// This test used to be part of a run-pass test, but revised outlives // rule means that it no longer compiles. #![allow(unused_variables)] trait Trait<'a> { fn long(&'a self) -> isize; fn short<'b>(&'b self) -> isize; } fn object_invoke1<'d>(x: &'d dyn Trait<'d>) -> (isize, isize) { loop { } } trait MakerTrait { fn mk() -> Self; } fn make_val() -> T { MakerTrait::mk() } impl<'t> MakerTrait for Box+'static> { fn mk() -> Box+'static> { loop { } } } pub fn main() { let m : Box = make_val(); assert_eq!(object_invoke1(&*m), (4,5)); //~^ ERROR `*m` does not live long enough // the problem here is that the full type of `m` is // // Box+'static> // // Here `'m` must be exactly the lifetime of the variable `m`. // This is because of two requirements: // 1. First, the basic type rules require that the // type of `m`'s value outlives the lifetime of `m`. This puts a lower // bound `'m`. // // 2. Meanwhile, the signature of `object_invoke1` requires that // we create a reference of type `&'d Trait<'d>` for some `'d`. // `'d` cannot outlive `'m`, so that forces the lifetime to be `'m`. // // This then conflicts with the dropck rules, which require that // the type of `m` *strictly outlives* `'m`. Hence we get an // error. }