error[E0106]: missing lifetime specifier
  --> $DIR/impl-fn-hrtb-bounds.rs:19:38
   |
LL | fn d() -> impl Fn() -> (impl Debug + '_) {
   |                                      ^^ expected named lifetime parameter
   |
   = help: this function's return type contains a borrowed value, but there is no value for it to be borrowed from
help: consider using the `'static` lifetime, but this is uncommon unless you're returning a borrowed value from a `const` or a `static`, or if you will only have owned values
   |
LL | fn d() -> impl Fn() -> (impl Debug + 'static) {
   |                                      ~~~~~~~

error[E0657]: `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
  --> $DIR/impl-fn-hrtb-bounds.rs:4:41
   |
LL | fn a() -> impl Fn(&u8) -> (impl Debug + '_) {
   |                                         ^^
   |
note: lifetime declared here
  --> $DIR/impl-fn-hrtb-bounds.rs:4:19
   |
LL | fn a() -> impl Fn(&u8) -> (impl Debug + '_) {
   |                   ^

error[E0657]: `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
  --> $DIR/impl-fn-hrtb-bounds.rs:9:52
   |
LL | fn b() -> impl for<'a> Fn(&'a u8) -> (impl Debug + 'a) {
   |                                                    ^^
   |
note: lifetime declared here
  --> $DIR/impl-fn-hrtb-bounds.rs:9:20
   |
LL | fn b() -> impl for<'a> Fn(&'a u8) -> (impl Debug + 'a) {
   |                    ^^

error[E0657]: `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
  --> $DIR/impl-fn-hrtb-bounds.rs:14:52
   |
LL | fn c() -> impl for<'a> Fn(&'a u8) -> (impl Debug + '_) {
   |                                                    ^^
   |
note: lifetime declared here
  --> $DIR/impl-fn-hrtb-bounds.rs:14:20
   |
LL | fn c() -> impl for<'a> Fn(&'a u8) -> (impl Debug + '_) {
   |                    ^^

error: aborting due to 4 previous errors

Some errors have detailed explanations: E0106, E0657.
For more information about an error, try `rustc --explain E0106`.