Separate Debug from PyPayload by youknowone · Pull Request #6320 · RustPython/RustPython

youknowone

Walkthrough

This PR refactors the VM object system's trait bounds, replacing PyObjectPayload with PyPayload across public APIs and adding std::fmt::Debug constraints to ensure debug-printability. The PyPayload trait itself is narrowed by removing Debug from supertraits, with Debug requirements instead added to specific methods via where clauses.

Changes

Cohort / File(s)	Summary
Foundational trait updates `crates/vm/src/object/payload.rs`	Removed `std::fmt::Debug` from `PyPayload` supertrait; added `where Self: std::fmt::Debug` to five public methods (`into_pyobject`, `_into_ref`, `into_exact_ref`, `into_ref`, `into_ref_with_type`). Updated `PyObjectPayload` impl to require `Debug` on generic parameter.
Object system refactoring `crates/vm/src/object/core.rs`, `crates/vm/src/object/ext.rs`	Broadly replaced `PyObjectPayload` with `PyPayload` across downcasting APIs, trait impls (Borrow, AsRef, Hash, PartialEq, Eq, Debug), and weak reference handling. Added `std::fmt::Debug` bounds to debug-related functions and trait implementations. Updated `PyRef`, `Py<T>`, `PyWeakRef<T>`, `PyExact<T>`, `PyRefExact<T>`, `PyLease<'a, T>`, and `PyAtomicRef<T>` generic constraints.
Trait bound additions `crates/vm/src/builtins/dict.rs`, `crates/vm/src/types/slot.rs`, `crates/vm/src/vm/context.rs`	Added `std::fmt::Debug` constraint to `DictView::ReverseIter` associated type, `DefaultConstructor` trait supertraits, and `Context::new_pyref<T, P>` generic parameter.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Areas requiring extra attention:

payload.rs: The removal of Debug from trait supertraits and shift to method-level where clauses should be verified to ensure all implementors can satisfy the constraints without breaking downstream code.
core.rs & ext.rs: The large-scale replacement of PyObjectPayload with PyPayload across many impl blocks should be spot-checked for completeness and correctness, particularly in downcasting and weak reference paths.
Trait impact: Verify that the Debug constraints on PyPayload methods do not conflict with existing trait object usage patterns or generic specializations.

Possibly related PRs

Integrate PyTupleTyped into PyTuple #5959: Overlapping refactors to payload/traverse/type-bounds in the same files (payload.rs, object/core.rs, vm/context.rs), modifying related trait bounds and APIs.
Downcastable #5986: Related changes to PyObject downcasting APIs in object/core.rs affecting downcast/payload methods and trait bounds.

Suggested reviewers

arihant2math
coolreader18

Poem

🐰 Debug bounds hop through every trait,
PyPayload now leads our fate,
Constraints tighten, types align—
Where clauses make the code just fine,
A refactor clean, no bugs in sight!

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	You can run `@coderabbitai generate docstrings` to improve docstring coverage.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'Separate Debug from PyPayload' accurately captures the main objective of this PR, which systematically decouples the Debug trait requirement from the PyPayload trait across the codebase.

✨ Finishing touches

📝 Generate docstrings

🧪 Generate unit tests (beta)

Create PR with unit tests
Post copyable unit tests in a comment

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