https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95349
--- Comment #3 from rguenther at suse dot de <rguenther at suse dot de> --- On Wed, 27 May 2020, redi at gcc dot gnu.org wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95349 > > --- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> --- > Using > > auto t = new(p) std::uint64_t; > std::memcpy(t, std::launder(storage), sizeof(storage)); > return t; > > also prevents GCC from propagating the dynamic type of p to t. So the language lawyer question is whether the testcase is valid or not and what std::launder makes a difference semantics wise (the dynamic type is still transfered, just the compiler no longer knows which one it is).
