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<h1 id="rust-新版解读--189--todo"><a class="header" href="#rust-新版解读--189--todo">Rust 新版解读 | 1.89 | TODO</a></h1>
|
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<blockquote>
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<p>Rust 1.89 官方 release doc: <a href="https://blog.rust-lang.org/2025/08/07/Rust-1.89.0/">Announcing Rust 1.89.0 | Rust Blog</a></p>
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</blockquote>
|
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<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 1.89 版本:</p>
|
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<pre><code class="language-shell">$ rustup update stable
|
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</code></pre>
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<h2 id="常量泛型的显式推断参数"><a class="header" href="#常量泛型的显式推断参数">常量泛型的显式推断参数</a></h2>
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<p>Rust现在支持在常量泛型参数中使用 <code>_</code>，从上下文推断其值：</p>
|
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<pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
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</span><span class="boring">fn main() {
|
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</span>pub fn all_false<const LEN: usize>() -> [bool; LEN] {
|
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[false; _]
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}
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<span class="boring">}</span></code></pre>
|
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<p>与类型中使用 <code>_</code> 的规则类似，在函数签名中不允许将 <code>_</code> 作为常量泛型参数：</p>
|
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<pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>// 不允许这样做
|
|
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pub const fn all_false<const LEN: usize>() -> [bool; _] {
|
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[false; LEN]
|
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}
|
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// 这个也不允许
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|
|
pub const ALL_FALSE: [bool; _] = all_false::<10>();
|
|
|
<span class="boring">}</span></code></pre>
|
|
|
<h2 id="生命周期语法不匹配的警告"><a class="header" href="#生命周期语法不匹配的警告">生命周期语法不匹配的警告</a></h2>
|
|
|
<p>函数签名中的<a href="https://doc.rust-lang.org/1.89.0/book/ch10-03-lifetime-syntax.html#lifetime-elision">生命周期省略</a>是 Rust 语言的一个便利特性，但也可能成为新手和专家的绊脚石。特别是当类型中隐含生命周期但语法上不明显时：</p>
|
|
|
<pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>// 返回类型 `std::slice::Iter` 有一个生命周期，
|
|
|
// 但是看起来没有任何提示。
|
|
|
//
|
|
|
// 生命周期省略推断返回类型的生命周期
|
|
|
// 与 `scores` 相同。
|
|
|
fn items(scores: &[u8]) -> std::slice::Iter<u8> {
|
|
|
scores.iter()
|
|
|
}
|
|
|
<span class="boring">}</span></code></pre>
|
|
|
<p>类似这样的代码现在会默认产生警告：</p>
|
|
|
<pre><code class="language-text">warning: hiding a lifetime that's elided elsewhere is confusing
|
|
|
--> src/lib.rs:1:18
|
|
|
|
|
|
|
1 | fn items(scores: &[u8]) -> std::slice::Iter<u8> {
|
|
|
| ^^^^^ -------------------- the same lifetime is hidden here
|
|
|
| |
|
|
|
| the lifetime is elided here
|
|
|
|
|
|
|
= help: the same lifetime is referred to in inconsistent ways, making the signature confusing
|
|
|
= note: `#[warn(mismatched_lifetime_syntaxes)]` on by default
|
|
|
