unpacking the first 5 fields and tags, allowing a single join
+// to strongly constrain the available candidates.
+private predicate hasComponentTypeAndTag(StructType s, int i, string name, Type tp, string tag) {
+  component_types(s, i, name, tp) and component_tags(s, i, tag)
+}
+
+private newtype TOptStructComponent =
+  MkNoComponent() or
+  MkSomeComponent(string name, Type tp, string tag) { hasComponentTypeAndTag(_, _, name, tp, tag) }
+
+private class OptStructComponent extends TOptStructComponent {
+  OptStructComponent getWithDeepUnaliasedType() {
+    this = MkNoComponent() and result = MkNoComponent()
+    or
+    exists(string name, Type tp, string tag |
+      this = MkSomeComponent(name, tp, tag) and
+      result = MkSomeComponent(name, tp.getDeepUnaliasedType(), tag)
+    )
   }
-  
-  private newtype TOptStructComponent =
-    MkNoComponent() or
-    MkSomeComponent(string name, Type tp, string tag) { hasComponentTypeAndTag(_, _, name, tp, tag) }
-  
-  private class OptStructComponent extends TOptStructComponent {
-    OptStructComponent getWithDeepUnaliasedType() {
-      this = MkNoComponent() and result = MkNoComponent()
-      or
-      exists(string name, Type tp, string tag |
-        this = MkSomeComponent(name, tp, tag) and
-        result = MkSomeComponent(name, tp.getDeepUnaliasedType(), tag)
-      )
-    }
-  
-    string toString() { result = "struct component" }
+
+  string toString() { result = "struct component" }
+}
+
+private class StructComponent extends MkSomeComponent {
+  string toString() { result = "struct component" }
+
+  predicate isComponentOf(StructType s, int i) {
+    exists(string name, Type tp, string tag |
+      hasComponentTypeAndTag(s, i, name, tp, tag) and
+      this = MkSomeComponent(name, tp, tag)
+    )
   }
-  
-  private class StructComponent extends MkSomeComponent {
-    string toString() { result = "struct component" }
-  
-    predicate isComponentOf(StructType s, int i) {
-      exists(string name, Type tp, string tag |
-        hasComponentTypeAndTag(s, i, name, tp, tag) and
-        this = MkSomeComponent(name, tp, tag)
-      )
-    }
+}
+
+pragma[nomagic]
+predicate unpackStructType(
+  StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
+  TOptStructComponent c3, TOptStructComponent c4, int nComponents
+) {
+  nComponents = count(int i | component_types(s, i, _, _)) and
+  (
+    if nComponents >= 1
+    then c0 = any(StructComponent sc | sc.isComponentOf(s, 0))
+    else c0 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 2
+    then c1 = any(StructComponent sc | sc.isComponentOf(s, 1))
+    else c1 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 3
+    then c2 = any(StructComponent sc | sc.isComponentOf(s, 2))
+    else c2 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 4
+    then c3 = any(StructComponent sc | sc.isComponentOf(s, 3))
+    else c3 = MkNoComponent()
+  ) and
+  (
+    if nComponents >= 5
+    then c4 = any(StructComponent sc | sc.isComponentOf(s, 4))
+    else c4 = MkNoComponent()
+  )
+}
+
+pragma[nomagic]
+predicate unpackAndUnaliasStructType(
+  StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
+  TOptStructComponent c3, TOptStructComponent c4, int nComponents
+) {
+  exists(
+    OptStructComponent c0a, OptStructComponent c1a, OptStructComponent c2a, OptStructComponent c3a,
+    OptStructComponent c4a
+  |
+    unpackStructType(s, c0a, c1a, c2a, c3a, c4a, nComponents) and
+    c0 = c0a.getWithDeepUnaliasedType() and
+    c1 = c1a.getWithDeepUnaliasedType() and
+    c2 = c2a.getWithDeepUnaliasedType() and
+    c3 = c3a.getWithDeepUnaliasedType() and
+    c4 = c4a.getWithDeepUnaliasedType()
+  )
+}
+
+/** A struct type. */
+class StructType extends @structtype, CompositeType {
+  private StructType getDeepUnaliasedTypeCandidate() {
+    exists(
+      OptStructComponent c0, OptStructComponent c1, OptStructComponent c2, OptStructComponent c3,
+      OptStructComponent c4, int nComponents
+    |
+      unpackAndUnaliasStructType(this, c0, c1, c2, c3, c4, nComponents) and
+      unpackStructType(result, c0, c1, c2, c3, c4, nComponents)
+    )
   }
-  
-  pragma[nomagic]
-  predicate unpackStructType(
-    StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
-    TOptStructComponent c3, TOptStructComponent c4, int nComponents
-  ) {
-    nComponents = count(int i | component_types(s, i, _, _)) and
-    (
-      if nComponents >= 1
-      then c0 = any(StructComponent sc | sc.isComponentOf(s, 0))
-      else c0 = MkNoComponent()
-    ) and
-    (
-      if nComponents >= 2
-      then c1 = any(StructComponent sc | sc.isComponentOf(s, 1))
-      else c1 = MkNoComponent()
-    ) and
-    (
-      if nComponents >= 3
-      then c2 = any(StructComponent sc | sc.isComponentOf(s, 2))
-      else c2 = MkNoComponent()
-    ) and
+
+  private predicate isDeepUnaliasedTypeUpTo(StructType unaliased, int i) {
+    // Note we must use component_types not hasOwnField here because component_types may specify
+    // interface-in-struct embedding, but hasOwnField does not return such members.
