[Bug middle-end/85602] -Wsizeof-pointer-memaccess for strncat with size of source

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85602

--- Comment #3 from Martin Sebor <msebor at gcc dot gnu.org> ---
I agree that's not an improvement.  Would something like this be better? (at
least until utmp_ent is marked nonstring and GCC taught to suppress the
diagnostic)

  size_t utmpsize = sizeof UT_ID (utmp_ent);
  char *comment = xmalloc (strlen (_("id=")) + utmpsize + 1);

  strcpy (comment, _("id="));
  strncat (comment, UT_ID (utmp_ent), utmpsize);

I'll try to remember to test coreutils with new warnings in the future.