E0050 - Error codes index
Description: Book listing all Rust error codes

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# Error code E0050

An attempted implementation of a trait method has the wrong number of function parameters.

Erroneous code example:

    #![allow(unused)]
    fn main() {
    trait Foo {
        fn foo(&self, x: u8) -> bool;
    }

    struct Bar;

    // error: method `foo` has 1 parameter but the declaration in trait `Foo::foo`
    // has 2
    impl Foo for Bar {
        fn foo(&self) -> bool { true }
    }
    }

For example, the `Foo` trait has a method `foo` with two function parameters (`&self` and `u8`), but the implementation of `foo` for the type `Bar` omits the `u8` parameter. To fix this error, they must have the same parameters:

    #![allow(unused)]
    fn main() {
    trait Foo {
        fn foo(&self, x: u8) -> bool;
    }

    struct Bar;

    impl Foo for Bar {
        fn foo(&self, x: u8) -> bool { // ok!
            true
        }
    }
    }