Summary

RFC: #3243
Documentation: https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#open-namespaces
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)
• fix(pkgid): Allow open namespaces in PackageIdSpec's #14467
• 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
• 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?
• Should we allow renames like "foo::bar" = { package = "foo_bar", version = "1.0" } in Cargo.toml?
• How precisely should this be represented in the index trie?
• How we should name the .crate file / download URL

Future Extensions

No response

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