// check-pass

#![allow(dead_code)]
#![allow(unused_assignments)]
#![allow(unused_variables)]
#![feature(type_alias_impl_trait)]

fn main() {
    assert_eq!(foo().to_string(), "foo");
    assert_eq!(bar1().to_string(), "bar1");
    assert_eq!(bar2().to_string(), "bar2");
    let mut x = bar1();
    x = bar2();
    assert_eq!(my_iter(42u8).collect::<Vec<u8>>(), vec![42u8]);
}

use defining_use_scope::*;

mod defining_use_scope {
    // single definition
    pub type Foo = impl std::fmt::Display;

    pub fn foo() -> Foo {
        "foo"
    }

    // two definitions
    pub type Bar = impl std::fmt::Display;

    pub fn bar1() -> Bar {
        "bar1"
    }

    pub fn bar2() -> Bar {
        "bar2"
    }

    pub type MyIter<T> = impl Iterator<Item = T>;

    pub fn my_iter<T>(t: T) -> MyIter<T> {
        std::iter::once(t)
    }

    fn my_iter2<T>(t: T) -> MyIter<T> {
        std::iter::once(t)
    }

    // param names should not have an effect!
    fn my_iter3<U>(u: U) -> MyIter<U> {
        std::iter::once(u)
    }

    // param position should not have an effect!
    fn my_iter4<U, V>(_: U, v: V) -> MyIter<V> {
        std::iter::once(v)
    }

    // param names should not have an effect!
    type MyOtherIter<T> = impl Iterator<Item = T>;

    fn my_other_iter<U>(u: U) -> MyOtherIter<U> {
        std::iter::once(u)
    }

    trait Trait {}
    type GenericBound<'a, T: Trait + 'a> = impl Sized + 'a;

    fn generic_bound<'a, T: Trait + 'a>(t: T) -> GenericBound<'a, T> {
        t
    }

    mod pass_through {
        pub type Passthrough<T: 'static> = impl Sized + 'static;

        fn define_passthrough<T: 'static>(t: T) -> Passthrough<T> {
            t
        }
    }

    fn use_passthrough(x: pass_through::Passthrough<u32>) -> pass_through::Passthrough<u32> {
        x
    }

}