#![crate_type = "lib"] #![feature(transmutability)] #![allow(dead_code)] mod assert { use std::mem::{Assume, BikeshedIntrinsicFrom}; pub fn is_maybe_transmutable() where Dst: BikeshedIntrinsicFrom< Src, { Assume { alignment: true, lifetimes: true, safety: true, validity: true } }, >, { } } fn test() { type NaughtyLenArray = [u32; 3.14159]; //~ ERROR mismatched types type JustUnit = (); assert::is_maybe_transmutable::(); }