# Error code E0186

An associated function for a trait was defined to be a method (i.e., to take a `self` parameter), but an implementation of the trait declared the same function to be static.

Erroneous code example:

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

    struct Bar;

    impl Foo for Bar {
        // error, method `foo` has a `&self` declaration in the trait, but not in
        // the impl
        fn foo() {}
    }
    }

When a type implements a trait's associated function, it has to use the same signature. So in this case, since `Foo::foo` takes `self` as argument and does not return anything, its implementation on `Bar` should be the same:

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

    struct Bar;

    impl Foo for Bar {
        fn foo(&self) {} // ok!
    }
    }