https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111598
Bug ID: 111598
Summary: Wimplicit-fallthrough print for a code that is not
compiled in
Product: gcc
Version: 13.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: Hi-Angel at yandex dot ru
Target Milestone: ---
When a switch-case has a "fallthrough" case that is surrounded by an `#ifdef`
and is not compiled in, GCC does not recognize the `// fallthrough` comment and
prints a `this statement may fall through` warning.
# Steps to reproduce
$ cat test2.c
#include <stdio.h>
int main() {
enum {Field1, Field2} e = 0;
switch (e) {
case Field1:
puts("field1");
// fallthrough
#ifdef SOME_UNDEFINED_MACRO
case Field2:
puts("field2");
// fallthrough
#endif
default:
puts("default");
}
}
$ gcc test2.c -o /dev/null -Wimplicit-fallthrough
test2.c: In function ‘main’:
test2.c:7:13: warning: this statement may fall through
[-Wimplicit-fallthrough=]
7 | puts("field1");
| ^~~~~~~~~~~~~~
test2.c:14:9: note: here
14 | default:
| ^~~~~~~
## Expected
No warning, because every case ends with a fallthrough comment
## Actual
There's a warning