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 5 and
     (
-      if nComponents >= 4
-      then c3 = any(StructComponent sc | sc.isComponentOf(s, 3))
-      else c3 = MkNoComponent()
+      i = 5 or
+      this.isDeepUnaliasedTypeUpTo(unaliased, i - 1)
     ) and
-    (
-      if nComponents >= 5
-      then c4 = any(StructComponent sc | sc.isComponentOf(s, 4))
-      else c4 = MkNoComponent()
+    exists(string name, Type tp, string tag | hasComponentTypeAndTag(this, i, name, tp, tag) |
+      hasComponentTypeAndTag(unaliased, i, name, tp.getDeepUnaliasedType(), tag)
     )
   }
-  
-  pragma[nomagic]
-  predicate unpackAndUnaliasStructType(
-    StructType s, TOptStructComponent c0, TOptStructComponent c1, TOptStructComponent c2,
-    TOptStructComponent c3, TOptStructComponent c4, int nComponents
-  ) {
-    exists(
-      OptStructComponent c0a, OptStructComponent c1a, OptStructComponent c2a, OptStructComponent c3a,
-      OptStructComponent c4a
-    |
-      unpackStructType(s, c0a, c1a, c2a, c3a, c4a, nComponents) and
-      c0 = c0a.getWithDeepUnaliasedType() and
-      c1 = c1a.getWithDeepUnaliasedType() and
-      c2 = c2a.getWithDeepUnaliasedType() and
-      c3 = c3a.getWithDeepUnaliasedType() and
-      c4 = c4a.getWithDeepUnaliasedType()
+
+  override StructType getDeepUnaliasedType() {
+    result = this.getDeepUnaliasedTypeCandidate() and
+    exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
+      this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
+      or
+      nComponents <= 5
     )
   }
-  
-  /** A struct type. */
-  class StructType extends @structtype, CompositeType {
-    private StructType getDeepUnaliasedTypeCandidate() {
-      exists(
-        OptStructComponent c0, OptStructComponent c1, OptStructComponent c2, OptStructComponent c3,
-        OptStructComponent c4, int nComponents
-      |
-        unpackAndUnaliasStructType(this, c0, c1, c2, c3, c4, nComponents) and
-        unpackStructType(result, c0, c1, c2, c3, c4, nComponents)
-      )
-    }
-  
-    private predicate isDeepUnaliasedTypeUpTo(StructType unaliased, int i) {
-      // Note we must use component_types not hasOwnField here because component_types may specify
-      // interface-in-struct embedding, but hasOwnField does not return such members.
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 5 and
-      (
-        i = 5 or
-        this.isDeepUnaliasedTypeUpTo(unaliased, i - 1)
-      ) and
-      exists(string name, Type tp, string tag | hasComponentTypeAndTag(this, i, name, tp, tag) |
-        hasComponentTypeAndTag(unaliased, i, name, tp.getDeepUnaliasedType(), tag)
-      )
-    }
-  
-    override StructType getDeepUnaliasedType() {
-      result = this.getDeepUnaliasedTypeCandidate() and
-      exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
-        this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
-        or
-        nComponents <= 5
-      )
-    }
+}
+
+/** A pointer type. */
+class PointerType extends @pointertype, CompositeType {
+  /** Gets the base type of this pointer type. */
+  Type getBaseType() { base_type(this, result) }
+
+  override PointerType getDeepUnaliasedType() {
+    result.getBaseType() = this.getBaseType().getDeepUnaliasedType()
   }
-  
-  /** A pointer type. */
-  class PointerType extends @pointertype, CompositeType {
-    /** Gets the base type of this pointer type. */
-    Type getBaseType() { base_type(this, result) }
-  
-    override PointerType getDeepUnaliasedType() {
-      result.getBaseType() = this.getBaseType().getDeepUnaliasedType()
-    }
+}
+
+private predicate isInterfaceComponentWithQualifiedName(
+  InterfaceType intf, int idx, string qualifiedName, Type tp
+) {
+  exists(string name | component_types(intf, idx, name, tp) |
+    interface_private_method_ids(intf, idx, qualifiedName)
+    or
+    not interface_private_method_ids(intf, idx, _) and qualifiedName = name
+  )
+}
+
+private newtype TOptInterfaceComponent =
+  MkNoIComponent() or
+  MkSomeIComponent(string name, Type tp) {
+    isInterfaceComponentWithQualifiedName(any(InterfaceType i), _, name, tp)
   }
-  
-  private newtype TOptInterfaceComponent =
-    MkNoIComponent() or
-    MkSomeIComponent(string name, Type tp) { component_types(any(InterfaceType i), _, name, tp) }
-  
-  private class OptInterfaceComponent extends TOptInterfaceComponent {
-    OptInterfaceComponent getWithDeepUnaliasedType() {
-      this = MkNoIComponent() and result = MkNoIComponent()
-      or
-      exists(string name, Type tp |
-        this = MkSomeIComponent(name, tp) and
-        result = MkSomeIComponent(name, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    string toString() { result = "interface component" }
