cargo nono - Detect (possible) no_std compatibility of your crate and dependencies

Motivation

From embedded programming, over smart contracts in Rust, to general cross-platform portable crates, #![no_std] crates are becoming more and more widespread. However it is currently a very cumbersome process to find out if and why (not) a crate is compatible with no_std usage, and often requires a lengthy trial and error process, and digging through the source of all your dependencies.

cargo nono tries to aid you in navigating the current minefield that is no_std usage, and it's biggest "no no"s.

Installation

Prebuilt binaries

cargo-nono also comes as prebuilt binaries (useful for CI):

curl -LSfs https://japaric.github.io/trust/install.sh | \
    sh -s -- --git hobofan/cargo-nono

From crates.io

cargo install cargo-nono
# For warnings with more informative messages install like this
RUSTFLAGS="--cfg procmacro2_semver_exempt" cargo install cargo-nono

Demo

Usage

Run in the crate directory you want to check:

cargo nono check

The cargo nono check subcommand also understands the --no-default-features and --features <FEATURES> flags to help in conditional no_std setups.

Features

• Tries to infer no_std compatibility in dependencies by looking for a #![no_std] attribute or the often used conditional #![cfg_attr(not(feature = "std"), no_std)]
• Helps in pinpointing which dependencies and feature flags activate std feature flags
• Warn of use std:: statements in code

Planned features

• Warn of [build-dependencies] features bleeding over: cargo#5730

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.