https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94226
Martin Sebor <msebor at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Blocks| |84774
Status|UNCONFIRMED |NEW
Ever confirmed|0 |1
CC| |msebor at gcc dot gnu.org
Keywords| |diagnostic
Last reconfirmed| |2020-03-19
--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
$ cat pr94226.c && gcc -O2 -S -Wall -fdump-tree-strlen=/dev/stdout pr94226.c
extern char a2[2][22];
int f (void)
{
return __builtin_sprintf (a2[1], "%s", a2[1] + 1); // expect -Wrestrict
}
;; Function f (f, funcdef_no=0, decl_uid=1931, cgraph_uid=1, symbol_order=0)
;; 1 loops found
;;
;; Loop 0
;; header 0, latch 1
;; depth 0, outer -1
;; nodes: 0 1 2
;; 2 succs { 1 }
pr94226.c:5: __builtin_sprintf: objsize = 22, fmtstr = "%s"
Directive 1 at offset 0: "%s"
Result: 0, 20, 20, 20 (0, 20, 20, 20)
Directive 2 at offset 2: "", length = 1
Setting in-bounds return value range [0, 20].
f ()
{
int _3;
<bb 2> [local count: 1073741824]:
_3 = __builtin_sprintf (&a2[1], "%s", &MEM <char[22]> [(void *)&a2 + 23B]);
return _3;
}
Prior to the change GCC issued the warning below:
a.c: In function ‘f’:
a.c:7:10: warning: ‘__builtin_sprintf’ argument 3 may overlap destination
object ‘a2’ [-Wrestrict]
7 | return __builtin_sprintf (a2[1], "%s", a2[1] + 1);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
a.c:3:13: note: destination object referenced by ‘restrict’-qualified argument
1 was declared here
3 | extern char a2[2][22];
| ^~
The warning code in gimple-ssa-sprintf.c most likely needs adjusting.
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84774
[Bug 84774] [meta-bug] bogus/missing -Wrestrict
