feat(manifest): allow git dependency alongside alternate registry

[enricobolzonello]

What does this PR try to resolve?

Removes the restriction that prevented combining git with registry (or registry-index), bringing alternate registries to parity with crates.io for the multiple locations feature.

Previously, any combination of git + registry was rejected. Now:

• git + path is still always rejected
• registry + registry_index together is still rejected
• git + registry is allowed: the git arm (Some(git), None, _, _) handles it

At publishing time, it already stripped all git fields, leaving only registry, so it required no changes.

Fixes #10875

How to test and review this PR?

Run tests:

• registry_and_git_dep_works
• publish_with_git_and_registry_dep

in alt_registry test suite, and:

• git_registry

in cargo_add test suite.

[rustbot]

r? @ehuss

rustbot has assigned @ehuss.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

Why was this reviewer chosen?

The reviewer was selected based on:

• Owners of files modified in this PR: @ehuss, @epage, @weihanglo
• @ehuss, @epage, @weihanglo expanded to ehuss, epage, weihanglo
• Random selection from ehuss, epage, weihanglo

[epage]

Please update your commits for how they should be revewered and merged, rather than reflecting your development process. Within a PR, there isn't much reason to have a revert commit.

[enricobolzonello]

Please update your commits for how they should be revewered and merged, rather than reflecting your development process. Within a PR, there isn't much reason to have a revert commit.

ok, I squashed the revert commit into the original commit.

[epage]

@rfcbot fcp merge cargo

Currently, you can have

dep = { version = "1", git = "..." }

which gets stripped on publish to

dep = { version = "1" }

but you can't have

dep = { version = "1", registry = "foo", git = "..." }

This PR fixes so registry can be used with git as discussed in a Cargo team meeting around Oct 28, 2025

[rust-rfcbot]

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

• @0xPoe
• @Eh2406
• @Muscraft
• @arlosi
• @ehuss
• @epage
• @joshtriplett
• @weihanglo

No concerns currently listed.

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.