Add extra_cargo_args support for prepare phase

[enthropy7]

this adds an extra_cargo_args() method to BuildBuilder that forwards extra arguments to all cargo commands during Prepare::prepare(): validate_manifest, capture_lockfile, and fetch_deps. without this, crates that require unstable cargo flags for manifest parsing (e.g. -Zbindeps for artifact dependencies) fail at the prepare phase with InvalidCargoTomlSyntax, because there's no way for callers to pass these flags.

needed by docs.rs: rust-lang/docs.rs#3111

[syphar]

Thanks!

This is missing tests.

we have "integration-like" tests / examples in tests/.

[enthropy7]

added and tested :)

[syphar]

added and tested :)

I realized that I totally missed this comment, and in my "reviews requested" this PR didn't pop up. Will recheck.

( generally: I did "some" refactoring in the codebase that means you need to update this PR too

[enthropy7]

done! :)

[syphar]

One small API change, two small things for the tests.

Generally:
Right now we assume that the same extra_cargo_args are accepted by cargo metadata, generate-lockfile andfetch, and probably other commands that come later.

Also I wonder if users of the lib would expect that these commands are also automatically added to other cargo calls in the same build.

But: I think when we do the small things from above, we can merge / release this.

[enthropy7]

thanks! fixed the review comments.

also yeah, I agree the naming is a bit subtle here. for this PR I kept the scope to prepare-time cargo invocations only, since that’s the docs.rs use case and matches the current method docs. I don’t think we should automatically add these args to build.cargo() calls, because callers can already pass those explicitly there and it might be surprising.

rebased on latest main, ci is running again.

[enthropy7]

rebased on latest main, ci is running again.

one test was failing cause of cargo updates

[oli-obk]

The user has been banned from the rust-lang org and will not be providing more updates here

[syphar]

The user has been banned from the rust-lang org and will not be providing more updates here

oh, thanks for the info!