Irritating "unused" warning

[FlorianDyck]

Code

fn main() {
    let mut vec = vec![[0].iter(), [1].iter()];
    vec.remove(0);
}

Current output

warning: unused `std::slice::Iter` that must be used
  --> src\main.rs:52:5
   |
52 |     vec.remove(0);
   |     ^^^^^^^^^^^^^^
   |
   = note: iterators are lazy and do nothing unless consumed

Desired output

No warning when nothing is done to an iterator or similar when they are returned from a function with side effects.

If a warning is shown, it should be like this:

warning: unused return value.
You can use `let _ = vec.remove(0)` to signify that dropping it without usage is the intended behavior.

Rationale and extra context

rustc finds that remove returns an iterator.
Obviously I am not doing anything with it.
But the of the line is not to do something with the iterator, but to remove it from the list.

Other cases

No response

Anything else?

No response

[workingjubilee]

You may silence the warning with let _ = vec.remove(0);

[workingjubilee]

This diagnostic should recommend that.

[FlorianDyck]

In this case I think the output could be improved to:

warning: unused return value.
You can use "let _ = ..." to signify that dropping it without usage is the intended behavior.

[Ezrashaw]

@rustbot claim