[flang-commits] [flang] [flang] Add cmake error if building with clang-cl and MSVC 17.12 (PR #120114)

[Casey Carter via flang-commits]

CaseyCarter wrote:

For posterity: The underlying MSVC problem is https://github.com/microsoft/STL/issues/4959. 

https://github.com/llvm/llvm-project/pull/120114