error: concrete type differs from previous defining opaque type use
  --> $DIR/different-bound-vars.rs:13:37
   |
LL |         let _: for<'b> fn(&'b ()) = foo::<U, T>(false);
   |                                     ^^^^^^^^^^^^^^^^^^ expected `for<'a> fn(&'a ())`, got `for<'b> fn(&'b ())`
   |
note: previous use here
  --> $DIR/different-bound-vars.rs:12:37
   |
LL |         let _: for<'a> fn(&'a ()) = foo::<T, U>(false);
   |                                     ^^^^^^^^^^^^^^^^^^

error: aborting due to 1 previous error