diff --git a/src/SUMMARY.md b/src/SUMMARY.md index deb8668a..b3aea018 100644 --- a/src/SUMMARY.md +++ b/src/SUMMARY.md @@ -216,7 +216,7 @@ - [不错的unsafe队列](too-many-lists/unsafe-queue/intro.md) - [数据布局](too-many-lists/unsafe-queue/layout.md) - [基本操作](too-many-lists/unsafe-queue/basics.md) - + - [Miri](too-many-lists/unsafe-queue/miri.md) - [Rust 性能优化 todo](profiling/intro.md) - [深入内存 todo](profiling/memory/intro.md) - [指针和引用 todo](profiling/memory/pointer-ref.md) diff --git a/src/too-many-lists/unsafe-queue/miri.md b/src/too-many-lists/unsafe-queue/miri.md new file mode 100644 index 00000000..0cb65bf5 --- /dev/null +++ b/src/too-many-lists/unsafe-queue/miri.md @@ -0,0 +1,175 @@ +# Miri +看到这里，大家是不是暗中松了口气？unsafe 不过如此嘛，不知道为何其它人都谈之色变。 + +怎么说呢？你以为的编译器已经不是以前的编译器了，它不报错不代表没有错误。包括测试用例也是，正常地运行不能意味着代码没有任何错误。 + +在周星驰电影功夫中，还有一个奇怪大叔 10 元一本主动上门卖如来神掌，那么有没有 10 元一本的 Rust 秘笈呢？( 喂，Rust语言圣经都免费让你读了，有了摩托车，还要什么拖拉机... 哈哈，开个玩笑 ) + +有的，奇怪大叔正在赶来，他告诉我们先来安装一个命令: +```shell +rustup +nightly-2022-01-21 component add miri +info: syncing channel updates for 'nightly-2022-01-21-x86_64-pc-windows-msvc' +info: latest update on 2022-01-21, rust version 1.60.0-nightly (777bb86bc 2022-01-20) +info: downloading component 'cargo' +info: downloading component 'clippy' +info: downloading component 'rust-docs' +info: downloading component 'rust-std' +info: downloading component 'rustc' +info: downloading component 'rustfmt' +info: installing component 'cargo' +info: installing component 'clippy' +info: installing component 'rust-docs' +info: installing component 'rust-std' +info: installing component 'rustc' +info: installing component 'rustfmt' +info: downloading component 'miri' +info: installing component 'miri' +``` + +等等，你在我电脑上装了什么奇怪的东西？！ "好东西" + + +> miri 目前只能在 nightly Rust 上安装，`+nightly-2022-01-21` 告诉 `rustup` 我们想要安装的 `nightly` 版本，事实上，你可以直接通过 `rustup +nightly component add miri` 安装，这里指定版本主要因为 `miri` 有时候会因为某些版本而出错。 +> +> 2022-01-21 是我所知的 miri 可以成功运行的版本，你可以检查[这个网址](https://rust-lang.github.io/rustup-components-history/)获取更多信息 +> +> + 是一种临时性的规则运用，如果你不想每次都使用 `+nightly-2022-01-21`，可以使用 [`rustup override set`](https://course.rs/appendix/rust-version.html#rustup-和-rust-nightly-的职责) 命令对当前项目的 Rust 版本进行覆盖 + +```shell +> cargo +nightly-2022-01-21 miri test + +I will run `"cargo.exe" "install" "xargo"` to install +a recent enough xargo. Proceed? [Y/n] +``` + +额，`xargo` 是什么东东？"不要担心，选择 y 就行，我像是会坑你的人吗？" + +```shell +> y + + Updating crates.io index + Installing xargo v0.3.24 +... + Finished release [optimized] target(s) in 10.65s + Installing C:\Users\ninte\.cargo\bin\xargo-check.exe + Installing C:\Users\ninte\.cargo\bin\xargo.exe + Installed package `xargo v0.3.24` (executables `xargo-check.exe`, `xargo.exe`) + +I will run `"rustup" "component" "add" "rust-src"` to install +the `rust-src` component for the selected toolchain. Proceed? [Y/n] +``` + +额？ "不要怕，多给你一份 Rust 源代码，不开心嘛？" + +```shell +> y + +info: downloading component 'rust-src' +info: installing component 'rust-src' +``` + +"看吧，我就说我不会骗你的，不相信我，等着错误砸脸吧!" 