src/test/ui/regions/regions-variance-invariant-use-covariant.rs

   1 // Test that a type which is invariant with respect to its region
   2 // parameter used in a covariant way yields an error.
   3 //
   4 // Note: see variance-regions-*.rs for the tests that check that the
   5 // variance inference works in the first place.
   6
   7 struct Invariant<'a> {
   8     f: &'a mut &'a isize
   9 }
  10
  11 fn use_<'b>(c: Invariant<'b>) {
  12
  13     // For this assignment to be legal, Invariant<'b> <: Invariant<'static>.
  14     // Since 'b <= 'static, this would be true if Invariant were covariant
  15     // with respect to its parameter 'a.
  16
  17     let _: Invariant<'static> = c;
  18     //~^ ERROR lifetime may not live long enough
  19 }
  20
  21 fn main() { }