C# LangVersion options only available up to version 6
You can specify the C# language version to use through target_compile_options(${TARGET_NAME} PRIVATE "/langversion:X")
I noticed that only these C# LangVersion property values are currently available: "3, 4, 5, 6, default". Possible values seem to be defined in Templates\MSBuild\FlagTables\v142_CSharp.json
There are apparently quite a few more versions by now: https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/compiler-options/language
For my build I need at least version 7. The work around is to either use "default" or to not specify this option at all. target_compile_options(${TARGET_NAME} PRIVATE "/langversion:default")
Both ways will effectively unlock the latest major version number.
That's good enough for me (and probably most people). However, I was modifying an existing CMakeLists.txt which had version set to "6" for by now outdated reasons, and I was wondering why changing it to "7" didn't work. Since I could only figure out the reason by looking at the CMake code, I thought I at least let you know and make this easier for people to find through Google.