Over half of our 50 man development team still uses Visual Studio 2013. Despite this, we would like to use C# 6. So we tried using this solution: https://stackoverflow.com/a/32010632/3997704.
Compilation with Microsoft.Net.Compilers works fine, as does our CI environment. However, Visual Studio shows a lot of errors in the Error List related to C# 6 features. I tried getting rid of the errors by using clean solution, rebuild, restarting Visual Studio and clearing ReSharper caches but none worked.