Crates using `license-file` get an empty license section in the dropdown

[Nemo157]

Example: https://docs.rs/serde-util/0.1.0/serde_util/

On crates.io this shows as "non-standard":

[AndreLaranjeira]

From what I analysed, this is caused by how the information for the crate's license is initialized.

In the code for crates.io, whenever a new version for the crate is published, the crate's metadata is parsed and that information is used to instantiate a NewVersion struct. When a NewVersion struct is created, the call to the validate_license method checks the license file argument and sets the license field to "non-standard" if that field was previously empty and the license file is not empty.

In the code for docs.rs, when the metadata for the root package is generated by this call to cargo, it appears the metadata for all the project's packages is simply deserialized using serde_json into a vector of Package structs, which do not have a field for license file.

Maybe the aforementioned serde_json deserialization logic for Package could be altered to set the license field to "non-standard" instead of leaving it empty when the license_file field is not empty and that would solve the problem?

[Nemo157]

Yep, that sounds about what I would expect to be required. That will fix it for new builds, so would probably also pay to handle the license being None in the template for existing builds by putting a default there (can this also just be non-standard, or is there another reason the license would be None?).

[AndreLaranjeira]

@Nemo157 You raise a good point. Since docs.rs only hosts the documentation for crates published on crates.io and publishing a crate on crates.io requires a license or license-file, then I think the license field could just default to non-standard both on the template (for existing builds) and on the serde_json deserialization logic (for new builds) because any crate documented on docs.rs should have a license or license-file.

Having said that, I'm fairly new to the Rust community, so I'm not certain if all the past editions of Rust had a license requirement for publishing to crates.io.