E0034 - Error codes index
Description: Book listing all Rust error codes

## Keyboard shortcuts

Press `←` or `→` to navigate between chapters

Press `S` or `/` to search in the book

Press `?` to show this help

Press `Esc` to hide this help

# Error code E0034

The compiler doesn’t know what method to call because more than one method has the same prototype.

Erroneous code example:

    struct Test;

    trait Trait1 {
        fn foo();
    }

    trait Trait2 {
        fn foo();
    }

    impl Trait1 for Test { fn foo() {} }
    impl Trait2 for Test { fn foo() {} }

    fn main() {
        Test::foo() // error, which foo() to call?
    }

To avoid this error, you have to keep only one of them and remove the others. So let’s take our example and fix it:

    struct Test;

    trait Trait1 {
        fn foo();
    }

    impl Trait1 for Test { fn foo() {} }

    fn main() {
        Test::foo() // and now that's good!
    }

However, a better solution would be using fully explicit naming of type and trait:

    struct Test;

    trait Trait1 {
        fn foo();
    }

    trait Trait2 {
        fn foo();
    }

    impl Trait1 for Test { fn foo() {} }
    impl Trait2 for Test { fn foo() {} }

    fn main() {
        <Test as Trait1>::foo()
    }

One last example:

    trait F {
        fn m(&self);
    }

    trait G {
        fn m(&self);
    }

    struct X;

    impl F for X { fn m(&self) { println!("I am F"); } }
    impl G for X { fn m(&self) { println!("I am G"); } }

    fn main() {
        let f = X;

        F::m(&f); // it displays "I am F"
        G::m(&f); // it displays "I am G"
    }