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使用 cargo expand 查看被宏隐藏的代码

发布时间 2023-09-23 12:16:05作者: liuzonglin

使用 cargo expand 查看被宏隐藏的代码

使用 VScode 安装扩展 Rust Macro Expand

需要安装以下软件:

  • cargo-expand A cargo crate for easier handling of compiler commands
  • Rust nightly compiler, you can install it with rustup toolchain install nightly

cargo expand简介

  • cargo expand 目前这个需要安装 nightly 的 toolchain，rustup toolchain install nightly-x86_64-unknown-linux-gnu

    ~> rustup toolchain install nightly
info: syncing channel updates for 'nightly-x86_64-pc-windows-msvc'
info: latest update on 2023-07-26, rust version 1.73.0-nightly (864bdf784 2023-07-25)
info: downloading component 'cargo'
info: downloading component 'clippy'
info: downloading component 'rust-docs'
info: downloading component 'rust-std'
info: downloading component 'rustc'
58.2 MiB /  58.2 MiB (100 %)  40.5 MiB/s in  1s ETA:  0s
info: downloading component 'rustfmt'
info: installing component 'cargo'
info: installing component 'clippy'
info: installing component 'rust-docs'
13.7 MiB /  13.7 MiB (100 %)   2.0 MiB/s in  4s ETA:  0s
info: installing component 'rust-std'
23.6 MiB /  23.6 MiB (100 %)  16.2 MiB/s in  1s ETA:  0s
info: installing component 'rustc'
58.2 MiB /  58.2 MiB (100 %)  17.4 MiB/s in  3s ETA:  0s
info: installing component 'rustfmt'

nightly-x86_64-pc-windows-msvc installed - rustc 1.73.0-nightly (864bdf784 2023-07-25)

info: checking for self-update

  • 安装命令：cargo +nightly install cargo-expand

    ~> cargo +nightly install cargo-expand
    Updating `ustc` index
Downloaded cargo-expand v1.0.62 (registry `ustc`)
Downloaded 1 crate (26.8 KB) in 1.29s
Installing cargo-expand v1.0.62
Downloaded ansi_colours v1.2.2 (registry `ustc`)
...
    Finished release [optimized] target(s) in 1m 25s
Installing C:\Users\liuzonglin\.cargo\bin\cargo-expand.exe
Installed package `cargo-expand v1.0.62` (executable `cargo-expand.exe`)

使用方法

  • 源代码

    #![allow(non_camel_case_types)]
use async_trait::async_trait;
fn main() {}
#[async_trait]
trait example {
    async fn fetch(trace_id: &str, span_id: &str);
}

  • 运行 cargo expand

    ~> cargo expand
    Checking lifetime_kata v0.1.0 (D:\.github\rust\lifetime_kata)
    Finished dev [unoptimized + debuginfo] target(s) in 0.04s

#![feature(prelude_import)]
#![allow(non_camel_case_types)]
#[prelude_import]
use std::prelude::rust_2021::*;
#[macro_use]
extern crate std;
use async_trait::async_trait;
fn main() {}
trait example {
    #[must_use]
    #[allow(clippy::type_complexity, clippy::type_repetition_in_bounds)]
    fn fetch<'life0, 'life1, 'async_trait>(
        trace_id: &'life0 str,
        span_id: &'life1 str,
    ) -> ::core::pin::Pin<
        Box<
            dyn ::core::future::Future<Output = ()> + ::core::marker::Send + 'async_trait,
        >,
    >
    where
        'life0: 'async_trait,
        'life1: 'async_trait;
}