https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48101
--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> --- You can't allocate const memory, but in essence yes, that's the reason. The standard says that an allocator's value type must be a non-const, non-volatile object type, so std::allocator<const T> is undefined behaviour.
