Restore filtering logic

src/EditorFeatures/Core/Implementation/FindReferences/IDefinitionsAndReferencesFactory.cs

@@ -11,6 +11,7 @@
 using Microsoft.CodeAnalysis.Host;
 using Microsoft.CodeAnalysis.Host.Mef;
 using Microsoft.CodeAnalysis.Shared.Extensions;
+using Microsoft.CodeAnalysis.Text;
 using Roslyn.Utilities;
 
 namespace Microsoft.CodeAnalysis.Editor.Implementation.FindReferences
@@ -30,12 +31,15 @@ internal class DefaultDefinitionsAndReferencesFactory : IDefinitionsAndReference
             var definitions = ImmutableArray.CreateBuilder<DefinitionItem>();
             var references = ImmutableArray.CreateBuilder<SourceReferenceItem>();
 
+            var uniqueLocations = new HashSet<ValueTuple<Document, TextSpan>>();
+
             // Order the symbols by precedence, then create the appropriate
             // definition item per symbol and all refernece items for its
             // reference locations.
             foreach (var referencedSymbol in referencedSymbols.OrderBy(GetPrecedence))
             {
-                ProcessReferencedSymbol(solution, referencedSymbol, definitions, references);
+                ProcessReferencedSymbol(
+                    solution, referencedSymbol, definitions, references, uniqueLocations);
             }
 
             return new DefinitionsAndReferences(definitions.ToImmutable(), references.ToImmutable());
@@ -80,7 +84,8 @@ private static int GetPrecedence(ReferencedSymbol referencedSymbol)
             Solution solution,
             ReferencedSymbol referencedSymbol,
             ImmutableArray<DefinitionItem>.Builder definitions,
-            ImmutableArray<SourceReferenceItem>.Builder references)
+            ImmutableArray<SourceReferenceItem>.Builder references,
+            HashSet<ValueTuple<Document, TextSpan>> uniqueLocations)
         {
             // See if this is a symbol we even want to present to the user.  If not,
             // ignore it entirely (including all its reference locations).
@@ -101,7 +106,7 @@ private static int GetPrecedence(ReferencedSymbol referencedSymbol)
 
             // Now, create the SourceReferenceItems for all the reference locations
             // for this definition.
-            CreateReferences(referencedSymbol, references, definitionItem);
+            CreateReferences(referencedSymbol, references, definitionItem, uniqueLocations);
 
             // Finally, see if there are any third parties that want to add their
             // own result to our collection.
@@ -214,21 +219,27 @@ private static ImmutableArray<Location> FilterDefinitionLocations(ISymbol defini
         private static void CreateReferences(
             ReferencedSymbol referencedSymbol,
             ImmutableArray<SourceReferenceItem>.Builder references,
-            DefinitionItem definitionItem)
+            DefinitionItem definitionItem,
+            HashSet<ValueTuple<Document, TextSpan>> uniqueLocations)
         {
             foreach (var referenceLocation in referencedSymbol.Locations)
             {
                 var location = referenceLocation.Location;
                 Debug.Assert(location.IsInSource);
 
-                var documentLocation = new DocumentLocation(
-                    referenceLocation.Document, referenceLocation.Location.SourceSpan);
-                if (!documentLocation.CanNavigateTo())
+                var document = referenceLocation.Document;
+                var sourceSpan = location.SourceSpan;
+
+                if (uniqueLocations.Add(ValueTuple.Create(document, sourceSpan)))
                 {
-                    continue;
-                }
+                    var documentLocation = new DocumentLocation(document, sourceSpan);
+                    if (!documentLocation.CanNavigateTo())
+                    {
+                        continue;
+                    }
 
-                references.Add(new SourceReferenceItem(definitionItem, documentLocation));
+                    references.Add(new SourceReferenceItem(definitionItem, documentLocation));
+                }
             }
         }