Update issubclass and make `mro` representation fit to CPython

[youknowone]

Summary by CodeRabbit

• New Features

  • Added utility methods for type checking and subtype determination, enhancing compatibility with Python's type system.
  • Improved handling of method resolution order (MRO) for core types to better reflect inheritance relationships.

• Refactor

  • Refined class and subclass checking logic for improved correctness and alignment with Python behavior.
  • Optimized single inheritance checks for better performance.
  • Streamlined creation of empty typed tuples by simplifying dependencies.

• Bug Fixes

  • Corrected initialization of MRO for fundamental types, ensuring accurate inheritance chains.

[coderabbitai[bot]]

Walkthrough

This set of changes refactors the handling of method resolution order (MRO), type checking, and subclass determination in the Python VM implementation. It introduces more precise MRO management, optimizes subclass checks, updates tuple initialization to use context directly, and aligns error handling and attribute checks with CPython semantics.

Changes

File(s)	Change Summary
vm/src/builtins/tuple.rs	Changed PyTupleTyped::empty to take &Context instead of &VirtualMachine and updated usage accordingly.
vm/src/frame.rs, vm/src/vm/mod.rs	Updated calls to PyTupleTyped::empty to pass &vm.ctx instead of the full VM.
vm/src/builtins/type.rs	Refined MRO handling: new is_subtype_with_mro, added check, check_exact, and is_subtype methods; adjusted MRO construction and attribute lookup to skip the type itself where appropriate; commented out MRO traversal in Traverse.
vm/src/object/core.rs	Updated type hierarchy initialization to set correct MROs for object_type, type_type, and weakref_type.
vm/src/protocol/object.rs	Refactored and optimized class and subclass checking: renamed and rewrote check_cls as check_class, added abstract_get_bases, improved abstract_issubclass and recursive_issubclass logic and error handling.

Sequence Diagram(s)

sequenceDiagram
    participant User
    participant VM
    participant Context
    participant PyType
    participant PyObject

    User->>VM: import(...)
    VM->>Context: get empty_tuple
    Context-->>VM: empty_tuple
    VM->>PyTupleTyped: empty(&Context)
    PyTupleTyped-->>VM: PyTupleTyped instance

    User->>PyObject: is_subclass_of(cls)
    PyObject->>PyType: check_class()
    PyType-->>PyObject: Ok/Err
    PyObject->>PyType: is_subtype(other)
    PyType->>PyType: is_subtype_with_mro(self.mro, self, other)
    PyType-->>PyObject: true/false

Suggested reviewers

• arihant2math

Poem

In the warren of code where the tuples reside,
The MRO bunnies now hop with more pride.
Context brings tuples, not the whole VM,
Type checks are sharper, subclassing’s a gem!
With a twitch of the nose and a hop in the flow,
Python’s inheritance just got more in the know!
🐇✨

✨ Finishing Touches

• [ ] 📝 Generate Docstrings

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

🪧 Tips

Chat

There are 3 ways to chat with CodeRabbit:

• Review comments: Directly reply to a review comment made by CodeRabbit. Example:
  • I pushed a fix in commit <commit_id>, please review it.
  • Explain this complex logic.
  • Open a follow-up GitHub issue for this discussion.
• Files and specific lines of code (under the "Files changed" tab): Tag @coderabbitai in a new review comment at the desired location with your query. Examples:
  • @coderabbitai explain this code block.
  • @coderabbitai modularize this function.
• PR comments: Tag @coderabbitai in a new PR comment to ask questions about the PR branch. For the best results, please provide a very specific query, as very limited context is provided in this mode. Examples:
  • @coderabbitai gather interesting stats about this repository and render them as a table. Additionally, render a pie chart showing the language distribution in the codebase.
  • @coderabbitai read src/utils.ts and explain its main purpose.
  • @coderabbitai read the files in the src/scheduler package and generate a class diagram using mermaid and a README in the markdown format.
  • @coderabbitai help me debug CodeRabbit configuration file.

Support

Need help? Create a ticket on our support page for assistance with any issues or questions.

Note: Be mindful of the bot's finite context window. It's strongly recommended to break down tasks such as reading entire modules into smaller chunks. For a focused discussion, use review comments to chat about specific files and their changes, instead of using the PR comments.

CodeRabbit Commands (Invoked using PR comments)

• @coderabbitai pause to pause the reviews on a PR.
• @coderabbitai resume to resume the paused reviews.
• @coderabbitai review to trigger an incremental review. This is useful when automatic reviews are disabled for the repository.
• @coderabbitai full review to do a full review from scratch and review all the files again.
• @coderabbitai summary to regenerate the summary of the PR.
• @coderabbitai generate docstrings to generate docstrings for this PR.
• @coderabbitai generate sequence diagram to generate a sequence diagram of the changes in this PR.
• @coderabbitai resolve resolve all the CodeRabbit review comments.
• @coderabbitai configuration to show the current CodeRabbit configuration for the repository.
• @coderabbitai help to get help.

Other keywords and placeholders

• Add @coderabbitai ignore anywhere in the PR description to prevent this PR from being reviewed.
• Add @coderabbitai summary to generate the high-level summary at a specific location in the PR description.
• Add @coderabbitai anywhere in the PR title to generate the title automatically.

CodeRabbit Configuration File (.coderabbit.yaml)

• You can programmatically configure CodeRabbit by adding a .coderabbit.yaml file to the root of your repository.
• Please see the configuration documentation for more information.
• If your editor has YAML language server enabled, you can add the path at the top of this file to enable auto-completion and validation: # yaml-language-server: $schema=https://coderabbit.ai/integrations/schema.v2.json

Documentation and Community

• Visit our Documentation for detailed information on how to use CodeRabbit.
• Join our Discord Community to get help, request features, and share feedback.
• Follow us on X/Twitter for updates and announcements.

[youknowone]

beacuse MRO is currently not weakrefs, this prevent RC=0 to release type objects