src/test/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 // revisions: base nll
   7 // ignore-compare-mode-nll
   8 //[nll] compile-flags: -Z borrowck=mir
   9
  10 trait Trait1<'x> {
  11     type Foo;
  12 }
  13
  14 // calling this fn should trigger a check that the type argument
  15 // supplied is well-formed.
  16 fn wf<T>() { }
  17
  18 fn func<'x, T:Trait1<'x>>(t: &'x T::Foo)
  19 {
  20     wf::<&'x T>();
  21     //~^ ERROR the parameter type `T` may not live long enough
  22 }
  23
  24 fn caller2<'x, T:Trait1<'x>>(t: &'x T)
  25 {
  26     wf::<&'x T::Foo>(); // OK
  27 }
  28
  29 fn caller3<'x, T:Trait1<'x>>(t: &'x T::Foo)
  30 {
  31     wf::<&'x T::Foo>(); // OK
  32 }
  33
  34 fn main() { }