83 lines
1.4 KiB
Rust
83 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::AsBytes;
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struct IsAsBytes<T: AsBytes>(T);
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// Fail compilation if `$ty: !AsBytes`.
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macro_rules! is_as_bytes {
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($ty:ty) => {
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const _: () = {
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let _: IsAsBytes<$ty>;
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};
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};
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}
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// A union is `AsBytes` if:
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// - all fields are `AsBytes`
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// - `repr(C)` or `repr(transparent)` and
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// - no padding (size of union equals size of each field type)
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// - `repr(packed)`
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#[derive(AsBytes, Clone, Copy)]
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#[repr(C)]
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union CZst {
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a: (),
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}
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is_as_bytes!(CZst);
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#[derive(AsBytes)]
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#[repr(C)]
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union C {
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a: u8,
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b: u8,
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}
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is_as_bytes!(C);
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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(AsBytes)]
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// #[repr(transparent)]
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// union Transparent {
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// a: u8,
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// b: CZst,
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// }
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// is_as_bytes!(Transparent);
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#[derive(AsBytes)]
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#[repr(C, packed)]
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union CZstPacked {
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a: (),
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}
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is_as_bytes!(CZstPacked);
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#[derive(AsBytes)]
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#[repr(C, packed)]
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union CPacked {
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a: u8,
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b: i8,
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}
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is_as_bytes!(CPacked);
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#[derive(AsBytes)]
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#[repr(C, packed)]
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union CMultibytePacked {
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a: i32,
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b: u32,
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c: f32,
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}
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is_as_bytes!(CMultibytePacked);
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