+
+private class OptInterfaceComponent extends TOptInterfaceComponent {
+  OptInterfaceComponent getWithDeepUnaliasedType() {
+    this = MkNoIComponent() and result = MkNoIComponent()
+    or
+    exists(string name, Type tp |
+      this = MkSomeIComponent(name, tp) and
+      result = MkSomeIComponent(name, tp.getDeepUnaliasedType())
+    )
   }
-  
-  private class InterfaceComponent extends MkSomeIComponent {
-    string toString() { result = "interface component" }
-  
-    predicate isComponentOf(InterfaceType intf, int i) {
-      exists(string name, Type tp |
-        component_types(intf, i, name, tp) and
-        this = MkSomeIComponent(name, tp)
-      )
-    }
+
+  string toString() { result = "interface component" }
+}
+
+private class InterfaceComponent extends MkSomeIComponent {
+  string toString() { result = "interface component" }
+
+  predicate isComponentOf(InterfaceType intf, int i) {
+    exists(string name, Type tp |
+      isInterfaceComponentWithQualifiedName(intf, i, name, tp) and
+      this = MkSomeIComponent(name, tp)
+    )
   }
-  
-  pragma[nomagic]
-  predicate unpackInterfaceType(
-    InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
-    TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
-    TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds
-  ) {
-    nComponents = count(int i | component_types(intf, i, _, _) and i >= 0) and
-    nEmbeds = count(int i | component_types(intf, i, _, _) and i < 0) and
-    (
-      if nComponents >= 1
-      then c0 = any(InterfaceComponent ic | ic.isComponentOf(intf, 0))
-      else c0 = MkNoIComponent()
-    ) and
-    (
-      if nComponents >= 2
-      then c1 = any(InterfaceComponent ic | ic.isComponentOf(intf, 1))
-      else c1 = MkNoIComponent()
-    ) and
+}
+
+pragma[nomagic]
+predicate unpackInterfaceType(
+  InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
+  TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
+  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds,
+  boolean isComparable
+) {
+  nComponents = count(int i | isInterfaceComponentWithQualifiedName(intf, i, _, _) and i >= 0) and
+  nEmbeds = count(int i | isInterfaceComponentWithQualifiedName(intf, i, _, _) and i < 0) and
+  (
+    if intf = any(ComparableType comparable).getBaseType()
+    then isComparable = true
+    else isComparable = false
+  ) and
+  (
+    if nComponents >= 1
+    then c0 = any(InterfaceComponent ic | ic.isComponentOf(intf, 0))
+    else c0 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 2
+    then c1 = any(InterfaceComponent ic | ic.isComponentOf(intf, 1))
+    else c1 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 3
+    then c2 = any(InterfaceComponent ic | ic.isComponentOf(intf, 2))
+    else c2 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 4
+    then c3 = any(InterfaceComponent ic | ic.isComponentOf(intf, 3))
+    else c3 = MkNoIComponent()
+  ) and
+  (
+    if nComponents >= 5
+    then c4 = any(InterfaceComponent ic | ic.isComponentOf(intf, 4))
+    else c4 = MkNoIComponent()
+  ) and
+  (
+    if nEmbeds >= 1
+    then e1 = any(InterfaceComponent ic | ic.isComponentOf(intf, -1))
+    else e1 = MkNoIComponent()
+  ) and
+  (
+    if nEmbeds >= 2
+    then e2 = any(InterfaceComponent ic | ic.isComponentOf(intf, -2))
+    else e2 = MkNoIComponent()
+  )
+}
+
+pragma[nomagic]
+predicate unpackAndUnaliasInterfaceType(
+  InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
+  TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
+  TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds,
+  boolean isComparable
+) {
+  exists(
+    OptInterfaceComponent c0a, OptInterfaceComponent c1a, OptInterfaceComponent c2a,
+    OptInterfaceComponent c3a, OptInterfaceComponent c4a, OptInterfaceComponent e1a,
+    OptInterfaceComponent e2a
+  |
+    unpackInterfaceType(intf, c0a, c1a, c2a, c3a, c4a, e1a, e2a, nComponents, nEmbeds, isComparable) and
+    c0 = c0a.getWithDeepUnaliasedType() and
+    c1 = c1a.getWithDeepUnaliasedType() and
+    c2 = c2a.getWithDeepUnaliasedType() and
+    c3 = c3a.getWithDeepUnaliasedType() and
+    c4 = c4a.getWithDeepUnaliasedType() and
+    e1 = e1a.getWithDeepUnaliasedType() and
+    e2 = e2a.getWithDeepUnaliasedType()
+  )
+}
+
+/** An interface type. */
+class InterfaceType extends @interfacetype, CompositeType {
+  private Type getMethodType(int i, string name) {
+    i >= 0 and isInterfaceComponentWithQualifiedName(this, i, name, result)
+  }
+
+  /**
+   * Holds if `tp` is a directly embedded type with index `index`.
+   *
+   * `tp` (or its underlying type) is either a type set literal type or an
+   * interface type.
