no_std clippy by youknowone · Pull Request #7043 · RustPython/RustPython

youknowone · 2026-02-08T02:07:51Z

Summary by CodeRabbit

Release Notes

Refactor
- Reduced reliance on the standard library to improve compatibility with restricted/no-std environments and broaden platform support.
- Multiple internal imports and memory/pointer handling paths migrated to core/alloc equivalents with no behavioral changes.
Chores
- Enabled additional Clippy lints (including suspicious and correctness) and clarified lint annotations for cross-platform code.
Compatibility
- Small, targeted public type adjustments to threading/module state to align with the allocator/core changes.

coderabbitai · 2026-02-08T02:08:00Z

📝 Walkthrough

Walkthrough

This PR enables additional Clippy lints and systematically replaces many std:: usages with core:: and alloc:: equivalents across the codebase (memory, pointers, atomics, collections, FFI and threading types) to align with no-std/no-std-like constraints.

Changes

Cohort / File(s)	Summary
Clippy Configuration `Cargo.toml`	Uncommented/enabled clippy lints: `alloc_instead_of_core`, `std_instead_of_alloc`, `std_instead_of_core`; added `suspicious` and `correctness` lint groups set to `warn`.
Memory & Pointer core:: Migration `crates/.../codegen/src/compile.rs`, `crates/common/src/crt_fd.rs`, `crates/common/src/fileutils.rs`, `crates/stdlib/src/mmap.rs`, `crates/vm/src/stdlib/nt.rs`, `crates/vm/src/stdlib/sys.rs`, `crates/vm/src/windows.rs`, `crates/vm/src/stdlib/winapi.rs`, `crates/vm/src/stdlib/winreg.rs`	Replaced `std::mem::`, `std::ptr::`, `std::mem::MaybeUninit`, `std::mem::zeroed`, and `std::mem::size_of*` usages with `core::` equivalents for initialization, sizing, and null pointers.
Slices / Iterators / Formatting Migration `crates/stdlib/src/_sqlite3.rs`, `crates/stdlib/src/math.rs`, `crates/stdlib/src/socket.rs`, `crates/stdlib/src/ssl.rs`, `crates/vm/src/stdlib/io.rs`, `crates/vm/src/stdlib/msvcrt.rs`	Swapped `std::slice`, `std::iter`, `std::fmt` and related calls with `core::slice`, `core::iter`, `core::fmt` equivalents (including Debug impl updates).
Atomic Types Migration `crates/stdlib/src/_asyncio.rs`, `crates/stdlib/src/posixsubprocess.rs`, `crates/vm/src/builtins/template.rs`, `crates/vm/src/stdlib/_abc.rs`, `crates/vm/src/stdlib/signal.rs`, `crates/vm/src/vm/interpreter.rs`, `crates/vm/src/vm/mod.rs`	Replaced `std::sync::atomic::{...}` imports and usages with `core::sync::atomic` counterparts; updated struct fields/initializers and Ordering references (notably `PyTemplateIter` fields).
Arc/Weak & Collections Migration `crates/stdlib/src/multiprocessing.rs`, `crates/stdlib/src/overlapped.rs`, `crates/stdlib/src/thread.rs`, `crates/vm/src/vm/thread.rs`, `crates/vm/src/vm/interpreter.rs`, `crates/vm/src/vm/mod.rs`	Replaced `std::sync::Arc`/`Weak` with `alloc::sync::{Arc, Weak}` and moved `std::collections::BTreeMap` uses to `alloc::collections::BTreeMap`/local imports; several public struct fields/types updated accordingly (thread-related types).
FFI / CString / c_void Migration `crates/common/src/fileutils.rs`, `crates/stdlib/src/multiprocessing.rs`, `crates/stdlib/src/os.rs`, `crates/vm/src/stdlib/ctypes.rs`	Replaced `std::ffi::CString` with `alloc::ffi::CString` in allocation contexts; switched `std::ffi::c_void` to `core::ffi::c_void` in function-pointer signatures.
Duration / Time types Migration `crates/stdlib/src/ssl.rs`, `crates/vm/src/stdlib/time.rs`	Replaced `std::time::Duration` with `core::time::Duration` in function parameters/usage and corresponding duration computations.
Clippy allow attributes & minor annotations `crates/vm/src/stdlib/ctypes/base.rs`, `crates/vm/src/stdlib/ctypes/function.rs`, `crates/vm/src/stdlib/ctypes/pointer.rs`, `crates/vm/src/stdlib/ctypes/simple.rs`, `crates/vm/src/stdlib/io.rs`	Added/expanded clippy allow attributes (e.g., `clippy::useless_conversion`, `clippy::unnecessary_cast`) with reason strings for platform-specific wchar_t conversions and added small comment/lint tweaks.
Small std→core/alloc swaps in VM internals `crates/vm/src/builtins/function.rs`, `crates/vm/src/builtins/tuple.rs`, `crates/vm/src/frame.rs`, `crates/vm/src/signal.rs`, `crates/vm/src/builtins/template.rs`, `crates/vm/src/stdlib/ctypes/*`, `crates/vm/src/stdlib/io.rs`, `crates/vm/src/stdlib/msvcrt.rs`	Replaced scattered `std::` usages (e.g., `mem::take`, `mem::replace`, `hint::unreachable_unchecked`, `cell::Cell`, `ptr::null_mut`) with `core::` equivalents; atomic and field signature adjustments where applicable.

