Merge pull request #335 from sjrd/fix-signature-name-of-nothing

Fix #334: Make the signatureName of Nothing be `scala.Nothing`.

tasty-query/shared/src/main/scala/tastyquery/Names.scala

@@ -71,6 +71,7 @@ object Names {
     val scalaPackageName: SimpleName = termName("scala")
     val javaPackageName: SimpleName = termName("java")
     val langPackageName: SimpleName = termName("lang")
+    val runtimePackageName: SimpleName = termName("runtime")
 
     val EmptyTuple: SimpleName = termName("EmptyTuple")
 
@@ -131,6 +132,8 @@ object Names {
 
     val scala2PackageObjectClass: TypeName = termName("package").withObjectSuffix.toTypeName
 
+    private[tastyquery] val runtimeNothing: TypeName = typeName("Nothing$")
+
     private[tastyquery] val internalRepeatedAnnot: TypeName = typeName("Repeated")
 
     private[tastyquery] val scala2LocalChild: TypeName = typeName("<local child>")
@@ -345,6 +348,7 @@ object Names {
     val emptyPackageName = FullyQualifiedName(nme.EmptyPackageName :: Nil)
     val scalaPackageName = FullyQualifiedName(nme.scalaPackageName :: Nil)
     val javaLangPackageName = FullyQualifiedName(nme.javaPackageName :: nme.langPackageName :: Nil)
+    val scalaRuntimePackageName = FullyQualifiedName(nme.scalaPackageName :: nme.runtimePackageName :: Nil)
 
     private[tastyquery] val scalaAnnotationInternalPackage =
       FullyQualifiedName(nme.scalaPackageName :: termName("annotation") :: termName("internal") :: Nil)

tasty-query/shared/src/main/scala/tastyquery/Symbols.scala

@@ -999,7 +999,10 @@ object Symbols {
     private[tastyquery] final def signatureName: FullyQualifiedName =
       def computeErasedName(owner: Symbol, name: TypeName): FullyQualifiedName = owner match
         case owner: PackageSymbol =>
-          owner.fullName.select(name)
+          val ownerFullName = owner.fullName
+          if name == tpnme.runtimeNothing && ownerFullName == FullyQualifiedName.scalaRuntimePackageName then
+            FullyQualifiedName(nme.scalaPackageName :: tpnme.Nothing :: Nil)
+          else ownerFullName.select(name)
 
         case owner: ClassSymbol =>
           owner.signatureName.mapLast(_.toTermName).select(name)

tasty-query/shared/src/test/scala/tastyquery/TypeSuite.scala

@@ -171,7 +171,11 @@ class TypeSuite extends UnrestrictedUnpicklingSuite {
     assert(clue(parentClasses) == List(defn.ObjectClass, ProductClass, SerializableClass))
   }
 
-  def applyOverloadedTest(name: String)(callMethod: String, checkParamType: Context ?=> Type => Boolean): Unit =
+  def applyOverloadedTest(name: String)(
+    callMethod: String,
+    checkParamType: Context ?=> Type => Boolean,
+    checkResultType: Context ?=> TermType => Boolean = _.isRef(defn.UnitClass)
+  ): Unit =
     testWithContext(name) {
       val OverloadedApplyClass = ctx.findTopLevelClass("simple_trees.OverloadedApply")
 
@@ -185,10 +189,10 @@ class TypeSuite extends UnrestrictedUnpicklingSuite {
         tree match
           case app @ Apply(fooRef @ Select(_, SignedName(SimpleName("foo"), _, _)), _) =>
             callCount += 1
-            assert(app.tpe.isRef(defn.UnitClass), clue(app))
+            assert(checkResultType(app.tpe), clue(app))
             val fooSym = fooRef.tpe.asInstanceOf[TermRef].symbol
             val mt = fooSym.declaredType.asInstanceOf[MethodType]
-            assert(clue(mt.resultType).isRef(defn.UnitClass))
+            assert(checkResultType(clue(mt.resultType)))
             assert(checkParamType(clue(mt.paramTypes.head)))
           case _ => ()
       }
@@ -226,6 +230,12 @@ class TypeSuite extends UnrestrictedUnpicklingSuite {
       List(_.isRef(defn.IntClass))
     )
   )
+  applyOverloadedTest("apply-overloaded-nothing")("callH", _.isRef(defn.StringClass), _.isType(_.isExactlyNothing))
+  applyOverloadedTest("apply-overloaded-null")(
+    "callI",
+    _.isRef(ctx.findTopLevelClass("java.lang.CharSequence")),
+    _.isRef(defn.NullClass)
+  )
 
   testWithContext("apply-overloaded-not-method") {
     val OverloadedApplyClass = ctx.findTopLevelClass("simple_trees.OverloadedApply")

test-sources/src/main/scala/simple_trees/OverloadedApply.scala

@@ -18,6 +18,8 @@ class OverloadedApply {
   def foo(a: Array[Foo.type]): Unit = ()
   def foo(a: => Num): Unit = ()
   def foo: String = "foo"
+  def foo(a: java.lang.String): Nothing = ???
+  def foo(a: CharSequence): Null = null
 
   @targetName("bar") def foo(a: Box[Int]): Unit = ()
 
@@ -28,5 +30,7 @@ class OverloadedApply {
   def callE = foo(Num())
   def callF = foo
   def callG = foo(Box(3))
+  def callH = foo("hello")
+  def callI = foo("hello": CharSequence)
 
 }