C#: Only use source locations from context.

Author: michaelnebel

csharp/extractor/Semmle.Extraction.CSharp/Entities/Base/CachedSymbol.cs

@@ -81,12 +81,12 @@ protected void ExtractCompilerGenerated(TextWriter trapFile)
         /// The location which is stored in the database and is used when highlighting source code.
         /// It's generally short, e.g. a method name.
         /// </summary>
-        public override Microsoft.CodeAnalysis.Location? ReportingLocation => Symbol.Locations.BestOrDefault();
+        public override Microsoft.CodeAnalysis.Location? ReportingLocation => Context.GetMsLocations(Symbol).BestOrDefault();
 
         /// <summary>
         /// The full text span of the entity, e.g. for binding comments.
         /// </summary>
-        public virtual Microsoft.CodeAnalysis.Location? FullLocation => Symbol.Locations.BestOrDefault();
+        public virtual Microsoft.CodeAnalysis.Location? FullLocation => Context.GetMsLocations(Symbol).BestOrDefault();
 
         public virtual IEnumerable<Location> Locations
         {

csharp/extractor/Semmle.Extraction.CSharp/Entities/Parameter.cs

@@ -115,10 +115,9 @@ public override void Populate(TextWriter trapFile)
             var type = Type.Create(Context, Symbol.Type);
             trapFile.@params(this, Name, type.TypeRef, Ordinal, ParamKind, Parent!, Original);
 
-            foreach (var l in Symbol.Locations)
-            {
-                WriteLocationToTrap(trapFile.param_location, this, Context.CreateLocation(l));
-            }
+            var locations = Context.GetLocations(Symbol);
+
+            WriteLocationsToTrap(trapFile.param_location, this, locations);
 
             if (!Symbol.Locations.Any() &&
                 Symbol.ContainingSymbol is IMethodSymbol ms &&

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

@@ -562,10 +562,20 @@ public bool ExtractLocation(ISymbol symbol) =>
         /// <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))
+            GetMsLocations(symbol)
                 .Select(CreateLocation);
 
+        /// <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<Location> GetMsLocations(ISymbol symbol) =>
+            symbol.Locations
+                .Where(l => !l.IsInSource || IsLocationInContext(l));
+
         public bool IsLocationInContext(Location location) =>
             location.SourceTree == SourceTree;