[llvm-branch-commits] [clang] [Clang] Define `__SIG_ATOMIC_TYPE__` macro (#213934) (PR #214138)

[Aaron Ballman via llvm-branch-commits]

AaronBallman wrote:

> Could this be considered an ABI/API break in the compiler?

I don't believe it should change the ABI of the compiler itself (the functionality ultimately puts some extra string content into a big string buffer, so this isn't changing layout of objects, etc). But it fixes a system header, so I think it's pretty important to land if we can.

https://github.com/llvm/llvm-project/pull/214138