[libcxx-commits] [libcxx] [libcxx] [regex] add `[[clang::fallthrough]]` to suppress fallthrough warning (PR #100821)

[Max Coplan via libcxx-commits]

vegerot wrote:

question for reviewer: what is the proper etiquette for stacked diffs? Should I open two PRs or have one PR with two commits?

https://github.com/llvm/llvm-project/pull/100821