cargo-expand

This is a wrapper around cargo rustc -- --pretty=expanded. Once installed, the command cargo expand prints out the result of macro expansion and #[derive] expansion applied to the current crate.

Installation

Install with cargo install cargo-expand.

This command optionally uses rustfmt to format the expanded output. If rustfmt is not available, the expanded code is not formatted. Install rustfmt with cargo install rustfmt.

Example

$ cat src/main.rs

fn main() { println!("Hello, world!"); }

`$ cargo expand`

> ```rust
#![feature(prelude_import)]
#![no_std]
#[prelude_import]
use std::prelude::v1::*;
#[macro_use]
extern crate std as std;
fn main() {
    ::std::io::_print(::std::fmt::Arguments::new_v1({
                                                        static __STATIC_FMTSTR:
                                                               &'static [&'static str]
                                                               =
                                                            &["Hello, world!\n"];
                                                        __STATIC_FMTSTR
                                                    },
                                                    &match () {
                                                        () => [],
                                                    }));
}

To expand a particular test target:

$ cargo expand --test test_something

To expand with rustfmt different from the one in $PATH:

$ RUSTFMT=/path/to/rustfmt cargo expand

To expand without rustfmt even though it is available in $PATH:

$ RUSTFMT= cargo expand

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in cargo-expand by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.