docs.rs/cratename redirect to version with failed build gives "The requested resource does not exist" and no links

[huonw]

The short-links like https://docs.rs/im seem to do a redirect to the latest published version of the crate (which is 12.0.0 for that crate at the time of filing, i.e. https://docs.rs/im/12.0.0/im/). If that version failed to build, then the page is rather useless: just "The requested resource does not exist". It would be nice to give more information, such as a link to the crate page (e.g. https://docs.rs/crate/im/12.0.0) which at least has info about build failures, and/or a link to the latest successful build.

(A more general form of this issue is arbitrary URLs that are invalid but still "obviously" referring to a specific crate, e.g. https://docs.rs/crate/im/100.0.0. These could also contain a link back to the crate they refer to.)

[dpc]

This is really bad user experience. Many of places all over the web have links like https://docs.rs/mycrate and then the "The requested resource does not exist" it's a big WAT for the user. There are not even any pointers how to find last version that did work.

[eddyb]

I stumbled onto this and discussed it with @QuietMisdreavus - I would prefer a redirect from a version that failed to build, to the crate/ page.
For the versionless link, I think it's fine for it to go to the last-known-good version, and the "go to the latest version" link would trigger the aforementioned redirect.