http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53532
Bug #: 53532
Summary: function call ignored when called with argument of
incompatible, undefined structure
Classification: Unclassified
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: mach...@post.cz
The following code...
struct aaa {};
extern int xxx(struct aaa e);
int main() {
xxx((struct bbb) {});
return 0;
}
... compiles without warnings and the call to xxx is ignored:
# gcc -Wall -Wextra -c foo.c
# objdump -x foo.o
[...]
Disassembly of section .text:
0000000000000000 <main>:
0: 55 push %rbp
1: 48 89 e5 mov %rsp,%rbp
4: b8 00 00 00 00 mov $0x0,%eax
9: 5d pop %rbp
a: c3 retq
[...]
The code above seems invalid, and I think that gcc should reject it.
The definition of struct aaa is somehow important. When dropped, GCC realizes
things are wrong, and complains abundantly.
# LANG=C gcc -Wall -Wextra -x c /dev/stdin
extern int xxx(struct aaa e);
int main() {
xxx((struct bbb) {});
return 0;
}
/dev/stdin:1:23: warning: 'struct aaa' declared inside parameter list [enabled
by default]
/dev/stdin:1:23: warning: its scope is only this definition or declaration,
which is probably not what you want [enabled by default]
/dev/stdin: In function 'main':
/dev/stdin:3:15: error: type of formal parameter 1 is incomplete
It also complains about struct bbb being incomplete, which it didn't mind at
all while aaa was there.
