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
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