help: use `'_` for type paths
|
|
|
|
|
|
|
1 | fn items(scores: &[u8]) -> std::slice::Iter<'_, u8> {
|
|
|
| +++
|
|
|
</code></pre>
|
|
|
<p>我们<a href="https://github.com/rust-lang/rust/pull/46254">最初在2018年</a>尝试改进这种情况，作为 <a href="https://github.com/rust-lang/rust/issues/54910"><code>rust_2018_idioms</code></a> 警告组的一部分，但关于 <code>elided_lifetimes_in_paths</code> 警告的<a href="https://github.com/rust-lang/rust/issues/131725">强烈反馈</a>表明它过于生硬，因为它会警告那些对理解函数无关紧要的生命周期：</p>
|
|
|
<pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>use std::fmt;
|
|
|
|
|
|
struct Greeting;
|
|
|
|
|
|
impl fmt::Display for Greeting {
|
|
|
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
|
|
|
// -----^^^^^^^^^ expected lifetime parameter
|
|
|
// 知道`Formatter`有生命周期并不会帮助程序员
|
|
|
"howdy".fmt(f)
|
|
|
}
|
|
|
}
|
|
|
<span class="boring">}</span></code></pre>
|
|
|
<p>我们随后意识到，我们想要消除的混淆发生在以下情况：</p>
|
|
|
<ol>
|
|
|
<li>生命周期省略推断规则将输入生命周期与输出生命周期<em>连接</em>起来</li>
|
|
|
<li>语法上不明显存在生命周期</li>
|
|
|
</ol>
|
|
|
<p>Rust中有两种语法表明生命周期的存在：<code>&</code> 和 <code>'</code>，其中 <code>'</code> 又分为推断生命周期 <code>'_</code> 和命名生命周期 <code>'a</code>。当类型使用命名生命周期时，生命周期省略不会为该类型推断生命周期。根据这些标准，我们可以构建三组：</p>
|
|
|
<div class="table-wrapper">
|
|
|
<table>
|
|
|
<thead>
|
|
|
<tr><th>明显有生命周期</th><th>允许生命周期省略推断生命周期</th><th>示例</th></tr>
|
|
|
</thead>
|
|
|
<tbody>
|
|
|
<tr><td>否</td><td>是</td><td><code>ContainsLifetime</code></td></tr>
|
|
|
<tr><td>是</td><td>是</td><td><code>&T</code>, <code>&'_ T</code>, <code>ContainsLifetime<'_></code></td></tr>
|
|
|
<tr><td>是</td><td>否</td><td><code>&'a T</code>, <code>ContainsLifetime<'a></code></td></tr>
|
|
|
</tbody>
|
|
|
</table>
|
|
|
</div>
|
|
|
<p><code>mismatched_lifetime_syntaxes</code> 警告检查函数的输入和输出是否属于同一组。对于上面的初始示例，<code>&[u8]</code> 属于第二组，而<code>std::slice::Iter<u8></code> 属于第一组。我们说第一组中的生命周期是<em>隐藏的</em>。</p>
|
|
|
<p>由于输入和输出生命周期属于不同组，警告会提示这个函数，减少对不明显但重要的生命周期的混淆。</p>
|
|
|
<p><code>mismatched_lifetime_syntaxes</code> 警告取代了 <code>elided_named_lifetimes</code> 警告，后者专门针对命名生命周期做了类似的事情。</p>
|
|
|
<p>未来对 <code>elided_lifetimes_in_paths</code> 警告的工作计划将其拆分为更集中的子警告，并考虑最终警告其中的一部分。</p>
|
|
|
<h2 id="更多-x86-目标特性"><a class="header" href="#更多-x86-目标特性">更多 x86 目标特性</a></h2>
|
|
|
<p><code>target_feature</code> 属性现在支持 x86 上的 <code>sha512</code>、<code>sm3</code>、<code>sm4</code>、<code>kl</code> 和 <code>widekl</code> 目标特性。此外，x86 上也支持许多 <code>avx512</code> 内部函数和目标特性：</p>
|
|
|
<pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>#[target_feature(enable = "avx512bw")]
|
|
|
pub fn cool_simd_code(/* .. */) -> /* ... */ {
|
|
|
/* ... */
|
|
|
}
|
|
|
<span class="boring">}</span></code></pre>
|
|
|
<h2 id="跨平台文档测试"><a class="header" href="#跨平台文档测试">跨平台文档测试</a></h2>
|
|
|
<p>现在运行 <code>cargo test --doc --target other_target</code> 时会测试文档测试，这可能会导致一些文档测试因失败而被测试出来。</p>
|
|
|
<p>可以通过用 <code>ignore-<target></code> 注解文档测试来禁用失败的测试（<a href="https://doc.rust-lang.org/stable/rustdoc/write-documentation/documentation-tests.html#ignoring-targets">文档</a>）：</p>
|
|
|
<pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>/// ```ignore-x86_64
|
|
|
/// panic!("something")
|
|
|
/// ```
|
|
|
pub fn my_function() { }
|
|
|
<span class="boring">}</span></code></pre>
|
|
|
<h2 id="extern-c-函数中的-i128-和-u128"><a class="header" href="#extern-c-函数中的-i128-和-u128"><code>extern "C"</code> 函数中的 <code>i128</code> 和 <code>u128</code></a></h2>
|
|
|
