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! } }