Add named path bases to cargo (v2)

[dpaoliello]

Introduce shared base directories in Cargo configuration files that in turn enable base-relative path dependencies.

Rendered

Draft Implementation PR: rust-lang/cargo#12974

This is a resurrection of @jonhoo's RFC (#3074). Many thanks and kudos to him for the idea, original RFC text and original implementation.

FCP proposed: checkboxes at #3529 (comment)

Tracking Issue: rust-lang/cargo#14355

[runiq]

Mind fixing the 'Rendered' link in the OP? https://github.com/dpaoliello/rfcs/blob/basepath/text/3529-cargo-path-bases.md :)

[dpaoliello]

Mind fixing the 'Rendered' link in the OP? https://github.com/dpaoliello/rfcs/blob/basepath/text/3529-cargo-path-bases.md :)

Oops, my bad, thanks!

[dpaoliello]

Creating a thread on Rust internals to discuss alternative solutions for this issue: https://internals.rust-lang.org/t/integration-with-mono-repos-via-intermediate-directories/20160

[joshtriplett]

We discussed this in today's @rust-lang/cargo meeting. We were generally in favor, but wanted to see a few changes made.

@rfcbot merge

First, this should be base-paths, rather than base_path, for consistency with other manifest fields which use plurals and dashes.

@rfcbot concern rename-to-base-paths

Second, it should be possible to define this in Cargo.toml, not only in config.toml. config.toml or environment variables can always override, but Cargo.toml should be able to define the default values.

@rfcbot concern define-in-manifest-override-in-config

Third, we should restrict the possible names for bases, to reserve space for extension in the future. We felt that base names should be restricted to the same naming as package names: "The name must use only alphanumeric characters or - or _, and cannot be empty."

@rfcbot concern base-names-alphanumeric-with-dash-or-underscore

Finally, this should define a mechanism for Cargo to provide built-in base paths. User-defined base paths should shadow built-in base paths, so that we can add more in the future without creating conflicts. And we should provide a built-in workspace base path that refers to your workspace root.

@rfcbot concern allow-built-in-base-paths-with-shadowing
@rfcbot concern define-built-in-workspace-base-path

[rfcbot]

Team member @joshtriplett has proposed to merge this. The next step is review by the rest of the tagged team members:

• @Eh2406
• @Muscraft
• @arlosi
• @ehuss
• @epage
• @joshtriplett
• @weihanglo

Concerns:

• allow-built-in-base-paths-with-shadowing resolved by Add named path bases to cargo (v2) #3529 (comment)
• base-names-alphanumeric-with-dash-or-underscore resolved by Add named path bases to cargo (v2) #3529 (comment)
• comments resolved by Add named path bases to cargo (v2) #3529 (comment)
• define-built-in-workspace-base-path resolved by Add named path bases to cargo (v2) #3529 (comment)
• define-in-manifest-override-in-config resolved by Add named path bases to cargo (v2) #3529 (comment)
• need-for-manifest resolved by Add named path bases to cargo (v2) #3529 (comment)
• rename-to-base-paths resolved by Add named path bases to cargo (v2) #3529 (comment)

Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

See this document for info about what commands tagged team members can give me.

[dpaoliello]

@joshtriplett I've updated the RFC to address these concerns

Also, I especially love the built-in workspace base path - that's super nice!

[joshtriplett]

@rfcbot resolved rename-to-base-paths

[joshtriplett]

@rfcbot resolved allow-built-in-base-paths-with-shadowing
@rfcbot resolved define-built-in-workspace-base-path

[joshtriplett]

@rfcbot resolved base-names-alphanumeric-with-dash-or-underscore

[joshtriplett]

@rfcbot resolved define-in-manifest-override-in-config

[joshtriplett]

@dpaoliello Thank you for the updates!

[epage]

@rfcbot resolved comments

[rfcbot]

🔔 This is now entering its final comment period, as per the review above. 🔔

[rfcbot]

The final comment period, with a disposition to merge, as per the review above, is now complete.

As the automated representative of the governance process, I would like to thank the author for their work and everyone else who contributed.

This will be merged soon.

[arlosi]

Thanks for your work on this @dpaoliello and all commentors and reviewers!