src/test/ui/inference/type-infer-generalize-ty-var.rs

   1 // run-pass
   2
   3 #![allow(non_upper_case_globals)]
   4 #![allow(dead_code)]
   5 #![allow(unused_assignments)]
   6 #![allow(unused_variables)]
   7 // Test a scenario where we generate a constraint like `?1 <: &?2`.
   8 // In such a case, it is important that we instantiate `?1` with `&?3`
   9 // where `?3 <: ?2`, and not with `&?2`. This is a regression test for
  10 // #18653. The important thing is that we build.
  11
  12 use std::cell::RefCell;
  13
  14 enum Wrap<A> {
  15     WrapSome(A),
  16     WrapNone
  17 }
  18
  19 use Wrap::*;
  20
  21 struct T;
  22 struct U;
  23
  24 trait Get<T: ?Sized> {
  25     fn get(&self) -> &T;
  26 }
  27
  28 impl Get<dyn MyShow + 'static> for Wrap<T> {
  29     fn get(&self) -> &(dyn MyShow + 'static) {
  30         static x: usize = 42;
  31         &x
  32     }
  33 }
  34
  35 impl Get<usize> for Wrap<U> {
  36     fn get(&self) -> &usize {
  37         static x: usize = 55;
  38         &x
  39     }
  40 }
  41
  42 trait MyShow { fn dummy(&self) { } }
  43 impl<'a> MyShow for &'a (dyn MyShow + 'a) { }
  44 impl MyShow for usize { }
  45 fn constrain<'a>(rc: RefCell<&'a (dyn MyShow + 'a)>) { }
  46
  47 fn main() {
  48     let mut collection: Wrap<_> = WrapNone;
  49
  50     {
  51         let __arg0 = Get::get(&collection);
  52         let __args_cell = RefCell::new(__arg0);
  53         constrain(__args_cell);
  54     }
  55     collection = WrapSome(T);
  56 }