|
|
<!DOCTYPE HTML>
|
|
|
<html lang="zh-CN" class="light sidebar-visible" dir="ltr">
|
|
|
<head>
|
|
|
<!-- Book generated using mdBook -->
|
|
|
<meta charset="UTF-8">
|
|
|
<title>1.86 - Rust语言圣经(Rust Course)</title>
|
|
|
|
|
|
|
|
|
<!-- Custom HTML head -->
|
|
|
|
|
|
<meta name="description" content="">
|
|
|
<meta name="viewport" content="width=device-width, initial-scale=1">
|
|
|
<meta name="theme-color" content="#ffffff">
|
|
|
|
|
|
<link rel="icon" href="../../favicon-de23e50b.svg">
|
|
|
<link rel="shortcut icon" href="../../favicon-8114d1fc.png">
|
|
|
<link rel="stylesheet" href="../../css/variables-8adf115d.css">
|
|
|
<link rel="stylesheet" href="../../css/general-2459343d.css">
|
|
|
<link rel="stylesheet" href="../../css/chrome-ae938929.css">
|
|
|
<link rel="stylesheet" href="../../css/print-9e4910d8.css" media="print">
|
|
|
|
|
|
<!-- Fonts -->
|
|
|
<link rel="stylesheet" href="../../fonts/fonts-9644e21d.css">
|
|
|
|
|
|
<!-- Highlight.js Stylesheets -->
|
|
|
<link rel="stylesheet" id="mdbook-highlight-css" href="../../highlight-493f70e1.css">
|
|
|
<link rel="stylesheet" id="mdbook-tomorrow-night-css" href="../../tomorrow-night-4c0ae647.css">
|
|
|
<link rel="stylesheet" id="mdbook-ayu-highlight-css" href="../../ayu-highlight-3fdfc3ac.css">
|
|
|
|
|
|
<!-- Custom theme stylesheets -->
|
|
|
<link rel="stylesheet" href="../../theme/style-78591068.css">
|
|
|
|
|
|
|
|
|
<!-- Provide site root and default themes to javascript -->
|
|
|
<script>
|
|
|
const path_to_root = "../../";
|
|
|
const default_light_theme = "light";
|
|
|
const default_dark_theme = "navy";
|
|
|
window.path_to_searchindex_js = "../../searchindex-4a1a74fa.js";
|
|
|
</script>
|
|
|
<!-- Start loading toc.js asap -->
|
|
|
<script src="../../toc-42887675.js"></script>
|
|
|
</head>
|
|
|
<body>
|
|
|
<div id="mdbook-help-container">
|
|
|
<div id="mdbook-help-popup">
|
|
|
<h2 class="mdbook-help-title">Keyboard shortcuts</h2>
|
|
|
<div>
|
|
|
<p>Press <kbd>←</kbd> or <kbd>→</kbd> to navigate between chapters</p>
|
|
|
<p>Press <kbd>S</kbd> or <kbd>/</kbd> to search in the book</p>
|
|
|
<p>Press <kbd>?</kbd> to show this help</p>
|
|
|
<p>Press <kbd>Esc</kbd> to hide this help</p>
|
|
|
</div>
|
|
|
</div>
|
|
|
</div>
|
|
|
<div id="mdbook-body-container">
|
|
|
<!-- Work around some values being stored in localStorage wrapped in quotes -->
|
|
|
<script>
|
|
|
try {
|
|
|
let theme = localStorage.getItem('mdbook-theme');
|
|
|
let sidebar = localStorage.getItem('mdbook-sidebar');
|
|
|
|
|
|
if (theme.startsWith('"') && theme.endsWith('"')) {
|
|
|
localStorage.setItem('mdbook-theme', theme.slice(1, theme.length - 1));
|
|
|
}
|
|
|
|
|
|
if (sidebar.startsWith('"') && sidebar.endsWith('"')) {
|
|
|
localStorage.setItem('mdbook-sidebar', sidebar.slice(1, sidebar.length - 1));
|
|
|
}
|
|
|
} catch (e) { }
|
|
|
</script>
|
|
|
|
|
|
<!-- Set the theme before any content is loaded, prevents flash -->
|
|
|
<script>
|
|
|
const default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? default_dark_theme : default_light_theme;
