C#: Only extract locations in context.

Author: michaelnebel

csharp/extractor/Semmle.Extraction.CSharp/Entities/Types/NamedType.cs

@@ -81,7 +81,7 @@ public override void Populate(TextWriter trapFile)
             }
 
             // Class location
-            if ((!Symbol.IsGenericType || Symbol.IsReallyUnbound()) && Context.ExtractLocation(Symbol))
+            if (!Symbol.IsGenericType || Symbol.IsReallyUnbound())
             {
                 WriteLocationsToTrap(trapFile.type_location, this, Locations);
             }
@@ -111,15 +111,18 @@ public override IEnumerable<Location> Locations
             }
         }
 
-        private static IEnumerable<Microsoft.CodeAnalysis.Location> GetLocations(INamedTypeSymbol type)
+        private IEnumerable<Microsoft.CodeAnalysis.Location> GetLocations(INamedTypeSymbol type)
         {
-            return type.Locations
-                .Where(l => l.IsInMetadata)
-                .Concat(type.DeclaringSyntaxReferences
+            var metadataLocations = type.Locations
+                .Where(l => l.IsInMetadata);
+            var sourceLocations = type.DeclaringSyntaxReferences
                     .Select(loc => loc.GetSyntax())
                     .OfType<CSharpSyntaxNode>()
                     .Select(l => l.FixedLocation())
-                );
+                    .Where(Context.IsLocationInContext);
+
+            return metadataLocations
+                .Concat(sourceLocations);
         }
 
         public override Microsoft.CodeAnalysis.Location? ReportingLocation => GetLocations(Symbol).BestOrDefault();

csharp/extractor/Semmle.Extraction.CSharp/Extractor/Context.cs

@@ -554,6 +554,9 @@ public bool ExtractLocation(ISymbol symbol) =>
             SymbolEqualityComparer.Default.Equals(symbol, symbol.OriginalDefinition) &&
             scope.InScope(symbol);
 
+        public bool IsLocationInContext(Location location) =>
+            location.SourceTree == SourceTree;
+
         /// <summary>
         /// Runs the given action <paramref name="a"/>, guarding for trap duplication
         /// based on key <paramref name="key"/>.