https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89061
Bug ID: 89061
Summary: GCC 9 introduces false positive in -Wjump-misses-init
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: berrange at redhat dot com
Target Milestone: ---
The following demo program
$ cat demo.c
#include <stdlib.h>
struct demo {
const char *cmd;
};
int main(void)
{
struct demo demo = {0};
if ((demo.cmd = getenv("FOO")) == NULL) {
goto cleanup;
}
demo = (struct demo) { .cmd = "foo" };
cleanup:
return 0;
}
Results in new false positive warnings with GCC 9
$ gcc -Wjump-misses-init -o demo demo.c
demo.c: In function ‘main’:
demo.c:13:5: warning: jump skips variable initialization [-Wjump-misses-init]
13 | goto cleanup;
| ^~~~
demo.c:18:2: note: label ‘cleanup’ defined here
18 | cleanup:
| ^~~~~~~
demo.c:16:24: note: ‘({anonymous})’ declared here
16 | demo = (struct demo) { .cmd = "foo" };
| ^
'demo' is fully initialized at every step of the program, even taking into
account the jumps.
It appears to be triggered by the full struct assignment. If I change
demo = (struct demo) { .cmd = "foo" };
to
demo.cmd = "foo";
then it no longer triggers the false positive warning.
This is seen on Fedora 30 rawhide with gcc-9.0.1-0.1.fc30.x86_64 which appears
to be using a git master snapshot taken sometime on 2019/01/23.
