Looks like this is just one of possible "non-default" extension allocators, that can be selected during libstdc++ compile time: https://gcc.gnu.org/onlinedocs/l

Looks like this is just one of possible "non-default" extension allocators, that can be selected during libstdc++ compile time: https://gcc.gnu.org/onlinedocs/libstdc++/manual/memory.html#allocator.ext https://gcc.gnu.org/onlinedocs/libstdc++/manual/memory.html#...