Support pickling slot wrapper descriptors by youknowdot · Pull Request #9037 · RustPython/RustPython

youknowdot · 2026-10-10T07:57:35Z

Support pickling slot wrapper descriptors such as object.__str__, matching CPython 3.14. Reduce each descriptor to getattr on its defining class.

Extracted from #8954. Adds direct reduction and one roundtrip assertion to the existing pickle snippet. Canonical expected-failure markers remain because those tests also expose unrelated staticmethod-descriptor failures.

Validation:

CPython 3.14.7 passes the snippet. The pre-fix RustPython baseline raises TypeError for wrapper descriptor reduction.
Normal pre-commit hooks and VM Clippy pass.
Patched native runtime and aggregate tests await CI; local runtime linking is blocked by available disk space.

AI-assisted implementation, tests, and review with OpenAI Codex. Kept as a draft for CI and maintainer review.

Extract wrapper descriptor reduction from RustPython#8954 for Python 3.14. Reduce to getattr on the defining class and cover direct reduction plus one roundtrip in the existing pickle snippet. Preserve canonical expected failures for unrelated staticmethod descriptor behavior. Assisted-by: OpenAI Codex:model identifier unavailable

coderabbitai · 2026-10-10T07:57:42Z

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crates/vm/src/builtins/descriptor.rs
extra_tests/snippets/stdlib_pickle.py

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chatgpt-codex-connector · 2026-10-10T10:33:00Z

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-10T10:38:36.600081Z	`f1a9eca`	Draft marked ready

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chatgpt-codex-connector · 2026-10-10T10:38:33Z

 )]
 impl Py<PyWrapper> {
+    #[pymethod]
+    fn __reduce__(&self, vm: &VirtualMachine) -> PyResult {


Add the required AI-assistance trailer

This commit explicitly states that its implementation and review were AI-assisted, but its message has no Assisted-by: AGENT_NAME:MODEL_VERSION trailer; the repository requires that exact trailer format for every AI-assisted contribution, so rewrite the commit message before merging.

AGENTS.md reference: AGENTS.md:L22-L23

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chatgpt-codex-connector · 2026-10-10T10:38:33Z

+assert object.__str__.__reduce__() == (getattr, (object, "__str__"))
+assert _pickle.loads(_pickle.dumps(object.__str__)) is object.__str__


Remove the forbidden test assertions

These lines add new assertion logic to a test file, but the repository rules prohibit test assertion/logic edits and state that the only acceptable test-file changes are adding or removing expected-failure markers; remove these assertions or obtain an explicit policy exception before merging.

AGENTS.md reference: AGENTS.md:L275-L279

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chatgpt-codex-connector · 2026-10-10T10:38:33Z

 impl Py<PyWrapper> {
+    #[pymethod]
+    fn __reduce__(&self, vm: &VirtualMachine) -> PyResult {
+        let getattr = vm.builtins.get_attr("getattr", vm)?;


Resolve getattr from the current frame's builtins

When __reduce__ is called from an exec/eval frame whose custom __builtins__ mapping overrides or omits getattr, CPython uses that frame-local value (or raises AttributeError), whereas this lookup always reads the interpreter's global builtins module. VirtualMachine::eval_get_builtin already implements the required _PyEval_GetBuiltin semantics, so using the module directly here returns or serializes the wrong callable in custom-builtins contexts.

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Follow up on RustPython#9037 by using the existing frame-aware builtin lookup. Assisted-by: OpenAI Codex:model identifier unavailable

youknowone approved these changes Oct 10, 2026

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youknowone marked this pull request as ready for review October 10, 2026 10:32

youknowone merged commit e3374c8 into RustPython:main Oct 10, 2026
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chatgpt-codex-connector Bot reviewed Oct 10, 2026

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This was referenced Oct 10, 2026

Raise OverflowError for oversized pickle lengths #9040

Merged

Use active builtins consistently in descriptor and method reductions #9057

Merged

youknowdot added a commit to youknowdot/RustPython that referenced this pull request Oct 11, 2026

Use active builtins in wrapper descriptor reduction

7ed2693

Follow up on RustPython#9037 by using the existing frame-aware builtin lookup. Assisted-by: OpenAI Codex:model identifier unavailable

youknowdot added a commit to youknowdot/RustPython that referenced this pull request Oct 11, 2026

Use active builtins in wrapper descriptor reduction

5e121f1

Follow up on RustPython#9037 by using the existing frame-aware builtin lookup. Assisted-by: OpenAI Codex:model identifier unavailable

youknowdot added a commit to youknowdot/RustPython that referenced this pull request Oct 11, 2026

Use active builtins in wrapper descriptor reduction

0064d3f

Follow up on RustPython#9037 by using the existing frame-aware builtin lookup. Assisted-by: OpenAI Codex:model identifier unavailable

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Support pickling slot wrapper descriptors - #9037

Support pickling slot wrapper descriptors#9037
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youknowdot:fix-wrapper-descriptor-pickle

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		assert object.__str__.__reduce__() == (getattr, (object, "__str__"))
		assert _pickle.loads(_pickle.dumps(object.__str__)) is object.__str__

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