https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110816
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> --- (In reply to Jonathan Wakely from comment #3) > (In reply to Andrew Pinski from comment #2) > > The only way to access that byte is to use memcpy or via char. > > -ftrivial-auto-var-init is not designed for security this way but rather for > > normal code ... > > That's not what the manual says (emphasis mine): > > "Initialize automatic variables with either a pattern or with zeroes to > increase the security and predictability of a program by preventing > **uninitialized memory disclosure** and use." probably should add 'some' qualification here. > > IIRC atomic compare and swap will zero it out too ... > > The std::atomic and std::atomic_ref compare_exchange members will zero it, > but the compiler built-in won't.