+   */
+  private predicate hasDirectlyEmbeddedType(int index, Type tp) {
+    index >= 0 and isInterfaceComponentWithQualifiedName(this, -(index + 1), _, tp)
+  }
+
+  private InterfaceType getDeepUnaliasedTypeCandidate() {
+    exists(
+      OptInterfaceComponent c0, OptInterfaceComponent c1, OptInterfaceComponent c2,
+      OptInterfaceComponent c3, OptInterfaceComponent c4, OptInterfaceComponent e1,
+      OptInterfaceComponent e2, int nComponents, int nEmbeds, boolean isComparable
+    |
+      unpackAndUnaliasInterfaceType(this, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds,
+        isComparable) and
+      unpackInterfaceType(result, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds, isComparable)
+    )
+  }
+
+  private predicate hasDeepUnaliasedComponentTypesUpTo(InterfaceType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 5 and
     (
-      if nComponents >= 3
-      then c2 = any(InterfaceComponent ic | ic.isComponentOf(intf, 2))
-      else c2 = MkNoIComponent()
+      i = 5 or
+      this.hasDeepUnaliasedComponentTypesUpTo(unaliased, i - 1)
     ) and
+    exists(string name |
+      unaliased.getMethodType(i, name) = this.getMethodType(i, name).getDeepUnaliasedType()
+    )
+  }
+
+  private predicate hasDeepUnaliasedEmbeddedTypesUpTo(InterfaceType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 2 and
     (
-      if nComponents >= 4
-      then c3 = any(InterfaceComponent ic | ic.isComponentOf(intf, 3))
-      else c3 = MkNoIComponent()
+      i = 2 or
+      this.hasDeepUnaliasedEmbeddedTypesUpTo(unaliased, i - 1)
     ) and
-    (
-      if nComponents >= 5
-      then c4 = any(InterfaceComponent ic | ic.isComponentOf(intf, 4))
-      else c4 = MkNoIComponent()
+    exists(Type tp | this.hasDirectlyEmbeddedType(i, tp) |
+      unaliased.hasDirectlyEmbeddedType(i, tp.getDeepUnaliasedType())
+    )
+  }
+
+  override InterfaceType getDeepUnaliasedType() {
+    result = this.getDeepUnaliasedTypeCandidate() and
+    exists(int nComponents | nComponents = count(int i | exists(this.getMethodType(i, _))) |
+      this.hasDeepUnaliasedComponentTypesUpTo(result, nComponents - 1)
+      or
+      nComponents <= 5
     ) and
+    exists(int nEmbeds | nEmbeds = count(int i | this.hasDirectlyEmbeddedType(i, _)) |
+      this.hasDeepUnaliasedEmbeddedTypesUpTo(result, nEmbeds - 1)
+      or
+      nEmbeds <= 2
+    )
+  }
+}
+
+pragma[nomagic]
+private predicate unpackTupleType(
+  TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
+) {
+  nComponents = count(int i | component_types(tt, i, _, _)) and
+  (if nComponents >= 1 then c0 = MkSomeType(tt.getComponentType(0)) else c0 = MkNoType()) and
+  (if nComponents >= 2 then c1 = MkSomeType(tt.getComponentType(1)) else c1 = MkNoType()) and
+  (if nComponents >= 3 then c2 = MkSomeType(tt.getComponentType(2)) else c2 = MkNoType())
+}
+
+pragma[nomagic]
+private predicate unpackAndUnaliasTupleType(
+  TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
+) {
+  exists(OptType c0a, OptType c1a, OptType c2a |
+    unpackTupleType(tt, c0a, c1a, c2a, nComponents) and
+    c0 = c0a.getDeepUnaliasedType() and
+    c1 = c1a.getDeepUnaliasedType() and
+    c2 = c2a.getDeepUnaliasedType()
+  )
+}
+
+/** A tuple type. */
+class TupleType extends @tupletype, CompositeType {
+  /** Gets the `i`th component type of this tuple type. */
+  Type getComponentType(int i) { component_types(this, i, _, result) }
+
+  private TupleType getCandidateDeepUnaliasedType() {
+    exists(OptType c0, OptType c1, OptType c2, int nComponents |
+      unpackAndUnaliasTupleType(this, c0, c1, c2, nComponents) and
+      unpackTupleType(result, c0, c1, c2, nComponents)
+    )
+  }
+
+  private predicate isDeepUnaliasedTypeUpTo(TupleType tt, int i) {
+    tt = this.getCandidateDeepUnaliasedType() and
+    i >= 3 and
     (
-      if nEmbeds >= 1
-      then e1 = any(InterfaceComponent ic | ic.isComponentOf(intf, -1))
-      else e1 = MkNoIComponent()
+      i = 3
+      or
+      this.isDeepUnaliasedTypeUpTo(tt, i - 1)
     ) and
-    (
-      if nEmbeds >= 2
-      then e2 = any(InterfaceComponent ic | ic.isComponentOf(intf, -2))
-      else e2 = MkNoIComponent()
+    tt.getComponentType(i) = this.getComponentType(i).getDeepUnaliasedType()
+  }
+
+  override TupleType getDeepUnaliasedType() {
+    result = this.getCandidateDeepUnaliasedType() and
+    exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
+      this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
+      or
+      nComponents <= 3
     )
   }
-  
-  pragma[nomagic]
-  predicate unpackAndUnaliasInterfaceType(
-    InterfaceType intf, TOptInterfaceComponent c0, TOptInterfaceComponent c1,
-    TOptInterfaceComponent c2, TOptInterfaceComponent c3, TOptInterfaceComponent c4,
-    TOptInterfaceComponent e1, TOptInterfaceComponent e2, int nComponents, int nEmbeds
-  ) {
+}
+
+// Reasonably efficiently map from a signature type to its
+// deep-unaliased equivalent, by using a single join for the leading 5 parameters
+// and/or 3 results.
