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// Test the interaction between rested RPIT and HRTB.
trait Foo<'a> {
type Assoc;
}
impl Foo<'_> for () {
type Assoc = ();
}
// Alternative version of `Foo` whose impl uses `'a`.
trait Bar<'a> {
type Assoc;
}
impl<'a> Bar<'a> for () {
type Assoc = &'a ();
}
trait Qux<'a> {}
impl Qux<'_> for () {}
// This is not supported.
fn one_hrtb_outlives() -> impl for<'a> Foo<'a, Assoc = impl Sized + 'a> {}
//~^ ERROR `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
// This is not supported.
fn one_hrtb_trait_param() -> impl for<'a> Foo<'a, Assoc = impl Qux<'a>> {}
//~^ ERROR `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
fn one_hrtb_outlives_uses() -> impl for<'a> Bar<'a, Assoc = impl Sized + 'a> {}
//~^ ERROR `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
//~| ERROR implementation of `Bar` is not general enough
fn one_hrtb_trait_param_uses() -> impl for<'a> Bar<'a, Assoc = impl Qux<'a>> {}
//~^ ERROR `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
//~| ERROR: the trait bound `for<'a> &'a (): Qux<'_>` is not satisfied
// This should resolve.
fn one_hrtb_mention_fn_trait_param<'b>() -> impl for<'a> Foo<'a, Assoc = impl Qux<'b>> {}
// This should resolve.
fn one_hrtb_mention_fn_outlives<'b>() -> impl for<'a> Foo<'a, Assoc = impl Sized + 'b> {}
// This should resolve.
fn one_hrtb_mention_fn_trait_param_uses<'b>() -> impl for<'a> Bar<'a, Assoc = impl Qux<'b>> {}
//~^ ERROR: the trait bound `for<'a> &'a (): Qux<'b>` is not satisfied
// This should resolve.
fn one_hrtb_mention_fn_outlives_uses<'b>() -> impl for<'a> Bar<'a, Assoc = impl Sized + 'b> {}
//~^ ERROR implementation of `Bar` is not general enough
// This should resolve.
fn two_htrb_trait_param() -> impl for<'a> Foo<'a, Assoc = impl for<'b> Qux<'b>> {}
// `'b` is not in scope for the outlives bound.
fn two_htrb_outlives() -> impl for<'a> Foo<'a, Assoc = impl for<'b> Sized + 'b> {}
//~^ ERROR use of undeclared lifetime name `'b` [E0261]
// This should resolve.
fn two_htrb_trait_param_uses() -> impl for<'a> Bar<'a, Assoc = impl for<'b> Qux<'b>> {}
//~^ ERROR: the trait bound `for<'a, 'b> &'a (): Qux<'b>` is not satisfied
// `'b` is not in scope for the outlives bound.
fn two_htrb_outlives_uses() -> impl for<'a> Bar<'a, Assoc = impl for<'b> Sized + 'b> {}
//~^ ERROR use of undeclared lifetime name `'b` [E0261]
//~| ERROR implementation of `Bar` is not general enough
fn main() {}
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