library/coretests/tests/convert.rs

#[test]
fn convert() {
    const fn from(x: i32) -> i32 {
        i32::from(x)
    }

    const FOO: i32 = from(42);
    assert_eq!(FOO, 42);

    const fn into(x: Vec<String>) -> Vec<String> {
        x.into()
    }

    const BAR: Vec<String> = into(Vec::new());
    assert_eq!(BAR, Vec::<String>::new());
}

#[test]
fn into_as_try_into() {
    struct A;
    struct B;

    impl Into<B> for A {
        fn into(self) -> B {
            B
        }
    }

    // This wouldn't compile if the `TryInto`/`TryFrom` blanket impls used
    // `U: From<T>` instead of `T: Into<U>`
    let Ok(B) = A.try_into();
    let Ok(B) = B::try_from(A);
}