Unused `extern fn` in dead code warns

[robertbastian]

Code

fn fun() {
    extern "C" {
        fn foo();
    }
    
    fn bar() {}
    
    unsafe { foo(); }
    bar();
}

Current output

warning: function `fun` is never used
 --> src/lib.rs:1:4
  |
1 | fn fun() {
  |    ^^^
  |
  = note: `#[warn(dead_code)]` on by default

warning: function `foo` is never used
 --> src/lib.rs:3:12
  |
3 |         fn foo();
  |            ^^^

Desired output

warning: function `fun` is never used
 --> src/lib.rs:1:4
  |
1 | fn fun() {
  |    ^^^
  |
  = note: `#[warn(dead_code)]` on by default

Rationale and extra context

foo's calling code already generates a dead code warning, so foo itself should not generate another one, like bar.

Other cases

No response

Anything else?

No response

[est31]

The dead code warnings in Rust are eagerly printing. The advantage of that is that you can address them all in one go instead of having to address one, then recompile, then have the next warning, then recompile, etc, until they are all gone.

[robertbastian]

bar doesn't eagerly warn though?