rust
/
rust-course
mirror of https://github.com/sunface/rust-course
5
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity
rust-course/appendix/rust-versions/1.84.html

291 lines
65 KiB
Raw Permalink Normal View History Unescape

deploy
1 month ago
<!DOCTYPE HTML>
<html lang="zh-CN" class="light" dir="ltr">
<head>
<!-- Book generated using mdBook -->
<meta charset="UTF-8">
<title>1.84 - 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.svg">
<link rel="shortcut icon" href="../../favicon.png">
<link rel="stylesheet" href="../../css/variables.css">
<link rel="stylesheet" href="../../css/general.css">
<link rel="stylesheet" href="../../css/chrome.css">
<link rel="stylesheet" href="../../css/print.css" media="print">
<!-- Fonts -->
<link rel="stylesheet" href="../../FontAwesome/css/font-awesome.css">
<link rel="stylesheet" href="../../fonts/fonts.css">
<!-- Highlight.js Stylesheets -->
<link rel="stylesheet" href="../../highlight.css">
<link rel="stylesheet" href="../../tomorrow-night.css">
<link rel="stylesheet" href="../../ayu-highlight.css">
<!-- Custom theme stylesheets -->
<link rel="stylesheet" href="../../theme/style.css">
</head>
<body class="sidebar-visible no-js">
<div id="body-container">
<!-- Provide site root to javascript -->
<script>
var path_to_root = "../../";
var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "navy" : "light";
</script>
<!-- Work around some values being stored in localStorage wrapped in quotes -->
<script>
try {
var theme = localStorage.getItem('mdbook-theme');
var 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>
var theme;
try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
if (theme === null || theme === undefined) { theme = default_theme; }
var html = document.querySelector('html');
html.classList.remove('light')
html.classList.add(theme);
var body = document.querySelector('body');
body.classList.remove('no-js')
body.classList.add('js');
</script>
<input type="checkbox" id="sidebar-toggle-anchor" class="hidden">
<!-- Hide / unhide sidebar before it is displayed -->
<script>
var body = document.querySelector('body');
var sidebar = null;
var sidebar_toggle = document.getElementById("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 = sidebar === 'visible';
body.classList.remove('sidebar-visible');
body.classList.add("sidebar-" + sidebar);
</script>
<nav id="sidebar" class="sidebar" aria-label="Table of contents">
<div class="sidebar-scrollbox">
<ol class="chapter"><li class="chapter-item affix "><a href="../../about-book.html">关于本书</a></li><li class="chapter-item affix "><a href="../../into-rust.html">进入 Rust 编程世界</a></li><li class="chapter-item affix "><a href="../../first-try/sth-you-should-not-do.html">避免从入门到放弃</a></li><li class="chapter-item affix "><a href="../../community.html">社区和锈书</a></li><li class="spacer"></li><li class="chapter-item affix "><a href="../../some-thoughts.html">Xobserve: 一切皆可观测</a></li><li class="chapter-item affix "><a href="../../beat-ai.html">BeatAI: 工程师 AI 入门圣经</a></li><li class="chapter-item affix "><li class="part-title">Rust 语言基础学习</li><li class="spacer"></li><li class="chapter-item "><a href="../../first-try/intro.html"><strong aria-hidden="true">1.</strong> 寻找牛刀，以便小试</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../first-try/installation.html"><strong aria-hidden="true">1.1.</strong> 安装 Rust 环境</a></li><li class="chapter-item "><a href="../../first-try/editor.html"><strong aria-hidden="true">1.2.</strong> 墙推 VSCode!</a></li><li class="chapter-item "><a href="../../first-try/cargo.html"><strong aria-hidden="true">1.3.</strong> 认识 Cargo</a></li><li class="chapter-item "><a href="../../first-try/hello-world.html"><strong aria-hidden="true">1.4.