src/test/ui/traits/issue-52893.rs

   1 // check-fail
   2 //
   3 // regression test for issue 52893
   4 trait At<Name> {
   5     type AtRes;
   6     fn at(self) -> Self::AtRes;
   7 }
   8
   9 trait Push<T> {
  10     type PushRes;
  11     fn push(self, other: T) -> Self::PushRes;
  12 }
  13
  14 trait AddClass<Name, F> {
  15     type AddRes;
  16     fn init(self, func: F);
  17 }
  18
  19 trait ToRef {
  20     type RefRes;
  21     fn to_ref(&self) -> Self::RefRes;
  22 }
  23
  24 struct Class<P>(P);
  25
  26 impl<P> Class<P> {
  27     fn with<Name, F>(self) -> <Self as AddClass<Name, F>>::AddRes
  28     where
  29         Self: AddClass<Name, F>,
  30     {
  31         todo!()
  32     }
  33
  34     fn from<F>(self) -> <Self as AddClass<P, F>>::AddRes
  35     where
  36         Self: AddClass<P, F>,
  37     {
  38         todo!()
  39     }
  40 }
  41
  42 impl<F, Name, P> AddClass<Name, F> for Class<P>
  43 where
  44     Self: At<Name>,
  45     <Self as At<Name>>::AtRes: Push<F>,
  46     <<Self as At<Name>>::AtRes as Push<F>>::PushRes: ToRef<RefRes = Self> + Push<F>,
  47 {
  48     type AddRes = ();
  49
  50     fn init(self, func: F) {
  51         let builder = self.at().push(func);
  52         let output = builder.to_ref();
  53         builder.push(output); //~ ERROR mismatched types [E0308]
  54     }
  55 }
  56
  57 fn main() {}