According to the C++23 standard, what is the output of this program?
#include <iostream>
struct S {
operator void() {
std::cout << "F";
}
};
int main() {
S s;
(void)s;
static_cast<void>(s);
s.operator void();
}A conversion function is never used to convert an object to void.
F
In this program, the object s is converted to void in three ways. First with a C-style cast, then with a static_cast, and finally by manually calling the conversion function.
According to the C++ standard, conversion functions will never be used to convert an object to void. So the conversion function is only called once, when we manually call it on the line s.operator void();.
A conversion function is never used to convert a (possibly cv-qualified) object to the (possibly cv-qualified) same object type (or a reference to it), to a (possibly cv-qualified) base class of that type (or a reference to it), or to cv
void.