</strong> 不仅仅是 Hello world</a></li><li class="chapter-item "><a href="../../first-try/slowly-downloading.html"><strong aria-hidden="true">1.5.</strong> 下载依赖太慢了？</a></li></ol></li><li class="chapter-item "><a href="../../basic/intro.html"><strong aria-hidden="true">2.</strong> Rust 基础入门</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../basic/variable.html"><strong aria-hidden="true">2.1.</strong> 变量绑定与解构</a></li><li class="chapter-item "><a href="../../basic/base-type/index.html"><strong aria-hidden="true">2.2.</strong> 基本类型</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../basic/base-type/numbers.html"><strong aria-hidden="true">2.2.1.</strong> 数值类型</a></li><li class="chapter-item "><a href="../../basic/base-type/char-bool.html"><strong aria-hidden="true">2.2.2.</strong> 字符、布尔、单元类型</a></li><li class="chapter-item "><a href="../../basic/base-type/statement-expression.html"><strong aria-hidden="true">2.2.3.</strong> 语句与表达式</a></li><li class="chapter-item "><a href="../../basic/base-type/function.html"><strong aria-hidden="true">2.2.4.</strong> 函数</a></li></ol></li><li class="chapter-item "><a href="../../basic/ownership/index.html"><strong aria-hidden="true">2.3.</strong> 所有权和借用</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../basic/ownership/ownership.html"><strong aria-hidden="true">2.3.1.</strong> 所有权</a></li><li class="chapter-item "><a href="../../basic/ownership/borrowing.html"><strong aria-hidden="true">2.3.2.</strong> 引用与借用</a></li></ol></li><li class="chapter-item "><a href="../../basic/compound-type/intro.html"><strong aria-hidden="true">2.4.</strong> 复合类型</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../basic/compound-type/string-slice.html"><strong aria-hidden="true">2.4.1.</strong> 字符串与切片</a></li><li class="chapter-item "><a href="../../basic/compound-type/tuple.html"><strong aria-hidden="true">2.4.2.</strong> 元组</a></li><li class="chapter-item "><a href="../../basic/compound-type/struct.html"><strong aria-hidden="true">2.4.3.</strong> 结构体</a></li><li class="chapter-item "><a href="../../basic/compound-type/enum.html"><strong aria-hidden="true">2.4.4.</strong> 枚举</a></li><li class="chapter-item "><a href="../../basic/compound-type/array.html"><strong aria-hidden="true">2.4.5.</strong> 数组</a></l
</div>
<div id="sidebar-resize-handle" class="sidebar-resize-handle">
<div class="sidebar-resize-indicator"></div>
</div>
</nav>
<!-- Track and set sidebar scroll position -->
<script>
var sidebarScrollbox = document.querySelector('#sidebar .sidebar-scrollbox');
sidebarScrollbox.addEventListener('click', function(e) {
if (e.target.tagName === 'A') {
sessionStorage.setItem('sidebar-scroll', sidebarScrollbox.scrollTop);
}
}, { passive: true });
var sidebarScrollTop = sessionStorage.getItem('sidebar-scroll');
sessionStorage.removeItem('sidebar-scroll');
if (sidebarScrollTop) {
// preserve sidebar scroll position when navigating via links within sidebar
sidebarScrollbox.scrollTop = sidebarScrollTop;
} else {
// scroll sidebar to current active section when navigating via "next/previous chapter" buttons
var activeSection = document.querySelector('#sidebar .active');
if (activeSection) {
activeSection.scrollIntoView({ block: 'center' });
}
}
</script>
<div id="page-wrapper" class="page-wrapper">
<div class="page">
<div id="menu-bar-hover-placeholder"></div>
<div id="menu-bar" class="menu-bar sticky">
<div class="left-buttons">
<label id="sidebar-toggle" class="icon-button" for="sidebar-toggle-anchor" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar">
<i class="fa fa-bars"></i>
</label>
<button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list">
<i class="fa fa-paint-brush"></i>
</button>
<ul id="theme-list" class="theme-popup" aria-label="Themes" role="menu">
