Joshua Liebow-Feeser

When you were a kid, you had to learn to brush your teeth. It may be easy now, but at one point it was a skill. You would get toothpaste everywhere, and your mom or dad would have to remind you to brush every tooth.

Imagine you're writing this macro:

/// Types that can be frobnicated.
///
/// # Safety
///
/// It must be sound to frobnicate `Self`.
unsafe trait Frobnicatable {}

/// Implements `Frobnicatable` for `$t`.
///
/// # Safety
///
/// `$t` must satisfy the safety invariant of `Frobnicatable`.
macro_rules! unsafe_impl_frobnicatable {
    ($t:ty) => {
        // SAFETY: The caller has promised that `$t` satisfies
        // the safety invariant of `Frobnicatable`.
        unsafe impl Frobnicatable for $t {}  
    };
}