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~75 minutes

Possibly related PRs

finish no_std clippy #6587: Similar no-std/core+alloc migration across many stdlib modules (strong overlap in approach and affected files).
Fix asyncio related compiler/library issues #6837: Touches crates/codegen/src/compile.rs and may conflict with changes around t-string/template handling.
Upgrade threading to 3.13.11; sys.setprofile & impl more threading #6691: Changes threading types/APIs (ThreadHandle/ShutdownEntry/Arc/Weak) similar to the thread-related type migrations here.

Suggested reviewers

ShaharNaveh
arihant2math

"🐰 I hopped through code at break of dawn,
Swapped std for core before the lawn,
Pointers neat and atomics bright,
Clippy nods as I take flight —
A tiny hop, a cleaner night."

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 inconclusive)

Check name	Status	Explanation	Resolution
Title check	❓ Inconclusive	The title 'no_std clippy' is vague and generic, using non-descriptive terms that don't clearly convey the changeset's main objective despite referencing a related initiative.	Revise the title to be more specific and descriptive of the primary changes, such as 'Replace std library imports with core/alloc equivalents for no_std compatibility' or reference the issue more explicitly.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Docstring Coverage	✅ Passed	Docstring coverage is 96.75% which is sufficient. The required threshold is 80.00%.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing touches

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Post copyable unit tests in a comment

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github-actions · 2026-02-08T03:44:02Z

Code has been automatically formatted

The code in this PR has been formatted using:

cargo fmt --all
Please pull the latest changes before pushing again:

git pull origin no_std

ShaharNaveh · 2026-02-08T06:42:54Z

crates/vm/src/stdlib/ctypes/function.rs

    #[cfg(not(windows))]
    {
+        // wchar_t is i32 on some platforms and u32 on others
+        #[allow(clippy::useless_conversion)]


Suggested change

#[allow(clippy::useless_conversion)]

#[allow(clippy::useless_conversion, reason = "wchar_t is i32 on some platforms and u32 on others")]

ShaharNaveh · 2026-02-08T06:43:30Z

crates/vm/src/stdlib/ctypes/function.rs

                    #[cfg(not(windows))]
                    {
+                        // wchar_t is i32 on some platforms and u32 on others
+                        #[allow(clippy::useless_conversion)]


