unhelpful diagnostic regarding inferred 'static bound

[vxpm]

Code

struct Foo;

impl Foo {
    fn bar(&self) -> &() {
        &()
    }
}

fn takes_static(_s: &'static ()) {}

fn main() {
    let foo = Foo;
    let my_reference = foo.bar();

    takes_static(my_reference);
}

Current output

error[E0597]: `foo` does not live long enough
  --> src/main.rs:13:24
   |
12 |     let foo = Foo;
   |         --- binding `foo` declared here
13 |     let my_reference = foo.bar();
   |                        ^^^^^^^^^
   |                        |
   |                        borrowed value does not live long enough
   |                        argument requires that `foo` is borrowed for `'static`
...
16 | }
   | - `foo` dropped here while still borrowed

For more information about this error, try `rustc --explain E0597`.

Desired output

error[E0597]: `foo` does not live long enough
  --> src/main.rs:13:24
   |
12 |     let foo = Foo;
   |         --- binding `foo` declared here
13 |     let my_reference = foo.bar();
   |                        ^^^^^^^^^
   |                        |
   |                        borrowed value does not live long enough
   |                        argument requires that `foo` is borrowed for `'static`
   |
15 |     takes_static(my_reference);
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: `my_reference` inferred to be `'static` here
...
16 | }
   | - `foo` dropped here while still borrowed

For more information about this error, try `rustc --explain E0597`.

Rationale and extra context

the current error message doesn't mention where the 'static bound comes from, making it seem very magical and not showing you where the problem actually arises. although obvious in a small example like this, it's pretty confusing in larger contexts.

Other cases

No response

Anything else?

No response

[tgross35]

I think this is somewhat similar to the issue I wrote up not too long ago: #112519

[aliemjay]

stderr under #113917

error[E0597]: `foo` does not live long enough
  --> /tmp/tto12.rs:13:24
   |
12 |     let foo = Foo;
   |         --- binding `foo` declared here
13 |     let my_reference = foo.bar();
   |                        ^^^ borrowed value does not live long enough
14 |
15 |     takes_static(my_reference);
   |     -------------------------- argument requires that `foo` is borrowed for `'static`
16 | }
   | - `foo` dropped here while still borrowed

[vxpm]

awesome! way better :)

[aliemjay]

This should be closed automatically upon merge.

[dianne]

This was improved by #133858. Here's the current error on 1.86.0-beta:

error[E0597]: `foo` does not live long enough
  --> src/main.rs:13:24
   |
12 |     let foo = Foo;
   |         --- binding `foo` declared here
13 |     let my_reference = foo.bar();
   |                        ^^^ borrowed value does not live long enough
14 |
15 |     takes_static(my_reference);
   |     -------------------------- argument requires that `foo` is borrowed for `'static`
16 | }
   | - `foo` dropped here while still borrowed

For more information about this error, try `rustc --explain E0597`.