https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104367
Bug ID: 104367
Summary: Possible improvements for -Wmisleading-indentation
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: frantisek at sumsal dot cz
Target Milestone: ---
Hello!
Recently we encountered a pretty nasty bug in systemd[0], which makes me wonder
if this situation couldn't be prevented by throwing a compiler warning.
# cat /etc/redhat-release
Fedora release 36 (Rawhide)
# gcc --version
gcc (GCC) 12.0.1 20220125 (Red Hat 12.0.1-0)
Reproducer:
#include <stdio.h>
void bar(int *x) {
printf("%d\n", *x);
}
void foo(int *x) {
if (!x)
return
bar(x);
}
int main(void) {
foo(NULL);
return 0;
}
The culprit here is, obviously, the missing semicolon after the return
statement, which currently leads to a segmentation fault:
# gcc -Wall -Wextra -Wmisleading-indentation -o main main.c
# ./main
Segmentation fault (core dumped)
That is, however, silently accepted, since the resulting expression (return
bar(x);) is still valid in this context.
I wonder if this couldn't/shouldn't be detected by -Wmisleading-indentation
(since this definitely falls into that category).
Possibly related to other similar bugs like:
- https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66298
- https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70968
- and others
[0] https://github.com/systemd/systemd/pull/22387/files
