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GeezerVison is showing github.com — Add allocator functions to c-api by bschoenmaeckers · Pull Request #8168 · RustPython/RustPython

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bschoenmaeckers commented Jun 25, 2026 •

edited by coderabbitai Bot

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Summary by CodeRabbit

New Features
- Added Python-compatible C API memory allocation/free entry points, including both standard and “raw” variants.
- Standard variants normalize zero-size allocation requests, while raw variants pass sizes through directly.
Chores
- Updated the spelling dictionary to recognize the new term introduced by these changes.

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coderabbitai Bot commented Jun 25, 2026 •

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No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yml

Review profile: CHILL

Plan: Pro

Run ID: 8dbf6876-848a-4092-8bc7-492a90c527dd

📥 Commits

Reviewing files that changed from the base of the PR and between ea59686 and 5e7a490.

⛔ Files ignored due to path filters (1)

Cargo.lock is excluded by !**/*.lock

📒 Files selected for processing (4)

.cspell.dict/cpython.txt
crates/capi/Cargo.toml
crates/capi/src/lib.rs
crates/capi/src/pymem.rs

✅ Files skipped from review due to trivial changes (3)

.cspell.dict/cpython.txt
crates/capi/Cargo.toml
crates/capi/src/lib.rs

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

crates/capi/src/pymem.rs

📝 Walkthrough

Walkthrough

The crate adds a new public pymem module and exports PyMem_* and PyMem_Raw* C-ABI allocation functions backed by libc.

Changes

C API pymem exports

Layer / File(s)	Summary
Crate wiring `crates/capi/Cargo.toml`, `crates/capi/src/lib.rs`, `.cspell.dict/cpython.txt`	`libc` is added as a workspace dependency, `pymem` is publicly exported from the crate module list, and `pymem` is added to the CPython cspell word list.
PyMem FFI shims `crates/capi/src/pymem.rs`	Eight exported allocation and free functions are added, with `PyMem_` normalizing zero sizes before calling `libc` and `PyMem_Raw` forwarding arguments directly.

Sequence Diagram(s)

sequenceDiagram
  participant CCaller
  participant PymemRs
  participant Libc
  CCaller->>PymemRs: call PyMem_* or PyMem_Raw*
  PymemRs->>Libc: malloc/calloc/realloc/free
  Libc-->>PymemRs: allocation result or completion
  PymemRs-->>CCaller: return pointer or void

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Suggested reviewers

youknowone

Poem

A bunny hopped through pymem night,
With libc hops, all neat and right.
PyMem_* sprang out with care,
Raw memory juggling in the air.
🐇✨

🚥 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 summarizes the main change: adding allocator functions to the c-api.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
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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✨ Finishing Touches

🧪 Generate unit tests (beta)

Create PR with unit tests

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bschoenmaeckers force-pushed the c-api-mem branch from bc43086 to ea59686 Compare

June 25, 2026 10:59

coderabbitai Bot reviewed

Jun 25, 2026

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Actionable comments posted: 1

🤖 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/capi/src/pymem.rs`:
- Around line 4-15: Normalize zero-size inputs in the CPython memory wrappers so
they satisfy the C-API contract: update PyMem_Malloc, PyMem_Calloc, and
PyMem_Realloc to treat zero-byte requests as 1-byte allocations and ensure
realloc with a zero new_size does not free the block. Apply the same zero-size
normalization consistently to PyMem_RawMalloc, PyMem_RawCalloc, and
PyMem_RawRealloc so all memory entry points in pymem.rs behave the same way
instead of forwarding raw zero values directly to libc.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

Push a commit to this branch (recommended)
Create a new PR with the fixes

ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yml

Review profile: CHILL

Plan: Pro

Run ID: a41f31dc-588b-4ce4-9d78-2a6eb0c7ed5b

📥 Commits

Reviewing files that changed from the base of the PR and between 870ad2d and bc43086.

⛔ Files ignored due to path filters (1)

Cargo.lock is excluded by !**/*.lock

📒 Files selected for processing (3)

crates/capi/Cargo.toml
crates/capi/src/lib.rs
crates/capi/src/pymem.rs

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crates/capi/src/pymem.rs Resolved

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          Add allocator functions to c-api

5e7a490

bschoenmaeckers force-pushed the c-api-mem branch from ea59686 to 5e7a490 Compare

June 25, 2026 11:11

ShaharNaveh approved these changes

Jun 25, 2026

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youknowone approved these changes

Jun 25, 2026

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youknowone merged commit dda5516 into RustPython:main

Jun 25, 2026

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bschoenmaeckers deleted the c-api-mem branch

June 25, 2026 13:34

youknowone pushed a commit that referenced this pull request

Sep 16, 2026


          Add allocator functions to c-api (#8168)

ab3d050

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bschoenmaeckers commented Jun 25, 2026 • edited by coderabbitai Bot Loading Uh oh! There was an error while loading. Please reload this page.

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Summary by CodeRabbit

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Walkthrough

Changes

Sequence Diagram(s)

Estimated code review effort

Suggested reviewers

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bschoenmaeckers commented Jun 25, 2026 •

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coderabbitai Bot commented Jun 25, 2026 •

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