https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91974
Bug ID: 91974
Summary: function not sequenced before function argument
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: barry.revzin at gmail dot com
Target Milestone: ---
>From StackOverflow (https://stackoverflow.com/q/58204296/2069064), reduced:
extern void call(int);
void a(int) {
call(0);
}
void b(int) {
call(1);
}
int main() {
using T = void(*)(int);
T f = a;
f((f=b,0));
}
This is a well-defined (if weird) program that should a - that is call(0). With
gcc, it invokes call(1) (that is, the assignment that happens in the
initialization of the function parameter happens before the load of the
function itself). On -O2, the codegen is:
main:
sub rsp, 8
mov edi, 1
call call(int)
xor eax, eax
add rsp, 8
ret
