Macro static_assertions::assert_impl

macro_rules! assert_impl {
    (
        $x:ty,
        $(
            $y:ident
            $(< $($args:ty),+ $(,)* >)*
        ),+ $(,)*
    ) => { ... };
    ($label:ident; $($xs:tt)+) => { ... };
}

Asserts at compile-time that the type implements the given traits.