Can't override trait method with RPITIT if there's an unconstrained lifetime parameter.

I tried this code:

trait Trait<'a> {}

trait Foo {
    fn lol() -> impl Sized + use<Self>;
}
impl<'a, T: Trait<'a>> Foo for T {
    fn lol() -> impl Sized + use<T> {}
}

I expected the above code to compile. Instead, I got the following error:

error[E0207]: the lifetime parameter `'a` is not constrained by the impl trait, self type, or predicates
 --> src/lib.rs:6:6
  |
6 | impl<'a, T: Trait<'a>> Foo for T {
  |      ^^ unconstrained lifetime parameter

For more information about this error, try `rustc --explain E0207`.

Changing use<T> to use<'a, T> or use<Self> doesn't fix the error.

In contrast, the default trait method body can be "inherited" without any errors:

// compiles without errors
trait Trait<'a> {}

trait Foo {
    fn lol() -> impl Sized + use<Self> {}
}
impl<'a, T: Trait<'a>> Foo for T {}

This seems very strange.

Meta

Reproducible on the playground with version 1.97.0-nightly (2026-05-04 cb40c25f6aebb637163d)

Start with the minimal reproducer in the Playground using the reported nightly version, and compare the explicit RPITIT implementation with the inherited default method. Confirm the E0207 diagnostic for the implementation and the successful compilation of the default; done means the behavior is resolved consistently with the intended lifetime handling.