tests/ui/generic-associated-types/issue-79422.rs

   1 // revisions: base extended
   2
   3 #![cfg_attr(extended, feature(generic_associated_types_extended))]
   4 #![cfg_attr(extended, allow(incomplete_features))]
   5
   6 trait RefCont<'a, T> {
   7     fn t(&'a self) -> &'a T;
   8 }
   9
  10 impl<'a, T> RefCont<'a, T> for &'a T {
  11     fn t(&'a self) -> &'a T {
  12         self
  13     }
  14 }
  15
  16 impl<'a, T> RefCont<'a, T> for Box<T> {
  17     fn t(&'a self) -> &'a T {
  18         self.as_ref()
  19     }
  20 }
  21
  22 trait MapLike<K, V> {
  23     type VRefCont<'a>: RefCont<'a, V> where Self: 'a;
  24     fn get<'a>(&'a self, key: &K) -> Option<Self::VRefCont<'a>>;
  25 }
  26
  27 impl<K: Ord, V: 'static> MapLike<K, V> for std::collections::BTreeMap<K, V> {
  28     type VRefCont<'a> = &'a V where Self: 'a;
  29     fn get<'a>(&'a self, key: &K) -> Option<&'a V> {
  30         std::collections::BTreeMap::get(self, key)
  31     }
  32 }
  33
  34 struct Source;
  35
  36 impl<K, V: Default> MapLike<K, V> for Source {
  37     type VRefCont<'a> = Box<V>;
  38     fn get<'a>(&self, _: &K) -> Option<Box<V>> {
  39         Some(Box::new(V::default()))
  40     }
  41 }
  42
  43 fn main() {
  44     let m = Box::new(std::collections::BTreeMap::<u8, u8>::new())
  45     //[base]~^ ERROR the trait
  46     //[extended]~^^ type mismatch
  47         as Box<dyn MapLike<u8, u8, VRefCont = dyn RefCont<'_, u8>>>;
  48       //~^ ERROR missing generics for associated type
  49       //[base]~^^ ERROR the trait
  50 }