|
|
|
let theme;
|
|
|
try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
|
|
|
if (theme === null || theme === undefined) { theme = default_theme; }
|
|
|
const html = document.documentElement;
|
|
|
html.classList.remove('light')
|
|
|
html.classList.add(theme);
|
|
|
html.classList.add("js");
|
|
|
</script>
|
|
|
|
|
|
<input type="checkbox" id="mdbook-sidebar-toggle-anchor" class="hidden">
|
|
|
|
|
|
<!-- Hide / unhide sidebar before it is displayed -->
|
|
|
<script>
|
|
|
let sidebar = null;
|
|
|
const sidebar_toggle = document.getElementById("mdbook-sidebar-toggle-anchor");
|
|
|
if (document.body.clientWidth >= 1080) {
|
|
|
try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { }
|
|
|
sidebar = sidebar || 'visible';
|
|
|
} else {
|
|
|
sidebar = 'hidden';
|
|
|
sidebar_toggle.checked = false;
|
|
|
}
|
|
|
if (sidebar === 'visible') {
|
|
|
sidebar_toggle.checked = true;
|
|
|
} else {
|
|
|
html.classList.remove('sidebar-visible');
|
|
|
}
|
|
|
</script>
|
|
|
|
|
|
<nav id="mdbook-sidebar" class="sidebar" aria-label="Table of contents">
|
|
|
<!-- populated by js -->
|
|
|
<mdbook-sidebar-scrollbox class="sidebar-scrollbox"></mdbook-sidebar-scrollbox>
|
|
|
<noscript>
|
|
|
<iframe class="sidebar-iframe-outer" src="../../toc.html"></iframe>
|
|
|
</noscript>
|
|
|
<div id="mdbook-sidebar-resize-handle" class="sidebar-resize-handle">
|
|
|
<div class="sidebar-resize-indicator"></div>
|
|
|
</div>
|
|
|
</nav>
|
|
|
|
|
|
<div id="mdbook-page-wrapper" class="page-wrapper">
|
|
|
|
|
|
<div class="page">
|
|
|
<div id="mdbook-menu-bar-hover-placeholder"></div>
|
|
|
<div id="mdbook-menu-bar" class="menu-bar sticky">
|
|
|
<div class="left-buttons">
|
|
|
<label id="mdbook-sidebar-toggle" class="icon-button" for="mdbook-sidebar-toggle-anchor" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="mdbook-sidebar">
|
|
|
<span class=fa-svg><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 448 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M0 96C0 78.3 14.3 64 32 64H416c17.7 0 32 14.3 32 32s-14.3 32-32 32H32C14.3 128 0 113.7 0 96zM0 256c0-17.7 14.3-32 32-32H416c17.7 0 32 14.3 32 32s-14.3 32-32 32H32c-17.7 0-32-14.3-32-32zM448 416c0 17.7-14.3 32-32 32H32c-17.7 0-32-14.3-32-32s14.3-32 32-32H416c17.7 0 32 14.3 32 32z"/></svg></span>
|
|
|
</label>
|
|
|
<button id="mdbook-theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="mdbook-theme-list">
|
|
|
<span class=fa-svg><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 576 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M371.3 367.1c27.3-3.9 51.9-19.4 67.2-42.9L600.2 74.1c12.6-19.5 9.4-45.3-7.6-61.2S549.7-4.4 531.1 9.6L294.4 187.2c-24 18-38.2 46.1-38.4 76.1L371.3 367.1zm-19.6 25.4l-116-104.4C175.9 290.3 128 339.6 128 400c0 3.9 .2 7.8 .6 11.6c1.8 17.5-10.2 36.4-27.8 36.4H96c-17.7 0-32 14.3-32 32s14.3 32 32 32H240c61.9 0 112-50.1 112-112c0-2.5-.1-5-.2-7.5z"/></svg></span>
|
|
|
</button>
|
|
|
<ul id="mdbook-theme-list" class="theme-popup" aria-label="Themes" role="menu">
|
