error: ambiguous `+` in a type --> $DIR/impl-fn-parsing-ambiguities.rs:4:27 | LL | fn a() -> impl Fn(&u8) -> impl Debug + '_ { | ^^^^^^^^^^^^^^^ help: use parentheses to disambiguate: `(impl Debug + '_)` error: ambiguous `+` in a type --> $DIR/impl-fn-parsing-ambiguities.rs:10:24 | LL | fn b() -> impl Fn() -> impl Debug + Send { | ^^^^^^^^^^^^^^^^^ help: use parentheses to disambiguate: `(impl Debug + Send)` error: higher kinded lifetime bounds on nested opaque types are not supported yet --> $DIR/impl-fn-parsing-ambiguities.rs:4:40 | LL | fn a() -> impl Fn(&u8) -> impl Debug + '_ { | ^^ | note: lifetime declared here --> $DIR/impl-fn-parsing-ambiguities.rs:4:19 | LL | fn a() -> impl Fn(&u8) -> impl Debug + '_ { | ^ error: aborting due to 3 previous errors