Align is_instance by youknowone · Pull Request #5855 · RustPython/RustPython

youknowone

Walkthrough

The changes refactor type instance and subclass checking in the virtual machine. The __instancecheck__ method on PyType now accepts a VirtualMachine argument and returns PyResult<bool>, delegating to a new real_is_instance method. The is_instance and is_subclass methods are enhanced to handle union types, reorder checks to match CPython, and avoid infinite recursion by using real_is_instance.

Changes

File(s)	Change Summary
vm/src/builtins/type.rs	Modified `PyType::__instancecheck__` signature to include `vm` and return `PyResult<bool>`. Updated implementation to use `real_is_instance`.
vm/src/protocol/object.rs	Added `real_is_instance` method to `PyObject`. Refactored `is_instance` and `is_subclass` to handle union types, reorder checks, and avoid recursion.
Lib/test/test_isinstance.py	Adjusted imports and recursion depth in tests. Changed union type order in one test. Minor whitespace and formatting cleanup.

Sequence Diagram(s)

sequenceDiagram
    participant Caller
    participant PyType
    participant PyObject
    participant VirtualMachine

    Caller->>PyType: __instancecheck__(obj, vm)
    PyType->>PyObject: real_is_instance(self.as_object(), vm)
    PyObject->>VirtualMachine: (uses vm for context)
    PyObject-->>PyType: PyResult<bool>
    PyType-->>Caller: PyResult<bool>

sequenceDiagram
    participant Caller
    participant PyObject
    participant VirtualMachine

    Caller->>PyObject: is_instance(cls, vm)
    alt cls is a type
        PyObject->>PyObject: real_is_instance(cls, vm)
    else cls is a union
        loop each member in union
            PyObject->>PyObject: is_instance(member, vm)
        end
    else cls is a tuple
        loop each member in tuple
            PyObject->>PyObject: is_instance(member, vm)
        end
    else cls has __instancecheck__
        PyObject->>cls: __instancecheck__(self, vm)
    else
        PyObject->>PyObject: real_is_instance(cls, vm)
    end
    PyObject-->>Caller: PyResult<bool>

Poem

In the warren of types, a new path we define,
With real_is_instance, the checks are more fine.
No more recursion traps, nor confusion in sight,
Union and tuple types now handled just right.
With each hop and check, our logic aligns—
A rabbit’s delight in these elegant lines! 🐇

📜 Recent review details

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Review profile: CHILL
Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 1b40c45 and dd90515.

📒 Files selected for processing (3)

Lib/test/test_isinstance.py (7 hunks)
vm/src/builtins/type.rs (1 hunks)
vm/src/protocol/object.rs (4 hunks)

🚧 Files skipped from review as they are similar to previous changes (2)

vm/src/builtins/type.rs
vm/src/protocol/object.rs

🧰 Additional context used

📓 Path-based instructions (2)

`Lib/**/*`: Files in the Lib/ directory (Python standard library copied from CPy...

Lib/**/*: Files in the Lib/ directory (Python standard library copied from CPython) should be edited very conservatively; modifications should be minimal and only to work around RustPython limitations.

📄 Source: CodeRabbit Inference Engine (.github/copilot-instructions.md)

List of files the instruction was applied to:

Lib/test/test_isinstance.py

`Lib/test/**/*`: Tests in Lib/test often use markers such as '# TODO: RUSTPYTHON...

Lib/test/**/*: Tests in Lib/test often use markers such as '# TODO: RUSTPYTHON', 'unittest.skip("TODO: RustPython ")', or 'unittest.expectedFailure' with a '# TODO: RUSTPYTHON ' comment when modifications are made.
NEVER comment out or delete any test code lines except for removing '@unittest.expectedFailure' decorators and upper TODO comments.
NEVER modify test assertions, test logic, or test data in Lib/test files.
The only acceptable modifications to test files are: (1) removing '@unittest.expectedFailure' decorators and the upper TODO comments when tests actually pass, (2) adding '@unittest.expectedFailure' decorators when tests cannot be fixed.
When a test cannot pass due to missing language features, keep it as expectedFailure and document the reason.

📄 Source: CodeRabbit Inference Engine (.github/copilot-instructions.md)

List of files the instruction was applied to:

Lib/test/test_isinstance.py

🧠 Learnings (1)

Lib/test/test_isinstance.py (1)

Learnt from: CR
PR: RustPython/RustPython#0
File: .github/copilot-instructions.md:0-0
Timestamp: 2025-06-26T12:52:11.109Z
Learning: When a test fails due to unsupported Python syntax or features, keep the test as '@unittest.expectedFailure' and document the reason, rather than modifying the test logic or data.

⏰ Context from checks skipped due to timeout of 90000ms (11)

GitHub Check: Run snippets and cpython tests (macos-latest)
GitHub Check: Check Rust code with rustfmt and clippy
GitHub Check: Run tests under miri
GitHub Check: Run snippets and cpython tests on wasm-wasi
GitHub Check: Run snippets and cpython tests (windows-latest)
GitHub Check: Check the WASM package and demo
GitHub Check: Run rust tests (windows-latest)
GitHub Check: Run snippets and cpython tests (ubuntu-latest)
GitHub Check: Run rust tests (macos-latest)
GitHub Check: Run rust tests (ubuntu-latest)
GitHub Check: Ensure compilation on various targets

🔇 Additional comments (3)

Lib/test/test_isinstance.py (3)

355-356: Approve import localization improvement.

Moving the sys import from module level to function level improves code organization by placing the import close to its usage.

227-227: Verify that union type order change is necessary and doesn't alter test intent.

The order of types in the union was changed from (int | str | list[int] | float) to (float | str | list[int] | int). According to coding guidelines, test data modifications in Lib/test files should be avoided.

Please confirm this change is necessary to align with core implementation behavior and doesn't fundamentally alter the test's intent:
#!/bin/bash
# Description: Search for related changes in core isinstance/issubclass implementation
# Expected: Find evidence of union type ordering changes in core files

rg -A 5 -B 5 "union.*type.*order|type.*union.*order" 
ast-grep --pattern 'isinstance($_, $union_type)' 
313-313: Verify recursion depth parameter changes align with core implementation.

The support.infinite_recursion() calls now include a depth parameter of 25. This appears to accommodate core implementation changes but modifies test behavior.

Please verify these parameter changes are necessary:
#!/bin/bash
# Description: Check for changes in infinite_recursion support function and core recursion handling
# Expected: Find evidence of recursion depth changes in core or test support

rg -A 3 -B 3 "infinite_recursion.*25|recursion.*25"
ast-grep --pattern 'infinite_recursion($depth)'
rg "support\.infinite_recursion" --type py
Also applies to: 347-347

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