error[E0631]: type mismatch in function arguments --> $DIR/enum-variant-arg-mismatch.rs:8:9 | LL | Ident(&'a str), | ----- found signature defined here ... LL | map(Sexpr::Ident); | --- ^^^^^^^^^^^^ expected due to this | | | required by a bound introduced by this call | = note: expected function signature `fn(String) -> _` found function signature `fn(&str) -> _` note: required by a bound in `map` --> $DIR/enum-variant-arg-mismatch.rs:5:15 | LL | fn map<'a, F: Fn(String) -> Sexpr<'a>>(f: F) {} | ^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `map` error: aborting due to previous error For more information about this error, try `rustc --explain E0631`.