<li role="none"><button role="menuitem" class="theme" id="light">Light</button></li>
<li role="none"><button role="menuitem" class="theme" id="rust">Rust</button></li>
<li role="none"><button role="menuitem" class="theme" id="coal">Coal</button></li>
<li role="none"><button role="menuitem" class="theme" id="navy">Navy</button></li>
<li role="none"><button role="menuitem" class="theme" id="ayu">Ayu</button></li>
</ul>
<button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
<i class="fa fa-search"></i>
</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">
<i id="print-button" class="fa fa-print"></i>
</a>
<a href="https://github.com/sunface/rust-course" title="Git repository" aria-label="Git repository">
<i id="git-repository-button" class="fa fa-github"></i>
</a>
<a href="https://github.com/sunface/rust-course/edit/main/src/appendix/rust-versions/1.84.md" title="Suggest an edit" aria-label="Suggest an edit">
<i id="git-edit-button" class="fa fa-edit"></i>
</a>
</div>
</div>
<div id="search-wrapper" class="hidden">
<form id="searchbar-outer" class="searchbar-outer">
<input type="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header">
</form>
<div id="searchresults-outer" class="searchresults-outer hidden">
<div id="searchresults-header" class="searchresults-header"></div>
<ul id="searchresults">
</ul>
</div>
</div>
<!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM -->
<script>
document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible');
document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible');
Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) {
link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1);
});
</script>
<div id="content" class="content">
<!-- Page table of contents -->
<div class="sidetoc"><nav class="pagetoc"></nav></div>
<main>
<h1 id="rust-新版解读--184--const-能力拓展"><a class="header" href="#rust-新版解读--184--const-能力拓展">Rust 新版解读 | 1.84 | Const 能力拓展</a></h1>
<blockquote>
<p>Rust 1.84 官方 release doc: <a href="https://blog.rust-lang.org/2025/01/09/Rust-1.84.0.html">Announcing Rust 1.84.0 | 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 1.84 版本:</p>
<pre><code class="language-shell">$ rustup update stable
</code></pre>
<h2 id="cargo-在依赖版本选择中考虑-rust-版本"><a class="header" href="#cargo-在依赖版本选择中考虑-rust-版本">Cargo 在依赖版本选择中考虑 Rust 版本</a></h2>
<p>1.84.0 稳定了支持最低 Rust 版本（MSRV, minimum supported Rust version）的解析器，该解析器优先选择与项目声明的 MSRV （<code>Cargo.toml</code> 里的 <code>package.rust_version</code>） 兼容的依赖版本。通过支持 MSRV 的版本选择，维护者可以减少支持旧工具链的工作量，因为不再需要为每个依赖手动选择旧版本。</p>
<p>你可以通过 <code>.cargo/config.toml</code> 启用支持 MSRV 的解析器：</p>
<pre><code class="language-toml">[resolver]
incompatible-rust-versions = &quot;fallback&quot;
</code></pre>
<p>然后在添加依赖时：</p>
<pre><code class="language-bash">$ cargo add clap
Updating crates.io index
warning: ignoring clap@4.5.23 (which requires rustc 1.74) to maintain demo's rust-version of 1.60
Adding clap v4.0.32 to dependencies
Updating crates.io index
Locking 33 packages to latest Rust 1.60 compatible versions
Adding clap v4.0.32 (available: v4.5.23, requires Rust 1.74)
</code></pre>
<p>在 CI 中<a href="https://doc.rust-lang.org/cargo/guide/continuous-integration.html#verifying-latest-dependencies">验证最新依赖</a>时，你可以覆盖此行为：</p>
<pre><code class="language-bash">$ CARGO_RESOLVER_INCOMPATIBLE_RUST_VERSIONS=allow cargo update
Updating crates.io index
Locking 12 packages to latest compatible versions
Updating clap v4.0.32 -&gt; v4.5.23
</code></pre>
<p>你也可以通过在 <code>Cargo.toml</code> 清单文件中设置 <a href="https://doc.rust-lang.org/cargo/reference/resolver.html#resolver-versions"><code>package.resolver = &quot;3&quot;</code></a> 来启用此功能，但这需要将 MSRV 提升到 1.84。对于使用 Rust 2024 的项目（将在 1.85 中稳定），新的解析器将默认启用。</p>
