Unify `PyObject` dereferencing in c-api by bschoenmaeckers · Pull Request #8292 · RustPython/RustPython

bschoenmaeckers · 2026-07-16T13:14:43Z

Summary by CodeRabbit

Improvements
- Updated Python C API pointer handling across object, collection, numeric, iterator, and other interfaces. Existing API behavior and results are intended to remain unchanged.
- Improved handling of optional and null pointers in several C API operations.

coderabbitai · 2026-07-16T13:14:50Z

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Reviewing files that changed from the base of the PR and between 98b6e30 and 51216ec.

📒 Files selected for processing (9)

crates/capi/src/abstract_.rs
crates/capi/src/abstract_/number.rs
crates/capi/src/bytesobject.rs
crates/capi/src/descrobject.rs
crates/capi/src/iterobject.rs
crates/capi/src/longobject.rs
crates/capi/src/object.rs
crates/capi/src/tupleobject.rs
crates/capi/src/unicodeobject.rs

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

crates/capi/src/abstract_.rs

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📝 Walkthrough

Walkthrough

The C API now uses shared FfiPtrExt helpers to convert raw pointers into borrowed or owned Python objects, including optional pointers and typed casts. The changes cover many C API modules and make PyRef raw-pointer constructors public.

Changes

C API pointer conversion

Layer / File(s)	Summary
Pointer conversion helpers and PyRef access `crates/capi/src/util.rs`, `crates/vm/src/object/core.rs`	`FfiPtrExt` adds owned, borrowed, optional, error, and typed-cast conversions, with null-pointer tests. `PyRef::from_non_null` and `PyRef::from_raw` become public.
Object, call, and iterator APIs `crates/capi/src/abstract_.rs`, `crates/capi/src/abstract_/iter.rs`, `crates/capi/src/object.rs`, `crates/capi/src/object/pytype.rs`, `crates/capi/src/boolobject.rs`	These APIs use the pointer helpers. Attribute-existence functions use `obj.has_attr`; several `PyTypeObject` parameters change from const to mutable pointers.
Mapping, sequence, and numeric APIs `crates/capi/src/abstract_/{mapping,sequence,number}.rs`	These APIs use borrowed-pointer helpers. Their existing operation dispatch and mapping error handling remain in place.
Container and scalar APIs `crates/capi/src/{dictobject,listobject,setobject,tupleobject,sliceobject,bytesobject,bytearrayobject,floatobject,longobject,unicodeobject,genericaliasobject}.rs`	Container and scalar APIs use borrowed, owned, optional, and typed pointer conversions. `PyDict_GetItem` treats its key as a binary `PyObject`.
Evaluation and runtime APIs `crates/capi/src/{ceval,codecs,complexobject,descrobject,import,moduleobject,memoryobject,objimpl,osmodule,pycapsule,pyframe,traceback,warnings,weakrefobject,iterobject}.rs`	These APIs use `FfiPtrExt` to convert incoming pointers, including nullable pointers and native return pointers.
Native ownership and exception APIs `crates/capi/src/{methodobject,pyerrors,refcount}.rs`	Native method returns use `assume_owned_or_err`. Reference-counting and exception APIs use the shared owned and borrowed conversions.

Estimated code review effort: 3 (Moderate) | ~25 minutes

Suggested reviewers: youknowone

Merge Risk: 🟡 Moderate · up to 51216

Clarify the ownership contract for the public raw-pointer constructors before merging; callers otherwise risk dropping a reference they do not own.

🚥 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 accurately and concisely describes the main change: standardizing PyObject pointer dereferencing across the C API.
Docstring Coverage	✅ Passed	Docstring coverage is 95.61% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 319 functions across 41 files.
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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youknowone · 2026-09-23T12:08:14Z

Rebased onto current main.

The first commit (codecs.c-api) was already in #8267, so it was skipped. Conflicts were resolved by keeping FfiPtrExt while preserving APIs that landed later (invoke_exception(&Py<PyType>), encode_unicode, no_memory_error, frame locals/globals/builtins).

Local cargo check --all-targets in crates/capi passed.

— commented by Grok

youknowone · 2026-09-23T12:24:34Z

Follow-up: PyObject_HasAttr* now uses get_attribute_opt again. obj.has_attr raised AttributeError for missing names, which broke object::tests::hasattr (pyo3 maps that to PyObject_HasAttrWithError). crates/capi lib tests: 112 passed.

