[llvm-dev] [RFC] Raise the minimum Visual Studio version to VS2019

[Simon Pilgrim via llvm-dev]

Now that VS2022 is on general release, LLVM is expected to build on 
VS2017, VS2019 and VS2022.

What are people's thoughts on raising the minimum supported version to 
latest VS2019 (_MSC_VER = 1927)? Customarily, we've only specifically 
supported the latest 2 versions of Visual Studio, with older versions 
being "allowed" (at your own risk) via the LLVM_FORCE_USE_OLD_TOOLCHAIN 
cmake flag.

I'm thinking we should either make the switch now, in plenty of time 
before the next release of LLVM, or we postpone it until shortly after 
the release branch is created (which I assume will be early 2022).

For the record, I haven't so far noticed any issues with supporting 
VS2017, VS2019 and VS2022 builds, so at this time I don't consider this 
very urgent, just a general maintenance task - although somebody out 
there may know of specific fixes in VS2019+ that could simplify LLVM 
handling for MSVC etc.

Cheers, Simon.