Thoughts on Compile-Time Function Evaluation and Type Systems

[kennytm]

@RalfJung

My only worry is using this accidentally because unsafe opts into so many things at once.

Agreed. Perhaps require unsafe obligations:

const FALSE: bool = unsafe(const::call_non_const_fn) {
    is_ascii('😉')
};
const fn ptr_eq<T>(x: &T, y: &T) -> bool {
   unsafe(const::compare_ptrs) { x as *const _ == y as *const _ }
}