diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Comments/CommentBlock.cs b/csharp/extractor/Semmle.Extraction.CSharp/Comments/CommentBlock.cs
index 48dcd9f85a18..08db5bba0138 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Comments/CommentBlock.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Comments/CommentBlock.cs
@@ -12,7 +12,7 @@ internal class CommentBlock
 
         public IEnumerable<CommentLine> CommentLines => lines;
 
-        public Location Location { get; private set; }
+        public Microsoft.CodeAnalysis.Location Location { get; private set; }
 
         public CommentBlock(CommentLine firstLine)
         {
@@ -49,7 +49,7 @@ public void AddCommentLine(CommentLine line)
         {
             Location = !lines.Any()
                 ? line.Location
-                : Location.Create(
+                : Microsoft.CodeAnalysis.Location.Create(
                     line.Location.SourceTree!,
                     new TextSpan(Location.SourceSpan.Start, line.Location.SourceSpan.End - Location.SourceSpan.Start));
 
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Comments/CommentProcessor.cs b/csharp/extractor/Semmle.Extraction.CSharp/Comments/CommentProcessor.cs
index d8c9152bec11..6b6e363ba5f7 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Comments/CommentProcessor.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Comments/CommentProcessor.cs
@@ -19,10 +19,10 @@ public void AddComment(CommentLine comment)
         }
 
         // Comments sorted by location.
-        private readonly SortedDictionary<Location, CommentLine> comments = new SortedDictionary<Location, CommentLine>(new LocationComparer());
+        private readonly SortedDictionary<Microsoft.CodeAnalysis.Location, CommentLine> comments = new SortedDictionary<Microsoft.CodeAnalysis.Location, CommentLine>(new LocationComparer());
 
         // Program elements sorted by location.
-        private readonly SortedDictionary<Location, Label> elements = new SortedDictionary<Location, Label>(new LocationComparer());
+        private readonly SortedDictionary<Microsoft.CodeAnalysis.Location, Label> elements = new SortedDictionary<Microsoft.CodeAnalysis.Location, Label>(new LocationComparer());
 
         private readonly Dictionary<Label, Key> duplicationGuardKeys = new Dictionary<Label, Key>();
 
@@ -33,9 +33,9 @@ public void AddComment(CommentLine comment)
             return null;
         }
 
-        private class LocationComparer : IComparer<Location>
+        private class LocationComparer : IComparer<Microsoft.CodeAnalysis.Location>
         {
-            public int Compare(Location? l1, Location? l2) => CommentProcessor.Compare(l1, l2);
+            public int Compare(Microsoft.CodeAnalysis.Location? l1, Microsoft.CodeAnalysis.Location? l2) => CommentProcessor.Compare(l1, l2);
         }
 
         /// <summary>
@@ -44,7 +44,7 @@ private class LocationComparer : IComparer<Location>
         /// <param name="l1">First location</param>
         /// <param name="l2">Second location</param>
         /// <returns>&lt;0 if l1 before l2, &gt;0 if l1 after l2, else 0.</returns>
-        private static int Compare(Location? l1, Location? l2)
+        private static int Compare(Microsoft.CodeAnalysis.Location? l1, Microsoft.CodeAnalysis.Location? l2)
         {
             if (object.ReferenceEquals(l1, l2))
                 return 0;
@@ -68,7 +68,7 @@ private static int Compare(Location? l1, Location? l2)
         /// <param name="elementLabel">The label of the element in the trap file.</param>
         /// <param name="duplicationGuardKey">The duplication guard key of the element, if any.</param>
         /// <param name="loc">The location of the element.</param>
-        public void AddElement(Label elementLabel, Key? duplicationGuardKey, Location? loc)
+        public void AddElement(Label elementLabel, Key? duplicationGuardKey, Microsoft.CodeAnalysis.Location? loc)
         {
             if (loc is not null && loc.IsInSource)
                 elements[loc] = elementLabel;
@@ -78,7 +78,7 @@ public void AddElement(Label elementLabel, Key? duplicationGuardKey, Location? l
 
         // Ensure that commentBlock and element refer to the same file
         // which can happen when processing multiple files.
-        private static void EnsureSameFile(Comments.CommentBlock commentBlock, ref KeyValuePair<Location, Label>? element)
+        private static void EnsureSameFile(Comments.CommentBlock commentBlock, ref KeyValuePair<Microsoft.CodeAnalysis.Location, Label>? element)
         {
             if (element is not null && element.Value.Key.SourceTree != commentBlock.Location.SourceTree)
                 element = null;
@@ -96,9 +96,9 @@ private static void EnsureSameFile(Comments.CommentBlock commentBlock, ref KeyVa
         /// <param name="callback">Output binding information.</param>
         private void GenerateBindings(
             Comments.CommentBlock commentBlock,
-            KeyValuePair<Location, Label>? previousElement,
-            KeyValuePair<Location, Label>? nextElement,
-            KeyValuePair<Location, Label>? parentElement,
+            KeyValuePair<Microsoft.CodeAnalysis.Location, Label>? previousElement,
+            KeyValuePair<Microsoft.CodeAnalysis.Location, Label>? nextElement,
+            KeyValuePair<Microsoft.CodeAnalysis.Location, Label>? parentElement,
             CommentBindingCallback callback
             )
         {
@@ -125,7 +125,7 @@ CommentBindingCallback callback
             }
 
             // Heuristic to decide which is the "best" element associated with the comment.
-            KeyValuePair<Location, Label>? bestElement;
+            KeyValuePair<Microsoft.CodeAnalysis.Location, Label>? bestElement;
 
             if (previousElement is not null && previousElement.Value.Key.EndLine() == commentBlock.Location.StartLine())
             {
@@ -180,14 +180,14 @@ CommentBindingCallback callback
         private class ElementStack
         {
             // Invariant: the top of the stack must be contained by items below it.
-            private readonly Stack<KeyValuePair<Location, Label>> elementStack = new Stack<KeyValuePair<Location, Label>>();
+            private readonly Stack<KeyValuePair<Microsoft.CodeAnalysis.Location, Label>> elementStack = new();
 
             /// <summary>
             /// Add a new element to the stack.
             /// </summary>
             /// The stack is maintained.
             /// <param name="value">The new element to push.</param>
-            public void Push(KeyValuePair<Location, Label> value)
+            public void Push(KeyValuePair<Microsoft.CodeAnalysis.Location, Label> value)
             {
                 // Maintain the invariant by popping existing elements
                 while (elementStack.Count > 0 && !elementStack.Peek().Key.Contains(value.Key))
@@ -201,7 +201,7 @@ public void Push(KeyValuePair<Location, Label> value)
             /// </summary>
             /// <param name="l">The location of the comment.</param>
             /// <returns>An element completely containing l, or null if none found.</returns>
-            public KeyValuePair<Location, Label>? FindParent(Location l) =>
+            public KeyValuePair<Microsoft.CodeAnalysis.Location, Label>? FindParent(Microsoft.CodeAnalysis.Location l) =>
                 elementStack.Where(v => v.Key.Contains(l)).FirstOrNull();
 
