Fix frozenset subclass keyword arguments by kyokuping · Pull Request #8287 · RustPython/RustPython

kyokuping · 2026-07-15T16:59:34Z

Assisted-by: Codex:gpt-5.6

Closes #xxxx
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Summary

Fix frozenset subclass construction to match CPython’s keyword-argument behavior.
Allow subclasses with a custom __init__ to receive keyword arguments while frozenset.__new__ consumes the positional iterable.
Preserve strict argument validation for exact frozenset and subclasses inheriting frozenset.__init__.
Keep exact-type reuse and empty-singleton optimizations limited to exact frozenset instances.
Re-enable TestFrozenSetSubclass.test_keywords_in_subclass by removing its expectedFailure marker.

Summary by CodeRabbit

Bug Fixes
- Improved frozenset construction by detecting the exact builtin type for a faster initialization path.
- Returns existing builtin frozenset inputs directly when appropriate.
- For frozenset subclasses, enforces “at most 1 argument” and raises TypeError when more than one positional argument is provided.
- Optimized empty frozenset creation to reuse the existing empty singleton instead of allocating a new one.

coderabbitai · 2026-07-15T16:59:55Z

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Reviewing files that changed from the base of the PR and between 3d5c9b6 and 67e489b.

⛔ Files ignored due to path filters (1)

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

📒 Files selected for processing (1)

crates/vm/src/builtins/set.rs

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

crates/vm/src/builtins/set.rs

📝 Walkthrough

Walkthrough

Refactors PyFrozenSet::slot_new to select optimized or subclass argument handling based on type and __init__ compatibility, reuse builtin frozenset inputs, enforce argument limits, and consolidate empty frozenset singleton construction.

Changes

Frozenset construction

Layer / File(s)	Summary
Constructor dispatch and result handling `crates/vm/src/builtins/set.rs`	`slot_new` distinguishes exact and builtin-compatible constructors, validates subclass argument counts, reuses builtin frozenset inputs, converts iterables, and returns the empty singleton for empty exact frozensets.

Estimated code review effort: 2 (Simple) | ~10 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly matches the main change: frozenset subclass construction now handles keyword arguments correctly.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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Actionable comments posted: 3

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@crates/vm/src/builtins/set.rs`:
- Around line 992-1002: Update the argument match in the subclass-instantiation
branch to add an explicit zero-positional-arguments arm that returns an empty
vector, matching the fallback used by the main branch. Keep the single-iterable
handling and TypeError for more than one positional argument unchanged.
- Around line 992-1002: Update the argument match in the frozenset subclass
constructor path to handle zero positional arguments explicitly with an empty
collection value. Keep the existing single-iterable handling and
excessive-argument TypeError behavior unchanged.
- Around line 975-1002: Update the element-selection logic in the frozenset
constructor to first derive a single optional iterable: preserve the
exact-frozenset fast path, accept one positional argument, and treat zero
positional arguments as absent while still rejecting more than one. Then perform
iterable.try_to_value(vm)? or return an empty vector once after the branches,
eliminating the duplicated extraction logic and allowing subclass construction
with only keyword arguments.

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📥 Commits

Reviewing files that changed from the base of the PR and between c1bc99a and 845acfd.

⛔ Files ignored due to path filters (1)

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

📒 Files selected for processing (1)

crates/vm/src/builtins/set.rs

github-actions · 2026-07-15T19:43:06Z

📦 Library Dependencies

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

[ ] test: cpython/Lib/test/test_set.py (TODO: 4)

dependencies:

dependent tests: (no tests depend on set)

Legend:

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

fanninpm · 2026-07-16T16:11:47Z

If the CI failure bothers you, you can rebase this branch onto a fresh copy of main.

Assisted-by: Codex:gpt-5.6

youknowone

Looks good, thank you!

coderabbitai Bot reviewed Jul 15, 2026

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Comment thread crates/vm/src/builtins/set.rs

Comment thread crates/vm/src/builtins/set.rs

kyokuping force-pushed the codex/frozenset-subclass-keywords branch from 845acfd to e37b7c9 Compare July 15, 2026 17:51

kyokuping marked this pull request as draft July 15, 2026 18:41

kyokuping marked this pull request as ready for review July 16, 2026 08:26

moreal added the z-ca-2026 Tag to track Contribution Academy 2026 label Jul 16, 2026

moreal assigned kyokuping Jul 16, 2026

kyokuping force-pushed the codex/frozenset-subclass-keywords branch from 592806f to 3d5c9b6 Compare July 16, 2026 12:49

Fix frozenset subclass keyword arguments

67e489b

Assisted-by: Codex:gpt-5.6

kyokuping force-pushed the codex/frozenset-subclass-keywords branch from 3d5c9b6 to 67e489b Compare July 16, 2026 18:12

youknowone approved these changes Jul 17, 2026

View reviewed changes

youknowone merged commit ea6880b into RustPython:main Jul 17, 2026
27 checks passed

kyokuping deleted the codex/frozenset-subclass-keywords branch August 8, 2026 05:58

coderabbitai Bot mentioned this pull request Aug 11, 2026

Reuse stored hashes when building a set from a set/frozenset/dict #8491

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Fix frozenset subclass keyword arguments - #8287

Fix frozenset subclass keyword arguments#8287
youknowone merged 1 commit into
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kyokuping:codex/frozenset-subclass-keywords

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📦 Library Dependencies

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kyokuping commented Jul 15, 2026 •

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