Support resolving optional dependencies and dependency groups

[olivier-lacroix]

This PR refactors the recursion resolution of dependency-groups into a trait, and implements it for both

• dependency groups, and
• optional dependencies as well.

Let me know what you think.

[konstin]

I would prefer handling this without self_reference_name and instead have the caller pass in the name of the package if they want to have self-referential optional dependencies resolved.

Can we implement this without introducing a new trait? The logic should be small enough that we should be able to implement without public helper types.

[olivier-lacroix]

@konstin okay. Let me do that.

[olivier-lacroix]

@konstin done. I kept the trait but made it internal to this crate. Hopefully this aligns with what you had in mind!

[konstin]

I've tried to simplify the code by inlining the trait (https://github.com/PyO3/pyproject-toml-rs/compare/konsti/refactor-resolve?expand=1), but hit a bigger problem: When we want to resolve a dependency group for a project foo that depends on foo[bar], we need to have the optional dependencies in the dependency group resolution to resolve bar, so I think the methods need to move to the PyProjectToml top level to provide proper resolution.

[olivier-lacroix]

Goddam it. That’s a diabolical corner case…

[dhirschfeld]

Super exciting to see this passing, but for the lint:

    Checking pyproject-toml v0.13.5 (/home/runner/work/pyproject-toml-rs/pyproject-toml-rs)
error: very complex type used. Consider factoring parts into `type` definitions
  --> src/resolution.rs:15:10
   |
15 |       ) -> Result<
   |  __________^
16 | |         (
17 | |             Option<IndexMap<String, Vec<Requirement>>>,
18 | |             Option<IndexMap<String, Vec<Requirement>>>,
19 | |         ),
20 | |         RecursionResolutionError,
21 | |     > {
   | |_____^
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#type_complexity
   = note: `-D clippy::type-complexity` implied by `-D warnings`
   = help: to override `-D warnings` add `#[allow(clippy::type_complexity)]`

error: could not compile `pyproject-toml` (lib) due to 1 previous error

Being able to support pip's nested dependencies will make transitioning to pixi easier.

[olivier-lacroix]

@konstin I found the time to get back to this.

• there is now a single top level PyProjectToml::resolve method, that resolves both dependency groups and optional dependencies
• name collision between dependency groups and optional dependencies will raise an error during that resolution
• resolved dependency groups and optional dependencies are returned as a tuple: it would feel maybe cleaner to wrap dependency groups and optional dependencies into a Resolved / Unresolved Enum, but let me know what you think.

ps: I somehow missed your refactor 🫨 ... I'll integrate it if you are happy with the direction and feel it would still be beneficial.

[olivier-lacroix]

I have tried to integrate your proposed refactor @konstin

[dhirschfeld]

CI is green, @olivier-lacroix I assume this is ready for review/merge from your PoV?

[olivier-lacroix]

Indeed 👍

[olivier-lacroix]

@konstin any chance you could take a look at this PR ?

[dhirschfeld]

Thank you @olivier-lacroix & @konstin! I'm super excited to be able to make use of this (via pixi)!