             /// <summary>
@@ -209,7 +209,7 @@ public void Push(KeyValuePair<Location, Label> value)
             /// </summary>
             /// <param name="l">The location of the comment.</param>
             /// <returns>The element before l, or null.</returns>
-            public KeyValuePair<Location, Label>? FindBefore(Location l)
+            public KeyValuePair<Microsoft.CodeAnalysis.Location, Label>? FindBefore(Microsoft.CodeAnalysis.Location l)
             {
                 return elementStack
                     .Where(v => v.Key.SourceSpan.End < l.SourceSpan.Start)
@@ -222,7 +222,7 @@ public void Push(KeyValuePair<Location, Label> value)
             /// <param name="comment">The location of the comment.</param>
             /// <param name="next">The next element.</param>
             /// <returns>The next element.</returns>
-            public KeyValuePair<Location, Label>? FindAfter(Location comment, KeyValuePair<Location, Label>? next)
+            public KeyValuePair<Microsoft.CodeAnalysis.Location, Label>? FindAfter(Microsoft.CodeAnalysis.Location comment, KeyValuePair<Microsoft.CodeAnalysis.Location, Label>? next)
             {
                 var p = FindParent(comment);
                 return next.HasValue && p.HasValue && p.Value.Key.Before(next.Value.Key) ? null : next;
@@ -233,7 +233,7 @@ public void Push(KeyValuePair<Location, Label> value)
         private void GenerateBindings(
             Comments.CommentBlock block,
             ElementStack elementStack,
-            KeyValuePair<Location, Label>? nextElement,
+            KeyValuePair<Microsoft.CodeAnalysis.Location, Label>? nextElement,
             CommentBindingCallback cb
             )
         {
@@ -259,8 +259,8 @@ CommentBindingCallback cb
         /// <param name="cb">Where to send the results.</param>
         /// <returns>true if there are more comments to process, false otherwise.</returns>
         private bool GenerateBindings(
-            IEnumerator<KeyValuePair<Location, CommentLine>> commentEnumerator,
-            KeyValuePair<Location, Label>? nextElement,
+            IEnumerator<KeyValuePair<Microsoft.CodeAnalysis.Location, CommentLine>> commentEnumerator,
+            KeyValuePair<Microsoft.CodeAnalysis.Location, Label>? nextElement,
             ElementStack elementStack,
             CommentBindingCallback cb
             )
@@ -319,8 +319,8 @@ public void GenerateBindings(CommentBindingCallback cb)
 
             var elementStack = new ElementStack();
 
-            using IEnumerator<KeyValuePair<Location, Label>> elementEnumerator = elements.GetEnumerator();
-            using IEnumerator<KeyValuePair<Location, CommentLine>> commentEnumerator = comments.GetEnumerator();
+            using IEnumerator<KeyValuePair<Microsoft.CodeAnalysis.Location, Label>> elementEnumerator = elements.GetEnumerator();
+            using IEnumerator<KeyValuePair<Microsoft.CodeAnalysis.Location, CommentLine>> commentEnumerator = comments.GetEnumerator();
             if (!commentEnumerator.MoveNext())
             {
                 // There are no comments to process.
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Assembly.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Assembly.cs
index 0fa9422e08ca..ed13fb28a903 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Assembly.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Assembly.cs
@@ -3,7 +3,7 @@
 
 namespace Semmle.Extraction.CSharp.Entities
 {
-    internal class Assembly : Extraction.Entities.Location
+    internal class Assembly : Location
     {
         public override Context Context => (Context)base.Context;
 
@@ -56,7 +56,7 @@ public override bool Equals(object? obj)
             return false;
         }
 
-        public static Extraction.Entities.Location Create(Context cx, Microsoft.CodeAnalysis.Location loc) => AssemblyConstructorFactory.Instance.CreateEntity(cx, loc, loc);
+        public static Location Create(Context cx, Microsoft.CodeAnalysis.Location loc) => AssemblyConstructorFactory.Instance.CreateEntity(cx, loc, loc);
 
         private class AssemblyConstructorFactory : CachedEntityFactory<Microsoft.CodeAnalysis.Location?, Assembly>
         {
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Attribute.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Attribute.cs
index a70b84dde1df..e4799c05507f 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Attribute.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Attribute.cs
@@ -151,9 +151,9 @@ private void ExtractArguments(TextWriter trapFile)
 
         public override Microsoft.CodeAnalysis.Location? ReportingLocation => attributeSyntax?.Name.GetLocation();
 
-        private Semmle.Extraction.Entities.Location? location;
+        private Location? location;
 
-        private Semmle.Extraction.Entities.Location Location =>
+        private Location Location =>
             location ??= Context.CreateLocation(attributeSyntax is null
                 ? entity.ReportingLocation
                 : attributeSyntax.Name.GetLocation());
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/Base/CachedEntityFactory.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Base/CachedEntityFactory.cs
similarity index 100%
rename from csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/Base/CachedEntityFactory.cs
rename to csharp/extractor/Semmle.Extraction.CSharp/Entities/Base/CachedEntityFactory.cs
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/Base/CachedEntityFactoryExtensions.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Base/CachedEntityFactoryExtensions.cs
similarity index 100%
rename from csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/Base/CachedEntityFactoryExtensions.cs
rename to csharp/extractor/Semmle.Extraction.CSharp/Entities/Base/CachedEntityFactoryExtensions.cs
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/Base/CachedEntity`1.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Base/CachedEntity`1.cs
similarity index 100%
rename from csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/Base/CachedEntity`1.cs
rename to csharp/extractor/Semmle.Extraction.CSharp/Entities/Base/CachedEntity`1.cs
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/Base/Entity.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Base/Entity.cs
similarity index 100%
rename from csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/Base/Entity.cs
rename to csharp/extractor/Semmle.Extraction.CSharp/Entities/Base/Entity.cs
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/Base/FreshEntity.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Base/FreshEntity.cs
similarity index 100%
rename from csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/Base/FreshEntity.cs
rename to csharp/extractor/Semmle.Extraction.CSharp/Entities/Base/FreshEntity.cs
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/Base/IEntity.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Base/IEntity.cs
similarity index 100%
rename from csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/Base/IEntity.cs
rename to csharp/extractor/Semmle.Extraction.CSharp/Entities/Base/IEntity.cs
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/Base/LabelledEntity.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Base/LabelledEntity.cs
similarity index 100%
rename from csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/Base/LabelledEntity.cs
rename to csharp/extractor/Semmle.Extraction.CSharp/Entities/Base/LabelledEntity.cs
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/Base/UnlabelledEntity.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Base/UnlabelledEntity.cs
similarity index 100%
rename from csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/Base/UnlabelledEntity.cs
rename to csharp/extractor/Semmle.Extraction.CSharp/Entities/Base/UnlabelledEntity.cs
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/CachedSymbol.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/CachedSymbol.cs
index 4a4d483ea372..ad5640b90e65 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/CachedSymbol.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/CachedSymbol.cs
@@ -89,7 +89,7 @@ protected void ExtractCompilerGenerated(TextWriter trapFile)
         /// </summary>
         public virtual Microsoft.CodeAnalysis.Location? FullLocation => Symbol.Locations.BestOrDefault();
 
