src/test/ui/hrtb/hrtb-just-for-static.rs

   1 // Test a case where you have an impl of `Foo<X>` for all `X` that
   2 // is being applied to `for<'a> Foo<&'a mut X>`. Issue #19730.
   3
   4 trait Foo<X> {
   5     fn foo(&self, x: X) { }
   6 }
   7
   8 fn want_hrtb<T>()
   9     where T : for<'a> Foo<&'a isize>
  10 {
  11 }
  12
  13 // AnyInt implements Foo<&'a isize> for any 'a, so it is a match.
  14 struct AnyInt;
  15 impl<'a> Foo<&'a isize> for AnyInt { }
  16 fn give_any() {
  17     want_hrtb::<AnyInt>()
  18 }
  19
  20 // StaticInt only implements Foo<&'static isize>, so it is an error.
  21 struct StaticInt;
  22 impl Foo<&'static isize> for StaticInt { }
  23 fn give_static() {
  24     want_hrtb::<StaticInt>() //~ ERROR
  25 }
  26
  27 // &'a u32 only implements Foo<&'a isize> for specific 'a, so it is an error.
  28 impl<'a> Foo<&'a isize> for &'a u32 { }
  29 fn give_some<'a>() {
  30     want_hrtb::<&'a u32>()
  31     //~^ ERROR lifetime may not live long enough
  32     //~| ERROR implementation of `Foo` is not general enough
  33 }
  34
  35 fn main() { }