|
|
<li role="none"><button role="menuitem" class="theme" id="mdbook-theme-default_theme">Auto</button></li>
|
|
|
<li role="none"><button role="menuitem" class="theme" id="mdbook-theme-light">Light</button></li>
|
|
|
<li role="none"><button role="menuitem" class="theme" id="mdbook-theme-rust">Rust</button></li>
|
|
|
<li role="none"><button role="menuitem" class="theme" id="mdbook-theme-coal">Coal</button></li>
|
|
|
<li role="none"><button role="menuitem" class="theme" id="mdbook-theme-navy">Navy</button></li>
|
|
|
<li role="none"><button role="menuitem" class="theme" id="mdbook-theme-ayu">Ayu</button></li>
|
|
|
</ul>
|
|
|
<button id="mdbook-search-toggle" class="icon-button" type="button" title="Search (`/`)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="/ s" aria-controls="mdbook-searchbar">
|
|
|
<span class=fa-svg><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M416 208c0 45.9-14.9 88.3-40 122.7L502.6 457.4c12.5 12.5 12.5 32.8 0 45.3s-32.8 12.5-45.3 0L330.7 376c-34.4 25.2-76.8 40-122.7 40C93.1 416 0 322.9 0 208S93.1 0 208 0S416 93.1 416 208zM208 352c79.5 0 144-64.5 144-144s-64.5-144-144-144S64 128.5 64 208s64.5 144 144 144z"/></svg></span>
|
|
|
</button>
|
|
|
</div>
|
|
|
|
|
|
<h1 class="menu-title">Rust语言圣经(Rust Course)</h1>
|
|
|
|
|
|
<div class="right-buttons">
|
|
|
<a href="../../print.html" title="Print this book" aria-label="Print this book">
|
|
|
<span class=fa-svg id="print-button"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M128 0C92.7 0 64 28.7 64 64v96h64V64H354.7L384 93.3V160h64V93.3c0-17-6.7-33.3-18.7-45.3L400 18.7C388 6.7 371.7 0 354.7 0H128zM384 352v32 64H128V384 368 352H384zm64 32h32c17.7 0 32-14.3 32-32V256c0-35.3-28.7-64-64-64H64c-35.3 0-64 28.7-64 64v96c0 17.7 14.3 32 32 32H64v64c0 35.3 28.7 64 64 64H384c35.3 0 64-28.7 64-64V384zm-16-88c-13.3 0-24-10.7-24-24s10.7-24 24-24s24 10.7 24 24s-10.7 24-24 24z"/></svg></span>
|
|
|
</a>
|
|
|
<a href="https://github.com/sunface/rust-course" title="Git repository" aria-label="Git repository">
|
|
|
<span class=fa-svg><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 496 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M165.9 397.4c0 2-2.3 3.6-5.2 3.6-3.3.3-5.6-1.3-5.6-3.6 0-2 2.3-3.6 5.2-3.6 3-.3 5.6 1.3 5.6 3.6zm-31.1-4.5c-.7 2 1.3 4.3 4.3 4.9 2.6 1 5.6 0 6.2-2s-1.3-4.3-4.3-5.2c-2.6-.7-5.5.3-6.2 2.3zm44.2-1.7c-2.9.7-4.9 2.6-4.6 4.9.3 2 2.9 3.3 5.9 2.6 2.9-.7 4.9-2.6 4.6-4.6-.3-1.9-3-3.2-5.9-2.9zM244.8 8C106.1 8 0 113.3 0 252c0 110.9 69.8 205.8 169.5 239.2 12.8 2.3 17.3-5.6 17.3-12.1 0-6.2-.3-40.4-.3-61.4 0 0-70 15-84.7-29.8 0 0-11.4-29.1-27.8-36.6 0 0-22.9-15.7 1.6-15.4 0 0 24.9 2 38.6 25.8 21.9 38.6 58.6 27.5 72.9 20.9 2.3-16 8.8-27.1 16-33.7-55.9-6.2-112.3-14.3-112.3-110.5 0-27.5 7.6-41.3 23.6-58.9-2.6-6.5-11.1-33.3 2.6-67.9 20.9-6.5 69 27 69 27 20-5.6 41.5-8.5 62.8-8.5s42.8 2.9 62.8 8.5c0 0 48.1-33.6 69-27 13.7 34.7 5.2 61.4 2.6 67.9 16 17.7 25.8 31.5 25.8 58.9 0 96.5-58.9 104.2-114.8 110.5 9.2 7.9 17 22.9 17 46.4 0 33.7-.3 75.4-.3 83.6 0 6.5 4.6 14.4 17.3 12.1C428.2 457.8 496 362.9 496 252 496 113.3 383.5 8 244.8 8zM97.2 352.9c-1.3 1-1 3.3.7 5.2 1.6 1.6 3.9 2.3 5.2 1 1.3-1 1-3.3-.7-5.2-1.6-1.6-3.9-2.3-5.2-1zm-10.8-8.1c-.7 1.3.3 2.9 2.3 3.9 1.6 1 3.6.7 4.3-.7.7-1.3-.3-2.9-2.3-3.9-2-.6-3.6-.3-4.3.7zm32.4 35.6c-1.6 1.3-1 4.3 1.3 6.2 2.3 2.3 5.2 2.6 6.5 1 1.3-1.3.7-4.3-1.3-6.2-2.2-2.3-5.2-2.6-6.5-1zm-11.4-14.7c-1.6 1-1.6 3.6 0 5.9 1.6 2.3 4.3 3.3 5.6 2.3 1.6-1.3 1.6-3.9 0-6.2-1.4-2.3-4-3.3-5.6-2z"/></svg></span>