<p>这为库作者在决定采用新 Rust 工具链功能的策略时提供了更大的灵活性。以前，库采用新 Rust 工具链的功能会迫使使用旧 Rust 版本的下游用户要么升级工具链，要么手动选择与工具链兼容的旧版本库（并避免运行 <code>cargo update</code>）。现在，这些用户将能够自动使用与其旧工具链兼容的旧库版本。</p>
<p>有关决定 MSRV 策略时的更多注意事项，请参阅<a href="https://doc.rust-lang.org/cargo/reference/rust-version.html#setting-and-updating-rust-version">文档</a>。</p>
<h2 id="新-trait-求解器的迁移开始"><a class="header" href="#新-trait-求解器的迁移开始">新 trait 求解器的迁移开始</a></h2>
<p>Rust 编译器正在迁移到新的 trait 求解器实现。下一代 trait 求解器是 Rust 类型系统核心组件的重新实现。它不仅负责检查 trait 边界（例如 <code>Vec&lt;T&gt;: Clone</code>）是否成立，还被类型系统的许多其他部分使用，例如规范化（确定 <code>&lt;Vec&lt;T&gt; as IntoIterator&gt;::Item</code> 的基础类型）和类型等价（检查 <code>T</code> 和 <code>U</code> 是否相同）。</p>
<p>在 1.84 中，新求解器用于检查 trait 实现的一致性。从高层次来看，一致性负责确保在考虑其他 crate 中尚未编写或不可见的代码时，给定类型的 trait 实现最多只有一个。</p>
<p>此稳定化修复了旧实现中的一些主要理论上的正确性问题，导致可能会报告以前未报告的“trait 冲突实现”错误。根据 <a href="https://github.com/rust-lang/crater/">Crater</a> 对可用代码的评估，我们预计受影响的模式非常罕见。此次稳定版本还提高了我们证明实现不重叠的能力，在某些情况下允许编写更多代码。</p>
<p>有关更多详细信息，请参阅之前的<a href="https://blog.rust-lang.org/inside-rust/2024/12/04/trait-system-refactor-initiative.html">博客文章</a>和<a href="https://github.com/rust-lang/rust/pull/130654">稳定报告</a>。</p>
<h2 id="严格来源-api"><a class="header" href="#严格来源-api">严格来源 API</a></h2>
<p>在 Rust 中，<a href="https://rust-lang.github.io/rfcs/3559-rust-has-provenance.html">指针不仅仅是“整数”或“地址”</a>。例如，“释放后使用”是未定义行为，即使你“幸运”并且在读取/写入之前重新分配了释放的内存。另一个例子是，通过从 <code>&amp;i32</code> 引用派生的指针写入是未定义行为，即使通过不同指针写入同一地址是合法的。这里的底层模式是，指针的计算方式很重要，而不仅仅是计算结果的地址。因此，我们说指针具有<strong>来源</strong>：要完全描述 Rust 中与指针相关的未定义行为，我们不仅需要知道指针指向的地址，还需要跟踪它是从哪些其他指针“派生”的。</p>
<p>大多数情况下，程序员不需要过多担心来源，指针的派生方式非常清晰。然而，当将指针转换为整数并返回时，结果指针的来源是不明确的。在此版本中，Rust 添加了一组 API，可以在许多情况下替代整数指针转换的使用，从而避免此类转换固有的歧义。特别是，现在可以在不将指针转换为整数(或反方向将整数转换成指针)的情况下实现使用对齐指针的最低有效位存储额外信息的模式。这使得代码更易于推理，更易于编译器分析，并且还有益于像 <a href="https://github.com/rust-lang/miri">Miri</a> 这样的工具和像 <a href="https://www.cl.cam.ac.uk/research/security/ctsrd/cheri/">CHERI</a> 这样的架构，旨在检测和诊断指针滥用。</p>
<p>有关更多详细信息，请参阅标准库中关于<a href="https://doc.rust-lang.org/std/ptr/index.html#provenance">来源</a>的文档。</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，包括上述 <code>provenance</code> 相关 API，参考<a href="https://blog.rust-lang.org/2025/01/09/Rust-1.84.0.html#stabilized-apis">原Blog</a></p>
<div id="giscus-container"></div>
</main>
<nav class="nav-wrapper" aria-label="Page navigation">
<!-- Mobile navigation buttons -->
<a rel="prev" href="../../appendix/rust-versions/1.83.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
<i class="fa fa-angle-left"></i>
</a>
<a rel="next prefetch" href="../../appendix/rust-versions/1.85.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
<i class="fa fa-angle-right"></i>
</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/1.83.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
<i class="fa fa-angle-left"></i>
</a>
<a rel="next prefetch" href="../../appendix/rust-versions/1.85.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
<i class="fa fa-angle-right"></i>
</a>
</nav>
</div>
<script>
window.playground_copyable = true;
</script>
<script src="../../ace.js"></script>
<script src="../../editor.js"></script>
<script src="../../mode-rust.js"></script>
<script src="../../theme-dawn.js"></script>
<script src="../../theme-tomorrow_night.js"></script>
<script src="../../elasticlunr.min.js"></script>
<script src="../../mark.min.js"></script>
<script src="../../searcher.js"></script>
<script src="../../clipboard.min.js"></script>
<script src="../../highlight.js"></script>
<script src="../../book.js"></script>
<script type="text/javascript" charset="utf-8">
var pagePath = "appendix/rust-versions/1.84.md"
</script>
<!-- Custom JS scripts -->
<script src="../../assets/custom.js"></script>
<script src="../../assets/bigPicture.js"></script>
</div>
</body>
</html>