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# Error code E0053

The parameters of any trait method must match between a trait implementation and the trait definition.

Erroneous code example:

    #![allow(unused)]
    fn main() {
    trait Foo {
        fn foo(x: u16);
        fn bar(&self);
    }

    struct Bar;

    impl Foo for Bar {
        // error, expected u16, found i16
        fn foo(x: i16) { }

        // error, types differ in mutability
        fn bar(&mut self) { }
    }
    }