1 // Copyright 2019 The Fuchsia Authors
2 //
3 // Licensed under a BSD-style license <LICENSE-BSD>, Apache License, Version 2.0
4 // <LICENSE-APACHE or https://www.apache.org/licenses/LICENSE-2.0>, or the MIT
5 // license <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your option.
6 // This file may not be copied, modified, or distributed except according to
7 // those terms.
8 
9 #![allow(warnings)]
10 
11 #[macro_use]
12 mod util;
13 
14 use std::{marker::PhantomData, option::IntoIter};
15 
16 use {static_assertions::assert_impl_all, zerocopy::FromZeroes};
17 
18 // A union is `FromZeroes` if:
19 // - all fields are `FromZeroes`
20 
21 #[derive(Clone, Copy, FromZeroes)]
22 union Zst {
23     a: (),
24 }
25 
26 assert_impl_all!(Zst: FromZeroes);
27 
28 #[derive(FromZeroes)]
29 union One {
30     a: bool,
31 }
32 
33 assert_impl_all!(One: FromZeroes);
34 
35 #[derive(FromZeroes)]
36 union Two {
37     a: bool,
38     b: Zst,
39 }
40 
41 assert_impl_all!(Two: FromZeroes);
42 
43 #[derive(FromZeroes)]
44 union TypeParams<'a, T: Copy, I: Iterator>
45 where
46     I::Item: Copy,
47 {
48     a: T,
49     c: I::Item,
50     d: u8,
51     e: PhantomData<&'a [u8]>,
52     f: PhantomData<&'static str>,
53     g: PhantomData<String>,
54 }
55 
56 assert_impl_all!(TypeParams<'static, (), IntoIter<()>>: FromZeroes);
57 
58 // Deriving `FromZeroes` should work if the union has bounded parameters.
59 
60 #[derive(FromZeroes)]
61 #[repr(C)]
62 union WithParams<'a: 'b, 'b: 'a, const N: usize, T: 'a + 'b + FromZeroes>
63 where
64     'a: 'b,
65     'b: 'a,
66     T: 'a + 'b + Copy + FromZeroes,
67 {
68     a: [T; N],
69     b: PhantomData<&'a &'b ()>,
70 }
71 
72 assert_impl_all!(WithParams<'static, 'static, 42, u8>: FromZeroes);
73