ShaharNaveh · 2026-02-08T06:43:43Z

crates/vm/src/stdlib/ctypes/pointer.rs

                let addr = (ptr_value as isize + cur * wchar_size as isize) as *const libc::wchar_t;
                unsafe {
+                    // wchar_t is i32 on some platforms and u32 on others
+                    #[allow(clippy::unnecessary_cast)]


@youknowone you missed this one:)

I ran a project-wide appliance task. Let's handle this there

nvm, that task didn't catch this one 🤦

ShaharNaveh · 2026-02-08T06:44:03Z

crates/vm/src/stdlib/ctypes/simple.rs

                #[cfg(not(windows))]
                {
+                    // wchar_t is i32 on some platforms and u32 on others
+                    #[allow(clippy::useless_conversion)]


ShaharNaveh · 2026-02-08T07:26:09Z

crates/vm/src/stdlib/ctypes/pointer.rs

                let addr = (ptr_value as isize + cur * wchar_size as isize) as *const libc::wchar_t;
                unsafe {
+                    // wchar_t is i32 on some platforms and u32 on others
+                    #[allow(clippy::unnecessary_cast)]


@youknowone you missed this one:)

coderabbitai

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@crates/vm/src/stdlib/thread.rs`:
- Around line 20-23: The import is pulling fmt from alloc which triggers the
alloc_instead_of_core lint; change the use to import fmt from core (so types
like fmt::Debug, fmt::Formatter, fmt::Result come from core::fmt) while keeping
sync::{Arc, Weak} from alloc; update the use statement that currently reads use
alloc::{ fmt, sync::{Arc, Weak}, }; to import core::fmt instead and leave Arc
and Weak unchanged, and ensure any references to fmt types (Debug, Formatter,
Result) remain correct.

🧹 Nitpick comments (1)

crates/vm/src/stdlib/signal.rs (1)
31-31: Nit: use the existing atomic alias for brevity.

Line 15 already imports core::sync::atomic::{self, Ordering}, so the fully qualified core::sync::atomic::AtomicBool can be simplified.
♻️ Suggested simplification
-            static WAKEUP_IS_SOCKET: core::sync::atomic::AtomicBool = core::sync::atomic::AtomicBool::new(false);
+            static WAKEUP_IS_SOCKET: atomic::AtomicBool = atomic::AtomicBool::new(false);

coderabbitai · 2026-02-08T07:28:27Z

crates/vm/src/stdlib/thread.rs

+    use alloc::{
+        fmt,
+        sync::{Arc, Weak},
+    };


⚠️ Potential issue | 🟡 Minor

🧩 Analysis chain

🏁 Script executed:

# Check the current imports at lines 20-23 sed -n '15,30p' crates/vm/src/stdlib/thread.rs # Search for Clippy lint allow/deny configuration rg -n 'allow|deny|warn' crates/vm/src/stdlib/thread.rs | head -20 # Check if there's a clippy.toml or Cargo.toml with lint configuration find . -name "clippy.toml" -o -name "Cargo.toml" | grep -E "(^./Cargo.toml|clippy)" | head -5 # Check for Clippy lint configuration in the workspace Cargo.toml rg -A 20 '\[lints\]' crates/vm/Cargo.toml

Repository: RustPython/RustPython

Length of output: 932

🏁 Script executed:

# Check the workspace Cargo.toml for lint configuration rg -A 50 '\[lints\]' Cargo.toml # Check for alloc_instead_of_core and std_instead_of_alloc lint settings rg 'alloc_instead_of_core|std_instead_of_alloc' Cargo.toml # Examine what fmt is actually used for in the file rg -n 'fmt::' crates/vm/src/stdlib/thread.rs | head -20

Repository: RustPython/RustPython

Length of output: 570

🏁 Script executed:

# Double-check the full [lints] section to understand the context sed -n '/\[lints\]/,/^\[/p' Cargo.toml | head -50 # Verify this is the workspace lints head -20 Cargo.toml

Repository: RustPython/RustPython

Length of output: 827

🏁 Script executed:

