@dotnet/roslyn-compiler Please review

CC @jaredpar, @gafter For public API change.

@dotnet/roslyn-compiler Please review

I am fairly certain this does not work with VBCSCompiler.exe, which compiles C# projects. I am creating a Roslyn Diagnostic Analyzer, below is a snippet of the relevant code.

 public override void Initialize(AnalysisContext context)
 {
           context.RegisterCompilationStartAction(SetMetadataImportOptions);
 }

private void SetMetadataImportOptions(CompilationStartAnalysisContext obj)
{
          obj.Compilation.Options.WithMetadataImportOptions(MetadataImportOptions.All);
}

When I debug the process I can see the MetadataImportOptions value does not change when SetMetadataImportOptions is called. When I use reflection to set the MetadataImportOptions, everything works. Is this behavior expected?

I am running Visual Studio 2017 version 15.7.5 and Microsoft.CodeAnalysis.CSharp.Workspaces version 2.8.2