Add support for implementation edges

Fixes dotnet#59617

src/Features/Lsif/Generator/Generator.cs

@@ -14,6 +14,7 @@
 using Microsoft.CodeAnalysis.LanguageServerIndexFormat.Generator.ResultSetTracking;
 using Microsoft.CodeAnalysis.LanguageServerIndexFormat.Generator.Writing;
 using Microsoft.CodeAnalysis.LanguageService;
+using Microsoft.CodeAnalysis.Shared.Extensions;
 using Roslyn.Utilities;
 using Methods = Microsoft.VisualStudio.LanguageServer.Protocol.Methods;
 
@@ -228,6 +229,29 @@ SymbolKind.RangeVariable or
                     {
                         var definitionResultsId = symbolResultsTracker.GetResultIdForSymbol(declaredSymbol, Methods.TextDocumentDefinitionName, () => new DefinitionResult(idFactory));
                         lsifJsonWriter.Write(new Item(definitionResultsId.As<DefinitionResult, Vertex>(), lazyRangeVertex.Value.GetId(), documentVertex.GetId(), idFactory));
+
+                        // If this declared symbol also implements an interface member, we count this as a definition of the interface member as well.
+                        // Note in C# there are estoeric cases where a method can implement an interface member even though the containing type does not
+                        // implement the interface, for example in this case:
+                        //
+                        //     interface I { void M(); }
+                        //     class Base { public void M() { } }
+                        //     class Derived : Base, I { }
+                        //
+                        // We don't worry about supporting these cases here.
+                        var implementedMembers = declaredSymbol.ExplicitOrImplicitInterfaceImplementations();
+
+                        foreach (var implementedMember in implementedMembers)
+                        {
+                            // First we create a definition link for the reference results for the interface method
+                            var referenceResultsId = symbolResultsTracker.GetResultSetReferenceResultId(implementedMember.OriginalDefinition, idFactory);
+                            lsifJsonWriter.Write(new Item(referenceResultsId.As<ReferenceResult, Vertex>(), lazyRangeVertex.Value.GetId(), documentVertex.GetId(), idFactory, property: "definitions"));
+
+                            // Then also link the result set for the method to the moniker that it implements
+                            referenceResultsId = symbolResultsTracker.GetResultSetReferenceResultId(declaredSymbol.OriginalDefinition, idFactory);
+                            var implementedMemberMoniker = symbolResultsTracker.GetResultIdForSymbol<Moniker>(implementedMember.OriginalDefinition, "moniker", () => throw new Exception("When we produced the resultSet, we should have already created a moniker for it."));
+                            lsifJsonWriter.Write(new Item(referenceResultsId.As<ReferenceResult, Vertex>(), implementedMemberMoniker, documentVertex.GetId(), idFactory, property: "referenceLinks"));
+                        }
                     }
 
                     if (referencedSymbol != null)
@@ -236,7 +260,7 @@ SymbolKind.RangeVariable or
                         // symbol but the range can point a different symbol's resultSet. This can happen if the token is
                         // both a definition of a symbol (where we will point to the definition) but also a reference to some
                         // other symbol.
-                        var referenceResultsId = symbolResultsTracker.GetResultIdForSymbol(referencedSymbol.OriginalDefinition, Methods.TextDocumentReferencesName, () => new ReferenceResult(idFactory));
+                        var referenceResultsId = symbolResultsTracker.GetResultSetReferenceResultId(referencedSymbol.OriginalDefinition, idFactory);
                         lsifJsonWriter.Write(new Item(referenceResultsId.As<ReferenceResult, Vertex>(), lazyRangeVertex.Value.GetId(), documentVertex.GetId(), idFactory, property: "references"));
                     }
 

