//@ run-pass //! Test that #[derive(Copy, Clone)] produces a shallow copy //! even when a member violates RFC 1521 use std::sync::atomic::{AtomicBool, Ordering}; /// A struct that pretends to be Copy, but actually does something /// in its Clone impl #[derive(Copy)] struct Liar; /// Static cooperating with the rogue Clone impl static CLONED: AtomicBool = AtomicBool::new(false); impl Clone for Liar { fn clone(&self) -> Self { // this makes Clone vs Copy observable CLONED.store(true, Ordering::SeqCst); *self } } /// This struct is actually Copy... at least, it thinks it is! #[derive(Copy, Clone)] struct Innocent(#[allow(dead_code)] Liar); impl Innocent { fn new() -> Self { Innocent(Liar) } } fn main() { let _ = Innocent::new().clone(); // if Innocent was byte-for-byte copied, CLONED will still be false assert!(!CLONED.load(Ordering::SeqCst)); }