Make Razor a built in feature of the Roslyn language server

src/LanguageServer/Microsoft.CodeAnalysis.LanguageServer.UnitTests/Utilities/LanguageServerTestComposition.cs

@@ -24,7 +24,6 @@ internal sealed class LanguageServerTestComposition
             SessionId: null,
             ExtensionAssemblyPaths: extensionPaths ?? [],
             DevKitDependencyPath: devKitDependencyPath,
-            RazorDesignTimePath: null,
             CSharpDesignTimePath: null,
             ExtensionLogDirectory: string.Empty,
             ServerPipeName: null,

src/LanguageServer/Microsoft.CodeAnalysis.LanguageServer/HostWorkspace/LanguageServerProjectLoader.cs

@@ -22,6 +22,8 @@ namespace Microsoft.CodeAnalysis.LanguageServer.HostWorkspace;
 
 internal abstract class LanguageServerProjectLoader
 {
+    private static readonly string s_razorDesignTimePath = Path.Combine(AppContext.BaseDirectory, "Targets", "Microsoft.NET.Sdk.Razor.DesignTime.targets");
+
     private readonly AsyncBatchingWorkQueue<ProjectToLoad> _projectsToReload;
 
     protected readonly LanguageServerWorkspaceFactory _workspaceFactory;
@@ -126,10 +128,7 @@ private static ImmutableDictionary<string, string> BuildAdditionalProperties(Ser
             return properties;
         }
 
-        if (serverConfiguration.RazorDesignTimePath is { } razorDesignTimePath)
-        {
-            properties = properties.Add("RazorDesignTimeTargets", razorDesignTimePath);
-        }
+        properties = properties.Add("RazorDesignTimeTargets", s_razorDesignTimePath);
 
         if (serverConfiguration.CSharpDesignTimePath is { } csharpDesignTimePath)
         {

src/LanguageServer/Microsoft.CodeAnalysis.LanguageServer/LanguageServerExportProviderBuilder.cs

@@ -2,6 +2,7 @@
 // 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.Collections.Frozen;
 using System.Collections.Immutable;
 using Microsoft.CodeAnalysis.LanguageServer.Logging;
 using Microsoft.CodeAnalysis.LanguageServer.Services;
@@ -19,6 +20,17 @@ internal sealed class LanguageServerExportProviderBuilder : ExportProviderBuilde
     // For testing purposes, track the last cache write task.
     private static Task? s_cacheWriteTask_forTestingPurposesOnly;
 
+    private static readonly FrozenSet<string> s_dllsToExcludeFromMef =
+    [
+        // These DLLs are part of Razor, but should only be in their MEF composition not ours
+        "Microsoft.CodeAnalysis.Razor.Workspaces.dll",
+        "Microsoft.CodeAnalysis.Remote.Razor.dll",
+
+        // This is a runtime dependency of Remote.Razor, but its host-layer exports belong to the remote host
+        // composition and conflict with the language server's workspace services if included here.
+        "Microsoft.CodeAnalysis.Remote.ServiceHub.dll",
+    ];
+
     private LanguageServerExportProviderBuilder(
         ImmutableArray<string> assemblyPaths,
         Resolver resolver,
@@ -39,13 +51,16 @@ public static async Task<ExportProvider> CreateExportProviderAsync(
         ILoggerFactory loggerFactory,
         CancellationToken cancellationToken)
     {
-        // Load any Roslyn assemblies from the extension directory
+        // Load Roslyn assemblies from the language server directory.
         using var _ = ArrayBuilder<string>.GetInstance(out var assemblyPathsBuilder);
 
         // Don't catch IO exceptions as it's better to fail to build the catalog than give back
         // a partial catalog that will surely blow up later.
-        assemblyPathsBuilder.AddRange(Directory.EnumerateFiles(baseDirectory, "Microsoft.CodeAnalysis*.dll"));
-        assemblyPathsBuilder.AddRange(Directory.EnumerateFiles(baseDirectory, "Microsoft.ServiceHub*.dll"));
+        assemblyPathsBuilder.AddRange(FilterFiles(baseDirectory, "Microsoft.CodeAnalysis*.dll"));
+        assemblyPathsBuilder.AddRange(FilterFiles(baseDirectory, "Microsoft.ServiceHub*.dll"));
+
+        // The Razor extension ships with Roslyn and so needs to be in our MEF composition
+        assemblyPathsBuilder.Add(Path.Combine(baseDirectory, "Microsoft.VisualStudioCode.RazorExtension.dll"));
 
         // DevKit assemblies are not shipped in the main language server folder
         // and not included in ExtensionAssemblyPaths (they get loaded into the default ALC).
@@ -74,6 +89,15 @@ public static async Task<ExportProvider> CreateExportProviderAsync(
         return exportProvider;
     }
 
+    private static IEnumerable<string> FilterFiles(string baseDirectory, string filter)
+    {
+        foreach (var file in Directory.EnumerateFiles(baseDirectory, filter))
+        {
+            if (!s_dllsToExcludeFromMef.Contains(Path.GetFileName(file)))
+                yield return file;
+        }
+    }
+
     protected override void LogError(string message, Exception exception)
         => _logger.LogError(exception, message);
 

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

@@ -83,6 +83,8 @@
     <ProjectReference Include="..\ExternalAccess\CompilerDeveloperSDK\Microsoft.CodeAnalysis.ExternalAccess.CompilerDeveloperSDK.csproj" />
     <ProjectReference Include="..\ExternalAccess\Copilot\Microsoft.CodeAnalysis.LanguageServer.ExternalAccess.Copilot.csproj" />
     <ProjectReference Include="..\..\Tools\ExternalAccess\Razor\Features\Microsoft.CodeAnalysis.ExternalAccess.Razor.Features.csproj" />
+    <!-- Ship the VS Code Razor entrypoint as a real runtime dependency so it participates in the server deps.json. -->
+    <ProjectReference Include="..\..\Razor\src\Razor\src\Microsoft.VisualStudioCode.RazorExtension\Microsoft.VisualStudioCode.RazorExtension.csproj" />
   </ItemGroup>
 
   <ItemGroup>