Show all source locations for a source item.

src/EditorFeatures/Test2/FindReferences/FindReferencesTests.vb

@@ -52,8 +52,7 @@ Namespace Microsoft.CodeAnalysis.Editor.UnitTests.FindReferences
 
                     Dim actualDefinitions = GetFileNamesAndSpans(
                         context.Definitions.Where(AddressOf context.ShouldShow).
-                                            OfType(Of DefinitionItem.DocumentLocationDefinitionItem).
-                                            SelectMany(Function(d) d.AdditionalLocations.Concat(d.Location)))
+                                            SelectMany(Function(d) d.SourceLocations))
 
                     Assert.Equal(expectedDefinitions, actualDefinitions)
 

src/Features/Core/Portable/FindReferences/DefinitionItem.DocumentLocationDefinitionItem.cs

@@ -14,25 +14,21 @@ internal partial class DefinitionItem
         // internal for testing purposes.
         internal sealed class DocumentLocationDefinitionItem : DefinitionItem
         {
-            public readonly DocumentLocation Location;
-
             internal override bool IsExternal => false;
 
             public DocumentLocationDefinitionItem(
                 ImmutableArray<string> tags,
                 ImmutableArray<TaggedText> displayParts,
-                ImmutableArray<DocumentLocation> additionalLocations,
-                bool displayIfNoReferences,
-                DocumentLocation location)
+                ImmutableArray<DocumentLocation> sourceLocations,
+                bool displayIfNoReferences)
                 : base(tags, displayParts, 
-                      ImmutableArray.Create(new TaggedText(TextTags.Text, location.Document.Project.Name)),
-                      additionalLocations, displayIfNoReferences)
+                      ImmutableArray.Create(new TaggedText(TextTags.Text, sourceLocations[0].Document.Project.Name)),
+                      sourceLocations, displayIfNoReferences)
             {
-                Location = location;
             }
 
-            public override bool CanNavigateTo() => Location.CanNavigateTo();
-            public override bool TryNavigateTo() => Location.TryNavigateTo();
+            public override bool CanNavigateTo() => SourceLocations[0].CanNavigateTo();
+            public override bool TryNavigateTo() => SourceLocations[0].TryNavigateTo();
         }
     }
 }
\ No newline at end of file

src/Features/Core/Portable/FindReferences/DefinitionItem.cs

 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
+using System;
 using System.Collections.Immutable;
 using Microsoft.CodeAnalysis.Completion;
 
@@ -38,7 +39,7 @@ internal abstract partial class DefinitionItem
         /// Additional locations to present in the UI.  A definition may have multiple locations 
         /// for cases like partial types/members.
         /// </summary>
-        public ImmutableArray<DocumentLocation> AdditionalLocations { get; }
+        public ImmutableArray<DocumentLocation> SourceLocations { get; }
 
         /// <summary>
         /// Whether or not this definition should be presented if we never found any references to
@@ -58,13 +59,13 @@ internal abstract partial class DefinitionItem
             ImmutableArray<string> tags,
             ImmutableArray<TaggedText> displayParts,
             ImmutableArray<TaggedText> originationParts = default(ImmutableArray<TaggedText>),
-            ImmutableArray<DocumentLocation> additionalLocations = default(ImmutableArray<DocumentLocation>),
+            ImmutableArray<DocumentLocation> sourceLocations = default(ImmutableArray<DocumentLocation>),
             bool displayIfNoReferences = true)
         {
             Tags = tags;
             DisplayParts = displayParts;
             OriginationParts = originationParts.NullToEmpty();
-            AdditionalLocations = additionalLocations.NullToEmpty();
+            SourceLocations = sourceLocations.NullToEmpty();
             DisplayIfNoReferences = displayIfNoReferences;
         }
 
