Macro static_assertions::assert_impl

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

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

Examples

Can be used to ensure types implement Send, Sync, and other traits:

assert_impl!(str; String, Send, Sync, From<&'static str>);
assert_impl!(vec; &'static [u8], Into<Vec<u8>>);

fn main() {
    // Produces a compilation failure:
    // `*const u8` cannot be sent between threads safely
    // assert_impl!(*const u8, Send);
}