On Tue, 8 Oct 2024, Alejandro Colomar wrote: > How about adding the __lower__ version now as a GNU extension with > compatible semantics, and when it's closer to an ISO C2y release add the > _Upper one?
No, we don't need two names. Just _Lengthof suffices. If semantics change in some way during C2y development, we can update the implementation to match. We have a rule that the C++ library ABI is explicitly unstable for features in a new standard where support is still under development, and only commit to a stable C++ library ABI supporting existing binaries once the support for that version is mature enough. I think it's reasonable also to say that features from C2y (including when supported in older standards modes) are unstable and liable to change when the semantics in C2y change. (Liable to change doesn't mean changing on a release branch after the first release from that branch. But it could in some cases mean changing incompatibly while mainline is in regression fixes mode, to avoid releasing something significantly incompatible with later changes.) -- Joseph S. Myers josmy...@redhat.com
