Reduce number of string clones when compiling python source code#8103

ShaharNaveh

Closes #xxxx
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Summary

Summary by CodeRabbit

Refactor
- Optimized how source names and paths are passed during compilation and execution to avoid unnecessary string allocations across the runtime, standard library integration, examples, and benchmarks.
- Updated relevant VM APIs and related call sites to accept borrowed &str for source path/name parameters, plus a small cleanup of related string/Latin-1 cache initialization and test compilation helpers.

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📥 Commits

Reviewing files that changed from the base of the PR and between 0df603a and 215003a.

⛔ Files ignored due to path filters (1)

Lib/test/test_thread.py is excluded by !Lib/**

📒 Files selected for processing (1)

src/lib.rs

✅ Files skipped from review due to trivial changes (1)

src/lib.rs

📝 Walkthrough

Walkthrough

VirtualMachine::compile, compile_with_opts, run_string, run_code_string, and import_file change their source_path/file_path parameter from owned String to &str. PyGetSet::new and three Context getset helpers change name from impl Into<String> to &str. All call sites across the codebase are updated to remove .to_owned() and .clone(). context.rs also receives minor idiomatic Rust refactors unrelated to the signature changes.

Changes

source_path & name: String → &str refactor

Layer / File(s)	Summary
Core compile/run API signature changes `crates/vm/src/vm/compile.rs`, `crates/vm/src/vm/python_run.rs`, `crates/vm/src/import.rs`	`VirtualMachine::compile`, `compile_with_opts`, `run_string`, `run_code_string` change `source_path` from `String` to `&str`; `import_file` changes `file_path` likewise; internal forwarding calls updated accordingly.
PyGetSet::new and Context getset helper signature changes `crates/vm/src/builtins/getset.rs`, `crates/vm/src/vm/context.rs`	`PyGetSet::new` accepts `name: &str` with internal `into()` conversion; `Context::new_readonly_getset`, `new_static_getset`, and `new_getset` change from `impl Into<String>` to `&str`, removing the internal conversion.
VM-internal call-site updates `crates/vm/src/eval.rs`, `crates/vm/src/stdlib/builtins.rs`, `crates/vm/src/stdlib/sys.rs`, `crates/vm/src/vm/interpreter.rs`, `crates/vm/src/vm/mod.rs`	All VM-internal call sites remove `.to_owned()` or `.clone()` when passing `source_path` or `name` to the updated APIs.
External/entry-point call-site updates `crates/capi/src/ceval.rs`, `crates/wasm/src/vm_class.rs`, `crates/stdlib/src/_opcode.rs`, `src/shell.rs`, `src/lib.rs`, `examples/`, `benches/`	C API, WASM, stdlib tests, shell, main library, examples, and benchmarks remove `.to_owned()` / `.clone()` at their respective `vm.compile` / `vm.run_string` call sites.
context.rs idiomatic cleanups `crates/vm/src/vm/context.rs`	`latin1_char_cache` uses `u8::MIN..=u8::MAX`; `latin1_singleton_index` and `new_str` condensed to expression form; `interned_or_new_str` switches to `if let`; `new_exception_type` uses `unwrap_or_else`.
Cosmetic changes `crates/vm/src/vm/thread.rs`	Import reorder and two blank line insertions; no logic changes.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

RustPython/RustPython#7740: Both PRs modify src/lib.rs's run_file implementation, with the main change passing path by reference instead of to_owned().
RustPython/RustPython#8050: Both PRs modify crates/vm/src/builtins/getset.rs, adding #[must_use] to PyGetSet::new which this PR updates to accept name: &str.

Suggested reviewers

youknowone

Poem

🐇 No more to_owned(), no needless heap fuss,
A &str slice passed without any muss!
The compiler now borrows what once was owned,
Across every call site, the pattern is honed.
Fewer allocations, the rabbit hops free—
Just borrow the string and let memory be! 🌿

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 78.79% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and specifically describes the main change: reducing string clones during Python source code compilation, which aligns with all modified files throughout the PR.
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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📦 Library Dependencies

The following Lib/ modules were modified. Here are their dependencies:

[x] test: cpython/Lib/test/test_thread.py (TODO: 4)
[x] test: cpython/Lib/test/test_thread_local_bytecode.py
[x] test: cpython/Lib/test/test_threadsignals.py

dependencies:

dependent tests: (13 tests)
- [ ] concurrent.futures: test_asyncio test_compileall test_concurrent_futures test_context test_genericalias test_inspect test_struct test_wmi
- [x] asyncio: test_asyncio test_logging test_os test_pdb test_unittest

Legend:

[+] path exists in CPython
[x] up-to-date, [ ] outdated

ShaharNaveh added 2 commits June 14, 2026 15:03

Reduce to_owned calls

cccd1bd

fix more

7ab95fd

ShaharNaveh force-pushed the nits-6 branch 3 times, most recently from d39b8df to e949487 Compare June 14, 2026 12:21

Fix wasm

30f2075

ShaharNaveh force-pushed the nits-6 branch from e949487 to 30f2075 Compare June 14, 2026 12:27

doctest

0df603a

ShaharNaveh marked this pull request as ready for review June 14, 2026 12:43

ShaharNaveh added 2 commits June 14, 2026 17:05

Skip flaky test on windows

f38b304

fix when no hostenv

215003a

youknowone approved these changes Jun 15, 2026

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Reduce number of string clones when compiling python source code#8103