Currently I'm working on a .NET Core 3.1 project where I want to try out some new C#10 features. I get the CS1617 error which tells me I cannot do this and offers me to list available languages for this project by using <langversion>?</langversion> in .csproj.
My question is where the list of compatible languages shows up.
I've inquired at the dotnet/docs repo, and the answer can be found there.
It seems that creating this list of compatible language versions is a bit more tricky than it seemed. I'll stick with the list as Auditive suggested.