Add more build-info functions to c-api by bschoenmaeckers · Pull Request #8216 · RustPython/RustPython

bschoenmaeckers · 2026-07-06T12:58:00Z

Summary by CodeRabbit

New Features
- Added runtime system metadata access (build, compiler, copyright, and platform) via standard interfaces.
- Exposed additional system details through sys constants, including build info and compiler, alongside updated visibility for existing version-related constants.

coderabbitai · 2026-07-06T12:58:58Z

No actionable comments were generated in the recent review. 🎉

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📥 Commits

Reviewing files that changed from the base of the PR and between 44e1a4c and c567388.

📒 Files selected for processing (2)

crates/capi/src/pylifecycle.rs
crates/vm/src/stdlib/sys.rs

🚧 Files skipped from review as they are similar to previous changes (2)

crates/vm/src/stdlib/sys.rs
crates/capi/src/pylifecycle.rs

📝 Walkthrough

Walkthrough

Publicizes build metadata constants in sys and adds four C-ABI getters in pylifecycle that return those values as C-compatible strings.

Changes

Build metadata C API exposure

Layer / File(s)	Summary
Publicize sys module build metadata constants `crates/vm/src/stdlib/sys.rs`	Re-exports BUILD_INFO, COMPILER, COPYRIGHT, PLATFORM, and VERSION at module scope, and makes COPYRIGHT, VERSION, BUILD_INFO, and COMPILER public inside the inner `sys` module.
Add extern C functions for build metadata `crates/capi/src/pylifecycle.rs`	Imports `rustpython_vm::stdlib::sys` and adds `Py_GetBuildInfo`, `Py_GetCompiler`, `Py_GetCopyright`, and `Py_GetPlatform`, each returning a raw pointer from a lazily initialized `CString` built from the matching constant.

Estimated code review effort: 2 (Simple) | ~10 minutes

Suggested reviewers: ShaharNaveh, youknowone

🚥 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 matches the main change: adding new build-info related C-API functions.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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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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/pylifecycle.rs`:
- Around line 84-115: The four getter functions are duplicated and should be
refactored into a macro-based helper. Extract the shared CString/LazyLock/as_ptr
logic into a single reusable macro or helper and parameterize only the differing
sys constant, static identifier, and panic text for Py_GetBuildInfo,
Py_GetCompiler, Py_GetCopyright, and Py_GetPlatform. Keep the public extern "C"
function names unchanged and apply the same pattern consistently if
Py_GetVersion or similar getters in pylifecycle.rs use the same structure.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

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

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Configuration used: Path: .coderabbit.yml

Review profile: CHILL

Plan: Pro

Run ID: d582c5db-c613-42ea-a2b7-5f7d60708967

📥 Commits

Reviewing files that changed from the base of the PR and between 3f9d80b and 44e1a4c.

📒 Files selected for processing (2)

crates/capi/src/pylifecycle.rs
crates/vm/src/stdlib/sys.rs

coderabbitai · 2026-07-06T13:04:33Z

+#[unsafe(no_mangle)]
+pub extern "C" fn Py_GetBuildInfo() -> *const c_char {
+    static BUILD_INFO: LazyLock<CString> = LazyLock::new(|| {
+        CString::new(sys::BUILD_INFO).expect("build info must not contain interior NULs")
+    });
+    BUILD_INFO.as_ptr()
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn Py_GetCompiler() -> *const c_char {
+    static COMPILER: LazyLock<CString> = LazyLock::new(|| {
+        CString::new(sys::COMPILER).expect("compiler must not contain interior NULs")
+    });
+    COMPILER.as_ptr()
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn Py_GetCopyright() -> *const c_char {
+    static COPYRIGHT: LazyLock<CString> = LazyLock::new(|| {
+        CString::new(sys::COPYRIGHT).expect("copyright must not contain interior NULs")
+    });
+    COPYRIGHT.as_ptr()
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn Py_GetPlatform() -> *const c_char {
+    static PLATFORM: LazyLock<CString> = LazyLock::new(|| {
+        CString::new(sys::PLATFORM).expect("platform must not contain interior NULs")
+    });
+    PLATFORM.as_ptr()
+}
+


📐 Maintainability & Code Quality | 🟠 Major | ⚡ Quick win

Deduplicate the four near-identical build-metadata functions with a macro.

Py_GetBuildInfo, Py_GetCompiler, Py_GetCopyright, and Py_GetPlatform differ only in the source constant, static name, and panic message — everything else is copy-pasted.

