[Bug middle-end/104854] [11/12 Regression] -Wstringop-overread should not warn for strnlen and strndup

[siddhesh at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104854

--- Comment #2 from Siddhesh Poyarekar <siddhesh at gcc dot gnu.org> ---
(In reply to David Malcolm from comment #1)
> Compiler Explorer link for the above (with -fanalyzer -Wall
> -Wstringop-overread -O2; -O2 seems to be needed to trigger it):

Ah yes, sorry, I pasted an older reproducer.  This:

char *
foo (void)
{
  return __builtin_strndup ("test", 8);
}

doesn't need -O2.


$ gcc -S -Wall ../test.c
../test.c: In function ‘foo’:
../test.c:5:10: warning: ‘__builtin_strndup’ specified bound 8 exceeds source
size 5 [-Wstringop-overread]
    5 |   return __builtin_strndup ("test", 8);
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~