-        public virtual IEnumerable<Extraction.Entities.Location> Locations
+        public virtual IEnumerable<Location> Locations
         {
             get
             {
@@ -143,6 +143,6 @@ public ExpressionSyntax? ExpressionBody
 
         public override bool NeedsPopulation => Context.Defines(Symbol);
 
-        public Extraction.Entities.Location Location => Context.CreateLocation(ReportingLocation);
+        public Location Location => Context.CreateLocation(ReportingLocation);
     }
 }
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Constructor.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Constructor.cs
index 047a7b68ae6d..c3ce2bb6d29e 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Constructor.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Constructor.cs
@@ -116,7 +116,7 @@ protected override void ExtractInitializers(TextWriter trapFile)
             }
         }
 
-        private void ExtractSourceInitializer(TextWriter trapFile, ITypeSymbol? type, IMethodSymbol? symbol, ArgumentListSyntax arguments, Location location)
+        private void ExtractSourceInitializer(TextWriter trapFile, ITypeSymbol? type, IMethodSymbol? symbol, ArgumentListSyntax arguments, Microsoft.CodeAnalysis.Location location)
         {
             var initInfo = new ExpressionInfo(Context,
                 AnnotatedTypeSymbol.CreateNotAnnotated(type),
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expression.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expression.cs
index cdd2964ff216..f5021d38eeb5 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expression.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expression.cs
@@ -15,7 +15,7 @@ internal class Expression : FreshEntity, IExpressionParentEntity
     {
         private readonly IExpressionInfo info;
         public AnnotatedTypeSymbol? Type { get; private set; }
-        public Extraction.Entities.Location Location { get; }
+        public Location Location { get; }
         public ExprKind Kind { get; }
 
         internal Expression(IExpressionInfo info, bool shouldPopulate = true)
@@ -62,7 +62,7 @@ protected sealed override void Populate(TextWriter trapFile)
             type.PopulateGenerics();
         }
 
-        public override Location? ReportingLocation => Location.Symbol;
+        public override Microsoft.CodeAnalysis.Location? ReportingLocation => Location.Symbol;
 
         internal void SetType(ITypeSymbol? type)
         {
@@ -138,7 +138,7 @@ private static bool ContainsPattern(SyntaxNode node) =>
         /// Creates a generated expression from a typed constant.
         /// </summary>
         public static Expression? CreateGenerated(Context cx, TypedConstant constant, IExpressionParentEntity parent,
-            int childIndex, Extraction.Entities.Location location)
+            int childIndex, Location location)
         {
             if (constant.IsNull ||
                 constant.Type is null)
@@ -176,7 +176,7 @@ private static bool ContainsPattern(SyntaxNode node) =>
         /// Creates a generated expression for a default argument value.
         /// </summary>
         public static Expression? CreateGenerated(Context cx, IParameterSymbol parameter, IExpressionParentEntity parent,
-            int childIndex, Extraction.Entities.Location location)
+            int childIndex, Location location)
         {
             if (!parameter.HasExplicitDefaultValue ||
                 parameter.Type is IErrorTypeSymbol)
@@ -315,7 +315,7 @@ public static bool IsDynamic(Context cx, ExpressionSyntax node)
 
         /// <summary>
         /// Given `b` in `a?.b.c`, return `(a?.b, a?.b)`.
-        /// 
+        ///
         /// Given `c` in `a?.b?.c.d`, return `(b?.c, a?.b?.c)`.
         /// </summary>
         /// <param name="node">A MemberBindingExpression.</param>
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/ExpressionInfo.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/ExpressionInfo.cs
index 3474ad4a8183..8ebc0e2a0efa 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/ExpressionInfo.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/ExpressionInfo.cs
@@ -10,14 +10,14 @@ internal class ExpressionInfo : IExpressionInfo
     {
         public Context Context { get; }
         public AnnotatedTypeSymbol? Type { get; }
-        public Extraction.Entities.Location Location { get; }
+        public Location Location { get; }
         public ExprKind Kind { get; }
         public IExpressionParentEntity Parent { get; }
         public int Child { get; }
         public bool IsCompilerGenerated { get; }
         public string? ExprValue { get; }
 
-        public ExpressionInfo(Context cx, AnnotatedTypeSymbol? type, Extraction.Entities.Location location, ExprKind kind,
+        public ExpressionInfo(Context cx, AnnotatedTypeSymbol? type, Location location, ExprKind kind,
             IExpressionParentEntity parent, int child, bool isCompilerGenerated, string? value)
         {
             Context = cx;
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/ExpressionNodeInfo.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/ExpressionNodeInfo.cs
index a78f7e8c80b9..924382a55507 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/ExpressionNodeInfo.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/ExpressionNodeInfo.cs
@@ -115,9 +115,9 @@ public string? ExprValue
             }
         }
 
-        private Extraction.Entities.Location? cachedLocation;
+        private Location? cachedLocation;
 
-        public Extraction.Entities.Location Location
+        public Location Location
         {
             get
             {
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/ArrayCreation.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/ArrayCreation.cs
index 302bcaded39a..72993e2db010 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/ArrayCreation.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/ArrayCreation.cs
@@ -88,7 +88,7 @@ private NormalArrayCreation(ExpressionNodeInfo info) : base(info) { }
 
         public static Expression Create(ExpressionNodeInfo info) => new NormalArrayCreation(info).TryPopulate();
 
-        public static Expression CreateGenerated(Context cx, IExpressionParentEntity parent, int childIndex, ITypeSymbol type, IEnumerable<TypedConstant> items, Semmle.Extraction.Entities.Location location)
+        public static Expression CreateGenerated(Context cx, IExpressionParentEntity parent, int childIndex, ITypeSymbol type, IEnumerable<TypedConstant> items, Location location)
         {
             var info = new ExpressionInfo(
                 cx,
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/Cast.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/Cast.cs
index 62e23e3b66dc..20a5dc611a31 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/Cast.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/Cast.cs
@@ -32,7 +32,7 @@ protected override void PopulateExpression(TextWriter trapFile)
 
         public override Microsoft.CodeAnalysis.Location ReportingLocation => Syntax.GetLocation();
 
-        public static Expression CreateGenerated(Context cx, IExpressionParentEntity parent, int childIndex, Microsoft.CodeAnalysis.ITypeSymbol type, object? value, Action<Expression, int> createChild, Extraction.Entities.Location location)
+        public static Expression CreateGenerated(Context cx, IExpressionParentEntity parent, int childIndex, Microsoft.CodeAnalysis.ITypeSymbol type, object? value, Action<Expression, int> createChild, Location location)
         {
             var info = new ExpressionInfo(
                 cx,
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/Default.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/Default.cs
index 968f2e8f43b7..a7758e4243f9 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/Default.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/Default.cs
@@ -15,7 +15,7 @@ protected override void PopulateExpression(TextWriter trapFile)
             TypeAccess.Create(Context, Syntax.Type, this, 0);
         }
 
