[libcxx-commits] [libcxx] [libc++] Fix UB in filesystem::__copy for non-existent destination. (PR #87615)

[Louis Dionne via libcxx-commits]

https://github.com/ldionne approved this pull request.

I went through the PR explanation and the discussions since the start of the PR, and reviewed the code itself.

This seems like a real problem to me, only one that we can't realistically find in our CI testing environments because of how our OSes implement these low level functions. I'm happy to hear that our existing tests would actually catch this issue on an OS where the stat functions are implemented in that particular (but legal) way.

I think there's no reason to hold off with this patch any longer. Thanks for the report, explanation and the fix @ivafanas .

https://github.com/llvm/llvm-project/pull/87615