https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92363
Bug ID: 92363
Summary: wrong subscript value printed when indexing into an
empty array
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: msebor at gcc dot gnu.org
Target Milestone: ---
The -Warray-bounds code takes a shortcut when it detects an access to an array
whose lower bound is equal to its upper bound and prints the same warning
message regardless of the subscript:
/* Empty array. */
if (up_bound && tree_int_cst_equal (low_bound, up_bound_p1))
warned = warning_at (location, OPT_Warray_bounds,
"array subscript %E is above array bounds of %qT",
low_bound, artype);
That can cause the message to mention the wrong subscript value such as in the
test case below:
$ cat b.c && gcc -O2 -S -Wall -Warray-bounds b.c
int f (void)
{
int a[] = { };
return a[-1];
}
b.c: In function ‘f’:
b.c:4:11: warning: array subscript 0 is above array bounds of ‘int[0]’
[-Warray-bounds]
4 | return a[-1];
| ~^~~~
b.c:3:7: note: while referencing ‘a’
3 | int a[] = { };
| ^
