tests/ui/regions/regions-implied-bounds-projection-gap-1.rs

   1 // Illustrates the "projection gap": in this test, even though we know
   2 // that `T::Foo: 'x`, that does not tell us that `T: 'x`, because
   3 // there might be other ways for the caller of `func` to show that
   4 // `T::Foo: 'x` holds (e.g., where-clause).
   5
   6 trait Trait1<'x> {
   7     type Foo;
   8 }
   9
  10 // calling this fn should trigger a check that the type argument
  11 // supplied is well-formed.
  12 fn wf<T>() { }
  13
  14 fn func<'x, T:Trait1<'x>>(t: &'x T::Foo)
  15 {
  16     wf::<&'x T>();
  17     //~^ ERROR the parameter type `T` may not live long enough
  18 }
  19
  20 fn caller2<'x, T:Trait1<'x>>(t: &'x T)
  21 {
  22     wf::<&'x T::Foo>(); // OK
  23 }
  24
  25 fn caller3<'x, T:Trait1<'x>>(t: &'x T::Foo)
  26 {
  27     wf::<&'x T::Foo>(); // OK
  28 }
  29
  30 fn main() { }