82 lines
2.0 KiB
Rust
82 lines
2.0 KiB
Rust
// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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#![feature(untagged_unions)]
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#![allow(unions_with_drop_fields)]
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#[repr(C)]
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struct Pair<T, U>(T, U);
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#[repr(C)]
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struct Triple<T>(T, T, T);
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#[repr(C)]
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union U<A, B> {
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a: Pair<A, A>,
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b: B,
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}
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#[repr(C)]
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union W<A, B> {
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a: A,
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b: B,
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}
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#[cfg(target_endian = "little")]
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unsafe fn check() {
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let mut u = U::<u8, u16> { b: 0xDE_DE };
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u.a.0 = 0xBE;
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assert_eq!(u.b, 0xDE_BE);
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let mut u = U::<u16, u32> { b: 0xDEAD_DEAD };
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u.a.0 = 0xBEEF;
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assert_eq!(u.b, 0xDEAD_BEEF);
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let mut u = U::<u32, u64> { b: 0xDEADBEEF_DEADBEEF };
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u.a.0 = 0xBAADF00D;
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assert_eq!(u.b, 0xDEADBEEF_BAADF00D);
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let mut w = W::<Pair<Triple<u8>, u8>, u32> { b: 0xDEAD_DEAD };
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w.a.0 = Triple(0, 0, 0);
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assert_eq!(w.b, 0xDE00_0000);
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let mut w = W::<Pair<u8, Triple<u8>>, u32> { b: 0xDEAD_DEAD };
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w.a.1 = Triple(0, 0, 0);
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assert_eq!(w.b, 0x0000_00AD);
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}
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#[cfg(target_endian = "big")]
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unsafe fn check() {
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let mut u = U::<u8, u16> { b: 0xDE_DE };
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u.a.0 = 0xBE;
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assert_eq!(u.b, 0xBE_DE);
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let mut u = U::<u16, u32> { b: 0xDEAD_DEAD };
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u.a.0 = 0xBEEF;
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assert_eq!(u.b, 0xBEEF_DEAD);
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let mut u = U::<u32, u64> { b: 0xDEADBEEF_DEADBEEF };
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u.a.0 = 0xBAADF00D;
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assert_eq!(u.b, 0xBAADF00D_DEADBEEF);
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let mut w = W::<Pair<Triple<u8>, u8>, u32> { b: 0xDEAD_DEAD };
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w.a.0 = Triple(0, 0, 0);
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assert_eq!(w.b, 0x0000_00AD);
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let mut w = W::<Pair<u8, Triple<u8>>, u32> { b: 0xDEAD_DEAD };
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w.a.1 = Triple(0, 0, 0);
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assert_eq!(w.b, 0xDE00_0000);
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}
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fn main() {
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unsafe {
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check();
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}
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}
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