Status

This tool has been DEPRECATED in favor of rustfmt. To transform try!s into ?s using rustfmt, add the following setting to your rustfmt.toml:

use_try_shorthand = true

-- @japaric, 2017-04-01

---

untry

Convert try!s into ?s

Usage

Pass the Rust files you want to modify as arguments. The files will be modified in place:

$ cat sinbad.rs
use std::fs::File;
use std::io::{self, Read, Write};

fn main() {
    run().unwrap();
}

fn run() -> io::Result<()> {
    let wishes = &mut String::new();
    try!(try!(File::open("sesame")).read_to_string(wishes));
    try!(try!(File::create("genie")).write_all(wishes.as_bytes()));
    Ok(())
}

$ untry sinbad.rs
Processing 1 file
sinbad.rs: OK

$ cat sinbad.rs
use std::fs::File;
use std::io::{self, Read, Write};

fn main() {
    run().unwrap();
}

fn run() -> io::Result<()> {
    let wishes = &mut String::new();
    File::open("sesame")?.read_to_string(wishes)?;
    File::create("genie")?.write_all(wishes.as_bytes())?;
    Ok(())
}

For larger projects you probably want to use this in conjunction with find:

$ find -name '*.rs' -type f | xargs untry

Notable examples

Automatic conversion of the rust-lang/rust repository.

Known issues

• This tool won't replace the try!s in doc comments or the ones inside macros. You'll have to convert those manually.
• This tool will also replace user-defined try!s with ?s. You'll have to manually undo those conversions.
• Converting multi-line try!s like the one shown may break alignment. untry doesn't attempt to be a formatting tool so it just informs the user about the issue by raising a warning.

// From
            try!(collect_tests_from_dir(config,
                                        base,
                                        &file_path,
                                        &relative_file_path,
                                        tests));

// To
            collect_tests_from_dir(config,
                                        base,
                                        &file_path,
                                        &relative_file_path,
                                        tests)?;

But you get warnings like these:

./src/librustc/middle/check_match.rs: OK
./src/librustc/middle/const_eval.rs: 2 warnings
./src/librustc/middle/const_eval.rs:829:28 warning: multiline try!
./src/librustc/middle/const_eval.rs:875:31 warning: multiline try!
./src/librustc/middle/dataflow.rs: 1 warnings
./src/librustc/middle/dataflow.rs:155:12 warning: multiline try!
./src/librustc/middle/def_id.rs: 2 warnings
./src/librustc/middle/def_id.rs:58:8 warning: multiline try!
./src/librustc/middle/def_id.rs:67:12 warning: multiline try!
./src/librustc/middle/expr_use_visitor.rs: OK

The spans get printed to stderr so the user can easily call rustfmt on the affected files:

$ find -name '*.rs' -type f | xargs untry 2>spans
./src/librustc/middle/check_match.rs: OK
./src/librustc/middle/const_eval.rs: 2 warnings
./src/librustc/middle/dataflow.rs: 1 warnings
./src/librustc/middle/def_id.rs: 2 warnings
./src/librustc/middle/expr_use_visitor.rs: OK

# possibly affected files
$ cat spans | cut -d':' -f1 | sort -u
./src/librustc/middle/const_eval.rs
./src/librustc/middle/dataflow.rs
./src/librustc/middle/def_id.rs

# reformat them
$ cat spans | cut -d':' -f1 | sort -u | xargs rustfmt

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 the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.