error[E0666]: nested `impl Trait` is not allowed --> $DIR/nested_impl_trait.rs:5:56 | LL | fn bad_in_ret_position(x: impl Into) -> impl Into { x } | ----------^^^^^^^^^^- | | | | | nested `impl Trait` here | outer `impl Trait` error[E0666]: nested `impl Trait` is not allowed --> $DIR/nested_impl_trait.rs:9:42 | LL | fn bad_in_fn_syntax(x: fn() -> impl Into) {} | ----------^^^^^^^^^^- | | | | | nested `impl Trait` here | outer `impl Trait` error[E0666]: nested `impl Trait` is not allowed --> $DIR/nested_impl_trait.rs:13:37 | LL | fn bad_in_arg_position(_: impl Into) { } | ----------^^^^^^^^^^- | | | | | nested `impl Trait` here | outer `impl Trait` error[E0666]: nested `impl Trait` is not allowed --> $DIR/nested_impl_trait.rs:18:44 | LL | fn bad(x: impl Into) -> impl Into { x } | ----------^^^^^^^^^^- | | | | | nested `impl Trait` here | outer `impl Trait` error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `fn` pointer return --> $DIR/nested_impl_trait.rs:9:32 | LL | fn bad_in_fn_syntax(x: fn() -> impl Into) {} | ^^^^^^^^^^^^^^^^^^^^^ error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait return --> $DIR/nested_impl_trait.rs:27:42 | LL | fn allowed_in_ret_type() -> impl Fn() -> impl Into { | ^^^^^^^^^^^^^^ error[E0277]: the trait bound `impl Debug: From>` is not satisfied --> $DIR/nested_impl_trait.rs:5:46 | LL | fn bad_in_ret_position(x: impl Into) -> impl Into { x } | ^^^^^^^^^^^^^^^^^^^^^ the trait `From>` is not implemented for `impl Debug` | = help: the trait `Into` is implemented for `T` = note: required because of the requirements on the impl of `Into` for `impl Into` error[E0277]: the trait bound `impl Debug: From>` is not satisfied --> $DIR/nested_impl_trait.rs:18:34 | LL | fn bad(x: impl Into) -> impl Into { x } | ^^^^^^^^^^^^^^^^^^^^^ the trait `From>` is not implemented for `impl Debug` | = help: the trait `Into` is implemented for `T` = note: required because of the requirements on the impl of `Into` for `impl Into` error: aborting due to 8 previous errors Some errors have detailed explanations: E0277, E0562, E0666. For more information about an error, try `rustc --explain E0277`.