CWG2813: extra move in calling of explicit object member function

[Fedr]

This program

struct A {
    A() {}
    A(A&&) = delete;
    void f(this A) {}
};

int main() {
    A{}.f();
}

must be accepted per CWG2813, and GCC does accept it, but not Clang unfortunately.

Online demo: https://gcc.godbolt.org/z/6x7PTsE4M

Related discussion: https://stackoverflow.com/q/78785176/7325599

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Fedor Chelnokov (Fedr)

This program ``` struct A { A() {} A(A&&) = delete; void f(this A) {} };

int main() {
A{}.f();
}

must be accepted per [CWG2813](https://cplusplus.github.io/CWG/issues/2813.html), and GCC does accept it, but not Clang unfortunately.

Online demo: https://gcc.godbolt.org/z/6x7PTsE4M

Related discussion: https://stackoverflow.com/q/78785176/7325599
</details>

[cor3ntin]

See #95112 @MitalAshok