src/test/ui/impl-trait/needs_least_region_or_bound.rs

   1 // check-pass
   2
   3 trait MultiRegionTrait<'a, 'b> {}
   4 impl<'a, 'b> MultiRegionTrait<'a, 'b> for (&'a u32, &'b u32) {}
   5
   6 fn no_least_region<'a, 'b>(x: &'a u32, y: &'b u32) -> impl MultiRegionTrait<'a, 'b> {
   7     // Here we have a constraint that:
   8     //
   9     // (x, y) has type (&'0 u32, &'1 u32)
  10     //
  11     // where
  12     //
  13     // 'a: '0
  14     //
  15     // then we require that `('0 u32, &'1 u32): MultiRegionTrait<'a,
  16     // 'b>`, which winds up imposing a requirement that `'0 = 'a` and
  17     // `'1 = 'b`.
  18     (x, y)
  19 }
  20
  21 fn main() {}