77 lines
2 KiB
Rust
77 lines
2 KiB
Rust
// Copyright 2019 The Fuchsia Authors
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//
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// Licensed under a BSD-style license <LICENSE-BSD>, Apache License, Version 2.0
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// <LICENSE-APACHE or https://www.apache.org/licenses/LICENSE-2.0>, or the MIT
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// license <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your option.
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// This file may not be copied, modified, or distributed except according to
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// those terms.
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#![allow(warnings)]
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use std::{marker::PhantomData, option::IntoIter};
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use {static_assertions::assert_impl_all, zerocopy::Unaligned};
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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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assert_impl_all!(Foo: Unaligned);
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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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// NOTE: The `u16` type is not guaranteed to have alignment 2, although it
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// does on many platforms. However, to fix this would require a custom type
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// with a `#[repr(align(2))]` attribute, and `#[repr(packed)]` types are not
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// allowed to transitively contain `#[repr(align(...))]` types. Thus, we
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// have no choice but to use `u16` here. Luckily, these tests run in CI on
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// platforms on which `u16` has alignment 2, so this isn't that big of a
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// deal.
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a: u16,
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}
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assert_impl_all!(Baz: Unaligned);
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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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assert_impl_all!(FooAlign: Unaligned);
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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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assert_impl_all!(TypeParams<'static, (), IntoIter<()>>: Unaligned);
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