https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116310
Bug ID: 116310
Summary: default equality operator== selects not-const
conversion operator
Product: gcc
Version: 14.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: fchelnokov at gmail dot com
Target Milestone: ---
This program
```
struct A {
int i = 0;
constexpr operator int() const { return i; }
constexpr operator int&() { return ++i; }
};
struct B {
A a;
bool operator==(const B &) const = default;
};
constexpr bool f() {
B x;
return x == x;
}
static_assert( f() ); // fails in GCC
```
is accepted by Clang and MSVC, but fails static assertion in GCC. Online demo:
https://gcc.godbolt.org/z/4xjTnM54M
GCC looks wrong here, because not-const `operator int&` should not be called
from within `B::operator==(const B &) const`.
Original discussion: https://stackoverflow.com/q/78850335/7325599
