| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/bytemuck-1.13.1/src/no_uninit.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>no_uninit.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../normalize.css"><link rel="stylesheet" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../ayu.css" disabled><link rel="stylesheet" href="../../dark.css" disabled><link rel="stylesheet" href="../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../storage.js"></script><script defer src="../../source-script.js"></script><script defer src="../../source-files.js"></script><script defer src="../../main.js"></script><noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../bytemuck/index.html"><div class="logo-container"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../bytemuck/index.html"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| </pre><pre class="rust"><code><span class="kw">use </span><span class="kw">crate</span>::Pod; |
| <span class="kw">use </span>core::num::{ |
| NonZeroI128, NonZeroI16, NonZeroI32, NonZeroI64, NonZeroI8, NonZeroIsize, |
| NonZeroU128, NonZeroU16, NonZeroU32, NonZeroU64, NonZeroU8, NonZeroUsize, |
| }; |
| |
| <span class="doccomment">/// Marker trait for "plain old data" types with no uninit (or padding) bytes. |
| /// |
| /// The requirements for this is very similar to [`Pod`], |
| /// except that it doesn't require that all bit patterns of the type are valid, |
| /// i.e. it does not require the type to be [`Zeroable`][crate::Zeroable]. |
| /// This limits what you can do with a type of this kind, but also broadens the |
| /// included types to things like C-style enums. Notably, you can only cast from |
| /// *immutable* references to a [`NoUninit`] type into *immutable* references of |
| /// any other type, no casting of mutable references or mutable references to |
| /// slices etc. |
| /// |
| /// [`Pod`] is a subset of [`NoUninit`], meaning that any `T: Pod` is also |
| /// [`NoUninit`] but any `T: NoUninit` is not necessarily [`Pod`]. If possible, |
| /// prefer implementing [`Pod`] directly. To get more [`Pod`]-like functionality |
| /// for a type that is only [`NoUninit`], consider also implementing |
| /// [`CheckedBitPattern`][crate::CheckedBitPattern]. |
| /// |
| /// # Derive |
| /// |
| /// A `#[derive(NoUninit)]` macro is provided under the `derive` feature flag |
| /// which will automatically validate the requirements of this trait and |
| /// implement the trait for you for both enums and structs. This is the |
| /// recommended method for implementing the trait, however it's also possible to |
| /// do manually. If you implement it manually, you *must* carefully follow the |
| /// below safety rules. |
| /// |
| /// # Safety |
| /// |
| /// The same as [`Pod`] except we disregard the rule about it must |
| /// allow any bit pattern (i.e. it does not need to be |
| /// [`Zeroable`][crate::Zeroable]). Still, this is a quite strong guarantee |
| /// about a type, so *be careful* whem implementing it manually. |
| /// |
| /// * The type must be inhabited (eg: no |
| /// [Infallible](core::convert::Infallible)). |
| /// * The type must not contain any uninit (or padding) bytes, either in the |
| /// middle or on the end (eg: no `#[repr(C)] struct Foo(u8, u16)`, which has |
| /// padding in the middle, and also no `#[repr(C)] struct Foo(u16, u8)`, which |
| /// has padding on the end). |
| /// * Structs need to have all fields also be `NoUninit`. |
| /// * Structs need to be `repr(C)` or `repr(transparent)`. In the case of |
| /// `repr(C)`, the `packed` and `align` repr modifiers can be used as long as |
| /// all other rules end up being followed. |
| /// * Enums need to have an explicit `#[repr(Int)]` |
| /// * Enums must have only fieldless variants |
| /// * It is disallowed for types to contain pointer types, `Cell`, `UnsafeCell`, |
| /// atomics, and any other forms of interior mutability. |
| /// * More precisely: A shared reference to the type must allow reads, and |
| /// *only* reads. RustBelt's separation logic is based on the notion that a |
| /// type is allowed to define a sharing predicate, its own invariant that must |
| /// hold for shared references, and this predicate is the reasoning that allow |
| /// it to deal with atomic and cells etc. We require the sharing predicate to |
| /// be trivial and permit only read-only access. |
| /// * There's probably more, don't mess it up (I mean it). |
| </span><span class="kw">pub unsafe trait </span>NoUninit: Sized + Copy + <span class="lifetime">'static </span>{} |
| |
| <span class="kw">unsafe impl</span><T: Pod> NoUninit <span class="kw">for </span>T {} |
| |
| <span class="kw">unsafe impl </span>NoUninit <span class="kw">for </span>char {} |
| |
| <span class="kw">unsafe impl </span>NoUninit <span class="kw">for </span>bool {} |
| |
| <span class="kw">unsafe impl </span>NoUninit <span class="kw">for </span>NonZeroU8 {} |
| <span class="kw">unsafe impl </span>NoUninit <span class="kw">for </span>NonZeroI8 {} |
| <span class="kw">unsafe impl </span>NoUninit <span class="kw">for </span>NonZeroU16 {} |
| <span class="kw">unsafe impl </span>NoUninit <span class="kw">for </span>NonZeroI16 {} |
| <span class="kw">unsafe impl </span>NoUninit <span class="kw">for </span>NonZeroU32 {} |
| <span class="kw">unsafe impl </span>NoUninit <span class="kw">for </span>NonZeroI32 {} |
| <span class="kw">unsafe impl </span>NoUninit <span class="kw">for </span>NonZeroU64 {} |
| <span class="kw">unsafe impl </span>NoUninit <span class="kw">for </span>NonZeroI64 {} |
| <span class="kw">unsafe impl </span>NoUninit <span class="kw">for </span>NonZeroU128 {} |
| <span class="kw">unsafe impl </span>NoUninit <span class="kw">for </span>NonZeroI128 {} |
| <span class="kw">unsafe impl </span>NoUninit <span class="kw">for </span>NonZeroUsize {} |
| <span class="kw">unsafe impl </span>NoUninit <span class="kw">for </span>NonZeroIsize {} |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="bytemuck" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