|
|
|
</a>
|
|
|
<a href="https://github.com/sunface/rust-course/edit/main/src/appendix/rust-versions/1.86.md" title="Suggest an edit" aria-label="Suggest an edit" rel="edit">
|
|
|
<span class=fa-svg id="git-edit-button"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M421.7 220.3l-11.3 11.3-22.6 22.6-205 205c-6.6 6.6-14.8 11.5-23.8 14.1L30.8 511c-8.4 2.5-17.5 .2-23.7-6.1S-1.5 489.7 1 481.2L38.7 353.1c2.6-9 7.5-17.2 14.1-23.8l205-205 22.6-22.6 11.3-11.3 33.9 33.9 62.1 62.1 33.9 33.9zM96 353.9l-9.3 9.3c-.9 .9-1.6 2.1-2 3.4l-25.3 86 86-25.3c1.3-.4 2.5-1.1 3.4-2l9.3-9.3H112c-8.8 0-16-7.2-16-16V353.9zM453.3 19.3l39.4 39.4c25 25 25 65.5 0 90.5l-14.5 14.5-22.6 22.6-11.3 11.3-33.9-33.9-62.1-62.1L314.3 67.7l11.3-11.3 22.6-22.6 14.5-14.5c25-25 65.5-25 90.5 0z"/></svg></span>
|
|
|
</a>
|
|
|
|
|
|
</div>
|
|
|
</div>
|
|
|
|
|
|
<div id="mdbook-search-wrapper" class="hidden">
|
|
|
<form id="mdbook-searchbar-outer" class="searchbar-outer">
|
|
|
<div class="search-wrapper">
|
|
|
<input type="search" id="mdbook-searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="mdbook-searchresults-outer" aria-describedby="searchresults-header">
|
|
|
<div class="spinner-wrapper">
|
|
|
<span class=fa-svg id="fa-spin"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M304 48c0-26.5-21.5-48-48-48s-48 21.5-48 48s21.5 48 48 48s48-21.5 48-48zm0 416c0-26.5-21.5-48-48-48s-48 21.5-48 48s21.5 48 48 48s48-21.5 48-48zM48 304c26.5 0 48-21.5 48-48s-21.5-48-48-48s-48 21.5-48 48s21.5 48 48 48zm464-48c0-26.5-21.5-48-48-48s-48 21.5-48 48s21.5 48 48 48s48-21.5 48-48zM142.9 437c18.7-18.7 18.7-49.1 0-67.9s-49.1-18.7-67.9 0s-18.7 49.1 0 67.9s49.1 18.7 67.9 0zm0-294.2c18.7-18.7 18.7-49.1 0-67.9S93.7 56.2 75 75s-18.7 49.1 0 67.9s49.1 18.7 67.9 0zM369.1 437c18.7 18.7 49.1 18.7 67.9 0s18.7-49.1 0-67.9s-49.1-18.7-67.9 0s-18.7 49.1 0 67.9z"/></svg></span>
|
|
|
</div>
|
|
|
</div>
|
|
|
</form>
|
|
|
<div id="mdbook-searchresults-outer" class="searchresults-outer hidden">
|
|
|
<div id="mdbook-searchresults-header" class="searchresults-header"></div>
|
|
|
<ul id="mdbook-searchresults">
|
|
|
</ul>
|
|
|
</div>
|
|
|
</div>
|
|
|
|
|
|
<!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM -->
|
|
|
<script>
|
|
|
document.getElementById('mdbook-sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible');
|
|
|
document.getElementById('mdbook-sidebar').setAttribute('aria-hidden', sidebar !== 'visible');
|
|
|
Array.from(document.querySelectorAll('#mdbook-sidebar a')).forEach(function(link) {
|
|
|
link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1);
|
|
|
});
|
|
|
</script>
|
|
|
|
|
|
