Why use such misleading names for functions?

D'oh! Of course, I misread, and of course memmove() is the name for memcpy_overlap(),
and your hypothetical memcpy_nooverlap() is just memcpy()... But, it has
literally ALWAYS been this way, and any C programmer worth half a damn knows
this is how memcpy() and memmove() works... It's widely documented in various
standards, and misusing memcpy() in place of memmove() will cause you lots of
trouble on various other libcs... Just because glibc has been forgiving of the
blatent misuse prior to now is no reason to continue to tolerate it...