-        public static Expression CreateGenerated(Context cx, IExpressionParentEntity parent, int childIndex, Extraction.Entities.Location location, string? value)
+        public static Expression CreateGenerated(Context cx, IExpressionParentEntity parent, int childIndex, Location location, string? value)
         {
             var info = new ExpressionInfo(
                 cx,
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/ImplicitCast.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/ImplicitCast.cs
index 3e886a9c3ac9..b0508bf83b7e 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/ImplicitCast.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/ImplicitCast.cs
@@ -55,7 +55,7 @@ private void AddOperatorCall(IMethodSymbol method)
         /// Creates a new generated expression with an implicit conversion added.
         /// </summary>
         public static Expression CreateGeneratedConversion(Context cx, IExpressionParentEntity parent, int childIndex, ITypeSymbol type, object value,
-            Extraction.Entities.Location location)
+            Location location)
         {
             ExpressionInfo create(ExprKind kind, string? v) =>
                 new ExpressionInfo(
@@ -85,7 +85,7 @@ ExpressionInfo create(ExprKind kind, string? v) =>
         /// Creates a new generated cast expression.
         /// </summary>
         public static Expression CreateGenerated(Context cx, IExpressionParentEntity parent, int childIndex, ITypeSymbol type, object value,
-                    Extraction.Entities.Location location)
+                    Location location)
         {
             var info = new ExpressionInfo(cx,
                     AnnotatedTypeSymbol.CreateNotAnnotated(type),
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/Initializer.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/Initializer.cs
index cdc2e87798ec..92e2b910f992 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/Initializer.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/Initializer.cs
@@ -36,7 +36,7 @@ protected override void PopulateExpression(TextWriter trapFile)
             }
         }
 
-        public static Expression CreateGenerated(Context cx, IExpressionParentEntity parent, int index, Extraction.Entities.Location location)
+        public static Expression CreateGenerated(Context cx, IExpressionParentEntity parent, int index, Location location)
         {
             var info = new ExpressionInfo(
                 cx,
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/Literal.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/Literal.cs
index 72d54abf6c1a..d471839f97a3 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/Literal.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/Literal.cs
@@ -37,7 +37,7 @@ private static ExprKind GetKind(ExpressionNodeInfo info)
             return GetExprKind(type, info.Node, info.Location, info.Context);
         }
 
-        private static ExprKind GetExprKind(ITypeSymbol? type, ExpressionSyntax? expr, Extraction.Entities.Location loc, Context context)
+        private static ExprKind GetExprKind(ITypeSymbol? type, ExpressionSyntax? expr, Location loc, Context context)
         {
             switch (type?.SpecialType)
             {
@@ -87,7 +87,7 @@ private static ExprKind GetExprKind(ITypeSymbol? type, ExpressionSyntax? expr, E
         }
 
         public static Expression CreateGenerated(Context cx, IExpressionParentEntity parent, int childIndex, ITypeSymbol type, object? value,
-            Extraction.Entities.Location location)
+            Location location)
         {
             var kind = value is null ? ExprKind.NULL_LITERAL : GetExprKind(type, null, location, cx);
             var info = new ExpressionInfo(
@@ -103,7 +103,7 @@ public static Expression CreateGenerated(Context cx, IExpressionParentEntity par
             return new Expression(info);
         }
 
-        public static Expression CreateGeneratedNullLiteral(Context cx, IExpressionParentEntity parent, int childIndex, Extraction.Entities.Location location)
+        public static Expression CreateGeneratedNullLiteral(Context cx, IExpressionParentEntity parent, int childIndex, Location location)
         {
             var info = new ExpressionInfo(
                 cx,
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/ObjectCreation/DateTimeObjectCreation.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/ObjectCreation/DateTimeObjectCreation.cs
index 012a30d81cc4..98f7a8bce924 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/ObjectCreation/DateTimeObjectCreation.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/ObjectCreation/DateTimeObjectCreation.cs
@@ -49,7 +49,7 @@ protected void PopulateExpression(TextWriter trapFile)
         // The `type` symbol must be a System.DateTime type and the value must be a System.DateTime object.
         // The expression that is being created is a call to the System.DateTime(long) constructor, where
         // the number of ticks from the `value` object is used as the argument to the constructor call.
-        public static Expression CreateGenerated(Context cx, IExpressionParentEntity parent, int childIndex, ITypeSymbol type, object? value, Extraction.Entities.Location location)
+        public static Expression CreateGenerated(Context cx, IExpressionParentEntity parent, int childIndex, ITypeSymbol type, object? value, Location location)
         {
             var constructorSymbol = GetDateTimeConstructor(type) ?? throw new InternalError("Could not find symbol for System.DateTime(long)");
             var expr = new DateTimeObjectCreation(constructorSymbol, new ExpressionInfo(
@@ -68,4 +68,4 @@ public static Expression CreateGenerated(Context cx, IExpressionParentEntity par
             return expr.TryPopulate();
         }
     }
-}
\ No newline at end of file
+}
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/This.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/This.cs
index 33f2ad9fbc78..53dfc84de094 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/This.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/This.cs
@@ -7,7 +7,7 @@ internal class This : Expression
     {
         private This(IExpressionInfo info) : base(info) { }
 
-        public static This CreateImplicit(Context cx, ITypeSymbol @class, Extraction.Entities.Location loc, IExpressionParentEntity parent, int child) =>
+        public static This CreateImplicit(Context cx, ITypeSymbol @class, Location loc, IExpressionParentEntity parent, int child) =>
             new This(new ExpressionInfo(cx, AnnotatedTypeSymbol.CreateNotAnnotated(@class), loc, Kinds.ExprKind.THIS_ACCESS, parent, child, isCompilerGenerated: true, null));
 
         public static This CreateExplicit(ExpressionNodeInfo info) => new This(info.SetKind(ExprKind.THIS_ACCESS));
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/TypeAccess.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/TypeAccess.cs
index b4e678d8ab6b..55afd83318ef 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/TypeAccess.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/TypeAccess.cs
@@ -35,7 +35,7 @@ protected override void PopulateExpression(TextWriter trapFile)
 
         public static Expression Create(ExpressionNodeInfo info) => new TypeAccess(info).TryPopulate();
 
-        public static Expression CreateGenerated(Context cx, IExpressionParentEntity parent, int childIndex, Microsoft.CodeAnalysis.ITypeSymbol type, Extraction.Entities.Location location)
+        public static Expression CreateGenerated(Context cx, IExpressionParentEntity parent, int childIndex, Microsoft.CodeAnalysis.ITypeSymbol type, Location location)
         {
             var typeAccessInfo = new ExpressionInfo(
                 cx,
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/TypeOf.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/TypeOf.cs
index b36c1e425a03..cb205d383ac0 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/TypeOf.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/TypeOf.cs
@@ -17,7 +17,7 @@ protected override void PopulateExpression(TextWriter trapFile)
             TypeAccess.Create(Context, Syntax.Type, this, TypeAccessIndex);
         }
 