<div id="mdbook-content" class="content">
|
|
|
<main>
|
|
|
<h1 id="rust-新版解读--186--trait-upcasting"><a class="header" href="#rust-新版解读--186--trait-upcasting">Rust 新版解读 | 1.86 | Trait upcasting</a></h1>
|
|
|
<blockquote>
|
|
|
<p>Rust 1.86 官方 release doc: <a href="https://blog.rust-lang.org/2025/04/03/Rust-1.86.0/">Announcing Rust 1.86.0 | Rust Blog</a></p>
|
|
|
</blockquote>
|
|
|
<p>通过 <a href="https://www.rust-lang.org/tools/install">rustup</a> 安装的同学可以使用以下命令升级到 1.86 版本:</p>
|
|
|
<pre><code class="language-shell">$ rustup update stable
|
|
|
</code></pre>
|
|
|
<h2 id="特征向上转型trait-upcasting"><a class="header" href="#特征向上转型trait-upcasting">特征向上转型(Trait upcasting)</a></h2>
|
|
|
<p>本次更新包含了一个期待已久的功能————特征对象的向上转型能力。如果一个特征拥有 <a href="https://doc.rust-lang.org/reference/items/traits.html#supertraits">supertrait</a>，你可以将指向该特征对象的引用强制转换为指向 supertrait 对象的引用：</p>
|
|
|
<pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>trait Trait: Supertrait {}
|
|
|
trait Supertrait {}
|
|
|
|
|
|
fn upcast(x: &dyn Trait) -> &dyn Supertrait {
|
|
|
x
|
|
|
}
|
|
|
<span class="boring">}</span></code></pre>
|
|
|
<p>该功能同样适用于其他类型的（智能）指针，例如 <code>Arc<dyn Trait> -> Arc<dyn Supertrait></code> 或 <code>*const dyn Trait -> *const dyn Supertrait</code>。</p>
|
|
|
<p>此前需要通过特征内部定义 <code>upcast</code> 方法（如 <code>fn as_supertrait(&self) -> &dyn Supertrait</code> ）来实现，且仅适用于单一引用/指针类型。现在不再需要此类变通方案。</p>
|
|
|
<p>需注意：这意味着特征对象的裸指针具有一个特别的约束：“泄漏”一个指向无效虚表的裸指针到安全代码可能导致未定义行为。当前尚不清楚在严格受控环境下临时创建此类裸指针是否会立即引发未定义行为，因此应避免在任何条件下创建此类指针（Miri 会强制执行此约束）。</p>
|
|
|
<p>特征向上转型在与 <code>Any</code> 特征结合时尤为实用，无需添加特征方法或使用外部crate即可将特征对象向上转型为 <code>dyn Any</code> 来调用 <code>Any</code> 的向下转型方法：</p>
|
|
|
<pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>use std::any::Any;
|
|
|
|
|
|
trait MyAny: Any {}
|
|
|
|
|
|
impl dyn MyAny {
|
|
|
fn downcast_ref<T>(&self) -> Option<&T> {
|
|
|
(self as &dyn Any).downcast_ref()
|
|
|
}
|
|
|
}
|
|
|
<span class="boring">}</span></code></pre>
|
|
|
<p>更多细节请参阅<a href="https://doc.rust-lang.org/reference/type-coercions.html#unsized-coercions">Rust参考文档中关于特征向上转型的内容</a>。</p>
|
|
|
<h2 id="hashmap和切片现支持可变索引多个元素"><a class="header" href="#hashmap和切片现支持可变索引多个元素">HashMap和切片现支持可变索引多个元素</a></h2>
|
|
|
<p>借用检查器原先会阻止通过重复调用 <code>get_mut</code> 方法获取的借用同时使用。为安全地支持获取多个可变引用，标准库现在为切片和 <code>HashMap</code> 提供 <code>get_disjoint_mut</code> 辅助方法，可同时获取多个元素的可变引用。示例取自 <a href="https://doc.rust-lang.org/stable/std/primitive.slice.html#method.get_disjoint_mut"><code>slice::get_disjoint_mut</code> API 文档</a>：</p>
|
|
|
<pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>let v = &mut [1, 2, 3];
|
|
|
if let Ok([a, b]) = v.get_disjoint_mut([0, 2]) {
|
|
|
*a = 413;
|
|
|
*b = 612;
|
|
|
}
|
|
|
assert_eq!(v, &[413, 2, 612]);
|
|
|
|
|
|
if let Ok([a, b]) = v.get_disjoint_mut([0..1, 1..3]) {
|
|
|
a[0] = 8;
|
|
|
b[0] = 88;
|
|
|
b[1] = 888;
|
|
|
}
|
|
|
assert_eq!(v, &[8, 88, 888]);
|
|
|
|
|
|
if let Ok([a, b]) = v.get_disjoint_mut([1..=2, 0..=0]) {
|
|
|
a[0] = 11;
|
|
|
a[1] = 111;
|
|
|
b[0] = 1;
|
|
|
}
|
|
|
assert_eq!(v, &[1, 11, 111]);
|
|