+private newtype TOptType =
+  MkNoType() or
+  MkSomeType(Type tp)
+
+private class OptType extends TOptType {
+  OptType getDeepUnaliasedType() {
+    exists(Type t | this = MkSomeType(t) | result = MkSomeType(t.getDeepUnaliasedType()))
+    or
+    this = MkNoType() and result = MkNoType()
+  }
+
+  string toString() {
+    exists(Type t | this = MkSomeType(t) | result = t.toString())
+    or
+    this = MkNoType() and result = "no type"
+  }
+}
+
+pragma[nomagic]
+private predicate unpackSignatureType(
+  SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
+  int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
+) {
+  nParams = sig.getNumParameter() and
+  nResults = sig.getNumResult() and
+  (if nParams >= 1 then param0 = MkSomeType(sig.getParameterType(0)) else param0 = MkNoType()) and
+  (if nParams >= 2 then param1 = MkSomeType(sig.getParameterType(1)) else param1 = MkNoType()) and
+  (if nParams >= 3 then param2 = MkSomeType(sig.getParameterType(2)) else param2 = MkNoType()) and
+  (if nParams >= 4 then param3 = MkSomeType(sig.getParameterType(3)) else param3 = MkNoType()) and
+  (if nParams >= 5 then param4 = MkSomeType(sig.getParameterType(4)) else param4 = MkNoType()) and
+  (if nResults >= 1 then result0 = MkSomeType(sig.getResultType(0)) else result0 = MkNoType()) and
+  (if nResults >= 2 then result1 = MkSomeType(sig.getResultType(1)) else result1 = MkNoType()) and
+  (if nResults >= 3 then result2 = MkSomeType(sig.getResultType(2)) else result2 = MkNoType()) and
+  (if sig.isVariadic() then isVariadic = true else isVariadic = false)
+}
+
+pragma[nomagic]
+private predicate unpackAndUnaliasSignatureType(
+  SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
+  int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
+) {
+  exists(
+    OptType param0a, OptType param1a, OptType param2a, OptType param3a, OptType param4a,
+    OptType result0a, OptType result1a, OptType result2a
+  |
+    unpackSignatureType(sig, param0a, param1a, param2a, param3a, param4a, nParams, result0a,
+      result1a, result2a, nResults, isVariadic)
+  |
+    param0 = param0a.getDeepUnaliasedType() and
+    param1 = param1a.getDeepUnaliasedType() and
+    param2 = param2a.getDeepUnaliasedType() and
+    param3 = param3a.getDeepUnaliasedType() and
+    param4 = param4a.getDeepUnaliasedType() and
+    result0 = result0a.getDeepUnaliasedType() and
+    result1 = result1a.getDeepUnaliasedType() and
+    result2 = result2a.getDeepUnaliasedType()
+  )
+}
+
+/** A signature type. */
+class SignatureType extends @signaturetype, CompositeType {
+  /** Gets the `i`th parameter type of this signature type. */
+  Type getParameterType(int i) { i >= 0 and component_types(this, i + 1, _, result) }
+
+  /** Gets the `i`th result type of this signature type. */
+  Type getResultType(int i) { i >= 0 and component_types(this, -(i + 1), _, result) }
+
+  /** Gets the number of parameters specified by this signature. */
+  int getNumParameter() { result = count(int i | exists(this.getParameterType(i))) }
+
+  /** Gets the number of results specified by this signature. */
+  int getNumResult() { result = count(int i | exists(this.getResultType(i))) }
+
+  /** Holds if this signature type is variadic. */
+  predicate isVariadic() { variadic(this) }
+
+  private SignatureType getDeepUnaliasedTypeCandidate() {
     exists(
-      OptInterfaceComponent c0a, OptInterfaceComponent c1a, OptInterfaceComponent c2a,
-      OptInterfaceComponent c3a, OptInterfaceComponent c4a, OptInterfaceComponent e1a,
-      OptInterfaceComponent e2a
+      OptType param0, OptType param1, OptType param2, OptType param3, OptType param4, int nParams,
+      OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
     |
-      unpackInterfaceType(intf, c0a, c1a, c2a, c3a, c4a, e1a, e2a, nComponents, nEmbeds) and
-      c0 = c0a.getWithDeepUnaliasedType() and
-      c1 = c1a.getWithDeepUnaliasedType() and
-      c2 = c2a.getWithDeepUnaliasedType() and
-      c3 = c3a.getWithDeepUnaliasedType() and
-      c4 = c4a.getWithDeepUnaliasedType() and
-      e1 = e1a.getWithDeepUnaliasedType() and
-      e2 = e2a.getWithDeepUnaliasedType()
+      unpackAndUnaliasSignatureType(this, param0, param1, param2, param3, param4, nParams, result0,
+        result1, result2, nResults, isVariadic) and
+      unpackSignatureType(result, param0, param1, param2, param3, param4, nParams, result0, result1,
+        result2, nResults, isVariadic)
     )
   }
-  
-  /** An interface type. */
-  class InterfaceType extends @interfacetype, CompositeType {
-    private InterfaceType getDeepUnaliasedTypeCandidate() {
-      exists(
-        OptInterfaceComponent c0, OptInterfaceComponent c1, OptInterfaceComponent c2,
-        OptInterfaceComponent c3, OptInterfaceComponent c4, OptInterfaceComponent e1,
-        OptInterfaceComponent e2, int nComponents, int nEmbeds
-      |
-        unpackAndUnaliasInterfaceType(this, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds) and
-        unpackInterfaceType(result, c0, c1, c2, c3, c4, e1, e2, nComponents, nEmbeds)
