[Bug libstdc++/114821] _M_realloc_append should use memcpy instead of loop to copy data when possible

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114821
--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Jan Hubicka from comment #2)
> This seems to do the trick, but for some reason I get memmove

What's the second overload for, and why does it depend on _GLIBCXX_HOSTED?