https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85623
Martin Sebor <msebor at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2018-05-08
Ever confirmed|0 |1
--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
Confirmed with the simpler test case below. GCC transforms the strncmp() call
to strcmp() because it can see that the bound is larger than the length of one
of the arguments but the warning doesn't consider this case (i.e., it triggers
even when the strcmp call cannot read past the end of the non-string array.
$ cat b.c && gcc -O2 -S -Wall b.c
extern __attribute__((nonstring)) char a[4];
int f (const char *s)
{
return __builtin_strcmp (a, "12");
}
b.c: In function ‘f’:
b.c:5:10: warning: ‘__builtin_strcmp’ argument 1 declared attribute ‘nonstring’
[-Wstringop-overflow=]
return __builtin_strcmp (a, "12");
^~~~~~~~~~~~~~~~~~~~~~~~~~
b.c:1:40: note: argument ‘a’ declared here
extern __attribute__((nonstring)) char a[4];
^
