venvlauncher by youknowone · Pull Request #6527 · RustPython/RustPython

youknowone

📝 Walkthrough

Walkthrough

Adds a new Windows-focused Rust venv launcher crate that discovers a virtualenv via pyvenv.cfg, selects python/pythonw, sets PYVENV_LAUNCHER, re-execs Python, and updates VM path resolution to be launcher-aware preserving the real base executable.

Changes

Cohort / File(s)	Summary
Spell Check Dictionary `.cspell.dict/cpython.txt`	Added tokens: `pythonw`, `venvlauncher`, `venvlaunchert`, `venvw`, `venvwlauncher`, `venvwlaunchert`.
Venvlauncher Manifest `crates/venvlauncher/Cargo.toml`	New Cargo manifest with package metadata, four binary targets (`venvlauncher`, `venvwlauncher`, `venvlaunchert`, `venvwlaunchert`), Windows-specific dependency features, and workspace lint settings.
Venvlauncher Build Script `crates/venvlauncher/build.rs`	New build script that detects `venvw`-named binaries and adds linker args to set the Windows GUI subsystem and `mainCRTStartup` entry point to suppress console windows.
Venvlauncher Implementation `crates/venvlauncher/src/main.rs`	New Windows-only launcher: derives target exe from its name, locates `pyvenv.cfg` (walks from `Scripts/`), parses `home=` (handles spaces/comments), validates Python executable under discovered home, sets `__PYVENV_LAUNCHER__`, and execs Python with original args; includes Windows-gated tests for `read_home`.
VM Path Resolution `crates/vm/src/getpath.rs`	Launcher-aware path logic: introduces `real_executable`, sets `paths.executable` to the launcher when `__PYVENV_LAUNCHER__` is present, preserves `base_executable` as the real Python, and computes `exe_dir` from the launcher parent; subsequent venv/prefix calculations unchanged.
CI Workflow `.github/workflows/ci.yaml`	Centralized workspace exclusion flags via `WORKSPACE_EXCLUDES` and replaced duplicated per-command excludes with the env variable.

Sequence Diagram

sequenceDiagram
    autonumber
    actor User
    participant Launcher as venvlauncher (exe)
    participant VenvCfg as pyvenv.cfg
    participant Python as python.exe / pythonw.exe
    participant VM as RustPython VM

    User->>Launcher: start with args
    Launcher->>Launcher: inspect exe name -> choose target (pythonw/python)
    Launcher->>VenvCfg: locate pyvenv.cfg (walk from Scripts/)
    VenvCfg-->>Launcher: return home path (home=...)
    Launcher->>Launcher: validate Python exists under home
    Launcher->>Launcher: set __PYVENV_LAUNCHER__ env
    Launcher->>Python: exec target Python with original args
    Python->>VM: VM startup reads __PYVENV_LAUNCHER__
    Note over VM: VM sets sys.executable=launcher\nand sys._base_executable=real python
    VM-->>User: exit code propagated

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~45 minutes

Possibly related PRs

Upgrade venv to v3.13.11 #6459: Related launcher-aware venv handling and PYVENV_LAUNCHER integration in the runtime.

Suggested reviewers

coolreader18

Poem

🐰 I hop from Scripts to cfg-lined den,
I sniff the home and find the den again.
I set the mark, then nudge Python on,
Silent windows, a quiet dawn.
Hoppity launch — rust and carrot song! 🥕

Pre-merge checks and finishing touches

❌ Failed checks (1 inconclusive)

Check name	Status	Explanation	Resolution
Title check	❓ Inconclusive	The title 'venvlauncher' is too generic and vague; it only names a component without conveying what changes or improvements are being made.	Provide a more descriptive title that explains the main change, such as 'Implement Windows venv launcher with pyvenv.cfg parsing' or 'Add venvlauncher binary targets and launcher-aware path detection'.

✅ 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 100.00% which is sufficient. The required threshold is 80.00%.

✨ Finishing touches

📝 Generate docstrings

🧪 Generate unit tests (beta)

Create PR with unit tests
Post copyable unit tests in a comment

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

_{Comment @coderabbitai help to get the list of available commands and usage tips.}