https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97207
--- Comment #11 from Jonathan Wakely <redi at gcc dot gnu.org> --- (In reply to rguent...@suse.de from comment #8) > 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? No there isn't. You deleted the move assignment operator, so there's no assignment at all. Swap uses move assignment anyway. > 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) Because you deleted it, that says you don't want assignment.
