Add package=sdist-wheel package type

[rahuldevikar]

Adds a new sdist-wheel package type that builds a wheel from a source distribution rather than directly from the source tree. This validates that the sdist is complete and that the package can be correctly built from it — catching missing files or packaging errors early.

Usage

[env_run_base]
package = "sdist-wheel"

[testenv]
package = sdist-wheel

How it works

1. Builds an sdist via build_sdist
2. Extracts the sdist to a temporary directory
3. Swaps the package root to the extracted source
4. Builds a wheel via build_wheel from that extracted sdist
5. Cleans up the sdist and extraction directory

• ran the linter to address style issues (tox -e fix)
• wrote descriptive pull request text
• ensured there are test(s) validating the fix
• added news fragment in docs/changelog folder
• updated/extended the documentation

[gaborbernat]

Suggested Simplification: Reuse wheel_build_env Infrastructure

The current implementation introduces sdist_wheel_build_env as a new build environment type, but this creates unnecessary complexity. The existing wheel_build_env infrastructure (used for package=wheel and package=editable) can be reused for sdist-wheel builds with minimal changes.

Proposed Architecture

Instead of creating a separate sdist_wheel_build_env system, sdist-wheel should follow the same two-environment pattern as regular wheel builds:

• .pkg environment: Builds and extracts the sdist (currently only builds, extraction is new)
• .pkg-cpython313 (or whatever wheel_build_env resolves to): Builds the wheel from the extracted sdist

This leverages the existing _wheel_build_envs dictionary and all the wheel-building machinery already in place.

Workflow Diagram

sequenceDiagram
    participant User
    participant RunEnv as Test Environment<br/>(py313)
    participant PkgEnv as .pkg<br/>(Package Env)
    participant WheelEnv as .pkg-cpython313<br/>(wheel_build_env)
    participant TmpDir as .pkg/tmp/

    User->>RunEnv: tox run with package=sdist-wheel
    RunEnv->>PkgEnv: Request package
    
    Note over PkgEnv,WheelEnv: Registration Phase
    PkgEnv->>PkgEnv: Add "sdist-wheel" to package.py:80<br/>wheel_build_env check
    PkgEnv->>WheelEnv: Register wheel_build_env<br/>(same as wheel/editable)
    
    rect rgb(255, 244, 225)
        Note over PkgEnv: Phase 1: Build sdist
        PkgEnv->>PkgEnv: Install build-system.requires
        PkgEnv->>PkgEnv: Build sdist → my-pkg.tar.gz
    end
    
    rect rgb(240, 225, 255)
        Note over PkgEnv,TmpDir: Phase 2: Extract
        PkgEnv->>TmpDir: Extract to env_tmp_dir/sdist-extract/
        Note over TmpDir: Same location as cmd_builder.py:111
        TmpDir-->>PkgEnv: Extracted source path
    end
    
    rect rgb(225, 255, 240)
        Note over WheelEnv: Phase 3: Build wheel
        PkgEnv->>WheelEnv: Get from _wheel_build_envs[wheel_build_env]
        PkgEnv->>WheelEnv: Set root = extracted_path
        Note over WheelEnv: Root setter closes old backend,<br/>creates new frontend
        WheelEnv->>WheelEnv: Read pyproject.toml from extracted sdist
        WheelEnv->>WheelEnv: Install build deps<br/>(from extracted pyproject.toml)
        WheelEnv->>WheelEnv: Build wheel using existing logic<br/>(lines 283-300 in pyproject.py)
        WheelEnv-->>PkgEnv: Return wheel
    end
    
    rect rgb(245, 245, 245)
        Note over TmpDir: Phase 4: Cleanup
        Note over TmpDir: env_tmp_dir cleared automatically<br/>on next setup (api.py:350-356)
        Note over PkgEnv: No manual shutil.rmtree needed
    end
    
    PkgEnv-->>RunEnv: Install wheel
    RunEnv->>User: Run tests

Loading

Benefits

1. Reuses existing infrastructure: No new sdist_wheel_build_env config or _sdist_wheel_build_envs dictionary needed
2. Automatic cleanup: Using env_tmp_dir for extraction means tox's lifecycle handles cleanup automatically (see api.py:350-356)—no manual shutil.rmtree required
3. Consistent with existing patterns: cmd_builder.py:111 already uses self.env_tmp_dir / "sdist-extract" for the exact same purpose
4. Less code: Eliminates duplicate environment management logic

Required Changes

1. package.py:80: Add "sdist-wheel" to the wheel_build_env check
2. pyproject.py:register_run_env: Simple registration that sets up both sdist and wheel hooks
3. pyproject.py:perform_packaging: Extract sdist to env_tmp_dir, delegate to existing wheel_build_env
4. Remove: sdist_wheel_build_env config, _sdist_wheel_build_envs dictionary, manual cleanup code

Let me know if you'd like me to clarify any part of this proposal!