Building “project-less” (no `.csproj`) Web Site Project (WSP) with Roslyn - not supported by MSBuildWorkspace

Question

We have a Roslyn-based static analysis tool. To build a C# project, either through an .sln or .csproj file, we use the MSBuildWorkspace . In this scenario, everything works well.

Recently, I bumped into an old-style Web Site Project (WSP) , one that does not contain a .csproj - pages are compiled on-demand by the server (unless if precompiled ). Not surprisingly, the MSBuildWorkspace doesn't support such "project-less" projects, as confirmed by item 2 in this reply .

The difficulty now is to feed the build with the necessary dependencies/assemblies. To deal with such use case, our static analysis tool offers a flag like -I path/to/dll so that users can specify directories where to find those DLLs - and I create MetadataRereferences for them. While this approach works, it doesn't come with the best user-experience, because the user is not always a developer and might not know all the locations/details.

I'd like to ask whether anyone is aware of an alternative approach to build a project-less Web Site Projects where we could "instruct"/setup Roslyn to mimic the process done by an actual web server to compile the aspx.cs files?

Thank you!