Expose inlay hints to Razor cohosting

src/LanguageServer/Protocol/Handler/InlayHint/InlayHintHandler.cs

@@ -38,18 +38,24 @@ public InlayHintHandler(IGlobalOptionService optionsService)
         public TextDocumentIdentifier GetTextDocumentIdentifier(InlayHintParams request)
             => request.TextDocument;
 
-        public async Task<LSP.InlayHint[]?> HandleRequestAsync(InlayHintParams request, RequestContext context, CancellationToken cancellationToken)
+        public Task<LSP.InlayHint[]?> HandleRequestAsync(InlayHintParams request, RequestContext context, CancellationToken cancellationToken)
         {
             var document = context.GetRequiredDocument();
+            var inlayHintCache = context.GetRequiredLspService<InlayHintCache>();
+            var options = _optionsService.GetInlineHintsOptions(document.Project.Language);
+
+            return GetInlayHintsAsync(document, request.TextDocument, request.Range, options, displayAllOverride: false, inlayHintCache, cancellationToken);
+        }
+
+        internal static async Task<LSP.InlayHint[]?> GetInlayHintsAsync(Document document, TextDocumentIdentifier textDocumentIdentifier, LSP.Range range, InlineHintsOptions options, bool displayAllOverride, InlayHintCache inlayHintCache, CancellationToken cancellationToken)
+        {
             var text = await document.GetValueTextAsync(cancellationToken).ConfigureAwait(false);
-            var textSpan = ProtocolConversions.RangeToTextSpan(request.Range, text);
+            var textSpan = ProtocolConversions.RangeToTextSpan(range, text);
 
             var inlineHintService = document.GetRequiredLanguageService<IInlineHintsService>();
-            var options = _optionsService.GetInlineHintsOptions(document.Project.Language);
-            var hints = await inlineHintService.GetInlineHintsAsync(document, textSpan, options, displayAllOverride: false, cancellationToken).ConfigureAwait(false);
+            var hints = await inlineHintService.GetInlineHintsAsync(document, textSpan, options, displayAllOverride, cancellationToken).ConfigureAwait(false);
 
             var syntaxVersion = await document.GetSyntaxVersionAsync(cancellationToken).ConfigureAwait(false);
-            var inlayHintCache = context.GetRequiredLspService<InlayHintCache>();
 
             // Store the members in the resolve cache so that when we get a resolve request for a particular
             // member we can re-use the inline hint.
@@ -83,7 +89,7 @@ public TextDocumentIdentifier GetTextDocumentIdentifier(InlayHintParams request)
                     ToolTip = null,
                     PaddingLeft = leftPadding,
                     PaddingRight = rightPadding,
-                    Data = new InlayHintResolveData(resultId, i, request.TextDocument)
+                    Data = new InlayHintResolveData(resultId, i, textDocumentIdentifier)
                 };
 
                 inlayHints[i] = inlayHint;

src/LanguageServer/Protocol/Handler/InlayHint/InlayHintResolveHandler.cs

@@ -2,14 +2,14 @@
 // 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.Text.Json;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.InlineHints;
 using Roslyn.LanguageServer.Protocol;
 using Roslyn.Utilities;
 using StreamJsonRpc;
 using LSP = Roslyn.LanguageServer.Protocol;
-using System.Text.Json;
 
 namespace Microsoft.CodeAnalysis.LanguageServer.Handler.InlayHint
 {
@@ -30,11 +30,16 @@ public InlayHintResolveHandler(InlayHintCache inlayHintCache)
         public TextDocumentIdentifier GetTextDocumentIdentifier(LSP.InlayHint request)
             => GetInlayHintResolveData(request).TextDocument;
 
-        public async Task<LSP.InlayHint> HandleRequestAsync(LSP.InlayHint request, RequestContext context, CancellationToken cancellationToken)
+        public Task<LSP.InlayHint> HandleRequestAsync(LSP.InlayHint request, RequestContext context, CancellationToken cancellationToken)
         {
             var document = context.GetRequiredDocument();
+            return ResolveInlayHintAsync(document, request, _inlayHintCache, cancellationToken);
+        }
+
+        internal static async Task<LSP.InlayHint> ResolveInlayHintAsync(Document document, LSP.InlayHint request, InlayHintCache inlayHintCache, CancellationToken cancellationToken)
+        {
             var resolveData = GetInlayHintResolveData(request);
-            var (cacheEntry, inlineHintToResolve) = GetCacheEntry(resolveData);
+            var (cacheEntry, inlineHintToResolve) = GetCacheEntry(resolveData, inlayHintCache);
 
             var currentSyntaxVersion = await document.GetSyntaxVersionAsync(cancellationToken).ConfigureAwait(false);
             var cachedSyntaxVersion = cacheEntry.SyntaxVersion;
@@ -53,9 +58,9 @@ public TextDocumentIdentifier GetTextDocumentIdentifier(LSP.InlayHint request)
             return request;
         }
 
