src/test/ui/issues/issue-57843.rs

   1 // Regression test for an ICE that occurred with the universes code:
   2 //
   3 // The signature of the closure `|_|` was being inferred to
   4 // `exists<'r> fn(&'r u8)`. This should result in a type error since
   5 // the signature `for<'r> fn(&'r u8)` is required. However, due to a
   6 // bug in the type variable generalization code, the placeholder for
   7 // `'r` was leaking out into the writeback phase, causing an ICE.
   8
   9 trait ClonableFn<T> {
  10     fn clone(&self) -> Box<dyn Fn(T)>;
  11 }
  12
  13 impl<T, F: 'static> ClonableFn<T> for F
  14 where
  15     F: Fn(T) + Clone,
  16 {
  17     fn clone(&self) -> Box<dyn Fn(T)> {
  18         Box::new(self.clone())
  19     }
  20 }
  21
  22 struct Foo(Box<dyn for<'a> ClonableFn<&'a bool>>);
  23
  24 fn main() {
  25     Foo(Box::new(|_| ())); //~ ERROR implementation of `FnOnce` is not general enough
  26 }