error: concrete type differs from previous defining opaque type use
  --> $DIR/impl-fn-predefined-lifetimes.rs:7:9
   |
LL |     |x| x
   |         ^ expected `impl Debug + '_`, got `&u8`
   |
note: previous use here
  --> $DIR/impl-fn-predefined-lifetimes.rs:7:5
   |
LL |     |x| x
   |     ^^^^^

error[E0720]: cannot resolve opaque type
  --> $DIR/impl-fn-predefined-lifetimes.rs:4:35
   |
LL | fn a<'a>() -> impl Fn(&'a u8) -> (impl Debug + '_) {
   |                                   ^^^^^^^^^^^^^^^ cannot resolve opaque type

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0720`.