Rustin Liu

I’m a passionate software engineer who specializes in distributed systems and dev tools.

Feedback on `cargo-info` to prepare it for merging

01 February 2024


I am working on merging the cargo-info subcommand into Cargo. There are a few points that need to be addressed before merging. I would like to get feedback on these points. You can find the key points of concern at the end of this post.


This adds a new subcommand to Cargo, cargo info. This subcommand would allow users to get information about a crate from the command line, without having to go to the web.

The main motivation for this is to make it easier to get information about a crate from the command line. Currently, the way to get information about a crate is to go to the web and look it up on or find the crate’s source code and look at the Cargo.toml file. This is not very convenient, especially not all information is displayed on the page. This command also has been requested by the community for a long time. You can find more discussion about this in cargo#948.

Another motivation is to make the workflow of finding and evaluating crates more efficient. In the current workflow, users can search for crates using cargo search, but then they have to go to the web to get more information about the crate. This is not very efficient, especially if the user is just trying to get a quick overview of the crate. This would allow users to quickly get information about a crate without having to leave the terminal.

Example usage:

$ cargo info clap
    Updating index
clap #argument #cli #arg #parser #parse
A simple to use, efficient, and full-featured Command Line Argument Parser
version: 4.4.18
license: MIT OR Apache-2.0
rust-version: 1.70.0
  default         = [std, color, help, usage, error-context, suggestions]
  std             = [clap_builder/std]
  color           = [clap_builder/color]
  help            = [clap_builder/help]
  usage           = [clap_builder/usage]
  error-context   = [clap_builder/error-context]
  suggestions     = [clap_builder/suggestions]
  cargo           = [clap_builder/cargo]
  debug           = [clap_builder/debug, clap_derive?/debug]
  deprecated      = [clap_builder/deprecated, clap_derive?/deprecated]
  derive          = [dep:clap_derive]
  env             = [clap_builder/env]
  string          = [clap_builder/string]
  unicode         = [clap_builder/unicode]
  unstable-doc    = [clap_builder/unstable-doc, derive]
  unstable-styles = [clap_builder/unstable-styles]
  unstable-v5     = [clap_builder/unstable-v5, clap_derive?/unstable-v5, deprecated]
  wrap_help       = [clap_builder/wrap_help]
  kbknapp (Kevin K.)
  github:rust-cli:maintainers (Maintainers)
  github:clap-rs:admins (Admins)

Detailed design

Content Explanation Why
clap Name The basic information.
#argument #cli #arg #parser #parse Keywords It’s more like a category, which you can use to search for relevant alternatives.
A simple to use, efficient, and full-featured Command Line Argument Parser Description The basic information.
version: 4.4.18 Version The basic information.
license: MIT OR Apache-2.0 License When choosing a crate, it is crucial to consider the license.
rust-version: 1.70.0 MSRV When choosing a crate, it is crucial to make sure it can work with your MSRV.
documentation: Documentation Link Use these links can find more docs and information.
repository: Repo Link Use these links can find more docs and information.
features: Default Features And Other Features It helps for enabling features.
dependencies: All dependencies It indicates what it depends on.
owners: Owners It indicates who maintains the crate.

Some important notes

Downloading the crate from any Cargo compatible registry

The cargo info command will download the crate from any Cargo compatible registry. It will then extract the information from the Cargo.toml file and display it in the terminal.

If the crate is already in the local cache, it will not download the crate again. It will get the information from the local cache.

Pick the correct version from the workspace

When executed in a workspace directory, the cargo info command chooses the version that the workspace is currently using.

If there’s a lock file available, the version from this file will be used. In the absence of a lock file, the command attempts to select a version that is compatible with the Minimum Supported Rust Version (MSRV). And the lock file will be generated automatically.

The following hierarchy is used to determine the MSRV:

Prior art


npm has a similar command called npm info. For example:

$ npm info lodash

lodash@4.17.21 | MIT | deps: none | versions: 114
Lodash modular utilities.

keywords: modules, stdlib, util

.shasum: 679591c564c3bffaae8454cf0b3df370c3d6911c
.integrity: sha512-v2kDEe57lecTulaDIuNTPy3Ry4gLGJ6Z1O3vE1krgXZNrsQ+LFTGHVxVjcXPs17LhbZVGedAJv8XZ1tvj5FvSg==
.unpackedSize: 1.4 MB

- mathias <>
- jdalton <>
- bnjmnt4n <>

latest: 4.17.21

published over a year ago by bnjmnt4n <>


Poetry has a similar command called poetry show.

For example:

$ poetry show pendulum

name        : pendulum
version     : 1.4.2
description : Python datetimes made easy

 - python-dateutil >=2.6.1
 - tzlocal >=1.4
 - pytzdata >=2017.2.2

required by
 - calendar >=1.4.0

Known Points of Concern

  1. Report crates metrics? cargo-information#20


    • recent download count (popularity)
    • last updated (give a feel for how active development is)
    • Only for
  2. What dependency fields might be relevant to indicate? cargo-information#23


    • From @epage: Dependencies are mostly an implementation detail (except public) but people sometimes care, so I figure that holding off on private dependencies to –verbose might buy us more space.
    • From @hi-rustin: How about we show all the dependencies and only show the dev-dependencies and build-dependencies for a –verbose. I guess checking its dependencies before you use it in your project would always be considered.
  3. How should we render features? cargo-information#26

    Proposal: Currently, it’s a simple list of features and their dependencies. We could consider a tree view:

  4. What version should we default to within a workspace? What if it isn’t the direct dependency but is a transitive dependency? cargo-information#29

— Rustin Liu