[clang] [Clang] [Sema] Error on reference types inside a union with msvc 1900+ (PR #102851)

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

I wonder whether we need to carry this extension at all any longer (if not, we could remove the changes in 0299dbd2ae89e81584cf95571ef0549862e10fea). VS 2013 is pretty old, but I suppose there's not significant harm in continuing to support it. @rnk @zmodem @majnemer any opinions?

https://github.com/llvm/llvm-project/pull/102851