-        public static Expression CreateGenerated(Context cx, IExpressionParentEntity parent, int childIndex, Microsoft.CodeAnalysis.ITypeSymbol type, Extraction.Entities.Location location)
+        public static Expression CreateGenerated(Context cx, IExpressionParentEntity parent, int childIndex, Microsoft.CodeAnalysis.ITypeSymbol type, Location location)
         {
             var info = new ExpressionInfo(
                 cx,
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/VariableDeclaration.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/VariableDeclaration.cs
index 5931feb070c0..c44f9e2b9468 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/VariableDeclaration.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/VariableDeclaration.cs
@@ -13,7 +13,7 @@ internal class VariableDeclaration : Expression
     {
         private VariableDeclaration(IExpressionInfo info) : base(info) { }
 
-        public static VariableDeclaration Create(Context cx, ISymbol symbol, AnnotatedTypeSymbol? type, TypeSyntax? optionalSyntax, Extraction.Entities.Location exprLocation, bool isVar, IExpressionParentEntity parent, int child)
+        public static VariableDeclaration Create(Context cx, ISymbol symbol, AnnotatedTypeSymbol? type, TypeSyntax? optionalSyntax, Location exprLocation, bool isVar, IExpressionParentEntity parent, int child)
         {
             var ret = new VariableDeclaration(new ExpressionInfo(cx, type, exprLocation, ExprKind.LOCAL_VAR_DECL, parent, child, isCompilerGenerated: false, null));
             cx.Try(null, null, () =>
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Field.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Field.cs
index 4894da062e3f..d95c0944f0fb 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Field.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Field.cs
@@ -105,7 +105,7 @@ public override void Populate(TextWriter trapFile)
             }
         }
 
-        private Expression AddInitializerAssignment(TextWriter trapFile, ExpressionSyntax initializer, Extraction.Entities.Location loc,
+        private Expression AddInitializerAssignment(TextWriter trapFile, ExpressionSyntax initializer, Location loc,
             string? constValue, ref int child)
         {
             var type = Symbol.GetAnnotatedType();
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/IExpressionInfo.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/IExpressionInfo.cs
index ea43b19456cf..167ad8066718 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/IExpressionInfo.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/IExpressionInfo.cs
@@ -18,7 +18,7 @@ internal interface IExpressionInfo
         /// <summary>
         /// The location of the expression.
         /// </summary>
-        Extraction.Entities.Location Location { get; }
+        Location Location { get; }
 
         /// <summary>
         /// The kind of the expression.
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/File.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Locations/File.cs
similarity index 76%
rename from csharp/extractor/Semmle.Extraction.CSharp/Entities/File.cs
rename to csharp/extractor/Semmle.Extraction.CSharp/Entities/Locations/File.cs
index bd2a7fbd181f..05b339edf013 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/File.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Locations/File.cs
@@ -6,21 +6,37 @@
 
 namespace Semmle.Extraction.CSharp.Entities
 {
-    internal class File : Extraction.Entities.File
+    public class File : Extraction.CachedEntity<string>
     {
+        protected readonly string originalPath;
+        private readonly Lazy<PathTransformer.ITransformedPath> transformedPathLazy;
+        protected PathTransformer.ITransformedPath TransformedPath => transformedPathLazy.Value;
         public override Context Context => (Context)base.Context;
+        public override Microsoft.CodeAnalysis.Location? ReportingLocation => null;
+
+        public override bool NeedsPopulation => true;
 
         protected File(Context cx, string path)
             : base(cx, path)
         {
+            originalPath = path;
+            var adjustedPath = BinaryLogExtractionContext.GetAdjustedPath(Context.ExtractionContext, originalPath) ?? path;
+            transformedPathLazy = new Lazy<PathTransformer.ITransformedPath>(() => Context.ExtractionContext.PathTransformer.Transform(adjustedPath));
         }
 
+        public override void WriteId(EscapingTextWriter trapFile)
+        {
+            trapFile.Write(TransformedPath.DatabaseId);
+            trapFile.Write(";sourcefile");
+        }
+
+
         public override void Populate(TextWriter trapFile)
         {
             trapFile.files(this, TransformedPath.Value);
 
             if (TransformedPath.ParentDirectory is PathTransformer.ITransformedPath dir)
-                trapFile.containerparent(Extraction.Entities.Folder.Create(Context, dir), this);
+                trapFile.containerparent(Folder.Create(Context, dir), this);
 
             var trees = Context.Compilation.SyntaxTrees.Where(t => t.FilePath == originalPath);
 
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/Folder.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Locations/Folder.cs
similarity index 63%
rename from csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/Folder.cs
rename to csharp/extractor/Semmle.Extraction.CSharp/Entities/Locations/Folder.cs
index 465d545d9833..5d0fdc422b89 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/Folder.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Locations/Folder.cs
@@ -1,10 +1,10 @@
 using System.IO;
 
-namespace Semmle.Extraction.Entities
+namespace Semmle.Extraction.CSharp.Entities
 {
-    public sealed class Folder : CachedEntity<PathTransformer.ITransformedPath>
+    public sealed class Folder : Extraction.CachedEntity<PathTransformer.ITransformedPath>
     {
-        private Folder(Context cx, PathTransformer.ITransformedPath init) : base(cx, init) { }
+        private Folder(Extraction.Context cx, PathTransformer.ITransformedPath init) : base(cx, init) { }
 
         public override void Populate(TextWriter trapFile)
         {
@@ -21,16 +21,16 @@ public override void WriteId(EscapingTextWriter trapFile)
             trapFile.Write(";folder");
         }
 
-        public static Folder Create(Context cx, PathTransformer.ITransformedPath folder) =>
+        public static Folder Create(Extraction.Context cx, PathTransformer.ITransformedPath folder) =>
             FolderFactory.Instance.CreateEntity(cx, folder, folder);
 
         public override Microsoft.CodeAnalysis.Location? ReportingLocation => null;
 
-        private class FolderFactory : CachedEntityFactory<PathTransformer.ITransformedPath, Folder>
+        private class FolderFactory : Extraction.CachedEntityFactory<PathTransformer.ITransformedPath, Folder>
         {
             public static FolderFactory Instance { get; } = new FolderFactory();
 
-            public override Folder Create(Context cx, PathTransformer.ITransformedPath init) => new Folder(cx, init);
+            public override Folder Create(Extraction.Context cx, PathTransformer.ITransformedPath init) => new Folder(cx, init);
         }
 
         public override int GetHashCode() => Symbol.GetHashCode();
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/GeneratedFile.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Locations/GeneratedFile.cs
similarity index 95%
rename from csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/GeneratedFile.cs
rename to csharp/extractor/Semmle.Extraction.CSharp/Entities/Locations/GeneratedFile.cs
index b4a771f53db1..5a62619fd060 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/GeneratedFile.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Locations/GeneratedFile.cs
@@ -1,6 +1,6 @@
 using System.IO;
 
-namespace Semmle.Extraction.Entities
+namespace Semmle.Extraction.CSharp.Entities
 {
     internal class GeneratedFile : File
     {
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/GeneratedLocation.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Locations/GeneratedLocation.cs
similarity index 85%
rename from csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/GeneratedLocation.cs
rename to csharp/extractor/Semmle.Extraction.CSharp/Entities/Locations/GeneratedLocation.cs
index db552f7e4529..01059bdd8bf9 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/GeneratedLocation.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Locations/GeneratedLocation.cs
@@ -1,6 +1,6 @@
 using System.IO;
 
