https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114940
--- Comment #7 from Arsen Arsenović <arsen at gcc dot gnu.org> --- (In reply to Jonathan Wakely from comment #6) > What would be needed to work without it? It looks like the allocation would > have to be larger so the size could be stored as a cookie at the start of > the allocated block? > > Tangentially, could _M_alloc_size use __ba - 1 instead of __ba? would it even require that? AIUI, that flag only affects global sized dealloc functions, so it'd only require changing the ::operator new/delete dealloc fn in the _Promise_alloc<void> case. but, clang appears to intend to flip the default soon: https://github.com/llvm/llvm-project/pull/90373 so I'm not sure it's worth it anyway re _M_alloc_size, do you mean _Promise_alloc<void> case or the non-void one? in the void case, I think so (but haven't ensured it by doing the math on paper yet; reasoning through it, it seems fine). in the non-void case, it might even be possible to do -2 (same disclaimer goes)