# Find the workspace Cargo.toml and check the [lints] section find . -name "Cargo.toml" -type f | xargs grep -l "workspace = true" | head -1 # Look for [lints] in the root Cargo.toml rg -B 5 -A 20 'alloc_instead_of_core' . # Also check if alloc::fmt is re-exported from core::fmt python3 <<'EOF' # Verify that alloc::fmt re-exports from core::fmt # This is Rust standard library fact-checking print("In Rust standard library:") print("- alloc::fmt re-exports core::fmt and adds format! macro") print("- core::fmt contains: Debug, Formatter, Result, etc.") print("- alloc_instead_of_core lint warns when using alloc for types from core") print("- std_instead_of_alloc lint warns when using std for types from alloc") print("\nFor fmt::Debug, fmt::Formatter, fmt::Result -> these are core::fmt types") print("Using alloc::fmt for these would trigger alloc_instead_of_core lint") EOF

Repository: RustPython/RustPython

Length of output: 961

Use core::fmt instead of alloc::fmt to comply with the alloc_instead_of_core Clippy lint.

The workspace has alloc_instead_of_core = "warn" enabled. Since fmt::Debug, fmt::Formatter, and fmt::Result are core::fmt types (not alloc::fmt), importing from alloc::fmt triggers this lint. The alloc::sync::{Arc, Weak} import is correct.

Suggested fix

-use alloc::{ - fmt, - sync::{Arc, Weak}, -}; +use alloc::sync::{Arc, Weak}; +use core::fmt;

📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change

use alloc::{

fmt,

sync::{Arc, Weak},

};

use alloc::sync::{Arc, Weak};

use core::fmt;

🤖 Prompt for AI Agents

In `@crates/vm/src/stdlib/thread.rs` around lines 20 - 23, The import is pulling fmt from alloc which triggers the alloc_instead_of_core lint; change the use to import fmt from core (so types like fmt::Debug, fmt::Formatter, fmt::Result come from core::fmt) while keeping sync::{Arc, Weak} from alloc; update the use statement that currently reads use alloc::{ fmt, sync::{Arc, Weak}, }; to import core::fmt instead and leave Arc and Weak unchanged, and ensure any references to fmt types (Debug, Formatter, Result) remain correct.

ShaharNaveh

Great!

youknowone force-pushed the no_std branch from 1c50a3e to 987295c Compare February 8, 2026 03:43

youknowone force-pushed the no_std branch 5 times, most recently from 44bf6bf to da9ad35 Compare February 8, 2026 06:21

ShaharNaveh reviewed Feb 8, 2026

View reviewed changes

youknowone force-pushed the no_std branch from da9ad35 to b351f28 Compare February 8, 2026 07:17

youknowone marked this pull request as ready for review February 8, 2026 07:18

youknowone requested a review from ShaharNaveh February 8, 2026 07:18

youknowone enabled auto-merge (squash) February 8, 2026 07:18

ShaharNaveh requested changes Feb 8, 2026

View reviewed changes

coderabbitai bot reviewed Feb 8, 2026

View reviewed changes

youknowone requested a review from ShaharNaveh February 8, 2026 07:32

no_std clippy

360fb1f

youknowone force-pushed the no_std branch from b351f28 to 360fb1f Compare February 8, 2026 07:36

Auto-format: cargo fmt --all

4e8cf97

ShaharNaveh approved these changes Feb 8, 2026

View reviewed changes

youknowone disabled auto-merge February 8, 2026 07:49

youknowone merged commit 07fc6ee into RustPython:main Feb 8, 2026
12 of 13 checks passed

youknowone deleted the no_std branch February 8, 2026 07:49

This was referenced Feb 8, 2026

no_std for wtf8, sre_engine, compiler-core, literal #7051

Merged

no_std for common, pylib, codegen #7056

Merged

	#[allow(clippy::useless_conversion)]
	#[allow(clippy::useless_conversion, reason = "wchar_t is i32 on some platforms and u32 on others")]

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Summary by CodeRabbit

Release Notes

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