[Clang-Tidy] `cppcoreguidelines-rvalue-reference-param-not-moved` false positive on rvalue references since C++20

[MagentaTreehouse]

Given this code:

struct A {
    A(A &&) = default;
    A &operator=(A &&) = default;
};

A f(A &&a) {
    return a;
}

Even in C++20, Clang-Tidy says:

<source>:6:9: warning: rvalue reference parameter 'a' is never moved from inside the function body [cppcoreguidelines-rvalue-reference-param-not-moved]
    6 | A f(A &&a) {
      |         ^

Seems like P1825 is not fully implemented in this check.

See https://compiler-explorer.com/z/47o1jdnx8.

[llvmbot]

@llvm/issue-subscribers-clang-tidy

Author: None (MagentaTreehouse)

Given this code: ```c++ struct A { A(A &&) = default; A &operator=(A &&) = default; };

A f(A &&a) {
return a;
}

Even in C++20, Clang-Tidy says:
```console
<source>:6:9: warning: rvalue reference parameter 'a' is never moved from inside the function body [cppcoreguidelines-rvalue-reference-param-not-moved]
    6 | A f(A &&a) {
      |         ^

Seems like P1825 is not fully implemented in this check.

See https://compiler-explorer.com/z/47o1jdnx8.