RFC: Make the authors field optional


This RFC proposes to make the package.authors field of Cargo.toml optional. This RFC also proposes preventing Cargo from auto-filling it, allowing crates to be published to crates.io without the field being present, and avoiding displaying its contents on the crates.io and docs.rs UI.


The crates.io registry does not allow users to change the contents of already published versions: this is highly desirable to ensure working builds don’t break in the future, but it also has the unfortunate side-effect of preventing people from updating the list of crate authors defined in Cargo.toml’s package.authors field.

This is especially problematic when people change their name or want to remove their name from the Internet, and the crates.io team doesn’t have any way to address that at the moment except for deleting the affected crates or versions altogether. We don’t do that lightly, but there were a few cases where we were forced to do so.

The contents of the field also tend to scale poorly as the size of a project grows, with projects either making the field useless by just stating “The $PROJECT developers” or only naming the original authors without mentioning other major contributors.

Guide-level explanation

crates.io will allow publishing crates without the package.authors field, and it will stop showing the contents of the field in its UI (the current owners will still be shown). docs.rs will also replace that data with the crate owners.

cargo init will stop pre-populating the field when running the command, and it will not include the field at all in the default Cargo.toml. Crate authors will still be able to manually include the field before publishing if they so choose.

Crates that currently rely on the field being present (for example by reading the CARGO_PKG_AUTHORS environment variable) will have to handle the field being missing (for example by switching from the env! macro to option_env!).

Reference-level explanation

The implementation of this RFC spans multiple parts of the Rust project:


Cargo will stop fetching the current user’s name and email address when running cargo init, and it will not include the field in the default template for Cargo.toml.


crates.io will allow publishing versions without the field and with the field empty. The Web UI will remove the authors section, while retaining the current owners section.

The API will continue returning the authors field in every endpoint which currently includes it, but the field will always be empty (even if the crate author manually adds data to it). The database dumps will also stop including the field.


docs.rs will replace the authors with the current owners in its UI.


Cargo currently provides author information to the crate via CARGO_PKG_AUTHORS, and some crates (such as clap) use this information. Making the authors field optional will require crates to account for a missing field if they want to work out of the box in projects without the field.

This RFC will make it harder for third-party tools to query the author information of crates published to crates.io.

By design, this RFC discourages adding the metadata allowing to know historical crate authors and makes it harder to retrieve it. In some cases, crate authors may have wanted that information preserved. After this RFC, crate authors who want to display historical authors who are not current crate owners will have to present that information in some other way.

Rationale and alternatives

This RFC reduces the problems related to changing the names in the authors field significantly, as people will now have to explicitly want to add that data instead of it being there by default.

We could do nothing, but that would increase the support load of the crates.io team and would result in more crates being removed from the registry due to this issue.

Prior art

  • JavaScript: package.json has an optional authors field, but it’s not required and the interactive npm init command does not prepopulate the field, leaving it empty by default. The npm Web UI does not show the contents of the field.
  • Python: setup.py does not require the authors field. The PyPI Web UI shows its contents when present.
  • Ruby: *.gemspec requires the authors field, and the RubyGems Web UI shows its contents.
  • PHP: composer.json has an optional authors field. While it’s not required, the interactive composer init command allows you to choose whether to pre-populate it based on the current environment or skip it. The Packagist Web UI does not show the contents of the field.

Unresolved questions

  • What should we do about the metadata in already published crates?

Future possibilities

The package.authors field could be deprecated and removed in a future edition.

A future RFC could propose separating metadata fields that could benefit from being mutable out of Cargo.toml and the crate tarball, allowing them to be changed without having to publish a new version. Such RFC should also propose a standardized way to update and distribute the extracted metadata.