@@ -74,12 +75,25 @@ internal abstract partial class DefinitionItem
         public static DefinitionItem Create(
             ImmutableArray<string> tags,
             ImmutableArray<TaggedText> displayParts,
-            DocumentLocation location,
-            ImmutableArray<DocumentLocation> additionalLocations = default(ImmutableArray<DocumentLocation>),
+            DocumentLocation sourceLocation,
             bool displayIfNoReferences = true)
         {
+            return Create(tags, displayParts, ImmutableArray.Create(sourceLocation), displayIfNoReferences);
+        }
+
+        public static DefinitionItem Create(
+           ImmutableArray<string> tags,
+           ImmutableArray<TaggedText> displayParts,
+           ImmutableArray<DocumentLocation> sourceLocations,
+           bool displayIfNoReferences = true)
+        {
+            if (sourceLocations.Length == 0)
+            {
+                throw new ArgumentException($"{nameof(sourceLocations)} cannot be empty.");
+            }
+
             return new DocumentLocationDefinitionItem(
-                tags, displayParts, additionalLocations, displayIfNoReferences, location);
+                tags, displayParts, sourceLocations, displayIfNoReferences);
         }
 
         internal static DefinitionItem CreateMetadataDefinition(

src/Features/Core/Portable/FindReferences/IDefinitionsAndReferencesFactory.cs

@@ -154,8 +154,7 @@ internal static class DefinitionItemExtensions
             var tags = GlyphTags.GetTags(definition.GetGlyph());
             var displayIfNoReferences = definition.ShouldShowWithNoReferenceLocations();
 
-            var additionalLocations = ImmutableArray.CreateBuilder<DocumentLocation>();
-            DocumentLocation? mainLocation = null;
+            var sourceLocations = ImmutableArray.CreateBuilder<DocumentLocation>();
 
             // If it's a namespace, don't create any normal lcoation.  Namespaces
             // come from many different sources, but we'll only show a single 
@@ -175,16 +174,16 @@ internal static class DefinitionItemExtensions
                         if (document != null)
                         {
                             var documentLocation = new DocumentLocation(document, location.SourceSpan);
-                            if (mainLocation == null)
+                            if (sourceLocations.Count == 0)
                             {
-                                mainLocation = documentLocation;
+                                sourceLocations.Add(documentLocation);
                             }
                             else
                             {
                                 if (uniqueLocations == null ||
                                     uniqueLocations.Add(documentLocation))
                                 {
-                                    additionalLocations.Add(documentLocation);
+                                    sourceLocations.Add(documentLocation);
                                 }
                             }
                         }
@@ -192,7 +191,7 @@ internal static class DefinitionItemExtensions
                 }
             }
 
-            if (mainLocation == null)
+            if (sourceLocations.Count == 0)
             {
                 // If we got no definition locations, then create a sentinel one
                 // that we can display but which will not allow navigation.
@@ -203,8 +202,7 @@ internal static class DefinitionItemExtensions
             }
 
             return DefinitionItem.Create(
-                tags, displayParts, mainLocation.Value,
-                additionalLocations.ToImmutable(), displayIfNoReferences);
+                tags, displayParts, sourceLocations.ToImmutable(), displayIfNoReferences);
         }
 
         public static SourceReferenceItem TryCreateSourceReferenceItem(

src/VisualStudio/Core/Def/Implementation/Library/FindResults/LibraryManager_FindReferences.cs

@@ -26,10 +26,12 @@ public void PresentDefinitionsAndReferences(DefinitionsAndReferences definitions
             DefinitionsAndReferences definitionsAndReferences)
         {
             var definitionDocuments =
-                definitionsAndReferences.Definitions.SelectMany(d => d.AdditionalLocations)
+                definitionsAndReferences.Definitions.SelectMany(d => d.SourceLocations)
                                         .Select(loc => loc.Document);
 
-            var referenceDocuments = definitionsAndReferences.References.Select(r => r.Location.Document);
+            var referenceDocuments = 
+                definitionsAndReferences.References
+                                        .Select(r => r.Location.Document);
 
             var allDocuments = definitionDocuments.Concat(referenceDocuments).WhereNotNull().ToSet();
             var commonPathElements = CountCommonPathElements(allDocuments);
@@ -51,8 +53,9 @@ public void PresentDefinitionsAndReferences(DefinitionsAndReferences definitions
 
             var definitionGlyph = definitionItem.Tags.GetGlyph();
 
+            // Skip the first definition.  We'll present it in the definition item.
             var definitionLocationsAndGlyphs =
-                from loc in definitionItem.AdditionalLocations
+                from loc in definitionItem.SourceLocations.Skip(1)
                 select ValueTuple.Create(loc, definitionGlyph);
 
             var referenceLocationsAndGlyphs =