[clang-tools-extra] [clang-tidy] unnecessary-value-param: Allow moving of value arguments. (PR #145871)

[Clement Courbet via cfe-commits]

legrosbuffle wrote:

Note that in the test I wrote I called a ctor for simplicity, but in general I want to avoid warning on anything that looks like this:

```
template <typename... Args>
void Eat(Args&&...);

void NegativeMoved(ExpensiveToCopyType A) {
  Eat(std::move(A));
}
```

The move ctor just happens to be a specific case of `Eat`.

If we wanted to be fully consistent we'd have to turn:

```
void NegativeMoved(ExpensiveToCopyType A) {
  Eat(A);
}
```

into:

```
void NegativeMoved(ExpensiveToCopyType A) {
  Eat(std::move(A));
}
```

We've actually had such a check internally for a few years (suggesting to `move` local objects, including parameters). This check is extremely complex (though it handles more cases than just a single reference to the parameter to make a copy, in particular it handles the case that @firewave mentions in [#57908](https://github.com/llvm/llvm-project/issues/57908). So I think suggesting the move is way beyond the scope of `unnecessary-value-param`. `unnecessary-value-param` happens to suggest the move in the very specific case of "a by-value parameter used exactly once as the argument of a copy constructor except if we're anywhere within a loop" , but that's a bit ad hoc and just there because it's a common pattern (in particular, in constructor init lists) that we don't want to pessimize.

https://github.com/llvm/llvm-project/pull/145871