tests/ui/specialization/issue-40582.rs

   1 // check-pass
   2 // known-bug: #40582
   3
   4 // Should fail. Should not be possible to implement `make_static`.
   5
   6 #![feature(specialization)]
   7 #![allow(incomplete_features)]
   8
   9 trait FromRef<'a, T: ?Sized> {
  10     fn from_ref(r: &'a T) -> Self;
  11 }
  12
  13 impl<'a, T: ?Sized> FromRef<'a, T> for &'a T {
  14     fn from_ref(r: &'a T) -> Self {
  15         r
  16     }
  17 }
  18
  19 impl<'a, T: ?Sized, R> FromRef<'a, T> for R {
  20     default fn from_ref(_: &'a T) -> Self {
  21         unimplemented!()
  22     }
  23 }
  24
  25 fn make_static<T: ?Sized>(data: &T) -> &'static T {
  26     fn helper<T: ?Sized, R>(data: &T) -> R {
  27         R::from_ref(data)
  28     }
  29     helper(data)
  30 }
  31
  32 fn main() {
  33     let s = "specialization".to_owned();
  34     println!("{:?}", make_static(s.as_str()));
  35 }