https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97207
--- Comment #8 from rguenther at suse dot de <rguenther at suse dot de> --- On Fri, 25 Sep 2020, redi at gcc dot gnu.org wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97207 > > --- Comment #7 from Jonathan Wakely <redi at gcc dot gnu.org> --- > (In reply to Richard Biener from comment #4) > > That swap couldn't have worked before because auto_vec eventually contains a > > pointer into itself. So the patch has improved things from broken to > > rejected. Rejected because while there's a move CTOR now, std::swap isn't > > happy with just that. > > > > No idea why - Jonathan? > > Because swap requires assignment, not just construction. > > I don't see a libstdc++ bug here. But there is assignment? Just no move assignment? I guess swap is really special because clearly formerly { auto_vec<int> a, b; a.safe_push (1); b = a; } would have caused a double-free. std::swap fixes this because, well, it swaps. Going to try implement move assignment then. Just wonder why when move assingment is not there it doesn't fall back to non-move assignment semantics (aka previous behavior)