src/Features/Lsif/Generator/Graph/Item.cs

@@ -5,7 +5,7 @@
 namespace Microsoft.CodeAnalysis.LanguageServerIndexFormat.Generator.Graph
 {
     /// <summary>
-    /// Represents a single item that points to a range from a result. See https://github.com/Microsoft/language-server-protocol/blob/master/indexFormat/specification.md#request-textdocumentreferences
+    /// Represents a single item that points to a range or moniker from a result. See https://github.com/Microsoft/language-server-protocol/blob/master/indexFormat/specification.md#request-textdocumentreferences
     /// for an example of item edges.
     /// </summary>
     internal sealed class Item : Edge
@@ -19,5 +19,12 @@ public Item(Id<Vertex> outVertex, Id<Range> range, Id<LsifDocument> document, Id
             Document = document;
             Property = property;
         }
+
+        public Item(Id<Vertex> outVertex, Id<Moniker> moniker, Id<LsifDocument> document, IdFactory idFactory, string? property = null)
+            : base(label: "item", outVertex, new[] { moniker.As<Moniker, Vertex>() }, idFactory)
+        {
+            Document = document;
+            Property = property;
+        }
     }
 }

src/Features/Lsif/Generator/ResultSetTracking/IResultSetTrackerExtensions.cs

@@ -0,0 +1,23 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.CodeAnalysis.LanguageServerIndexFormat.Generator.Graph;
+using Microsoft.VisualStudio.LanguageServer.Protocol;
+
+namespace Microsoft.CodeAnalysis.LanguageServerIndexFormat.Generator.ResultSetTracking
+{
+    internal static class IResultSetTrackerExtensions
+    {
+        /// <summary>
+        /// Returns the ID of the <see cref="ReferenceResult"/> for a <see cref="ResultSet"/>.
+        /// </summary>
+        public static Id<ReferenceResult> GetResultSetReferenceResultId(this IResultSetTracker tracker, ISymbol symbol, IdFactory idFactory)
+            => tracker.GetResultIdForSymbol(symbol, Methods.TextDocumentReferencesName, () => new ReferenceResult(idFactory));
+    }
+}

src/Features/Lsif/Generator/ResultSetTracking/SymbolHoldingResultSetTracker.cs

@@ -80,8 +80,8 @@ private TrackedResultSet GetTrackedResultSet(ISymbol symbol)
 
                 if (monikerVertex != null)
                 {
-                    _lsifJsonWriter.Write(monikerVertex);
-                    _lsifJsonWriter.Write(Edge.Create("moniker", trackedResultSet.Id, monikerVertex.GetId(), _idFactory));
+                    // Attach the moniker vertex for this result set
+                    _ = GetResultIdForSymbol(symbol, "moniker", () => monikerVertex);
                 }
             }
 
@@ -157,15 +157,15 @@ public TrackedResultSet(Id<ResultSet> id)
                 Id = id;
             }
 
-            public Id<T> GetResultId<T>(string edgeKind, Func<T> vertexCreator, ILsifJsonWriter lsifJsonWriter, IdFactory idFactory) where T : Vertex
+            public Id<T> GetResultId<T>(string edgeLabel, Func<T> vertexCreator, ILsifJsonWriter lsifJsonWriter, IdFactory idFactory) where T : Vertex
             {
                 lock (_edgeKindToVertexId)
                 {
-                    if (_edgeKindToVertexId.TryGetValue(edgeKind, out var existingId))
+                    if (_edgeKindToVertexId.TryGetValue(edgeLabel, out var existingId))
                     {
                         if (!existingId.HasValue)
                         {
-                            throw new Exception($"This ResultSet already has an edge of {edgeKind} as {nameof(ResultSetNeedsInformationalEdgeAdded)} was called with this edge kind.");
+                            throw new Exception($"This ResultSet already has an edge of {edgeLabel} as {nameof(ResultSetNeedsInformationalEdgeAdded)} was called with this edge label.");
                         }
 
                         // TODO: this is a violation of the type system here, really: we're assuming that all calls to this function with the same edge kind
@@ -174,10 +174,10 @@ public Id<T> GetResultId<T>(string edgeKind, Func<T> vertexCreator, ILsifJsonWri
                     }
 
                     var vertex = vertexCreator();
-                    _edgeKindToVertexId.Add(edgeKind, vertex.GetId().As<T, Vertex>());
+                    _edgeKindToVertexId.Add(edgeLabel, vertex.GetId().As<T, Vertex>());
 
                     lsifJsonWriter.Write(vertex);
-                    lsifJsonWriter.Write(Edge.Create(edgeKind, Id, vertex.GetId(), idFactory));
+                    lsifJsonWriter.Write(Edge.Create(edgeLabel, Id, vertex.GetId(), idFactory));
 
                     return vertex.GetId();
                 }