https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91356
--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> --- No, it needs co-operation between G++ and all other compilers using the same ABI, which makes it out of scope for GCC's bugzilla. G++ cannot unilaterally change the ABI here, and even if we could, libstdc++ would not take advantage of it because it would break the library's stable ABI. So WONTFIX.