type.__new__: preserve caller namespace when reading __qualname__ by wheevu · Pull Request #7524 · RustPython/RustPython

wheevu · 2026-03-28T09:22:12Z

type(name, bases, ns) currently mutates the caller-provided namespace by popping __qualname__.

This changes PyType::slot_new to read __qualname__ without mutating the input namespace, then remove it from the copied attributes. That keeps the caller namespace while still keeping __qualname__ out of the created type’s __dict__, which matches CPython.

This also removes the @unittest.expectedFailure marker from test_qualname_dict.

Tested with:

cargo run --release -- -m unittest test.test_descr.ClassPropertiesAndMethods.test_qualname_dict
cargo run --release -- -c "ns={'__qualname__':'some.name'}; tp=type('Foo',(),ns); print(tp.__qualname__); print('__qualname__' in tp.__dict__); print(ns)"
cargo run --release -- -c "ns={1: 2, '__qualname__': 1}; type('Foo', (), ns)"
cargo fmt
cargo clippy

Summary by CodeRabbit

Refactor
- Internal improvement to type-construction logic: metadata lookup is now separated from attribute extraction, and metadata is removed explicitly from attributes. No changes to public behavior, APIs, or user-facing functionality.

github-actions · 2026-03-28T09:22:59Z

📦 Library Dependencies

The following Lib/ modules were modified. Here are their dependencies:

[ ] test: cpython/Lib/test/test_descr.py (TODO: 38)
[ ] test: cpython/Lib/test/test_descrtut.py (TODO: 3)

dependencies:

dependent tests: (no tests depend on descr)

Legend:

[+] path exists in CPython
[x] up-to-date, [ ] outdated

coderabbitai · 2026-03-28T09:24:28Z

No actionable comments were generated in the recent review. 🎉

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📒 Files selected for processing (1)

crates/vm/src/builtins/type.rs

🚧 Files skipped from review as they are similar to previous changes (1)

crates/vm/src/builtins/type.rs

📝 Walkthrough

Walkthrough

Refactors PyType::slot_new to stop popping __qualname__ from the incoming dict; instead it first reads __qualname__ via get_item_opt(...), converts the dict to an attributes map, then removes __qualname__ from that map with attributes.shift_remove(...).

Changes

Cohort / File(s)	Summary
PyType Constructor Refactor `crates/vm/src/builtins/type.rs`	Changed `__qualname__` handling in `PyType::slot_new`: lookup with `get_item_opt(...)` before converting the dict to attributes, then remove `__qualname__` via `attributes.shift_remove(...)` instead of popping from the original dict.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Possibly related PRs

#6010: Concurrently modifies PyType constructor in the same file, affecting attribute and dict descriptor handling.

Poem

🐰 I peeked the qualname, gentle and sly,

I turned the dict to attributes by and by,
Then plucked the name with a careful shove,
No double-removal, just tidy love,
Hoppity code, neat as a glove!

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ 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%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ 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 'type.new: preserve caller namespace when reading qualname' directly describes the main change in the pull request, which is modifying how PyType::slot_new handles qualname to avoid mutating the caller-provided namespace.

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coderabbitai

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@crates/vm/src/builtins/type.rs`:
- Around line 1870-1873: The code calls dict.to_attributes(vm) before extracting
__qualname__, which can force early iteration/validation and panic on non-string
keys; instead, remove and validate the __qualname__ entry from the original dict
prior to converting to attributes. Concretely: call
dict.shift_remove(identifier!(vm, __qualname__)) (or an equivalent safe lookup)
on the incoming dict first and run downcast_qualname on that result, then call
dict.to_attributes(vm) to build attributes; reference symbols:
dict.to_attributes(vm), identifier!(vm, __qualname__), shift_remove,
downcast_qualname, and the type.__new__ namespace handling where this ordering
occurs.

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Fix all unresolved CodeRabbit comments on this PR:

Push a commit to this branch (recommended)
Create a new PR with the fixes

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Reviewing files that changed from the base of the PR and between 1a9b10e and f1c1470.

⛔ Files ignored due to path filters (1)

Lib/test/test_descr.py is excluded by !Lib/**

📒 Files selected for processing (1)

crates/vm/src/builtins/type.rs

crates/vm/src/builtins/type.rs

ShaharNaveh

lgmt!
ty, and welcome to the project:)

youknowone

Thank you!

type.__new__: preserve caller namespace when reading __qualname__

f1c1470

coderabbitai bot reviewed Mar 28, 2026

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crates/vm/src/builtins/type.rs Outdated Show resolved Hide resolved

type.__new__: preserve caller namespace when reading __qualname__

5bcc7b7

ShaharNaveh approved these changes Mar 28, 2026

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youknowone approved these changes Mar 28, 2026

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youknowone merged commit da440db into RustPython:main Mar 28, 2026
16 checks passed

wheevu deleted the fix-type-qualname-ns-mutation branch March 28, 2026 15:54

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type.new: preserve caller namespace when reading qualname#7524

type.new: preserve caller namespace when reading qualname#7524
youknowone merged 2 commits intoRustPython:mainfrom
wheevu:fix-type-qualname-ns-mutation

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