https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94849
--- Comment #7 from Rachel Mant <rachel at rachelmant dot com> --- Continuing to think on this a bit, and.. if it is undefined behaviour as you say, then granted this is not a bug on ASAN/TSAN.. but it is still a bug as UBSAN does and says nothing when faced with this even though it clearly should terminate the program for invoking UB, with a suitable diagnostic.