-      )
-    }
-  
-    private predicate hasDeepUnaliasedComponentTypesUpTo(InterfaceType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 5 and
-      (
-        i = 5 or
-        this.hasDeepUnaliasedComponentTypesUpTo(unaliased, i - 1)
-      ) and
-      exists(string name, Type tp | component_types(this, i, name, tp) |
-        component_types(unaliased, i, name, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    private predicate hasDeepUnaliasedEmbeddedTypesUpTo(InterfaceType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 3 and
-      (
-        i = 3 or
-        this.hasDeepUnaliasedEmbeddedTypesUpTo(unaliased, i - 1)
-      ) and
-      exists(string name, Type tp | component_types(this, -i, name, tp) |
-        component_types(unaliased, -i, name, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    override InterfaceType getDeepUnaliasedType() {
-      result = this.getDeepUnaliasedTypeCandidate() and
-      exists(int nComponents |
-        nComponents = count(int i | component_types(this, i, _, _) and i >= 0)
-      |
-        this.hasDeepUnaliasedComponentTypesUpTo(result, nComponents - 1)
-        or
-        nComponents <= 5
-      ) and
-      exists(int nEmbeds | nEmbeds = count(int i | component_types(this, i, _, _) and i < 0) |
-        // Note no -1 here, because the first embedded type is at -1
-        this.hasDeepUnaliasedEmbeddedTypesUpTo(result, nEmbeds)
-        or
-        nEmbeds <= 2
-      )
-    }
-  }
-  
-  pragma[nomagic]
-  private predicate unpackTupleType(
-    TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
-  ) {
-    nComponents = count(int i | component_types(tt, i, _, _)) and
-    (if nComponents >= 1 then c0 = MkSomeType(tt.getComponentType(0)) else c0 = MkNoType()) and
-    (if nComponents >= 2 then c1 = MkSomeType(tt.getComponentType(1)) else c1 = MkNoType()) and
-    (if nComponents >= 3 then c2 = MkSomeType(tt.getComponentType(2)) else c2 = MkNoType())
+
+  // These incremental recursive implementations only apply from parameter 5 or result 3
+  // upwards to avoid constructing large squares of candidates -- the initial parameters
+  // and results are taken care of by the candidate predicate.
+  private predicate hasDeepUnaliasedParameterTypesUpTo(SignatureType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 5 and
+    (i = 5 or this.hasDeepUnaliasedParameterTypesUpTo(unaliased, i - 1)) and
+    unaliased.getParameterType(i) = this.getParameterType(i).getDeepUnaliasedType()
   }
-  
-  pragma[nomagic]
-  private predicate unpackAndUnaliasTupleType(
-    TupleType tt, TOptType c0, TOptType c1, TOptType c2, int nComponents
-  ) {
-    exists(OptType c0a, OptType c1a, OptType c2a |
-      unpackTupleType(tt, c0a, c1a, c2a, nComponents) and
-      c0 = c0a.getDeepUnaliasedType() and
-      c1 = c1a.getDeepUnaliasedType() and
-      c2 = c2a.getDeepUnaliasedType()
-    )
+
+  private predicate hasDeepUnaliasedResultTypesUpTo(SignatureType unaliased, int i) {
+    unaliased = this.getDeepUnaliasedTypeCandidate() and
+    i >= 3 and
+    (i = 3 or this.hasDeepUnaliasedResultTypesUpTo(unaliased, i - 1)) and
+    unaliased.getResultType(i) = this.getResultType(i).getDeepUnaliasedType()
   }
-  
-  /** A tuple type. */
-  class TupleType extends @tupletype, CompositeType {
-    /** Gets the `i`th component type of this tuple type. */
-    Type getComponentType(int i) { component_types(this, i, _, result) }
-  
-    private TupleType getCandidateDeepUnaliasedType() {
-      exists(OptType c0, OptType c1, OptType c2, int nComponents |
-        unpackAndUnaliasTupleType(this, c0, c1, c2, nComponents) and
-        unpackTupleType(result, c0, c1, c2, nComponents)
-      )
-    }
-  
-    private predicate isDeepUnaliasedTypeUpTo(TupleType tt, int i) {
-      tt = this.getCandidateDeepUnaliasedType() and
-      i >= 3 and
+
+  override SignatureType getDeepUnaliasedType() {
+    result = this.getDeepUnaliasedTypeCandidate() and
+    exists(int nParams, int nResults |
+      this.getNumParameter() = nParams and this.getNumResult() = nResults
+    |
       (
-        i = 3
+        nParams <= 5
         or
-        this.isDeepUnaliasedTypeUpTo(tt, i - 1)
+        this.hasDeepUnaliasedParameterTypesUpTo(result, nParams - 1)
       ) and
-      exists(Type tp | component_types(this, i, _, tp) |
-        component_types(tt, i, _, tp.getDeepUnaliasedType())
-      )
-    }
-  
-    override TupleType getDeepUnaliasedType() {
-      result = this.getCandidateDeepUnaliasedType() and
-      exists(int nComponents | nComponents = count(int i | component_types(this, i, _, _)) |
-        this.isDeepUnaliasedTypeUpTo(result, nComponents - 1)
+      (
+        nResults <= 3
         or
-        nComponents <= 3
+        this.hasDeepUnaliasedResultTypesUpTo(result, nResults - 1)
       )
-    }
-  }
-  
-  // Reasonably efficiently map from a signature type to its
-  // deep-unaliased equivalent, by using a single join for the leading 5 parameters
-  // and/or 3 results.
