Expose folding range functionality to Razor

src/Features/LanguageServer/Protocol/Handler/FoldingRanges/FoldingRangesHandler.cs

@@ -14,6 +14,7 @@
 using Microsoft.CodeAnalysis.Structure;
 using Microsoft.CodeAnalysis.Text;
 using Roslyn.LanguageServer.Protocol;
+using Roslyn.Utilities;
 
 namespace Microsoft.CodeAnalysis.LanguageServer.Handler
 {
@@ -35,13 +36,21 @@ public FoldingRangesHandler(IGlobalOptionService globalOptions)
 
         public TextDocumentIdentifier GetTextDocumentIdentifier(FoldingRangeParams request) => request.TextDocument;
 
-        public async Task<FoldingRange[]?> HandleRequestAsync(FoldingRangeParams request, RequestContext context, CancellationToken cancellationToken)
+        public Task<FoldingRange[]?> HandleRequestAsync(FoldingRangeParams request, RequestContext context, CancellationToken cancellationToken)
         {
             var document = context.Document;
             if (document is null)
-                return null;
+                return SpecializedTasks.Null<FoldingRange[]>();
 
-            var options = _globalOptions.GetBlockStructureOptions(document.Project) with
+            return SpecializedTasks.AsNullable(GetFoldingRangesAsync(_globalOptions, document, cancellationToken));
+        }
+
+        internal static Task<FoldingRange[]> GetFoldingRangesAsync(
+            IGlobalOptionService globalOptions,
+            Document document,
+            CancellationToken cancellationToken)
+        {
+            var options = globalOptions.GetBlockStructureOptions(document.Project) with
             {
                 // Need to set the block structure guide options to true since the concept does not exist in vscode
                 // but we still want to categorize them as the correct BlockType.
@@ -50,7 +59,7 @@ public FoldingRangesHandler(IGlobalOptionService globalOptions)
                 ShowBlockStructureGuidesForCodeLevelConstructs = true
             };
 
-            return await GetFoldingRangesAsync(document, options, cancellationToken).ConfigureAwait(false);
+            return GetFoldingRangesAsync(document, options, cancellationToken);
         }
 
         /// <summary>

src/Features/LanguageServer/Protocol/Microsoft.CodeAnalysis.LanguageServer.Protocol.csproj

@@ -34,7 +34,11 @@
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.EditorFeatures2.UnitTests" />
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.ExternalAccess.AspNetCore" />
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.ExternalAccess.FSharp" />
+    <!-- Full IVT is through ExternalAccess for functionality -->
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.ExternalAccess.Razor" />
+    <!-- Restricted IVT is direct for protocol types only -->
+    <RestrictedInternalsVisibleTo Include="Microsoft.CodeAnalysis.Remote.Razor" Namespace="Roslyn.LanguageServer.Protocol" Partner="Razor" Key="$(RazorKey)" />
+    <RestrictedInternalsVisibleTo Include="Microsoft.VisualStudio.LanguageServices.Razor" Namespace="Roslyn.LanguageServer.Protocol" Partner="Razor" Key="$(RazorKey)" />
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.ExternalAccess.Xaml" />
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.CSharp.EditorFeatures" />
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.CSharp.Features.UnitTests" />

src/Tools/ExternalAccess/Razor/Cohost/Handlers/FoldingRanges.cs

@@ -0,0 +1,25 @@
+// 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.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.CodeAnalysis.LanguageServer.Handler;
+using Microsoft.CodeAnalysis.Options;
+using Roslyn.LanguageServer.Protocol;
+
+namespace Microsoft.CodeAnalysis.ExternalAccess.Razor.Cohost.Handlers
+{
+    internal static class FoldingRanges
+    {
+        public static Task<FoldingRange[]> GetFoldingRangesAsync(Document document, CancellationToken cancellationToken)
+        {
+            // We need to manually get the IGlobalOptionsService out of the Mef composition, because Razor has its own
+            // composition so can't import it (and its internal anyway)
+            var globalOptions = document.Project.Solution.Services.ExportProvider.GetExports<IGlobalOptionService>().First().Value;
+
+            return FoldingRangesHandler.GetFoldingRangesAsync(globalOptions, document, cancellationToken);
+        }
+    }
+}

src/Tools/ExternalAccess/Razor/RazorLanguageServerFactoryWrapper.cs

@@ -67,7 +67,7 @@ internal override DocumentInfo CreateDocumentInfo(
 
         internal override void AddJsonConverters(JsonSerializerOptions options)
         {
-            VSInternalExtensionUtilities.AddVSInternalExtensionConverters(options);
+            ProtocolConversions.AddLspSerializerOptions(options);
         }
 
         private class RazorCapabilitiesProvider : ICapabilitiesProvider