-namespace Semmle.Extraction.Entities
+namespace Semmle.Extraction.CSharp.Entities
 {
     public class GeneratedLocation : SourceLocation
     {
@@ -28,7 +28,7 @@ public override void WriteId(EscapingTextWriter trapFile)
 
         public override bool Equals(object? obj) => obj is not null && obj.GetType() == typeof(GeneratedLocation);
 
-        public static GeneratedLocation Create(Context cx) => GeneratedLocationFactory.Instance.CreateEntity(cx, typeof(GeneratedLocation), null);
+        public static GeneratedLocation Create(Extraction.Context cx) => GeneratedLocationFactory.Instance.CreateEntity(cx, typeof(GeneratedLocation), null);
 
         private class GeneratedLocationFactory : CachedEntityFactory<string?, GeneratedLocation>
         {
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/Location.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Locations/Location.cs
similarity index 72%
rename from csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/Location.cs
rename to csharp/extractor/Semmle.Extraction.CSharp/Entities/Locations/Location.cs
index d77fb46544d5..0e67eac507b9 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/Location.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Locations/Location.cs
@@ -1,7 +1,7 @@
-namespace Semmle.Extraction.Entities
+namespace Semmle.Extraction.CSharp.Entities
 {
 #nullable disable warnings
-    public abstract class Location : CachedEntity<Microsoft.CodeAnalysis.Location?>
+    public abstract class Location : Extraction.CachedEntity<Microsoft.CodeAnalysis.Location?>
     {
 #nullable restore warnings
         protected Location(Context cx, Microsoft.CodeAnalysis.Location? init)
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/NonGeneratedSourceLocation.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Locations/NonGeneratedSourceLocation.cs
similarity index 78%
rename from csharp/extractor/Semmle.Extraction.CSharp/Entities/NonGeneratedSourceLocation.cs
rename to csharp/extractor/Semmle.Extraction.CSharp/Entities/Locations/NonGeneratedSourceLocation.cs
index df41abd524d3..f0db29a606b4 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/NonGeneratedSourceLocation.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Locations/NonGeneratedSourceLocation.cs
@@ -1,22 +1,20 @@
-using System;
 using System.IO;
 using Microsoft.CodeAnalysis;
-using Semmle.Util.Logging;
 
 namespace Semmle.Extraction.CSharp.Entities
 {
-    internal class NonGeneratedSourceLocation : Extraction.Entities.SourceLocation
+    internal class NonGeneratedSourceLocation : SourceLocation
     {
         public override Context Context => (Context)base.Context;
 
-        protected NonGeneratedSourceLocation(Context cx, Location init)
+        protected NonGeneratedSourceLocation(Context cx, Microsoft.CodeAnalysis.Location init)
             : base(cx, init)
         {
             Position = init.GetLineSpan();
             FileEntity = File.Create(Context, Position.Path);
         }
 
-        public static NonGeneratedSourceLocation Create(Context cx, Location loc) => SourceLocationFactory.Instance.CreateEntity(cx, loc, loc);
+        public static NonGeneratedSourceLocation Create(Context cx, Microsoft.CodeAnalysis.Location loc) => SourceLocationFactory.Instance.CreateEntity(cx, loc, loc);
 
         public override void Populate(TextWriter trapFile)
         {
@@ -28,7 +26,7 @@ public override void Populate(TextWriter trapFile)
             if (mapped.HasMappedPath && mapped.IsValid)
             {
                 var path = Context.TryAdjustRelativeMappedFilePath(mapped.Path, Position.Path);
-                var mappedLoc = Create(Context, Location.Create(path, default, mapped.Span));
+                var mappedLoc = Create(Context, Microsoft.CodeAnalysis.Location.Create(path, default, mapped.Span));
 
                 trapFile.locations_mapped(this, mappedLoc);
             }
@@ -58,11 +56,11 @@ public override void WriteId(EscapingTextWriter trapFile)
             trapFile.Write(Position.Span.End.Character);
         }
 
-        private class SourceLocationFactory : CachedEntityFactory<Location, NonGeneratedSourceLocation>
+        private class SourceLocationFactory : CachedEntityFactory<Microsoft.CodeAnalysis.Location, NonGeneratedSourceLocation>
         {
             public static SourceLocationFactory Instance { get; } = new SourceLocationFactory();
 
-            public override NonGeneratedSourceLocation Create(Context cx, Location init) => new NonGeneratedSourceLocation(cx, init);
+            public override NonGeneratedSourceLocation Create(Context cx, Microsoft.CodeAnalysis.Location init) => new NonGeneratedSourceLocation(cx, init);
         }
     }
 }
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/SourceLocation.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Locations/SourceLocation.cs
similarity index 84%
rename from csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/SourceLocation.cs
rename to csharp/extractor/Semmle.Extraction.CSharp/Entities/Locations/SourceLocation.cs
index d126f5521658..382a4899a833 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/SourceLocation.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Locations/SourceLocation.cs
@@ -1,4 +1,4 @@
-namespace Semmle.Extraction.Entities
+namespace Semmle.Extraction.CSharp.Entities
 {
     public abstract class SourceLocation : Location
     {
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Method.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Method.cs
index c1a2082a3ba2..6890ca490847 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Method.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Method.cs
@@ -290,7 +290,7 @@ public static void AddExplicitInterfaceQualifierToId(Context cx, EscapingTextWri
 
         public Method OriginalDefinition => Create(Context, Symbol.OriginalDefinition);
 
-        public override Location? FullLocation => ReportingLocation;
+        public override Microsoft.CodeAnalysis.Location? FullLocation => ReportingLocation;
 
         public override bool IsSourceDeclaration => Symbol.IsSourceDeclaration();
 
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Modifier.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Modifier.cs
index 390311ca94b1..aa68593d7d3c 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Modifier.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Modifier.cs
@@ -8,7 +8,7 @@ internal class Modifier : Extraction.CachedEntity<string>
         private Modifier(Context cx, string init)
             : base(cx, init) { }
 
-        public override Location? ReportingLocation => null;
+        public override Microsoft.CodeAnalysis.Location? ReportingLocation => null;
 
         public override void WriteId(EscapingTextWriter trapFile)
         {
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Namespace.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Namespace.cs
index 874d8e1b69f3..e431ff0a7202 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Namespace.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Namespace.cs
@@ -8,7 +8,7 @@ internal sealed class Namespace : CachedEntity<INamespaceSymbol>
         private Namespace(Context cx, INamespaceSymbol init)
             : base(cx, init) { }
 
-        public override Location? ReportingLocation => null;
+        public override Microsoft.CodeAnalysis.Location? ReportingLocation => null;
 
         public override void Populate(TextWriter trapFile)
         {
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Types/NamedType.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Types/NamedType.cs
index 75a931e2266f..189a07f6f476 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Types/NamedType.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Types/NamedType.cs
@@ -101,7 +101,7 @@ public override void Populate(TextWriter trapFile)
 
         public override IEnumerable<Type> TypeMentions => TypeArguments;
 
