Move ICompilationException to Diagnostics.Abstractions

[pranavkm]

We use ICompilationException as a contract between diagnostics and other middlewares (primarily Mvc) that perform runtime compilation to show a pretty printed compilation failure. Currently the contract for this exception is located in Microsoft.Extensions.CompilationAbstractions. This would allow removing the CompilationAbstractions dependency.

[davidfowl]

It also means that hosting will end up depending on this weird assembly 😄

[pranavkm]

Why would hosting need to depend on this assembly?

[Tratcher]

Oh, it's used here for the startup exception page: https://github.com/aspnet/Hosting/blob/5bb737b6ad24edb8d9f77aa3b48b17b24b4dfc0d/src/Microsoft.AspNet.Hosting/Startup/StartupExceptionPage.cs#L54

[pranavkm]

That's meant for compile time exceptions (stuff coming from DNX) which we can leave as is. This was specifically for runtime compilation.

[davidfowl]

Assigned to you @pranavkm. You'll have to leave a copy in DNX so that nothing breaks while we transition over. You can also remove the compilation error support from the Hosting page.

[pranavkm]

Yeah - I'm going to rename the namespace for this interface so the current one can co-exist until we transition. For aspnet/Hosting#510, are we simply gutting the code?