//! Validity must be satisfiable, even if validity is assumed. #![crate_type = "lib"] #![feature(transmutability)] #![allow(dead_code, incomplete_features, non_camel_case_types)] mod assert { use std::mem::BikeshedIntrinsicFrom; pub struct Context; pub fn is_maybe_transmutable() where Dst: BikeshedIntrinsicFrom // validity IS assumed --------------------------------^^^^ {} } #[derive(Clone, Copy)] #[repr(u8)] enum Ox00 { V = 0x00 } #[derive(Clone, Copy)] #[repr(u8)] enum Ox01 { V = 0x01 } #[derive(Clone, Copy)] #[repr(u8)] enum OxFF { V = 0xFF } fn test() { #[repr(C)] union A { a: Ox00, b: OxFF, } #[repr(C)] union B { c: Ox01, } assert::is_maybe_transmutable::(); //~ ERROR cannot be safely transmuted assert::is_maybe_transmutable::(); //~ ERROR cannot be safely transmuted }