Compatibility.CompilerFeatures (nuget): Source code only package to support c# 11 `required` feature of net7, `init-only and record` of c# 9 in the old frameworks net4x, netstandard2.x, NET6 and NET5.
Keywords: c#11|c#9|IsExternalInit|required|CompilerFeatureRequired|record|init-only|roslyne-compiler