error[E0057]: this function takes 1 argument but 0 arguments were supplied --> $DIR/E0057.rs:3:13 | LL | let a = f(); | ^-- an argument is missing | note: closure defined here --> $DIR/E0057.rs:2:13 | LL | let f = |x| x * 3; | ^^^ help: provide the argument | LL | let a = f(/* x */); | ~~~~~~~~~ error[E0057]: this function takes 1 argument but 2 arguments were supplied --> $DIR/E0057.rs:5:13 | LL | let c = f(2, 3); | ^ --- | | | | | unexpected argument of type `{integer}` | help: remove the extra argument | note: closure defined here --> $DIR/E0057.rs:2:13 | LL | let f = |x| x * 3; | ^^^ error: aborting due to 2 previous errors For more information about this error, try `rustc --explain E0057`.