Tracking Issue for Packages as (optional) namespaces

[epage]

Summary

RFC: #3243
Documentation: https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#my-feature
rustc tracking issue: rust-lang/rust#122349
crates.io tracking issue: rust-lang/crates.io#8292

Allow a parent package to open its API namespace for other packages to participate

Implementation

• Unstable flag (feat: Add 'open-namespaces' feature #13591)
• Allow one :: in the middle of package names, prevent publish (feat: Add 'open-namespaces' feature #13591)
• Test cases
  • Depending on a package whose lib.name puts it in a namespace
  • Path or git dependency under a registry package namespace
  • Build scripts, see caeg-industries@f4305ca
  • Package IDs, parsing and generating both "name-only" and "URL"
• Publish support including index file system layout

Unresolved Issues

• For an implicit bin in a namespaced package, should do something (e.g. warn, error) about cross-platform hazard of :: being in the name?

Future Extensions

No response

About tracking issues

Tracking issues are used to record the overall progress of implementation.
They are also used as hubs connecting to other relevant issues, e.g., bugs or open design questions.
A tracking issue is however not meant for large scale discussion, questions, or bug reports about a feature.
Instead, open a dedicated issue for the specific matter and add the relevant feature gate label.