|
<span class="boring">}</span></code></pre>
|
|
|
<h2 id="允许安全函数标记-target_feature-属性"><a class="header" href="#允许安全函数标记-target_feature-属性">允许安全函数标记 <code>#[target_feature]</code> 属性</a></h2>
|
|
|
<p>此前仅 <code>unsafe</code> 函数可标记 <code>#[target_feature]</code> 属性，因未启用目标特性时调用此类函数会导致未定义行为。本次更新稳定了 <code>target_feature_11</code> 特性，允许<em>安全</em>函数标记该属性。</p>
|
|
|
<p>标记目标特性的安全函数仅可被同标记函数安全调用，但不可传递给以 <code>Fn*</code> 特征约束的泛型函数，且仅支持在标记函数内部强制转换为函数指针。</p>
|
|
|
<p>在未标记函数内部可通过 <code>unsafe</code> 块调用，但调用者需确保目标特性可用：</p>
|
|
|
<pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>#[target_feature(enable = "avx2")]
|
|
|
fn requires_avx2() {
|
|
|
// ... 省略
|
|
|
}
|
|
|
|
|
|
#[target_feature(enable = "avx2")]
|
|
|
fn safe_callsite() {
|
|
|
requires_avx2(); // 安全调用
|
|
|
}
|
|
|
|
|
|
fn unsafe_callsite() {
|
|
|
if is_x86_feature_detected!("avx2") {
|
|
|
unsafe { requires_avx2() }; // 需手动验证
|
|
|
}
|
|
|
}
|
|
|
<span class="boring">}</span></code></pre>
|
|
|
<p>详情参阅 <a href="https://github.com/rust-lang/rfcs/blob/master/text/2396-target-feature-1.1.md"><code>target_features_11</code> RFC</a>。</p>
|
|
|
<h2 id="为保障内存安全添加指针非空调试断言"><a class="header" href="#为保障内存安全添加指针非空调试断言">为保障内存安全添加指针非空调试断言</a></h2>
|
|
|
<p>编译器现会在以下场景插入调试断言：对非零大小类型的读写操作前，以及将指针重新借用为引用时。例如以下代码在启用调试断言时将触发 panic：</p>
|
|
|
<pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>let _x = *std::ptr::null::<u8>();
|
|
|
let _x = &*std::ptr::null::<u8>();
|
|
|
<span class="boring">}</span></code></pre>
|
|
|
<p>自Rust 1.53.0起简单案例已产生警告，新运行时检查可检测任意复杂场景。这些断言仅在调试模式下生效，因此<strong>不应该</strong>依赖其保障内存安全。且调试模式禁用的依赖项（如标准库）即使被调试模式代码调用也不会触发断言。</p>
|
|
|
<h2 id="默认启用-missing_abi-lint-警告"><a class="header" href="#默认启用-missing_abi-lint-警告">默认启用 <code>missing_abi</code> lint 警告</a></h2>
|
|
|
<p>在 extern 块和函数中省略 ABI（如 <code>extern {}</code> 和 <code>extern fn</code>）现在会触发 <code>missing_abi</code> lint 警告。<code>extern</code> 关键字后省略 ABI 始终隐式采用 <code>"C"</code> ABI，现建议显式指定（如 <code>extern "C" {}</code> 和 <code>extern "C" fn</code>）。</p>
|
|
|
<p>参阅<a href="https://rust-lang.github.io/rfcs/3722-explicit-extern-abis.html">显式外部 ABI RFC</a>获取详情。</p>
|
|
|
<h2 id="1870版本目标弃用警告"><a class="header" href="#1870版本目标弃用警告">1.87.0版本目标弃用警告</a></h2>
|
|
|
<p>Tier-2 目标 <code>i586-pc-windows-msvc</code> 将在Rust 1.87.0移除。该目标与更流行的<code>i686-pc-windows-msvc</code>的区别在于不要求SSE2指令支持，所有<code>windows</code>目标（除<code>win7</code>目标外）的最低要求系统版本，即 Windows 10 本身就需要SSE2指令。</p>
|
|
|
<p>当前使用该目标的用户应在1.87.0发布前迁移至<code>i686-pc-windows-msvc</code>。详情参见<a href="https://github.com/rust-lang/compiler-team/issues/840">重大变更提案</a>。</p>
|
|
|
<h2 id="others"><a class="header" href="#others">Others</a></h2>
|
|
|
<p>其它更新细节，和稳定的 API 列表，参考<a href="https://blog.rust-lang.org/2025/04/03/Rust-1.86.0.html#stabilized-apis">原Blog</a></p>
|
|
|
|
|
|
</main>
|
|
|
|
|
|
<nav class="nav-wrapper" aria-label="Page navigation">
|
|
|
<!-- Mobile navigation buttons -->
|
|
|
<a rel="prev" href="../../appendix/rust-versions/1.85.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
|
|
|