真是一个奇怪的大叔... +```shell + Compiling lists v0.1.0 (C:\Users\ninte\dev\tmp\lists) + Finished test [unoptimized + debuginfo] target(s) in 0.25s + Running unittests (lists-5cc11d9ee5c3e924.exe) + +error: Undefined Behavior: trying to reborrow for Unique at alloc84055, + but parent tag <209678> does not have an appropriate item in + the borrow stack + + --> \lib\rustlib\src\rust\library\core\src\option.rs:846:18 + | +846 | Some(x) => Some(f(x)), + | ^ trying to reborrow for Unique at alloc84055, + | but parent tag <209678> does not have an + | appropriate item in the borrow stack + | + = help: this indicates a potential bug in the program: + it performed an invalid operation, but the rules it + violated are still experimental + = help: see https://github.com/rust-lang/unsafe-code-guidelines/blob/master/wip/stacked-borrows.md + for further information + + = note: inside `std::option::Option::>>::map::` at \lib\rustlib\src\rust\library\core\src\option.rs:846:18 + +note: inside `fifth::List::::pop` at src\fifth.rs:31:9 + --> src\fifth.rs:31:9 + | +31 | / self.head.take().map(|head| { +32 | | let head = *head; +33 | | self.head = head.next; +34 | | +... | +39 | | head.elem +40 | | }) + | |__________^ +note: inside `fifth::test::basics` at src\fifth.rs:74:20 + --> src\fifth.rs:74:20 + | +74 | assert_eq!(list.pop(), Some(1)); + | ^^^^^^^^^^ +note: inside closure at src\fifth.rs:62:5 + --> src\fifth.rs:62:5 + | +61 | #[test] + | ------- in this procedural macro expansion +62 | / fn basics() { +63 | | let mut list = List::new(); +64 | | +65 | | // Check empty list behaves right +... | +96 | | assert_eq!(list.pop(), None); +97 | | } + | |_____^ + ... +error: aborting due to previous error +``` + +咦还真有错误，大叔，这是什么错误？大叔？...奇怪的大叔默默离开了，留下我在风中凌乱。 + +果然不靠谱...还是得靠自己，首先得了解下何为 `miri`。 + + +[`miri`](https://github.com/rust-lang/miri) 可以生成 Rust 的中间层表示 MIR，对于编译器来说，我们的 Rust 代码首先会被编译为 MIR ，然后再提交给 LLVM 进行处理。 + +可以通过 `rustup component add miri` 来安装它，并通过 `cargo miri` 来使用，同时还可以使用 `cargo miri test` 来运行测试代码。 + +`miri` 可以帮助我们检查常见的未定义行为(UB = Undefined Behavior)，以下列出了一部分: + +- 内存越界检查和内存释放后再使用(use-after-free) +- 使用未初始化的数据 +- 数据竞争 +- 内存对齐问题 + +UB 检测是必须的，因为它发生在运行时，因此很难发现，如果 `miri` 能在编译期检测出来，那自然是最好不过的。 + +总之，`miri` 的使用很简单: +```shell +> cargo +nightly-2022-01-21 miri test +``` + +下面来看看具体的错误： +```shell +error: Undefined Behavior: trying to reborrow for Unique at alloc84055, but parent tag <209678> does not have an appropriate item in the borrow stack + + --> \lib\rustlib\src\rust\library\core\src\option.rs:846:18 + | +846 | Some(x) => Some(f(x)), + | ^ trying to reborrow for Unique at alloc84055, + | but parent tag <209678> does not have an + | appropriate item in the borrow stack + | + + = help: this indicates a potential bug in the program: it + performed an invalid operation, but the rules it + violated are still experimental + + = help: see + https://github.com/rust-lang/unsafe-code-guidelines/blob/master/wip/stacked-borrows.md + for further information +``` + +嗯，只能看出是一个错误，其它完全看不懂了，例如什么是 `borrow stack`？ + +