GeezerVison

Summary

Align function/type/module metadata contracts with CPython 3.15 final, with explicit publication and cleanup order when annotation callbacks or finalizers re-enter Python.

• Preserve the original code-name object when constructing a function without a name; accept explicit None as omitted while retaining explicit string/subclass behavior.
• Copy the standard metadata onto implicit __new__, __init_subclass__, and __class_getitem__ wrappers using the existing wrapping helper.
• Match annotation dict-subclass acceptance and qualified invalid-result diagnostics. Publish annotation/cache changes in CPython's observable phases, retain displaced Python owners until after releasing locks, and release callbacks before the corresponding validation/cache steps. Deleting function annotations also clears its annotator.
• Register slice's existing GenericAlias implementation.
• Migrate the complete test_type_annotations.py and test_genericalias.py files through scripts/update_lib from CPython d220409a13b77de7a6c30abe16ea90db01528edc. No hand-edited assertions or removed capability guards.

This is a bounded decomposition of #8954, with independently checked callback/finalizer ordering, rather than a wholesale copy of its type implementation.

Base and prerequisite

Based on main fd5b30eb5e6c1dd24bb98a305b1c5f47fa64820d, verified again on 2026-10-16. The branch includes the exact separate bf076f10c503749521d176b9b757fe5b3088fe63 benchmark import fix from #9161, which is still open and needed for strict all-target lint. The metadata changes are the following two commits, ending at 3d8adae764d7db2cf593fa58b61f658043970ecd. The prerequisite should disappear from the PR comparison once #9161 is merged/reconciled.

Validation

Fresh Linux validation at the exact source above:

• Normal repository commit hooks passed. Independent source review covered ownership release, callback re-entry, cache publication and canonical test provenance.
• cargo clippy --offline --locked -p rustpython -p rustpython-vm --all-targets -- -D warnings passed.
• cargo build --offline --locked -p rustpython --bin rustpython passed. This is a default-feature debug build, with two jobs, debug info disabled and incremental compilation disabled. Workspace artifacts, including pylib, were refreshed before building.
• Candidate: 36 selectors, each running exactly one unittest test, all 36 passed. These comprise 13 selected repository canonical methods, the complete canonical BaseTest.test_subscriptable method (all of its original parameters, including slice), one separately loaded unchanged canonical descriptor method, six supplemental metadata observations and 15 separately isolated finalizer/re-entry observations.
• Reference: the same six metadata and 15 finalizer observations passed first on the installed official CPython 3.15.0 final runtime. Its exact executable/library hashes were pinned; its build commit is not asserted to be d220. The C source and migrated test references are separately pinned to d220.
• Both groups had zero failures, errors, skips, expected failures or unexpected successes. Canonical capability checks and assertions were retained. Successful parameter subtests are not reported as extra unittest tests.

Each case ran in a fresh bounded process with verified actual module origins and the sealed executable. Candidate binary SHA-256: f8039c49f9e9c61380c9763eff1af4e1e0c19719b45c84714b33e94f89e992f0.

Limits

The two canonical files were migrated whole, but no complete canonical test module was executed locally. The GenericAlias result is the full selected method, not the full module. The unchanged external descriptor method and supplemental observations are separate evidence, not additional committed test-file migrations. Full workspace/C-API suites, other platforms, concurrency stress and broad GC/lifetime correctness were not validated by this packet. No broad type-layout, C-API or GC redesign is included.

AI assistance

OpenAI Codex assisted with implementation, independent source review, canonical migration, validation and this draft under maintainer direction. Commit trailers disclose assistance.