[clang] [Clang] Instantiate functions from constant evaluation. (PR #205557)

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

> @AaronBallman @efriedma-quic can you expand on the set of breakages you expect?

I don't have a code example at hand, just painful life experience that makes me conservative: if this can cause instantiations to happen at a different point in the TU, it's likely to break code somewhere because it seems like most times we modify point-of-instantiation, it has that kind of subtle fallout. So my concerns are likely more FUD at the moment.

https://github.com/llvm/llvm-project/pull/205557