-        public override IEnumerable<Extraction.Entities.Location> Locations
+        public override IEnumerable<Location> Locations
         {
             get
             {
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Types/Nullability.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Types/Nullability.cs
index 67a68958a0f4..9791f386a199 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Types/Nullability.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Types/Nullability.cs
@@ -102,7 +102,7 @@ public NullabilityEntity(Context cx, Nullability init) : base(cx, init)
         {
         }
 
-        public override Location ReportingLocation => throw new System.NotImplementedException();
+        public override Microsoft.CodeAnalysis.Location ReportingLocation => throw new System.NotImplementedException();
 
         public override bool NeedsPopulation => true;
 
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Types/TypeParameterConstraints.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Types/TypeParameterConstraints.cs
index 8684c0b820d1..6f85759dee0f 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Types/TypeParameterConstraints.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Types/TypeParameterConstraints.cs
@@ -49,7 +49,7 @@ public override void Populate(TextWriter trapFile)
             }
         }
 
-        public override Location? ReportingLocation => null;
+        public override Microsoft.CodeAnalysis.Location? ReportingLocation => null;
 
         public static TypeParameterConstraints Create(Context cx, TypeParameter p) =>
             TypeParameterConstraintsFactory.Instance.CreateEntity(cx, (typeof(TypeParameterConstraints), p), p);
@@ -62,4 +62,3 @@ private class TypeParameterConstraintsFactory : CachedEntityFactory<TypeParamete
         }
     }
 }
-
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Extractor/Context.cs b/csharp/extractor/Semmle.Extraction.CSharp/Extractor/Context.cs
index 654ce0cc0f50..4146cc810594 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Extractor/Context.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Extractor/Context.cs
@@ -11,7 +11,7 @@ namespace Semmle.Extraction.CSharp
     /// State that needs to be available throughout the extraction process.
     /// There is one Context object per trap output file.
     /// </summary>
-    internal class Context : Extraction.Context
+    public class Context : Extraction.Context
     {
         /// <summary>
         /// The program database provided by Roslyn.
@@ -117,17 +117,17 @@ public override void WithDuplicationGuard(Key key, Action a)
             }
         }
 
-        public override Extraction.Entities.Location CreateLocation()
+        public override Entities.Location CreateLocation()
         {
             return SourceTree is null
-                ? GeneratedLocation.Create(this)
+                ? Entities.GeneratedLocation.Create(this)
                 : CreateLocation(Microsoft.CodeAnalysis.Location.Create(SourceTree, Microsoft.CodeAnalysis.Text.TextSpan.FromBounds(0, 0)));
         }
 
-        public override Extraction.Entities.Location CreateLocation(Microsoft.CodeAnalysis.Location? location)
+        public override Entities.Location CreateLocation(Microsoft.CodeAnalysis.Location? location)
         {
             return (location is null || location.Kind == LocationKind.None)
-                ? GeneratedLocation.Create(this)
+                ? Entities.GeneratedLocation.Create(this)
                 : location.IsInSource
                     ? Entities.NonGeneratedSourceLocation.Create(this, location)
                     : Entities.Assembly.Create(this, location);
@@ -145,7 +145,7 @@ public void BindComments(Entity entity, Microsoft.CodeAnalysis.Location? l)
             CommentGenerator.AddElement(entity.Label, duplicationGuardKey, l);
         }
 
-        protected override bool IsEntityDuplicationGuarded(IEntity entity, [NotNullWhen(true)] out Extraction.Entities.Location? loc)
+        protected override bool IsEntityDuplicationGuarded(IEntity entity, [NotNullWhen(true)] out Entities.Location? loc)
         {
             if (CreateLocation(entity.ReportingLocation) is Entities.NonGeneratedSourceLocation l)
             {
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Tuples.cs b/csharp/extractor/Semmle.Extraction.CSharp/Tuples.cs
index 49d08fc80ef7..e8215ce90b52 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Tuples.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Tuples.cs
@@ -17,7 +17,7 @@ namespace Semmle.Extraction.CSharp
     /// </remarks>
     internal static class Tuples
     {
-        internal static void assemblies(this System.IO.TextWriter trapFile, Assembly assembly, Extraction.Entities.File file, string identifier, string name, string version) =>
+        internal static void assemblies(this System.IO.TextWriter trapFile, Assembly assembly, Entities.File file, string identifier, string name, string version) =>
             trapFile.WriteTuple("assemblies", assembly, file, identifier, name, version);
 
         internal static void accessor_location(this TextWriter trapFile, Accessor accessorKey, Location location) =>
@@ -74,10 +74,10 @@ internal static void compilation_expanded_args(this TextWriter trapFile, Compila
         internal static void compilation_info(this TextWriter trapFile, Compilation compilation, string infoKey, string infoValue) =>
             trapFile.WriteTuple("compilation_info", compilation, infoKey, infoValue);
 
-        internal static void compilation_compiling_files(this TextWriter trapFile, Compilation compilation, int index, Extraction.Entities.File file) =>
+        internal static void compilation_compiling_files(this TextWriter trapFile, Compilation compilation, int index, Entities.File file) =>
             trapFile.WriteTuple("compilation_compiling_files", compilation, index, file);
 
-        internal static void compilation_referencing_files(this TextWriter trapFile, Compilation compilation, int index, Extraction.Entities.File file) =>
+        internal static void compilation_referencing_files(this TextWriter trapFile, Compilation compilation, int index, Entities.File file) =>
             trapFile.WriteTuple("compilation_referencing_files", compilation, index, file);
 
         internal static void compilation_finished(this TextWriter trapFile, Compilation compilation, float cpuSeconds, float elapsedSeconds) =>
@@ -398,7 +398,7 @@ internal static void pragma_warnings(this TextWriter trapFile, PragmaWarningDire
         internal static void pragma_warning_error_codes(this TextWriter trapFile, PragmaWarningDirective pragma, string errorCode, int child) =>
             trapFile.WriteTuple("pragma_warning_error_codes", pragma, errorCode, child);
 
-        internal static void pragma_checksums(this TextWriter trapFile, PragmaChecksumDirective pragma, Extraction.Entities.File file, string guid, string bytes) =>
+        internal static void pragma_checksums(this TextWriter trapFile, PragmaChecksumDirective pragma, Entities.File file, string guid, string bytes) =>
             trapFile.WriteTuple("pragma_checksums", pragma, file, guid, bytes);
 
         internal static void directive_defines(this TextWriter trapFile, DefineDirective directive, string name) =>
@@ -422,7 +422,7 @@ internal static void directive_lines<T>(this TextWriter trapFile, LineOrSpanDire
         internal static void directive_line_value(this TextWriter trapFile, LineDirective directive, int line) =>
             trapFile.WriteTuple("directive_line_value", directive, line);
 
-        internal static void directive_line_file<T>(this TextWriter trapFile, LineOrSpanDirective<T> directive, Extraction.Entities.File file) where T : LineOrSpanDirectiveTriviaSyntax =>
+        internal static void directive_line_file<T>(this TextWriter trapFile, LineOrSpanDirective<T> directive, Entities.File file) where T : LineOrSpanDirectiveTriviaSyntax =>
             trapFile.WriteTuple("directive_line_file", directive, file);
 
         internal static void directive_line_offset(this TextWriter trapFile, LineSpanDirective directive, int offset) =>
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/_Base/Context.cs b/csharp/extractor/Semmle.Extraction.CSharp/_Base/Context.cs
index 8b7b750768c4..c3281e237250 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/_Base/Context.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/_Base/Context.cs
@@ -326,7 +326,7 @@ private void Populate(ISymbol? optionalSymbol, CachedEntity entity)
                 a();
         }
 
