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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 >
< blockquote >
< 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 >
< / 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 1.89 版本:< / p >
< pre > < code class = "language-shell" > $ rustup update stable
< / code > < / pre >
< 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 >
< 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 >
< pre class = "playground" > < code class = "language-rust edition2021" > < span class = "boring" > #![allow(unused)]
< / span > < span class = "boring" > fn main() {
< / span > pub fn all_false< const LEN: usize> () -> [bool; LEN] {
[false; _]
}
< span class = "boring" > }< / span > < / code > < / pre >
< 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 >
< 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
pub const fn all_false< const LEN: usize> () -> [bool; _] {
[false; LEN]
}
// 这个也不允许
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 >
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< 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， < 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， < 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（ < / 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， < 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， < 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， < 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 >
< / main >
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