-        private (InlayHintCache.InlayHintCacheEntry CacheEntry, InlineHint InlineHintToResolve) GetCacheEntry(InlayHintResolveData resolveData)
+        private static (InlayHintCache.InlayHintCacheEntry CacheEntry, InlineHint InlineHintToResolve) GetCacheEntry(InlayHintResolveData resolveData, InlayHintCache inlayHintCache)
         {
-            var cacheEntry = _inlayHintCache.GetCachedEntry(resolveData.ResultId);
+            var cacheEntry = inlayHintCache.GetCachedEntry(resolveData.ResultId);
             Contract.ThrowIfNull(cacheEntry, "Missing cache entry for inlay hint resolve request");
             return (cacheEntry, cacheEntry.InlayHintMembers[resolveData.ListIndex]);
         }

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

@@ -37,9 +37,12 @@
     <!-- 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="$(RazorKey)" />
     <RestrictedInternalsVisibleTo Include="Microsoft.CodeAnalysis.Razor.Workspaces" Namespace="Roslyn.LanguageServer.Protocol" Partner="Razor" Key="$(RazorKey)" />
+    <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)" />
+    <!-- Restricted IVT for protocol types for Razor tests -->
+    <RestrictedInternalsVisibleTo Include="Microsoft.VisualStudio.LanguageServices.Razor.Test" Namespace="Roslyn.LanguageServer.Protocol" Partner="Razor" Key="$(RazorKey)" />
+    <!-- Full IVT is through ExternalAccess for functionality -->
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.ExternalAccess.Xaml" />
     <!-- Restricted IVT is direct for protocol types only -->
     <RestrictedInternalsVisibleTo Include="Microsoft.VisualStudio.DesignTools.CodeAnalysis" Namespace="Roslyn.LanguageServer.Protocol" Partner="Xaml" Key="$(VisualStudioKey)" />

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

@@ -0,0 +1,49 @@
+// 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.Threading;
+using System.Threading.Tasks;
+using Microsoft.CodeAnalysis.InlineHints;
+using Microsoft.CodeAnalysis.LanguageServer.Handler.InlayHint;
+using Roslyn.LanguageServer.Protocol;
+using Roslyn.Utilities;
+
+namespace Microsoft.CodeAnalysis.ExternalAccess.Razor.Cohost.Handlers
+{
+    internal static class InlayHints
+    {
+        // In the Roslyn LSP server this cache has the same lifetime as the LSP server. For Razor, running OOP, we don't have
+        // that same lifetime anywhere, everything is just static. This is likely not ideal, but the inlay hint cache has a
+        // max size of 3 items, so it's not a huge deal.
+        private static InlayHintCache? s_resolveCache;
+
+        public static Task<InlayHint[]?> GetInlayHintsAsync(Document document, TextDocumentIdentifier textDocumentIdentifier, Range range, bool displayAllOverride, CancellationToken cancellationToken)
+        {
+            s_resolveCache ??= new();
+
+            // Currently Roslyn options don't sync to OOP so trying to get the real options out of IGlobalOptionsService will
+            // always just result in the defaults, which for inline hints are to not show anything. However, the editor has a
+            // setting for LSP inlay hints, so we can assume that if we get a request from the client, the user wants hints.
+            // When overriding however, Roslyn does a nicer job if type hints are off.
+            var options = InlineHintsOptions.Default;
+            if (!displayAllOverride)
+            {
+                options = options with
+                {
+                    TypeOptions = options.TypeOptions with { EnabledForTypes = true },
+                    ParameterOptions = options.ParameterOptions with { EnabledForParameters = true },
+                };
+            }
+
+            return InlayHintHandler.GetInlayHintsAsync(document, textDocumentIdentifier, range, options, displayAllOverride, s_resolveCache, cancellationToken);
+        }
+
+        public static Task<InlayHint> ResolveInlayHintAsync(Document document, InlayHint request, CancellationToken cancellationToken)
+        {
+            Contract.ThrowIfNull(s_resolveCache, "Cache should never be null for resolve, since it should have been created by the original request");
+
+            return InlayHintResolveHandler.ResolveInlayHintAsync(document, request, s_resolveCache, cancellationToken);
+        }
+    }
+}

src/Tools/ExternalAccess/Razor/Microsoft.CodeAnalysis.ExternalAccess.Razor.csproj

@@ -31,6 +31,7 @@
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.Razor.Workspaces" Key="$(RazorKey)" />
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.Razor.Workspaces.Test" Key="$(RazorKey)" />
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.Remote.Razor" Key="$(RazorKey)" />
+    <InternalsVisibleTo Include="Microsoft.CodeAnalysis.Remote.Razor.Test" Key="$(RazorKey)" />
     <InternalsVisibleTo Include="Microsoft.VisualStudio.Editor.Razor" Key="$(RazorKey)" />
     <InternalsVisibleTo Include="Microsoft.VisualStudio.LanguageServerClient.Razor" Key="$(RazorKey)" />
     <InternalsVisibleTo Include="Microsoft.VisualStudio.LanguageServerClient.Razor.Test" Key="$(RazorKey)" />