# Install cargo-careful with Homebrew, Nix

Execute Rust code carefully, with extra checking along the way. Version 0.4.10 via Homebrew; verified from local package data. Also installable with nix: nix profile install nixpkgs#cargo-careful.

## Install

```sh
sudo av install brew:cargo-careful
```

Additional install commands:

### macOS

- Homebrew (100%):

```sh
brew install cargo-careful
```

  Evidence: local Homebrew formula metadata

### Linux

- Nix (92%):

```sh
nix profile install nixpkgs#cargo-careful
```

  Evidence: nixpkgs package indexes: pkgs/by-name/ca/cargo-careful/package.nix from https://api.github.com/repos/NixOS/nixpkgs/git/trees/master?recursive=1

## Package facts

- **Package key:** brew:cargo-careful
- **Package manager:** Homebrew
- **Version:** 0.4.10
- **Source summary:** Execute Rust code carefully, with extra checking along the way
- **Homepage:** <https://github.com/RalfJung/cargo-careful>
- **Repository:** <https://github.com/RalfJung/cargo-careful>
- **Generated:** 2026-08-03T19:37:03+00:00

## Executables

- cargo-careful (alias)

## Install behavior

- Bottle: not available

## Freshness

- Page generated: 2026-08-03
- Package-manager version: 0.4.10
## Project history and usage

cargo-careful is a Cargo subcommand for running Rust programs and tests with extra nightly-only runtime checks, a standard library built with debug assertions, and optional sanitizer support.

### Project history

Ralf Jung's cargo-careful repository and first crates.io release both appeared in September 2022. The README describes it as a way to run Rust code extra carefully by opting into checks that help detect undefined behavior.

The tool builds or uses a checked standard library and passes rustc flags that enable stricter runtime behavior, including pointer alignment and null checks, collection consistency checks, strict initialization checks, and extra const-evaluation UB checks. Later versions also document sanitizer support and Apple Main Thread Checker integration on Apple platforms.

### Adoption history

cargo-careful is more specialized than general debugging Cargo plugins, but it fills an important space between ordinary `cargo test` and exhaustive interpreters. Crates.io reports more than 169,000 downloads, while the input records Homebrew and Nix packaging.

Its author and positioning connect it to Rust's unsafe-code verification culture. The README explicitly compares it with Miri: cargo-careful is less exhaustive but faster, supports arbitrary system and C FFI calls, and works on code Miri may not be able to run.

### How it is used

Users install it with `cargo install cargo-careful` and run commands such as `cargo +nightly careful test` or `cargo +nightly careful run`. The README says all `cargo test` and `cargo run` flags are supported and that a recent nightly toolchain is required.

On first use it may need the `rustc-src` rustup component to perform setup. It also honors common Rust flag sources such as `CARGO_ENCODED_RUSTFLAGS`, `RUSTFLAGS`, and Cargo's `build.rustflags`, and it sets a `cfg(careful)` configuration flag for conditional code.

### Why package nerds care

cargo-careful matters to package nerds because it packages unstable compiler and standard-library checking behavior into a repeatable Cargo command. It gives library maintainers a way to add stronger runtime checking to test workflows without rewriting tests for a separate interpreter.

It is also a good example of Cargo as a safety-tool host: the package itself is small, but it coordinates rustup components, nightly rustc flags, standard-library rebuilding, sanitizers, and target-specific platform diagnostics.

### Timeline

- 2022-09-22: GitHub repository RalfJung/cargo-careful was created.
- 2022-09-22: cargo-careful 0.1.0 was published on crates.io.
- 2020s: README documented the relationship with Miri, nightly-only UB checks, sanitizer support, and Main Thread Checker integration.
- 2026-04-01: Version 0.4.10 was published.

### Related projects

- Miri is the related Rust interpreter/checker that the README recommends for more exhaustive undefined-behavior detection.
- rustup and the `rustc-src` component are involved in cargo-careful setup.
- Rust nightly compiler flags and sanitizer support are the underlying mechanisms cargo-careful coordinates.

### Sources

- GitHub repository API metadata: https://api.github.com/repos/RalfJung/cargo-careful
- Official README: https://github.com/RalfJung/cargo-careful#readme
- Package-manager adoption from source_facts.package-manager.
- crates.io API metadata and versions: https://crates.io/api/v1/crates/cargo-careful


## Security Notes

narrow executable package without higher-risk signals.

- **Geiger risk:** green / low
- narrow executable package without higher-risk signals

## Other Package-Manager Records

- Nix - cargo-careful: normalized package name match | nixpkgs package indexes: pkgs/by-name/ca/cargo-careful/package.nix from https://api.github.com/repos/NixOS/nixpkgs/git/trees/master?recursive=1


## Related links

- [cargo-careful](https://pkg.so/pkg/cargo/cargo-careful/) - Same normalized package name exists in another local package ecosystem.

## Combined YAML source

View the package source record on GitHub. [combined/cargo-careful.yml](https://github.com/mxcl/pkgdb/blob/main/combined/cargo-careful.yml)


## Sources

- pkg.so package database
- Geiger risk classifier
- curated package history
- pkgdb category and tag curation
- external package-manager database matches
- cross-ecosystem install command graph