https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84395
Bug ID: 84395
Summary: -Wstringop-truncation where -Wstringop-overflow is
expected
Product: gcc
Version: 8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: msebor at gcc dot gnu.org
Target Milestone: ---
The test case below triggers what looks like a bogus -Wstringop-truncation
warning when it instead should trigger -Wstringop-overflow.
The -Wstringop-truncation warning indicates that the checker considers the size
of the entire array (i.e., 3 * 7 chars) when it should consider the size of the
subarray a[i] (i.e., 7 chars).
The missing -Wstringop-overflow suggests this checker is doing the same.
$ cat t.c && gcc -O2 -S -Wall -Wextra t.c
char a[3][7];
void f (const char *s, int i)
{
__builtin_strncpy (a[i], s, 21); // -Wstringop-truncation but no
-Wstringop-overflow?
a[i][6] = 0;
}
t.c: In function ‘f’:
t.c:5:3: warning: ‘__builtin_strncpy’ specified bound 21 equals destination
size [-Wstringop-truncation]
__builtin_strncpy (a[i], s, 21); // -Wstringop-truncation but no
-Wstringop-overflow?
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