<p><code>i128</code> 和 <code>u128</code> 不再触发 <code>improper_ctypes_definitions</code> 警告，意味着这些类型可以在 <code>extern "C"</code> 函数中使用而不产生警告。这有一些注意事项：</p>
|
|
|
<ul>
|
|
|
<li>当类型可用时，Rust 类型与 C 中的（无符号）<code>__int128</code> 在 ABI 和布局上是兼容的。</li>
|
|
|
<li>在 <code>__int128</code> 不可用的平台上，<code>i128</code> 和 <code>u128</code> 不一定与任何 C 类型对齐。</li>
|
|
|
<li><code>i128</code> 不一定与任何平台上的 <code>_BitInt(128)</code> 兼容，因为 <code>_BitInt(128)</code> 和 <code>__int128</code> 可能有不同的 ABI（如在 x86-64 上）。</li>
|
|
|
</ul>
|
|
|
<p>这是去年布局变更的最后一点后续工作：<a href="https://blog.rust-lang.org/2024/03/30/i128-layout-update">https://blog.rust-lang.org/2024/03/30/i128-layout-update</a>。</p>
|
|
|
<h2 id="将-x86_64-apple-darwin-降级为-tier-2-并保留工具链"><a class="header" href="#将-x86_64-apple-darwin-降级为-tier-2-并保留工具链">将 <code>x86_64-apple-darwin</code> 降级为 Tier 2 并保留工具链</a></h2>
|
|
|
<p>GitHub 将很快<a href="https://github.blog/changelog/2025-07-11-upcoming-changes-to-macos-hosted-runners-macos-latest-migration-and-xcode-support-policy-updates/">停止</a>为公共仓库提供免费的 macOS x86_64 运行器。苹果也宣布了<a href="https://en.wikipedia.org/wiki/Mac_transition_to_Apple_silicon#Timeline">计划</a>停止支持 x86_64 架构。</p>
|
|
|
<p>根据这些变化，Rust 项目正在<a href="https://github.com/rust-lang/rfcs/pull/3841">将 <code>x86_64-apple-darwin</code> 目标</a>从<a href="https://doc.rust-lang.org/stable/rustc/platform-support.html#tier-1-with-host-tools">带工具链的 Tier 1</a>降级为<a href="https://doc.rust-lang.org/stable/rustc/platform-support.html#tier-2-with-host-tools">带工具链的 Tier 2</a>。这意味着该目标（包括 <code>rustc</code> 和 <code>cargo</code> 等工具）将保证构建，但不保证通过我们的自动化测试套件。</p>
|
|
|
<p>我们预计在 Rust 1.89 和 1.90 发布之间会接受降级为带工具链的 Tier 2 的 RFC，这意味着 Rust 1.89 将是 <code>x86_64-apple-darwin</code> 作为 Tier 1 目标的最后一个 Rust 版本。</p>
|
|
|
<p>对于用户来说，这一变化不会立即产生影响。只要目标保持在 Tier 2，Rust 项目仍将通过 <code>rustup</code> 或其他安装方法分发标准库和编译器的构建。不过随着时间的推移，测试覆盖率的降低可能会导致问题或兼容性下降。</p>
|
|
|
<h2 id="wasm32-unknown-unknown-目标上的标准兼容c-abi"><a class="header" href="#wasm32-unknown-unknown-目标上的标准兼容c-abi"><code>wasm32-unknown-unknown</code> 目标上的标准兼容C ABI</a></h2>
|
|
|
<p><code>wasm32-unknown-unknown</code> 目标上的 <code>extern "C"</code> 函数现在具有标准兼容的 ABI。更多信息请参阅这篇博客文章：<a href="https://blog.rust-lang.org/2025/04/04/c-abi-changes-for-wasm32-unknown-unknown">https://blog.rust-lang.org/2025/04/04/c-abi-changes-for-wasm32-unknown-unknown</a>。</p>
|
|
|
<h2 id="平台支持"><a class="header" href="#平台支持">平台支持</a></h2>
|
|
|
<ul>
|
|
|
<li><a href="https://github.com/rust-lang/rfcs/pull/3841"><code>x86_64-apple-darwin</code>正在被降级为带工具链的Tier 2</a></li>
|
|
|
<li><a href="https://github.com/rust-lang/rust/pull/142053">添加新的Tier-3目标<code>loongarch32-unknown-none</code>和<code>loongarch32-unknown-none-softfloat</code></a></li>
|
|
|
</ul>
|
|
|
<p>有关 Rust 的分层平台支持的更多信息，请参阅 Rust 的<a href="https://doc.rust-lang.org/stable/rustc/platform-support.html">平台支持页面</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/2025/08/07/Rust-1.89.0/#stabilized-apis">原Blog</a></p>
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<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>
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<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>
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<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>
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<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>
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