C#: Respect the context when extracting locations for type parameters and tuple typles.

Author: michaelnebel

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

@@ -54,8 +54,8 @@ public override void Populate(TextWriter trapFile)
             // Note: symbol.Locations seems to be very inconsistent
             // about what locations are available for a tuple type.
             // Sometimes it's the source code, and sometimes it's empty.
-            foreach (var l in Symbol.Locations)
-                WriteLocationToTrap(trapFile.type_location, this, Context.CreateLocation(l));
+            var locations = Context.GetLocations(Symbol);
+            WriteLocationsToTrap(trapFile.type_location, this, locations);
         }
 
         private readonly Lazy<Field?[]> tupleElementsLazy;

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

@@ -28,10 +28,8 @@ public override void Populate(TextWriter trapFile)
 
             if (Context.ExtractLocation(Symbol))
             {
-                foreach (var l in Symbol.Locations)
-                {
-                    WriteLocationToTrap(trapFile.type_location, this, Context.CreateLocation(l));
-                }
+                var locations = Context.GetLocations(Symbol);
+                WriteLocationsToTrap(trapFile.type_location, this, locations);
             }
 
             if (IsSourceDeclaration)

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

@@ -554,6 +554,18 @@ public bool ExtractLocation(ISymbol symbol) =>
             SymbolEqualityComparer.Default.Equals(symbol, symbol.OriginalDefinition) &&
             scope.InScope(symbol);
 
+        /// <summary>
+        /// Gets the locations of the symbol that are either
+        /// (1) In assemblies.
+        /// (2) In the current context.
+        /// </summary>
+        /// <param name="symbol">The symbol</param>
+        /// <returns>List of locations</returns>
+        public IEnumerable<Entities.Location> GetLocations(ISymbol symbol) =>
+            symbol.Locations
+                .Where(l => !l.IsInSource || IsLocationInContext(l))
+                .Select(CreateLocation);
+
         public bool IsLocationInContext(Location location) =>
             location.SourceTree == SourceTree;