src/test/ui/type-alias-impl-trait/type-alias-impl-trait.rs

   1 // run-pass
   2
   3 #![allow(dead_code)]
   4 #![allow(unused_assignments)]
   5 #![allow(unused_variables)]
   6 #![feature(type_alias_impl_trait)]
   7
   8 fn main() {
   9     assert_eq!(foo().to_string(), "foo");
  10     assert_eq!(bar1().to_string(), "bar1");
  11     assert_eq!(bar2().to_string(), "bar2");
  12     let mut x = bar1();
  13     x = bar2();
  14     assert_eq!(boo::boo().to_string(), "boo");
  15     assert_eq!(my_iter(42u8).collect::<Vec<u8>>(), vec![42u8]);
  16 }
  17
  18 // single definition
  19 type Foo = impl std::fmt::Display;
  20
  21 fn foo() -> Foo {
  22     "foo"
  23 }
  24
  25 // two definitions
  26 type Bar = impl std::fmt::Display;
  27
  28 fn bar1() -> Bar {
  29     "bar1"
  30 }
  31
  32 fn bar2() -> Bar {
  33     "bar2"
  34 }
  35
  36 // definition in submodule
  37 type Boo = impl std::fmt::Display;
  38
  39 mod boo {
  40     pub fn boo() -> super::Boo {
  41         "boo"
  42     }
  43 }
  44
  45 type MyIter<T> = impl Iterator<Item = T>;
  46
  47 fn my_iter<T>(t: T) -> MyIter<T> {
  48     std::iter::once(t)
  49 }
  50
  51 fn my_iter2<T>(t: T) -> MyIter<T> {
  52     std::iter::once(t)
  53 }
  54
  55 // param names should not have an effect!
  56 fn my_iter3<U>(u: U) -> MyIter<U> {
  57     std::iter::once(u)
  58 }
  59
  60 // param position should not have an effect!
  61 fn my_iter4<U, V>(_: U, v: V) -> MyIter<V> {
  62     std::iter::once(v)
  63 }
  64
  65 // param names should not have an effect!
  66 type MyOtherIter<T> = impl Iterator<Item = T>;
  67
  68 fn my_other_iter<U>(u: U) -> MyOtherIter<U> {
  69     std::iter::once(u)
  70 }
  71
  72 trait Trait {}
  73 type GenericBound<'a, T: Trait> = impl Sized + 'a;
  74
  75 fn generic_bound<'a, T: Trait + 'a>(t: T) -> GenericBound<'a, T> {
  76     t
  77 }
  78
  79 mod pass_through {
  80     pub type Passthrough<T> = impl Sized + 'static;
  81
  82     fn define_passthrough<T: 'static>(t: T) -> Passthrough<T> {
  83         t
  84     }
  85 }
  86
  87 fn use_passthrough(x: pass_through::Passthrough<u32>) -> pass_through::Passthrough<u32> {
  88     x
  89 }