[Bug libfortran/80365] undefined memcpy while writing zero length array on unformatted stream in unix.c

[zeccav at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80365

--- Comment #4 from Vittorio Zecca <zeccav at gmail dot com> ---
Or you may add

assert(buf);

just before the memcpy library call.

If nbyte==0 then it should be harmless, but undefined.

assert(buf || !nbyte) should catch an error situation