[Bug middle-end/79538] missing -Wformat-overflow with %s and non-member array arguments

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79538

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2017-03-13
            Summary|missing -Wformat-overflow   |missing -Wformat-overflow
                   |with %s and global array    |with %s and non-member
                   |arguments                   |array arguments
     Ever confirmed|0                           |1

--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
Confirming my own bug and adjusting the Summary to make it clear that the
problem isn't specific to global arrays and affects local arrays as well.  The
following test case shows that.

$ cat z.c && gcc -O2 -S -Wall -Wextra -Wpedantic
-fdump-tree-printf-return-value=/dev/stdout z.c
int main ()
{
  char d[3];
  char s[] = "abcd";

  __builtin_sprintf (d, "%-s", s);
  __builtin_printf ("%s\n", d);
}


;; Function main (main, funcdef_no=0, decl_uid=1794, cgraph_uid=0,
symbol_order=0) (executed once)

z.c:6: __builtin_sprintf: objsize = 3, fmtstr = "%-s"
  Directive 1 at offset 0: "%-s"
    Result: 0, 0, -1, 9223372036854775807 (0, 0, -1, -1)
  Directive 2 at offset 3: "", length = 1

main ()
{
  char s[5];
  char d[3];

  <bb 2> [100.00%]:
  s = "abcd";
  __builtin_sprintf (&d, "%-s", &s);
  __builtin_puts (&d);
  d ={v} {CLOBBER};
  s ={v} {CLOBBER};
  return 0;

}