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Align type layouts and generic descriptors with Python 3.15 - #9175
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Import canonical descriptor tests through update_lib, preserving existing guards. Support tuple member slots, distinguish base reassignment from class layout compatibility, and share object-owned generic descriptors. Assisted-by: OpenAI Codex:model version unavailable
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Docstring coverage is 69.23% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 13 functions across 4 files. | Write docstrings for the functions missing them to satisfy the coverage threshold. |
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Check name Status Explanation Linked Issues check Check skipped because no linked issues were found for this pull request. Out of Scope Changes check Check skipped because no linked issues were found for this pull request. Description Check Check skipped - CodeRabbit’s high-level summary is enabled. Title check The title clearly and concisely summarizes the main changes: aligning type layouts and shared generic descriptors with Python 3.15.
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📦 Library DependenciesThe following Lib/ modules were modified. Here are their dependencies: :4: SyntaxWarning: invalid decimal literal dependencies: dependent tests: (no tests depend on descr) Legend:
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Actionable comments posted: 1
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Inline comments:
Review comments at @crates/vm/src/builtins/type.rs:
- Around line 3836-3838: Update compatible_for_assignment and the slot-update
flow around update_all_slots so a base reassignment cannot leave a class with
dictionary or weak-reference storage but no corresponding instance descriptors.
Install shared descriptors on affected heap classes, or reject the reassignment
when it would remove descriptors that the class relies on.
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⛔ Files ignored due to path filters: 1
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📒 Files selected for processing: 4
crates/vm/src/builtins/object.rscrates/vm/src/builtins/type.rscrates/vm/src/vm/interpreter.rscrates/vm/src/vm/mod.rs
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| self.assertEqual(repr(cm), '<classmethod(None)>') | ||
| self.assertIsNone(cm.__func__) | ||
| self.assertIsNone(cm.__wrapped__) | ||
| def test_gh146587(self): |
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Restore tests removed by the CPython sync
This hunk replaces test_staticmethod_new and test_classmethod_new, and the same sync removes the two test_refleaks_*___init__ methods, so four pre-existing regressions are no longer exercised. The repository's test policy explicitly forbids deleting test code and requires unsupported cases to remain as expected failures; restore these tests (using the prescribed marker if any now fail) while adding the new CPython coverage.
AGENTS.md reference: AGENTS.md:L276-L282
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These four removals are from the complete upstream CPython 3.15.0 file at d220409a13b77de7a6c30abe16ea90db01528edc, imported through scripts/update_lib under the requested canonical-only migration policy. They are not local deletions to suppress failures. The resulting test_descr.py is byte-identical to that pinned file apart from the two preserved RustPython expectedSuccess wrappers. Restoring older test bodies manually would violate that migration requirement. The full pinned suite ran on both interpreters: CPython 165 passed, 1 resource skip, 2 canonical expected failures; RustPython 155 passed and 13 canonical skips. I am retaining the canonical file and existing guards.
| && (!set_class | ||
| || (type_has_dict(child) == type_has_dict(parent) | ||
| && type_has_weakref(child) == type_has_weakref(parent))) |
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Preserve inherited descriptors across bases changes
When C inherits its dict/weakref storage from A (so neither descriptor is in C.__dict__) and C.__bases__ is reassigned to a layout-compatible slotted base, the set_class == false path now collapses across the HAS_DICT/HAS_WEAKREF boundary. storage_compatible accepts this because C's allocation has the prefixes, but set_bases only rewrites the MRO and slots and never installs the common descriptors; existing and new C instances still accept arbitrary attributes or weakrefs while c.__dict__ and c.__weakref__ start raising AttributeError. Either keep those inherited descriptors on C during reparenting or reject this transition.
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I reproduced this against the exact pinned CPython 3.15.0 commit d220409a13b77de7a6c30abe16ea90db01528edc and the unchanged PR binary. Their complete observations match: for dict-only, weakref-only, and combined storage, an empty-slotted subclass has no own common descriptor before or after compatible bases reassignment; after reparenting the descriptors are missing while the storage still works. Existing/new instances and descendants agree. Meta(type) also has no own dict descriptor in this pin.
The important source ordering is that type_new_descriptors runs before type_ready inheritance copies tp_dictoffset/tp_weaklistoffset. Its nonzero-offset checks therefore do not install these descriptors for inherited storage. type_set_bases subsequently updates MRO/slots without adding them. The proposed universal descriptor installation would change behavior relative to the requested pinned target, so I am retaining this implementation. This does not claim the upstream behavior is ideal; it establishes parity for the reported case.
Align type layouts and generic descriptors with Python 3.15
Split from #8954, based directly on main. This is a coherent native type-layout change with its complete canonical descriptor-test closure.
Changes
__bases__reparenting from strict__class__assignment checks, preserving allocated storage and the existing member-layout safeguards.__dict__and__weakref__descriptors within each interpreter, using existing descriptor ownership/traversal and storage checks.test_descr.pyfrom CPython 3.15.0 d220409a13 throughscripts/update_lib, preserving the two existing RustPythonexpectedSuccesswrappers. No new guards or test-logic edits.Preserves merged annotation/cache lifetime fixes from #9162 and layout safeguards from #9041. Does not depend on the separate weakref-lifecycle, lazy-import or startup-path PRs.
Validation
The missing
_testcapifixtures leave the null-constructor metaclass and before-items C-extension storage paths without candidate runtime coverage. They are not reported as passing. Local validation was on Linux with the default filesystem-library backend; hosted platform results are pending. Default resources are used; the million-wrapper CPU stress test remains canonically resource-gated.Each runtime uses bounded owned-process cleanup and a private library/temp environment. Source and artifact hashes reconcile; generated bytecode is hash-preserved separately. One oracle-to-build audit command initially used an incorrect relative path, so its full post-oracle audit completed immediately after build launch; it found no changes. The build's own sealed-source and zero-cache preflight succeeded before launch.
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Summary by CodeRabbit
__class__, including checks for compatible memory layout and dictionary or weak-reference support.__weakref__on instances without weak-reference support now raisesAttributeError.TypeErrorwhen the winning metaclass has no__new__method.