trait objects with late-bound regions and existential bounds are resolved badly

STR

fn assert_sync<T: Sync>(_t: T) {}

fn main() {
    let f: &(for<'a> Sync + Fn(&'a u32)->&'a u32) = &|x| x;
    assert_sync(f);
}

Expected Result

Code should compile and run

Actual result

<anon>:4:33: 4:35 error: use of undeclared lifetime name `'a` [E0261]
<anon>:4     let f: &(for<'a> Sync + Fn(&'a u32)->&'a u32) = &|x| x;
                                         ^~
<anon>:4:33: 4:35 help: see the detailed explanation for E0261
<anon>:4:43: 4:45 error: use of undeclared lifetime name `'a` [E0261]
<anon>:4     let f: &(for<'a> Sync + Fn(&'a u32)->&'a u32) = &|x| x;
                                                   ^~
<anon>:4:43: 4:45 help: see the detailed explanation for E0261
error: aborting due to 2 previous errors

1. Traige: still reproduces. Updated code that's had dyn added and rustfmt'd:

   fn assert_sync<T: Sync>(_t: T) {}
   
   fn main() {
       let f: &(dyn for<'a> Sync + Fn(&'a u32) -> &'a u32) = &|x| x;
       assert_sync(f);
   }
   
   

   Steve Klabnik at 2019-12-25 16:35:36