Macro static_assertions::assert_impl

macro_rules! assert_impl {
    ($($xs:tt)+) => { ... };
}

Asserts that the type implements the given traits.

This can be used to ensure types implement auto traits such as Send and Sync, as well as traits with blanket impls.

Examples

On stable Rust, using the macro requires a unique “label” when used in a module scope:

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

The labeling limitation is not necessary if compiling on nightly Rust with the nightly feature enabled:

#![feature(underscore_const_names)]

assert_impl!(u32, Copy, Send);

fn main() {
    assert_impl!(&str, Into<String>);
}

Raw pointers cannot be sent between threads safely:

assert_impl!(*const u8, Send);