Breaking changes to runtime compilation for Razor views and Razor Pages

[pranavkm]

As a consequence of cleaning up the ASP.NET Core shared framework to not depend on Roslyn, support for runtime compilation of Razor views and Razor Pages is being moved to a separate package.
Applications that require runtime compilation or re-compilation of Razor files should

• Add a reference to the Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation package
• Update the application's ConfigureServices to include a call to AddMvcRazorRuntimeCompilation:

services.AddMvc()
    .AddMvcRazorRuntimeCompilation();

The following APIs previously available on Microsoft.AspNetCore.Mvc.Razor.RazorViewEngineOptions to support runtime compilation would now be available via
Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation.MvcRazorRuntimeCompilationOptions:

• RazorViewEngineOptions.FileProviders -> MvcRazorRuntimeCompilationOptions.FileProviders
• RazorViewEngineOptions.AdditionalCompilationReferences -> MvcRazorRuntimeCompilationOptions.AdditionalReferencePaths

In addition, Microsoft.AspNetCore.Mvc.Razor.RazorViewEngineOptions.AllowRecompilingViewsOnFileChange has been removed. Recompilation on file changes is enabled by default by referencing the Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation package.

Related issues: #312, #325

Please use dotnet/aspnetcore#7647 for further discussions or questions.

This announcement has been migrated to dotnet/docs#14925