Fail to find unique implementation of From

[HKalbasi]

Sorry if it is duplicate. In this code:

fn foo<T>(_: impl From<T>) -> T {
    todo!()
}

struct S;

fn bar() {
    let x = foo(S);
      //^ x is `{unknown}`, but it should be `S`
}

We fail to infer the type of x. It should be S since the only From<S> implementation is the generic impl From<T> for T from the standard library.