E0057 - Error codes index
Description: Book listing all Rust error codes

# Error code E0057

An invalid number of arguments was given when calling a closure.

Erroneous code example:

    #![allow(unused)]
    fn main() {
    let f = |x| x * 3;
    let a = f();        // invalid, too few parameters
    let b = f(4);       // this works!
    let c = f(2, 3);    // invalid, too many parameters
    }

When invoking closures or other implementations of the function traits `Fn`, `FnMut` or `FnOnce` using call notation, the number of parameters passed to the function must match its definition.

A generic function must be treated similarly:

    #![allow(unused)]
    fn main() {
    fn foo<F: Fn()>(f: F) {
        f(); // this is valid, but f(3) would not work
    }
    }