cargo-limit

Cargo with less noise:

errors have highest priority
- they never appear in the middle of warnings
- warnings are skipped by default until errors are fixed
- all dependencies' warnings are skipped by default
all messages come in reversed order by default
- to avoid extra scrolling
duplicated messages are skipped
messages are grouped by filenames
number of messages can be limited
after encountering first error the rest of build time is limited by default

This tool is especially useful in combination with cargo-watch.

Installation

From crates.io

cargo install cargo-limit

From git

cargo install --force --git https://github.com/alopatindev/cargo-limit

Usage

Run any of these in your project:

cargo lbench
cargo lbuild
cargo lcheck
cargo lclippy
cargo lfix
cargo lrun
cargo ltest

For IntelliJ IDEA you might need to specify --color=always.

Environment variables

CARGO_MSG_LIMIT
- limit compiler messages number
- 0 means no limit, which is default
CARGO_TIME_LIMIT
- cargo execution time limit in seconds after encountering first compiling error
- 1 is default
- 0 means no limit
CARGO_ASC
- show compiler messages in ascending order
- false is default
CARGO_FORCE_WARN
- show warnings even if errors still exist
- false is default
CARGO_DEPS_WARN
- show dependencies' warnings
- false is default

Why?

It's a workaround for this issue. Consider a program:

fn f() -> Result<(), ()> {
    Ok(())
}

fn main() {
    let mut i: u32 = 0;
    i -= 1;
    f();
    println!("Hello world");
}

It's counterproductive to read this kind of compiler noise in attempt to run the program:

$ cargo run
   Compiling hello v0.1.0 (/tmp/hello)
warning: variable `i` is assigned to, but never used
 --> src/main.rs:6:9
  |
6 |     let mut i: u32 = 0;
  |         ^^^^^
  |
  = note: `#[warn(unused_variables)]` on by default
  = note: consider using `_i` instead

warning: value assigned to `i` is never read
 --> src/main.rs:7:5
  |
7 |     i -= 1;
  |     ^
  |
  = note: `#[warn(unused_assignments)]` on by default
  = help: maybe it is overwritten before being read?

warning: unused `std::result::Result` that must be used
 --> src/main.rs:8:5
  |
8 |     f();
  |     ^^^^
  |
  = note: `#[warn(unused_must_use)]` on by default
  = note: this `Result` may be an `Err` variant, which should be handled

error: this arithmetic operation will overflow
 --> src/main.rs:7:5
  |
7 |     i -= 1;
  |     ^^^^^^ attempt to compute `0_u32 - 1_u32` which would overflow
  |
  = note: `#[deny(arithmetic_overflow)]` on by default

error: aborting due to previous error; 3 warnings emitted

error: could not compile `hello`.

To learn more, run the command again with --verbose.

All we want on this development iteration is to focus on this error:

$ cargo lrun
   Compiling hello v0.1.0 (/tmp/hello)
error: this arithmetic operation will overflow
 --> src/main.rs:7:5
  |
7 |     i -= 1;
  |     ^^^^^^ attempt to compute `0_u32 - 1_u32` which would overflow
  |
  = note: `#[deny(arithmetic_overflow)]` on by default

error: could not compile `hello`.

To learn more, run the command again with --verbose.

After fixing it we probably want to see the first warning(s):

$ sed -i '/.*i -= 1;/d' src/main.rs
$ CARGO_MSG_LIMIT=1 cargo lrun
    Finished dev [unoptimized + debuginfo] target(s) in 0.00s
warning: unused variable: `i`
 --> src/main.rs:6:9
  |
6 |     let mut i: u32 = 0;
  |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_i`
  |
  = note: `#[warn(unused_variables)]` on by default

     Running `target/debug/hello`
Hello world

License

MIT/Apache-2.0

cargo-limit 0.0.5