— commented by Grok

codspeed · 2026-09-23T12:54:05Z

Merging this PR will not alter performance

✅ 62 untouched benchmarks
⏩ 4 skipped benchmarks¹

_{Comparing bschoenmaeckers:a-api-ffi-helper (5cb7941) with main (9d8709e)}

4 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

youknowone · 2026-09-24T11:59:04Z

@bschoenmaeckers is this good?

bschoenmaeckers · 2026-09-24T12:10:03Z

Yes! Thank you for getting this over the finish.

chatgpt-codex-connector · 2026-09-24T12:10:08Z

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Actionable comments posted: 1

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Inline comments:
In `@crates/vm/src/object/core.rs`:
- Around line 2665-2666: Update the public safety contracts on
PyRef::from_non_null and PyRef::from_raw to require that the caller owns one
strong reference to the Py<T> object, with the required type condition. Preserve
the existing pointer-validity requirement and document ownership in both
contracts.

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📥 Commits

Reviewing files that changed from the base of the PR and between 9d8709e and 5cb7941.

📒 Files selected for processing (38)

crates/capi/src/abstract_.rs
crates/capi/src/abstract_/iter.rs
crates/capi/src/abstract_/mapping.rs
crates/capi/src/abstract_/number.rs
crates/capi/src/abstract_/sequence.rs
crates/capi/src/boolobject.rs
crates/capi/src/bytearrayobject.rs
crates/capi/src/bytesobject.rs
crates/capi/src/ceval.rs
crates/capi/src/codecs.rs
crates/capi/src/complexobject.rs
crates/capi/src/descrobject.rs
crates/capi/src/dictobject.rs
crates/capi/src/floatobject.rs
crates/capi/src/genericaliasobject.rs
crates/capi/src/import.rs
crates/capi/src/listobject.rs
crates/capi/src/longobject.rs
crates/capi/src/memoryobject.rs
crates/capi/src/methodobject.rs
crates/capi/src/moduleobject.rs
crates/capi/src/object.rs
crates/capi/src/object/pytype.rs
crates/capi/src/objimpl.rs
crates/capi/src/osmodule.rs
crates/capi/src/pycapsule.rs
crates/capi/src/pyerrors.rs
crates/capi/src/pyframe.rs
crates/capi/src/refcount.rs
crates/capi/src/setobject.rs
crates/capi/src/sliceobject.rs
crates/capi/src/traceback.rs
crates/capi/src/tupleobject.rs
crates/capi/src/unicodeobject.rs
crates/capi/src/util.rs
crates/capi/src/warnings.rs
crates/capi/src/weakrefobject.rs
crates/vm/src/object/core.rs

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Assisted-by: Grok:4.6

bschoenmaeckers · 2026-09-24T14:38:21Z

@youknowone This can be merged now. I've updated all recent functions as well.

youknowone · 2026-09-24T14:42:55Z

THanks!

bschoenmaeckers changed the title ~~Make unify PyObject dereferencing in c-api~~ Unify PyObject dereferencing in c-api Jul 16, 2026

bschoenmaeckers force-pushed the a-api-ffi-helper branch 4 times, most recently from b975faf to c710ae8 Compare July 16, 2026 14:50

youknowone force-pushed the main branch from d1c4925 to 3191eca Compare September 16, 2026 17:13

youknowone force-pushed the a-api-ffi-helper branch 2 times, most recently from bb1e599 to 51dc726 Compare September 23, 2026 12:08

youknowone force-pushed the a-api-ffi-helper branch 4 times, most recently from 809b0d0 to 5cb7941 Compare September 24, 2026 09:01

bschoenmaeckers marked this pull request as ready for review September 24, 2026 12:10

bschoenmaeckers commented Sep 24, 2026

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Comment thread crates/capi/src/object.rs Outdated

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Comment thread crates/vm/src/object/core.rs

bschoenmaeckers commented Sep 24, 2026

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Comment thread crates/capi/src/descrobject.rs Outdated

bschoenmaeckers commented Sep 24, 2026

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Comment thread crates/capi/src/descrobject.rs Outdated

bschoenmaeckers commented Sep 24, 2026

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Comment thread crates/capi/src/descrobject.rs Outdated

youknowone force-pushed the a-api-ffi-helper branch from 5cb7941 to 98b6e30 Compare September 24, 2026 12:51

bschoenmaeckers and others added 3 commits September 24, 2026 16:15

Add FfiPtrExt for uniform pointer dereferences

e220eb1

Panic on NULL ptrs

c5f7e2a

capi: import type_name from core, not std

40f819f

Assisted-by: Grok:4.6

bschoenmaeckers force-pushed the a-api-ffi-helper branch from 98b6e30 to 40f819f Compare September 24, 2026 14:17

bschoenmaeckers added 2 commits September 24, 2026 16:19

Use assume_owned_or_err in PyGetSetDef

d3e5c3f

Update latest code

51216ec

bschoenmaeckers force-pushed the a-api-ffi-helper branch from 4f615c3 to 51216ec Compare September 24, 2026 14:37

youknowone merged commit a1971c1 into RustPython:main Sep 24, 2026
29 checks passed

bschoenmaeckers deleted the a-api-ffi-helper branch September 24, 2026 20:05

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Merging this PR will not alter performance

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