♻️ Proposed macro-based refactor

+macro_rules! build_metadata_getter { + ($fn_name:ident, $const_name:path, $what:literal) => { + #[unsafe(no_mangle)] + pub extern "C" fn $fn_name() -> *const c_char { + static VALUE: LazyLock<CString> = LazyLock::new(|| { + CString::new($const_name).expect(concat!($what, " must not contain interior NULs")) + }); + VALUE.as_ptr() + } + }; +} + +build_metadata_getter!(Py_GetBuildInfo, sys::BUILD_INFO, "build info"); +build_metadata_getter!(Py_GetCompiler, sys::COMPILER, "compiler"); +build_metadata_getter!(Py_GetCopyright, sys::COPYRIGHT, "copyright"); +build_metadata_getter!(Py_GetPlatform, sys::PLATFORM, "platform"); -#[unsafe(no_mangle)] -pub extern "C" fn Py_GetBuildInfo() -> *const c_char { - static BUILD_INFO: LazyLock<CString> = LazyLock::new(|| { - CString::new(sys::BUILD_INFO).expect("build info must not contain interior NULs") - }); - BUILD_INFO.as_ptr() -} - -#[unsafe(no_mangle)] -pub extern "C" fn Py_GetCompiler() -> *const c_char { - static COMPILER: LazyLock<CString> = LazyLock::new(|| { - CString::new(sys::COMPILER).expect("compiler must not contain interior NULs") - }); - COMPILER.as_ptr() -} - -#[unsafe(no_mangle)] -pub extern "C" fn Py_GetCopyright() -> *const c_char { - static COPYRIGHT: LazyLock<CString> = LazyLock::new(|| { - CString::new(sys::COPYRIGHT).expect("copyright must not contain interior NULs") - }); - COPYRIGHT.as_ptr() -} - -#[unsafe(no_mangle)] -pub extern "C" fn Py_GetPlatform() -> *const c_char { - static PLATFORM: LazyLock<CString> = LazyLock::new(|| { - CString::new(sys::PLATFORM).expect("platform must not contain interior NULs") - }); - PLATFORM.as_ptr() -}

As per coding guidelines: "When branches differ only in a value but share common logic, extract the differing value first, then call the common logic once to avoid duplicate code."

#!/bin/bash # Check whether Py_GetVersion (pre-existing) follows the same repeated pattern, # and whether existing pyo3-based tests cover similar getters. ast-grep run --pattern 'pub extern "C" fn Py_GetVersion() -> *const c_char { $$$ }' --lang rust crates/capi/src/pylifecycle.rs rg -n -A5 -B2 '"Py_Get' crates/capi/src/pylifecycle.rs rg -n 'fn test' -A10 crates/capi/src/pylifecycle.rs | rg -n 'Py_Get' -B5

🤖 Prompt for 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. In `@crates/capi/src/pylifecycle.rs` around lines 84 - 115, The four getter functions are duplicated and should be refactored into a macro-based helper. Extract the shared CString/LazyLock/as_ptr logic into a single reusable macro or helper and parameterize only the differing sys constant, static identifier, and panic text for Py_GetBuildInfo, Py_GetCompiler, Py_GetCopyright, and Py_GetPlatform. Keep the public extern "C" function names unchanged and apply the same pattern consistently if Py_GetVersion or similar getters in pylifecycle.rs use the same structure.

Source: Coding guidelines

youknowone · 2026-07-06T14:56:19Z

    const API_VERSION: u32 = 0x0; // what C api?
    #[pyattr(name = "copyright")]
-    const COPYRIGHT: &str = "Copyright (c) 2019 RustPython Team";
+    pub const COPYRIGHT: &str = "Copyright (c) 2019 RustPython Team";


hmm, another suggestion.
let's define this as

Suggested change

pub const COPYRIGHT: &str = "Copyright (c) 2019 RustPython Team";

pub const COPYRIGHT: &CStr = c"Copyright (c) 2019 RustPython Team";

Then add a IntoPyObject conversion from &CStr to String to ignore the tail null char.
This will not hurt any RustPython use case and also will make C api happier without LazyLock

coderabbitai Bot reviewed Jul 6, 2026

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Add more build-info functions to c-api

c567388

bschoenmaeckers force-pushed the c-api-buildinfo branch from 44e1a4c to c567388 Compare July 6, 2026 13:10

youknowone approved these changes Jul 6, 2026

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youknowone requested changes Jul 6, 2026

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Add more build-info functions to c-api#8216

Add more build-info functions to c-api#8216
bschoenmaeckers wants to merge 1 commit into
RustPython:mainfrom
bschoenmaeckers:c-api-buildinfo

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	pub const COPYRIGHT: &str = "Copyright (c) 2019 RustPython Team";
	pub const COPYRIGHT: &CStr = c"Copyright (c) 2019 RustPython Team";

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bschoenmaeckers commented Jul 6, 2026 •

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