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// When WF checking the hidden type in the ParamEnv of the opaque type,
// one complication arises when the hidden type is a closure/generator:
// the "parent_substs" of the type may reference lifetime parameters
// not present in the opaque type.
// These region parameters are not really useful in this check.
// So here we ignore them and replace them with fresh region variables.
// check-pass
#![feature(type_alias_impl_trait)]
#![allow(dead_code)]
// Basic test
mod test1 {
// Hidden type = Closure['_#0r]
type Opaque = impl Sized;
fn define<'a: 'a>() -> Opaque {
|| {}
}
}
// the region vars cannot both be equal to `'static` or `'empty`
mod test2 {
trait Trait {}
// Hidden type = Closure['a, '_#0r, '_#1r]
// Constraints = [('_#0r: 'a), ('a: '_#1r)]
type Opaque<'a>
where
&'a (): Trait,
= impl Sized + 'a;
fn define<'a, 'x, 'y>() -> Opaque<'a>
where
&'a (): Trait,
'x: 'a,
'a: 'y,
{
|| {}
}
}
// the region var cannot be equal to `'a` or `'b`
mod test3 {
trait Trait {}
// Hidden type = Closure['a, 'b, '_#0r]
// Constraints = [('_#0r: 'a), ('_#0r: 'b)]
type Opaque<'a, 'b>
where
(&'a (), &'b ()): Trait,
= impl Sized + 'a + 'b;
fn define<'a, 'b, 'x>() -> Opaque<'a, 'b>
where
(&'a (), &'b ()): Trait,
'x: 'a,
'x: 'b,
{
|| {}
}
}
fn main() {}
|
