Merged PR 30060: Workaround runtime assembly loading bug

See dotnet/runtime#83526

MEF uses the APIs affected to load assemblies.  To workaround the issue we pre-load all the assemblies we're adding to the MEF composition

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

@@ -4,6 +4,7 @@
 
 using System.Collections.Immutable;
 using System.Reflection;
+using System.Runtime.Loader;
 using Microsoft.CodeAnalysis.LanguageServer.Logging;
 using Microsoft.Extensions.Logging;
 using Microsoft.VisualStudio.Composition;
@@ -20,6 +21,16 @@ public static async Task<ExportProvider> CreateExportProviderAsync()
         var assembliesToDiscover = Directory.EnumerateFiles(baseDirectory, "Microsoft.CodeAnalysis*.dll");
         assembliesToDiscover = assembliesToDiscover.Concat(Directory.EnumerateFiles(baseDirectory, "Microsoft.ServiceHub*.dll"));
 
+        // Temporarily explicitly load the dlls we want to add to the MEF composition.  This is due to a runtime bug
+        // in the 7.0.4 runtime where the APIs MEF uses to load assemblies break with R2R assemblies.
+        // See https://github.com/dotnet/runtime/issues/83526
+        //
+        // Once a newer version of the runtime is widely available, we can remove this.
+        foreach (var path in assembliesToDiscover)
+        {
+            Assembly.LoadFrom(path);
+        }
+
         var discovery = PartDiscovery.Combine(
             new AttributedPartDiscovery(Resolver.DefaultInstance, isNonPublicSupported: true), // "NuGet MEF" attributes (Microsoft.Composition)
             new AttributedPartDiscoveryV1(Resolver.DefaultInstance));

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

@@ -37,7 +37,7 @@
         <!-- List of runtime identifiers that we want to publish an executable for -->
         <RuntimeIdentifiers>win-x64;win-x86;win-arm64;linux-x64;linux-arm64;alpine-x64;alpine-arm64;osx-x64;osx-arm64</RuntimeIdentifiers> 
         <!-- Publish ready to run executables when we're publishing platform specific executables. -->
-        <PublishReadyToRun Condition="'$(RuntimeIdentifier)' != '' Or '$(RestoreWithR2R)' == 'true'">true</PublishReadyToRun> 
+        <PublishReadyToRun Condition="'$(RuntimeIdentifier)' != '' Or '$(RestoreWithR2R)' == 'true'">true</PublishReadyToRun>
     </PropertyGroup>
 
     <ItemGroup Label="Project References">