Compiling with -Wunused-variable, we expect no warning to be emitted (constructor calls might have side effects), yet a warning is emitted for s2

struct S {
    S(int);
};

int main() {
    S s(0); // no warning
    S s2 = 0; // unused
    S s3{0}; // no warning
}

https://godbolt.org/z/6zzfE9c4a