Fix issues with VSCode LSP EA causing handlers to fail to load

src/LanguageServer/Microsoft.CodeAnalysis.LanguageServer/ExportProviderBuilder.cs

@@ -57,7 +57,7 @@ public static async Task<ExportProvider> CreateExportProviderAsync(
         var config = CompositionConfiguration.Create(catalog);
 
         // Verify we only have expected errors.
-        ThrowOnUnexpectedErrors(config, logger);
+        ThrowOnUnexpectedErrors(config, catalog, logger);
 
         // Prepare an ExportProvider factory based on this graph.
         var exportProviderFactory = config.CreateExportProviderFactory();
@@ -75,7 +75,7 @@ public static async Task<ExportProvider> CreateExportProviderAsync(
         return exportProvider;
     }
 
-    private static void ThrowOnUnexpectedErrors(CompositionConfiguration configuration, ILogger logger)
+    private static void ThrowOnUnexpectedErrors(CompositionConfiguration configuration, ComposableCatalog catalog, ILogger logger)
     {
         // Verify that we have exactly the MEF errors that we expect.  If we have less or more this needs to be updated to assert the expected behavior.
         // Currently we are expecting the following:
@@ -87,15 +87,16 @@ private static void ThrowOnUnexpectedErrors(CompositionConfiguration configurati
         //         part definition Microsoft.CodeAnalysis.ExternalAccess.Pythia.PythiaSignatureHelpProvider
         var erroredParts = configuration.CompositionErrors.FirstOrDefault()?.SelectMany(error => error.Parts).Select(part => part.Definition.Type.Name) ?? Enumerable.Empty<string>();
         var expectedErroredParts = new string[] { "PythiaSignatureHelpProvider" };
-        if (erroredParts.Count() != expectedErroredParts.Length || !erroredParts.All(part => expectedErroredParts.Contains(part)))
+        if (erroredParts.Count() != expectedErroredParts.Length || !erroredParts.All(part => expectedErroredParts.Contains(part)) || !catalog.DiscoveredParts.DiscoveryErrors.IsEmpty)
         {
             try
             {
+                catalog.DiscoveredParts.ThrowOnErrors();
                 configuration.ThrowOnErrors();
             }
             catch (CompositionFailedException ex)
             {
-                // The ToString for the composition failed exception doesn't output a nice set of errors by default, so log it separately here.
+                // The ToString for the composition failed exception doesn't output a nice set of errors by default, so log it separately
                 logger.LogError($"Encountered errors in the MEF composition:{Environment.NewLine}{ex.ErrorsAsString}");
                 throw;
             }

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

@@ -78,6 +78,7 @@
     <ProjectReference Include="..\..\Features\ExternalAccess\AspNetCore\Microsoft.CodeAnalysis.ExternalAccess.AspNetCore.csproj" />
     <ProjectReference Include="..\ExternalAccess\VisualDiagnostics\Microsoft.CodeAnalysis.ExternalAccess.VisualDiagnostics.csproj" />
     <ProjectReference Include="..\..\Tools\ExternalAccess\Xaml\Microsoft.CodeAnalysis.ExternalAccess.Xaml.csproj" />
+    <ProjectReference Include="..\ExternalAccess\CompilerDeveloperSDK\Microsoft.CodeAnalysis.ExternalAccess.CompilerDeveloperSDK.csproj" />
   </ItemGroup>
 
   <ItemGroup>

src/Tools/ExternalAccess/Xaml/External/ExportXamlLspServiceFactoryAttribute.cs

@@ -14,8 +14,14 @@ namespace Microsoft.CodeAnalysis.ExternalAccess.Xaml;
 [AttributeUsage(AttributeTargets.Class, AllowMultiple = false), MetadataAttribute]
 internal sealed class ExportXamlLspServiceFactoryAttribute : ExportLspServiceFactoryAttribute
 {
-    public ExportXamlLspServiceFactoryAttribute(Type type, WellKnownLspServerKinds serverKind = WellKnownLspServerKinds.Any)
+    [Obsolete("Use the constructor that takes only a type")]
+    public ExportXamlLspServiceFactoryAttribute(Type type, WellKnownLspServerKinds serverKind)
         : base(type, ProtocolConstants.RoslynLspLanguagesContract, serverKind)
     {
     }
+
+    public ExportXamlLspServiceFactoryAttribute(Type type)
+        : base(type, ProtocolConstants.RoslynLspLanguagesContract)
+    {
+    }
 }

src/Tools/ExternalAccess/Xaml/InternalAPI.Unshipped.txt

@@ -17,7 +17,8 @@ Microsoft.CodeAnalysis.ExternalAccess.Xaml.DescriptionService.DescriptionService
 Microsoft.CodeAnalysis.ExternalAccess.Xaml.DescriptionService.GetDescriptionAsync(Microsoft.CodeAnalysis.ISymbol! symbol, Microsoft.CodeAnalysis.Project! project, System.Threading.CancellationToken cancellationToken) -> System.Threading.Tasks.Task<System.Collections.Generic.IEnumerable<Microsoft.CodeAnalysis.TaggedText>!>!
 Microsoft.CodeAnalysis.ExternalAccess.Xaml.DescriptionService.GetMarkupContent(System.Collections.Immutable.ImmutableArray<Microsoft.CodeAnalysis.TaggedText> tags, string! language, bool featureSupportsMarkdown) -> (string! content, bool isMarkdown)
 Microsoft.CodeAnalysis.ExternalAccess.Xaml.ExportXamlLspServiceFactoryAttribute
-Microsoft.CodeAnalysis.ExternalAccess.Xaml.ExportXamlLspServiceFactoryAttribute.ExportXamlLspServiceFactoryAttribute(System.Type! type, Microsoft.CodeAnalysis.LanguageServer.WellKnownLspServerKinds serverKind = Microsoft.CodeAnalysis.LanguageServer.WellKnownLspServerKinds.Any) -> void
+Microsoft.CodeAnalysis.ExternalAccess.Xaml.ExportXamlLspServiceFactoryAttribute.ExportXamlLspServiceFactoryAttribute(System.Type! type) -> void
+Microsoft.CodeAnalysis.ExternalAccess.Xaml.ExportXamlLspServiceFactoryAttribute.ExportXamlLspServiceFactoryAttribute(System.Type! type, Microsoft.CodeAnalysis.LanguageServer.WellKnownLspServerKinds serverKind) -> void
 Microsoft.CodeAnalysis.ExternalAccess.Xaml.ExportXamlStatelessLspServiceAttribute
 Microsoft.CodeAnalysis.ExternalAccess.Xaml.ExportXamlStatelessLspServiceAttribute.ExportXamlStatelessLspServiceAttribute(System.Type! handlerType) -> void
 Microsoft.CodeAnalysis.ExternalAccess.Xaml.IClientCapabilityProvider