error[E0644]: closure/coroutine type that references itself --> $DIR/issue-25439.rs:8:9 | LL | fix(|_, x| x); | ^^^^^^ cyclic type of infinite size | = note: closures cannot capture themselves or take themselves as argument; this error may be the result of a recent compiler bug-fix, see issue #46062 for more information note: required by a bound in `fix` --> $DIR/issue-25439.rs:3:33 | LL | fn fix(f: F) -> i32 where F: Fn(Helper, i32) -> i32 { | ^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `fix` error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0644`.