-        protected virtual bool IsEntityDuplicationGuarded(IEntity entity, [NotNullWhen(returnValue: true)] out Entities.Location? loc)
+        protected virtual bool IsEntityDuplicationGuarded(IEntity entity, [NotNullWhen(returnValue: true)] out CSharp.Entities.Location? loc)
         {
             loc = null;
             return false;
@@ -363,7 +363,7 @@ public virtual void WithDuplicationGuard(Key key, Action a)
         /// <param name="location">The location of the error.</param>
         /// <param name="stackTrace">An optional stack trace of the error, or null.</param>
         /// <param name="severity">The severity of the error.</param>
-        public void ExtractionError(string message, string? entityText, Entities.Location? location, string? stackTrace = null, Severity severity = Severity.Error)
+        public void ExtractionError(string message, string? entityText, CSharp.Entities.Location? location, string? stackTrace = null, Severity severity = Severity.Error)
         {
             var msg = new Message(message, entityText, location, stackTrace, severity);
             ExtractionError(msg);
@@ -439,7 +439,7 @@ public void ModelError(ISymbol symbol, string msg)
         /// </summary>
         /// <param name="loc">The location of the error.</param>
         /// <param name="msg">The error message.</param>
-        public void ModelError(Entities.Location loc, string msg)
+        public void ModelError(CSharp.Entities.Location loc, string msg)
         {
             ReportError(new InternalError(loc.ReportingLocation, msg));
         }
@@ -491,10 +491,10 @@ public void Try(SyntaxNode? node, ISymbol? symbol, Action a)
             }
         }
 
-        public virtual Entities.Location CreateLocation() =>
-            GeneratedLocation.Create(this);
+        public virtual CSharp.Entities.Location CreateLocation() =>
+            CSharp.Entities.GeneratedLocation.Create(this);
 
-        public virtual Entities.Location CreateLocation(Microsoft.CodeAnalysis.Location? location) =>
+        public virtual CSharp.Entities.Location CreateLocation(Microsoft.CodeAnalysis.Location? location) =>
             CreateLocation();
     }
 }
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/File.cs b/csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/File.cs
deleted file mode 100644
index dda965920ae1..000000000000
--- a/csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/File.cs
+++ /dev/null
@@ -1,29 +0,0 @@
-using System;
-
-namespace Semmle.Extraction.Entities
-{
-    public abstract class File : CachedEntity<string>
-    {
-        protected File(Context cx, string path)
-            : base(cx, path)
-        {
-            originalPath = path;
-            var adjustedPath = BinaryLogExtractionContext.GetAdjustedPath(Context.ExtractionContext, originalPath) ?? path;
-            transformedPathLazy = new Lazy<PathTransformer.ITransformedPath>(() => Context.ExtractionContext.PathTransformer.Transform(adjustedPath));
-        }
-
-        protected readonly string originalPath;
-        private readonly Lazy<PathTransformer.ITransformedPath> transformedPathLazy;
-        protected PathTransformer.ITransformedPath TransformedPath => transformedPathLazy.Value;
-
-        public override bool NeedsPopulation => true;
-
-        public override void WriteId(EscapingTextWriter trapFile)
-        {
-            trapFile.Write(TransformedPath.DatabaseId);
-            trapFile.Write(";sourcefile");
-        }
-
-        public override Microsoft.CodeAnalysis.Location? ReportingLocation => null;
-    }
-}
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/ExtractionMessage.cs b/csharp/extractor/Semmle.Extraction.CSharp/_Base/ExtractionMessage.cs
similarity index 100%
rename from csharp/extractor/Semmle.Extraction.CSharp/_Base/Entities/ExtractionMessage.cs
rename to csharp/extractor/Semmle.Extraction.CSharp/_Base/ExtractionMessage.cs
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/_Base/Message.cs b/csharp/extractor/Semmle.Extraction.CSharp/_Base/Message.cs
index 7239c5880cb6..4e05a37eb6c8 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/_Base/Message.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/_Base/Message.cs
@@ -14,9 +14,9 @@ public class Message
         public string Text { get; }
         public string? StackTrace { get; }
         public string? EntityText { get; }
-        public Entities.Location? Location { get; }
+        public CSharp.Entities.Location? Location { get; }
 
-        public Message(string text, string? entityText, Entities.Location? location, string? stackTrace = null, Severity severity = Severity.Error)
+        public Message(string text, string? entityText, CSharp.Entities.Location? location, string? stackTrace = null, Severity severity = Severity.Error)
         {
             Severity = severity;
             Text = text;
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/_Base/Tuples.cs b/csharp/extractor/Semmle.Extraction.CSharp/_Base/Tuples.cs
index cddec9322863..fde03699f4ca 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/_Base/Tuples.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/_Base/Tuples.cs
@@ -7,27 +7,27 @@ namespace Semmle.Extraction
     /// </summary>
     public static class Tuples
     {
-        public static void containerparent(this System.IO.TextWriter trapFile, Folder parent, IEntity child)
+        public static void containerparent(this System.IO.TextWriter trapFile, CSharp.Entities.Folder parent, IEntity child)
         {
             trapFile.WriteTuple("containerparent", parent, child);
         }
 
-        internal static void extractor_messages(this System.IO.TextWriter trapFile, ExtractionMessage error, Semmle.Util.Logging.Severity severity, string errorMessage, string entityText, Location location, string stackTrace)
+        internal static void extractor_messages(this System.IO.TextWriter trapFile, ExtractionMessage error, Semmle.Util.Logging.Severity severity, string errorMessage, string entityText, CSharp.Entities.Location location, string stackTrace)
         {
             trapFile.WriteTuple("extractor_messages", error, (int)severity, "C# extractor", errorMessage, entityText, location, stackTrace);
         }
 
-        public static void files(this System.IO.TextWriter trapFile, File file, string fullName)
+        public static void files(this System.IO.TextWriter trapFile, CSharp.Entities.File file, string fullName)
         {
             trapFile.WriteTuple("files", file, fullName);
         }
 
-        internal static void folders(this System.IO.TextWriter trapFile, Folder folder, string path)
+        internal static void folders(this System.IO.TextWriter trapFile, CSharp.Entities.Folder folder, string path)
         {
             trapFile.WriteTuple("folders", folder, path);
         }
 
-        public static void locations_default(this System.IO.TextWriter trapFile, SourceLocation label, Entities.File file, int startLine, int startCol, int endLine, int endCol)
+        public static void locations_default(this System.IO.TextWriter trapFile, CSharp.Entities.SourceLocation label, CSharp.Entities.File file, int startLine, int startCol, int endLine, int endCol)
         {
             trapFile.WriteTuple("locations_default", label, file, startLine, startCol, endLine, endCol);
         }