Small error in "introduce explicit lifetime bound" suggestion

[estebank]

We currently give the following output:

error[E0311]: the parameter type `T` may not live long enough
  --> src/main.rs:25:11
   |
25 |     scope.spawn(move |_| {
   |           ^^^^^
   |
note: the parameter type `T` must be valid for the anonymous lifetime #2 defined on the function body at 24:1...
  --> src/main.rs:24:1
   |
24 | fn play_with<T: Animal + Send>(scope: &Scope, animal: T) {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
note: ...so that the type `[closure@src/main.rs:25:17: 27:6]` will meet its required lifetime bounds
  --> src/main.rs:25:11
   |
25 |     scope.spawn(move |_| {
   |           ^^^^^
help: consider introducing an explicit lifetime bound
   |
24 | fn play_with<'a, T: 'a + Animal + Send>(scope: &Scope, animal: T) {
25 |     scope.spawn + 'a(move |_| {
   |

The suggestion has a spurious extra + 'a in line 25 that shouldn't be there.

[0yoyoyo]

@rustbot claim

[0yoyoyo]

Should I just remove wrong + 'a in the suggestion? In this case, we have to add explicit lifetime to Scope to resolve the error.
like this:

fn play_with<'a, T: 'a + Animal + Send>(scope: &Scope<'a>, mut animal: T) {
    scope.spawn(move |_| {
        animal.sleep();
    });
}

Just removing + 'a is a little confusing?

[estebank]

@0yoyoyo ideally we would indeed suggest what you're proposing, but I can see how it might be hard. If the best we can do is change the structured suggestion with just a help note, let's leave this ticket open to eventually deal with the full suggestion. In order to do the right suggestion you might have to look for all types in the parameter list and look for structs and traits with implicit (not written out) lifetimes and point them out.

[0yoyoyo]

@estebank I agree it is difficult. And I think just removing + 'a is enough in the scope of this issue. (I wanted to make sure whether you expect for me to make full suggestion.)
I'll create PR to remove wrong + 'a.