使用 cargo expand 查看被宏隐藏的代码

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;
  }