<span class=fa-svg><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 320 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M41.4 233.4c-12.5 12.5-12.5 32.8 0 45.3l160 160c12.5 12.5 32.8 12.5 45.3 0s12.5-32.8 0-45.3L109.3 256 246.6 118.6c12.5-12.5 12.5-32.8 0-45.3s-32.8-12.5-45.3 0l-160 160z"/></svg></span>
|
|
|
</a>
|
|
|
|
|
|
<a rel="next prefetch" href="../../appendix/rust-versions/1.87.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
|
|
|
<span class=fa-svg><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 320 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M278.6 233.4c12.5 12.5 12.5 32.8 0 45.3l-160 160c-12.5 12.5-32.8 12.5-45.3 0s-12.5-32.8 0-45.3L210.7 256 73.4 118.6c-12.5-12.5-12.5-32.8 0-45.3s32.8-12.5 45.3 0l160 160z"/></svg></span>
|
|
|
</a>
|
|
|
|
|
|
<div style="clear: both"></div>
|
|
|
</nav>
|
|
|
</div>
|
|
|
</div>
|
|
|
|
|
|
<nav class="nav-wide-wrapper" aria-label="Page navigation">
|
|
|
<a rel="prev" href="../../appendix/rust-versions/1.85.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
|
|
|
<span class=fa-svg><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 320 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M41.4 233.4c-12.5 12.5-12.5 32.8 0 45.3l160 160c12.5 12.5 32.8 12.5 45.3 0s12.5-32.8 0-45.3L109.3 256 246.6 118.6c12.5-12.5 12.5-32.8 0-45.3s-32.8-12.5-45.3 0l-160 160z"/></svg></span>
|
|
|
</a>
|
|
|
|
|
|
<a rel="next prefetch" href="../../appendix/rust-versions/1.87.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
|
|
|
<span class=fa-svg><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 320 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M278.6 233.4c12.5 12.5 12.5 32.8 0 45.3l-160 160c-12.5 12.5-32.8 12.5-45.3 0s-12.5-32.8 0-45.3L210.7 256 73.4 118.6c-12.5-12.5-12.5-32.8 0-45.3s32.8-12.5 45.3 0l160 160z"/></svg></span>
|
|
|
</a>
|
|
|
</nav>
|
|
|
|
|
|
</div>
|
|
|
|
|
|
<template id=fa-eye><span class=fa-svg><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 576 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M288 32c-80.8 0-145.5 36.8-192.6 80.6C48.6 156 17.3 208 2.5 243.7c-3.3 7.9-3.3 16.7 0 24.6C17.3 304 48.6 356 95.4 399.4C142.5 443.2 207.2 480 288 480s145.5-36.8 192.6-80.6c46.8-43.5 78.1-95.4 93-131.1c3.3-7.9 3.3-16.7 0-24.6c-14.9-35.7-46.2-87.7-93-131.1C433.5 68.8 368.8 32 288 32zM432 256c0 79.5-64.5 144-144 144s-144-64.5-144-144s64.5-144 144-144s144 64.5 144 144zM288 192c0 35.3-28.7 64-64 64c-11.5 0-22.3-3-31.6-8.4c-.2 2.8-.4 5.5-.4 8.4c0 53 43 96 96 96s96-43 96-96s-43-96-96-96c-2.8 0-5.6 .1-8.4 .4c5.3 9.3 8.4 20.1 8.4 31.6z"/></svg></span></template>
|
|
|
<template id=fa-eye-slash><span class=fa-svg><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 640 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M38.8 5.1C28.4-3.1 13.3-1.2 5.1 9.2S-1.2 34.7 9.2 42.9l592 464c10.4 8.2 25.5 6.3 33.7-4.1s6.3-25.5-4.1-33.7L525.6 386.7c39.6-40.6 66.4-86.1 79.9-118.4c3.3-7.9 3.3-16.7 0-24.6c-14.9-35.7-46.2-87.7-93-131.1C465.5 68.8 400.8 32 320 32c-68.2 0-125 26.3-169.3 60.8L38.8 5.1zM223.1 149.5C248.6 126.2 282.7 112 320 