-  private newtype TOptType =
-    MkNoType() or
-    MkSomeType(Type tp)
-  
-  private class OptType extends TOptType {
-    OptType getDeepUnaliasedType() {
-      exists(Type t | this = MkSomeType(t) | result = MkSomeType(t.getDeepUnaliasedType()))
-      or
-      this = MkNoType() and result = MkNoType()
-    }
-  
-    string toString() {
-      exists(Type t | this = MkSomeType(t) | result = t.toString())
-      or
-      this = MkNoType() and result = "no type"
-    }
-  }
-  
-  pragma[nomagic]
-  private predicate unpackSignatureType(
-    SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
-    int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
-  ) {
-    nParams = sig.getNumParameter() and
-    nResults = sig.getNumResult() and
-    (if nParams >= 1 then param0 = MkSomeType(sig.getParameterType(0)) else param0 = MkNoType()) and
-    (if nParams >= 2 then param1 = MkSomeType(sig.getParameterType(1)) else param1 = MkNoType()) and
-    (if nParams >= 3 then param2 = MkSomeType(sig.getParameterType(2)) else param2 = MkNoType()) and
-    (if nParams >= 4 then param3 = MkSomeType(sig.getParameterType(3)) else param3 = MkNoType()) and
-    (if nParams >= 5 then param4 = MkSomeType(sig.getParameterType(4)) else param4 = MkNoType()) and
-    (if nResults >= 1 then result0 = MkSomeType(sig.getResultType(0)) else result0 = MkNoType()) and
-    (if nResults >= 2 then result1 = MkSomeType(sig.getResultType(1)) else result1 = MkNoType()) and
-    (if nResults >= 3 then result2 = MkSomeType(sig.getResultType(2)) else result2 = MkNoType()) and
-    (if sig.isVariadic() then isVariadic = true else isVariadic = false)
-  }
-  
-  pragma[nomagic]
-  private predicate unpackAndUnaliasSignatureType(
-    SignatureType sig, OptType param0, OptType param1, OptType param2, OptType param3, OptType param4,
-    int nParams, OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
-  ) {
-    exists(
-      OptType param0a, OptType param1a, OptType param2a, OptType param3a, OptType param4a,
-      OptType result0a, OptType result1a, OptType result2a
-    |
-      unpackSignatureType(sig, param0a, param1a, param2a, param3a, param4a, nParams, result0a,
-        result1a, result2a, nResults, isVariadic)
-    |
-      param0 = param0a.getDeepUnaliasedType() and
-      param1 = param1a.getDeepUnaliasedType() and
-      param2 = param2a.getDeepUnaliasedType() and
-      param3 = param3a.getDeepUnaliasedType() and
-      param4 = param4a.getDeepUnaliasedType() and
-      result0 = result0a.getDeepUnaliasedType() and
-      result1 = result1a.getDeepUnaliasedType() and
-      result2 = result2a.getDeepUnaliasedType()
     )
   }
-  
-  /** A signature type. */
-  class SignatureType extends @signaturetype, CompositeType {
-    /** Gets the `i`th parameter type of this signature type. */
-    Type getParameterType(int i) { i >= 0 and component_types(this, i + 1, _, result) }
-  
-    /** Gets the `i`th result type of this signature type. */
-    Type getResultType(int i) { i >= 0 and component_types(this, -(i + 1), _, result) }
-  
-    /** Gets the number of parameters specified by this signature. */
-    int getNumParameter() { result = count(int i | exists(this.getParameterType(i))) }
-  
-    /** Gets the number of results specified by this signature. */
-    int getNumResult() { result = count(int i | exists(this.getResultType(i))) }
-  
-    /** Holds if this signature type is variadic. */
-    predicate isVariadic() { variadic(this) }
-  
-    private SignatureType getDeepUnaliasedTypeCandidate() {
-      exists(
-        OptType param0, OptType param1, OptType param2, OptType param3, OptType param4, int nParams,
-        OptType result0, OptType result1, OptType result2, int nResults, boolean isVariadic
-      |
-        unpackAndUnaliasSignatureType(this, param0, param1, param2, param3, param4, nParams, result0,
-          result1, result2, nResults, isVariadic) and
-        unpackSignatureType(result, param0, param1, param2, param3, param4, nParams, result0, result1,
-          result2, nResults, isVariadic)
-      )
-    }
-  
-    // These incremental recursive implementations only apply from parameter 5 or result 3
-    // upwards to avoid constructing large squares of candidates -- the initial parameters
-    // and results are taken care of by the candidate predicate.
