Adding + Fixing Clippy rules to better align with #[no_std] by terryluan12 · Pull Request #6570 · RustPython/RustPython

terryluan12

Changes Summary

This PR addresses issue #6380 by systematically migrating the RustPython codebase to prefer core:: and alloc:: imports over std:: imports where appropriate, following Rust best practices for no-std compatibility. The work involves 184 changed files across all crates (codegen, common, compiler-core, stdlib, vm, etc.) and concludes with an auto-formatting pass to maintain consistency.

Type: refactoring

Components Affected: codegen, common, compiler-core, compiler, derive-impl, derive, literal, sre_engine, stdlib, vm, venvlauncher, examples

Files Changed

File	Summary	Change	Impact
`crates/common/src/str.rs`	Replaced std:: imports with core:: equivalents (ops, fmt, slice, iter, mem) where applicable, improved no-std support	✏️	🔴
`crates/stdlib/src/array.rs`	Migrated std:: to core:: and alloc:: for mem operations, memory layout calculations, and slice construction	✏️	🔴
`crates/codegen/src/lib.rs`	Added extern crate alloc declaration for proper allocation support in no-std context	✏️	🟡
`crates/compiler-core/src/lib.rs`	Added extern crate alloc declaration	✏️	🟡
`crates/common/src/lib.rs`	Added extern crate alloc declaration	✏️	🟡
`Cargo.toml`	Updated workspace lints to include clippy rules for std_instead_of_core, alloc_instead_of_core, std_instead_of_alloc	✏️	🟡

Architecture Impact

New Patterns: no-std compatibility, core/alloc crate separation, standards-based import organization
Dependencies: Added: clippy lint rules (std_instead_of_core, std_instead_of_alloc, alloc_instead_of_core)
Coupling: Reduces coupling to std library by preferring core:: and alloc:: modules, enabling better no-std support and potentially facilitating WASM targets

Risk Areas: Widespread import changes across 184 files could introduce subtle runtime behavior changes if core:: and std:: implementations differ, Changes to memory safety operations (mem::size_of, mem::swap, slice operations) need verification that no subtle bugs were introduced, Clippy lint enforcement (alloc_instead_of_core, std_instead_of_alloc) could break existing tooling if lints are too strict, Import reordering (as part of rustfmt) could affect code readability or introduce merge conflicts

Suggestions

Verify that no-std compilation works correctly with these changes (test with cargo build --no-default-features)
Run full test suite to ensure behavioral equivalence between std:: and core:: imports
Check that all memory safety operations (ManuallyDrop, size_of, swap, etc.) have identical semantics after refactoring
Review the handling of platform-specific features (Windows, WASM) to ensure no regressions
Validate that the new Cargo.toml lint rules don't incorrectly flag legitimate uses of std