https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105539
Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |rguenth at gcc dot gnu.org --- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> --- it does do the job in preventing uninitialized stack slots. It does not prevent optimization to occur based on the undefined behavior. I think that was exactly the constraints you outlined - it does _not_ make uninit uses well-defined?