-    private predicate hasDeepUnaliasedParameterTypesUpTo(SignatureType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 5 and
-      (i = 5 or this.hasDeepUnaliasedParameterTypesUpTo(unaliased, i - 1)) and
-      unaliased.getParameterType(i) = this.getParameterType(i).getDeepUnaliasedType()
-    }
-  
-    private predicate hasDeepUnaliasedResultTypesUpTo(SignatureType unaliased, int i) {
-      unaliased = this.getDeepUnaliasedTypeCandidate() and
-      i >= 3 and
-      (i = 3 or this.hasDeepUnaliasedResultTypesUpTo(unaliased, i - 1)) and
-      unaliased.getResultType(i) = this.getResultType(i).getDeepUnaliasedType()
-    }
-  
-    override SignatureType getDeepUnaliasedType() {
-      result = this.getDeepUnaliasedTypeCandidate() and
-      exists(int nParams, int nResults |
-        this.getNumParameter() = nParams and this.getNumResult() = nResults
-      |
-        (
-          nParams <= 5
-          or
-          this.hasDeepUnaliasedParameterTypesUpTo(result, nParams - 1)
-        ) and
-        (
-          nResults <= 3
-          or
-          this.hasDeepUnaliasedResultTypesUpTo(result, nResults - 1)
-        )
-      )
-    }
-  }
-  
-  /** A map type. */
-  class MapType extends @maptype, CompositeType {
-    /** Gets the key type of this map type. */
-    Type getKeyType() { key_type(this, result) }
-  
-    /** Gets the value type of this map type. */
-    Type getValueType() { element_type(this, result) }
-  
-    override MapType getDeepUnaliasedType() {
-      result.getKeyType() = this.getKeyType().getDeepUnaliasedType() and
-      result.getValueType() = this.getValueType().getDeepUnaliasedType()
-    }
-  }
-  
-  /** A channel type. */
-  class ChanType extends @chantype, CompositeType {
-    /** Gets the element type of this channel type. */
-    Type getElementType() { element_type(this, result) }
-  }
-  
-  /** A channel type that can only send. */
-  class SendChanType extends @sendchantype, ChanType {
-    override SendChanType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
-  }
-  
-  /** A channel type that can only receive. */
-  class RecvChanType extends @recvchantype, ChanType {
-    override RecvChanType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
+}
+
+/** A map type. */
+class MapType extends @maptype, CompositeType {
+  /** Gets the key type of this map type. */
+  Type getKeyType() { key_type(this, result) }
+
+  /** Gets the value type of this map type. */
+  Type getValueType() { element_type(this, result) }
+
+  override MapType getDeepUnaliasedType() {
+    result.getKeyType() = this.getKeyType().getDeepUnaliasedType() and
+    result.getValueType() = this.getValueType().getDeepUnaliasedType()
   }
-  
-  /** A channel type that can both send and receive. */
-  class SendRecvChanType extends @sendrcvchantype, ChanType {
-    override SendRecvChanType getDeepUnaliasedType() {
-      result.getElementType() = this.getElementType().getDeepUnaliasedType()
-    }
+}
+
+/** A channel type. */
+class ChanType extends @chantype, CompositeType {
+  /** Gets the element type of this channel type. */
+  Type getElementType() { element_type(this, result) }
+}
+
+/** A channel type that can only send. */
+class SendChanType extends @sendchantype, ChanType {
+  override SendChanType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  /** An alias type. */
-  class AliasType extends @typealias, CompositeType {
-    /** Gets the aliased type (i.e. that appears on the RHS of the alias definition). */
-    Type getRhs() { alias_rhs(this, result) }
-  
-    override Type getDeepUnaliasedType() { result = unalias(this).getDeepUnaliasedType() }
+}
+
+/** A channel type that can only receive. */
+class RecvChanType extends @recvchantype, ChanType {
+  override RecvChanType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  /**
-   * Gets the non-alias type at the end of the alias chain starting at `t`.
-   *
-   * If `t` is not an alias type then `result` is `t`.
-   */
-  Type unalias(Type t) {
-    not t instanceof AliasType and result = t
-    or
-    result = unalias(t.(AliasType).getRhs())
+}
+
+/** A channel type that can both send and receive. */
+class SendRecvChanType extends @sendrcvchantype, ChanType {
+  override SendRecvChanType getDeepUnaliasedType() {
+    result.getElementType() = this.getElementType().getDeepUnaliasedType()
   }
-  
-  predicate containsAliases(Type t) { t != t.getDeepUnaliasedType() }
-  // END ALIASES.QLL
-
-  from Type t
-  where variadic(t)
-  and not containsAliases(t)
-  select t
\ No newline at end of file
+}
+
+/** A named type. */
+class NamedType extends @namedtype, CompositeType {
+  Type getBaseType() { underlying_type(this, result) }
+}
+
+/**
+ * The predeclared `comparable` type.
+ */
+class ComparableType extends NamedType {
+  ComparableType() { typename(this, "comparable") }
+}
+
+/** An alias type. */
+class AliasType extends @typealias, CompositeType {
+  /** Gets the aliased type (i.e. that appears on the RHS of the alias definition). */
+  Type getRhs() { alias_rhs(this, result) }
+
+  override Type getDeepUnaliasedType() { result = unalias(this).getDeepUnaliasedType() }
+}
+
+/**
+ * Gets the non-alias type at the end of the alias chain starting at `t`.
+ *
+ * If `t` is not an alias type then `result` is `t`.
+ */
+Type unalias(Type t) {
+  not t instanceof AliasType and result = t
+  or
+  result = unalias(t.(AliasType).getRhs())
+}
+
+predicate containsAliases(Type t) { t != t.getDeepUnaliasedType() }
+// END ALIASES.QLL
+from Type t
+where
+  variadic(t) and
+  not containsAliases(t)
+select t