struct MyType; struct MyType2; struct MyType3; struct MyType4; impl std::fmt::Display for MyType { fn fmt(&self, x: &str) -> () { } //~^ ERROR method `fmt` has an incompatible type } impl std::fmt::Display for MyType2 { fn fmt(&self) -> () { } //~^ ERROR method `fmt` has 1 parameter } impl std::fmt::Display for MyType3 { fn fmt() -> () { } //~^ ERROR method `fmt` has a `&self` declaration in the trait } impl std::fmt::Display for MyType4 {} //~^ ERROR not all trait items fn main() {}