https://gcc.gnu.org/bugzilla/show_bug.cgi?id=32667
post+gcc at ralfj dot de changed:
What |Removed |Added
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CC| |post+gcc at ralfj dot de
--- Comment #23 from post+gcc at ralfj dot de ---
> Is glibc community ready to provide such guarantee?
This is indeed a key question here I think. Currently GCC makes assumptions
that *even the libc produced by the same project* does not document as stable
guarantees. That's rather dissonant. The GNU project should at least within
itself come to a proper conclusion on the question of whether memcpy should be
UB or not when both pointers are equal. Right now we have everyone pointing at
everyone else, and users are left in the rain with their valgrind errors.
Ideally of course the C standard would be updated to ensure that slowly but
steadily, the memcpy contract is updated to match reality. That will take a
while, but given that this issue was filed 16 years ago (!), there clearly
would have been enough time. (If someone does, please join forces with the
clang people that are interested in getting C updated:
https://reviews.llvm.org/D86993#4585590).
But GNU controls glibc so there's not really any excuse for not updating those
docs, I think? glibc making such a move would be a great step towards
convincing valgrind and the C committee that memcpy should have defined
behavior when both pointers are equal.