112c79.5 0 144 64.5 144 144c0 24.9-6.3 48.3-17.4 68.7L408 294.5c5.2-11.8 8-24.8 8-38.5c0-53-43-96-96-96c-2.8 0-5.6 .1-8.4 .4c5.3 9.3 8.4 20.1 8.4 31.6c0 10.2-2.4 19.8-6.6 28.3l-90.3-70.8zm223.1 298L373 389.9c-16.4 6.5-34.3 10.1-53 10.1c-79.5 0-144-64.5-144-144c0-6.9 .5-13.6 1.4-20.2L83.1 161.5C60.3 191.2 44 220.8 34.5 243.7c-3.3 7.9-3.3 16.7 0 24.6c14.9 35.7 46.2 87.7 93 131.1C174.5 443.2 239.2 480 320 480c47.8 0 89.9-12.9 126.2-32.5z"/></svg></span></template>
|
|
|
<template id=fa-copy><span class=fa-svg><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M502.6 70.63l-61.25-61.25C435.4 3.371 427.2 0 418.7 0H255.1c-35.35 0-64 28.66-64 64l.0195 256C192 355.4 220.7 384 256 384h192c35.2 0 64-28.8 64-64V93.25C512 84.77 508.6 76.63 502.6 70.63zM464 320c0 8.836-7.164 16-16 16H255.1c-8.838 0-16-7.164-16-16L239.1 64.13c0-8.836 7.164-16 16-16h128L384 96c0 17.67 14.33 32 32 32h47.1V320zM272 448c0 8.836-7.164 16-16 16H63.1c-8.838 0-16-7.164-16-16L47.98 192.1c0-8.836 7.164-16 16-16H160V128H63.99c-35.35 0-64 28.65-64 64l.0098 256C.002 483.3 28.66 512 64 512h192c35.2 0 64-28.8 64-64v-32h-47.1L272 448z"/></svg></span></template>
|
|
|
<template id=fa-play><span class=fa-svg><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 384 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M73 39c-14.8-9.1-33.4-9.4-48.5-.9S0 62.6 0 80V432c0 17.4 9.4 33.4 24.5 41.9s33.7 8.1 48.5-.9L361 297c14.3-8.7 23-24.2 23-41s-8.7-32.2-23-41L73 39z"/></svg></span></template>
|
|
|
<template id=fa-clock-rotate-left><span class=fa-svg><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M75 75L41 41C25.9 25.9 0 36.6 0 57.9V168c0 13.3 10.7 24 24 24H134.1c21.4 0 32.1-25.9 17-41l-30.8-30.8C155 85.5 203 64 256 64c106 0 192 86 192 192s-86 192-192 192c-40.8 0-78.6-12.7-109.7-34.4c-14.5-10.1-34.4-6.6-44.6 7.9s-6.6 34.4 7.9 44.6C151.2 495 201.7 512 256 512c141.4 0 256-114.6 256-256S397.4 0 256 0C185.3 0 121.3 28.7 75 75zm181 53c-13.3 0-24 10.7-24 24V256c0 6.4 2.5 12.5 7 17l72 72c9.4 9.4 24.6 9.4 33.9 0s9.4-24.6 0-33.9l-65-65V152c0-13.3-10.7-24-24-24z"/></svg></span></template>
|
|
|
|
|
|
|
|
|
|
|
|
<script>
|
|
|
window.playground_copyable = true;
|
|
|
</script>
|
|
|
|
|
|
<script src="../../ace-2a3cd908.js"></script>
|
|
|
<script src="../../mode-rust-2c9d5c9a.js"></script>
|
|
|
<script src="../../editor-16ca416c.js"></script>
|
|
|
<script src="../../theme-dawn-4493f9c8.js"></script>
|
|
|
<script src="../../theme-tomorrow_night-9dbe62a9.js"></script>
|
|
|
|
|
|
<script src="../../elasticlunr-ef4e11c1.min.js"></script>
|
|
|
<script src="../../mark-09e88c2c.min.js"></script>
|
|
|
<script src="../../searcher-c2a407aa.js"></script>
|
|
|
|
|
|
<script src="../../clipboard-1626706a.min.js"></script>
|
|
|
<script src="../../highlight-abc7f01d.js"></script>
|
|
|
<script src="../../book-a0b12cfe.js"></script>
|
|
|
|
|
|
<!-- Custom JS scripts -->
|
|
|
<script src="../../assets/custom-7d8ae1df.js"></script>
|
|
|
<script src="../../assets/bigPicture-be03f9c8.js"></script>
|
|
|
|
|
|
|
|
|
|
|
|
</div>
|
|
|
</body>
|
|
|
</html>
|
