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<h1 id="rust-新版解读--173--panic-报错展示优化"><a class="header" href="#rust-新版解读--173--panic-报错展示优化">Rust 新版解读 | 1.73 | panic 报错展示优化</a></h1>
<blockquote>
<p>Rust 1.73 官方 release doc: <a href="https://blog.rust-lang.org/2023/10/05/Rust-1.73.0.html">Announcing Rust 1.73.0 | 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 1.73 版本:</p>
<pre><code class="language-shell">$ rustup update stable
</code></pre>
<h2 id="更简洁的-panic-报错信息"><a class="header" href="#更简洁的-panic-报错信息">更简洁的 panic 报错信息</a></h2>
<p>默认的 panic handler 会把报错信息单独列出一行,当报错信息很长、包含多行或者嵌套结构的时候可读性会更强。</p>
<pre><pre class="playground"><code class="language-rust edition2021">fn main() {
let file = "ferris.txt";
panic!("oh no! {file:?} not found!");
}</code></pre></pre>
<p>Rust 1.73 之前的:</p>
<pre><code class="language-shell">thread 'main' panicked at 'oh no! "ferris.txt" not found!', src/main.rs:3:5
</code></pre>
<p>Rust 1.73 之后的:</p>
<pre><code class="language-shell">thread 'main' panicked at src/main.rs:3:5:
oh no! "ferris.txt" not found!
</code></pre>
<p>另外,由 <code>assert_eq</code><code>assert_ne</code> 产生的 panic 消息也把自定义信息部分(第三个参数)的展示位置改动了一下:</p>
<pre><pre class="playground"><code class="language-rust edition2021">fn main() {
assert_eq!("🦀", "🐟", "ferris is not a fish");
}</code></pre></pre>
<p>Rust 1.73 之前的:</p>
<pre><code class="language-shell">thread 'main' panicked at 'assertion failed: `(left == right)`
left: `"🦀"`,
right: `"🐟"`: ferris is not a fish', src/main.rs:2:5
</code></pre>
<p>Rust 1.73 之后的:</p>
<pre><code class="language-shell">thread 'main' panicked at src/main.rs:2:5:
assertion `left == right` failed: ferris is not a fish
left: "🦀"
right: "🐟"
</code></pre>
<h2 id="线程局部初始化"><a class="header" href="#线程局部初始化">线程局部初始化</a></h2>
<p><a href="https://github.com/rust-lang/rfcs/blob/master/text/3184-thread-local-cell-methods.md">RFC 3184</a> 提案, <code>LocalKey&lt;Cell&lt;T&gt;&gt;</code><code>LocalKey&lt;RefCell&lt;T&gt;&gt;</code> 现在可以直接用 <code>get()</code>, <code>set()</code>, <code>take()</code><code>replace()</code> 方法来操作,不再需要写 <code>with(|inner|...)</code> 的闭包形式。声明线程静态局部变量的宏 <code>thread_local!</code> 内部就是使用的就是 <code>LocalKey&lt;T&gt;</code></p>
<p>新的方法让代码更简洁,也避免了默认值在新线程运行额外的初始化代码。</p>
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>thread_local! {
static THINGS: Cell&lt;Vec&lt;i32&gt;&gt; = Cell::new(Vec::new());
}
fn f() {
// before:
THINGS.with(|i| i.set(vec![1, 2, 3]));
// now:
THINGS.set(vec![1, 2, 3]);
// ...
// before:
let v = THINGS.with(|i| i.take());
// now:
let v: Vec&lt;i32&gt; = THINGS.take();
}
<span class="boring">}</span></code></pre></pre>
<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/2023/10/05/Rust-1.73.0.html#stabilized-apis">原Blog</a></p>
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