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# Rust 新版解读 | 1.73 | panic 报错展示优化
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> Rust 1.73 官方 release doc: [Announcing Rust 1.73.0 | Rust Blog](https://blog.rust-lang.org/2023/10/05/Rust-1.73.0.html)
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通过 [rustup](https://www.rust-lang.org/tools/install) 安装的同学可以使用以下命令升级到 1.73 版本:
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```shell
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$ rustup update stable
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```
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## 更简洁的 panic 报错信息
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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。
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```rust
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fn main() {
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let file = "ferris.txt";
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panic!("oh no! {file:?} not found!");
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}
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```
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Rust 1.73 之前的：
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```shell
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thread 'main' panicked at 'oh no! "ferris.txt" not found!', src/main.rs:3:5
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```
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Rust 1.73 之后的：
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```shell
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thread 'main' panicked at src/main.rs:3:5:
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oh no! "ferris.txt" not found!
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```
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另外，由 `assert_eq` 和 `assert_ne` 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：
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```rust
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fn main() {
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assert_eq!("🦀", "🐟", "ferris is not a fish");
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}
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```
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Rust 1.73 之前的：
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```shell
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thread 'main' panicked at 'assertion failed: `(left == right)`
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left: `"🦀"`,
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right: `"🐟"`: ferris is not a fish', src/main.rs:2:5
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```
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Rust 1.73 之后的：
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```shell
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thread 'main' panicked at src/main.rs:2:5:
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assertion `left == right` failed: ferris is not a fish
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left: "🦀"
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right: "🐟"
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```
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## 线程局部初始化
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如 [RFC 3184](https://github.com/rust-lang/rfcs/blob/master/text/3184-thread-local-cell-methods.md) 提案， `LocalKey<Cell<T>>` 和 `LocalKey<RefCell<T>>` 现在可以直接用 `get()`, `set()`, `take()` 和 `replace()` 方法来操作，不再需要写 `with(|inner|...)` 的闭包形式。声明线程静态局部变量的宏 `thread_local!` 内部就是使用的就是 `LocalKey<T>`。
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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。
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```rust
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thread_local! {
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static THINGS: Cell<Vec<i32>> = Cell::new(Vec::new());
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}
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fn f() {
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// before:
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THINGS.with(|i| i.set(vec![1, 2, 3]));
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// now:
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THINGS.set(vec![1, 2, 3]);
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// ...
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// before:
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let v = THINGS.with(|i| i.take());
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// now:
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let v: Vec<i32> = THINGS.take();
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}
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```
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## Others
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其它更新细节，和稳定的API列表，参考[原Blog](https://blog.rust-lang.org/2023/10/05/Rust-1.73.0.html#stabilized-apis)
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