78 lines
1.4 KiB
Rust
78 lines
1.4 KiB
Rust
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// Copyright 2019 The Fuchsia Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#![allow(warnings)]
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use std::{marker::PhantomData, option::IntoIter};
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use zerocopy::Unaligned;
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struct IsUnaligned<T: Unaligned>(T);
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// Fail compilation if `$ty: !Unaligned`.
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macro_rules! is_unaligned {
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($ty:ty) => {
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const _: () = {
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let _: IsUnaligned<$ty>;
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};
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};
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}
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// A union is `Unaligned` if:
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// - `repr(align)` is no more than 1 and either
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// - `repr(C)` or `repr(transparent)` and
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// - all fields `Unaligned`
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// - `repr(packed)`
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#[derive(Unaligned)]
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#[repr(C)]
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union Foo {
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a: u8,
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}
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is_unaligned!(Foo);
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// Transparent unions are unstable; see issue #60405
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// <https://github.com/rust-lang/rust/issues/60405> for more information.
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// #[derive(Unaligned)]
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// #[repr(transparent)]
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// union Bar {
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// a: u8,
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// }
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// is_unaligned!(Bar);
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#[derive(Unaligned)]
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#[repr(packed)]
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union Baz {
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a: u16,
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}
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is_unaligned!(Baz);
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#[derive(Unaligned)]
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#[repr(C, align(1))]
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union FooAlign {
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a: u8,
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}
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is_unaligned!(FooAlign);
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#[derive(Unaligned)]
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#[repr(C)]
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union TypeParams<'a, T: Copy, I: Iterator>
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where
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I::Item: Copy,
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{
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a: T,
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c: I::Item,
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d: u8,
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e: PhantomData<&'a [u8]>,
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f: PhantomData<&'static str>,
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g: PhantomData<String>,
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}
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is_unaligned!(TypeParams<'static, (), IntoIter<()>>);
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