https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119611
Bug ID: 119611
Summary: Function call substitution cause confusing warning
messages
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: siddhesh at gcc dot gnu.org
Target Milestone: ---
Consider the following:
```
#include <string.h>
void f (void*);
void h (void)
{
char a[8];
stpcpy (stpcpy (a, "12345678"), "abcdefgh");
f (a);
}
$ gcc -D_FORTIFY_SOURCE=2 -O2 -S f.c
f.c: In function ‘h’:
f.c:7:3: warning: ‘__builtin___stpcpy_chk’ writing 9 bytes into a region of
size 8 [-Wstringop-overflow=]
7 | stpcpy (stpcpy (a, "12345678"), "abcdefgh");
| ^
f.c:6:8: note: destination object ‘a’ of size 8
6 | char a[8];
| ^
f.c:7:3: warning: ‘__builtin_memcpy’ writing 9 bytes into a region of size 8
[-Wstringop-overflow=]
7 | stpcpy (stpcpy (a, "12345678"), "abcdefgh");
| ^
f.c:6:8: note: at offset [0, 7] into destination object ‘a’ of size 8
6 | char a[8];
| ^
```
Here, instead of referring to stpcpy (or its _chk variant), the warning refers
to __builtin_memcpy, which does not appear anywhere in the program. It's not
exactly a serious issue, but it can cause some confusion for users.
When doing call substitution, there should be a way to somehow retain a
reference to the original function so that the warning message can refer to it
instead.
