https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109792
Bug ID: 109792
Summary: RFE: Warn about misuse of "pure" attribute
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: xry111 at gcc dot gnu.org
Target Milestone: ---
I've spent several hours on https://github.com/systemd/systemd/pull/27595,
which fixes a wrong use of the "pure" attribute. Consider the following:
$ cat t.c
extern int t(const char *, int *);
int t(const char *a, int *b)
{
if (!a)
return 114;
*b = __builtin_strlen(a);
return 0;
}
$ gcc t.c -S -Wall -Wextra -Werror && echo "no warning"
no warning
$ gcc t.c -S -Wall -Wextra -Werror -O1 && echo "no warning"
no warning
$ gcc t.c -S -Wall -Wextra -Werror -O2 && echo "no warning"
no warning
$ gcc t.c -S -Wall -Wextra -Werror -O3 && echo "no warning"
no warning
$ gcc t.c -S -Wall -Wextra -Werror -O3 -fanalyzer && echo "no warning"
no warning
If we had a warning here, it would have saved me several hours :).
