Request: Provide support for PEP517 builds

[DHolmanCoding]

Summary

Please add first-class PEP 517 build support so pillow-simd builds cleanly in isolated environments (pip/Poetry) on Python 3.12+. The current sdist path relies on legacy setuptools behavior that imports distutils, which is removed in Python 3.12, causing builds to fail. Repo reference: https://github.com/uploadcare/pillow-simd

Environment

• Python: 3.12.x
• OS: Ubuntu 20.04 (glibc ~2.31)
• pip: 25.2
• Build mode: PEP 517 isolated (default for pip/Poetry)

Repro

• Any clean environment where only an sdist is available (no cp312 wheel):

Commands:

python -m venv .venv && . .venv/bin/activate
pip install --upgrade pip
pip wheel --no-cache-dir --use-pep517 "pillow-simd==9.5.0.post2"

Error (excerpt):

Backend 'setuptools.build_meta:__legacy__' is not available
ModuleNotFoundError: No module named 'distutils'

Expected

• pip install pillow-simd succeeds under PEP 517 isolated builds on Python 3.12+.
• sdist contains metadata and build hooks sufficient to compile C extensions without legacy distutils paths.

Actual

• sdist build falls back to legacy setuptools backend that imports distutils, which is not present in Python 3.12, causing the build to fail.

Why this matters

• Modern Python packaging defaults to PEP 517 isolated builds.
• Many users consume pillow-simd via Poetry/pip in containers/CI where prebuilt wheels may not be available; they need a reliable sdist path.

Proposed changes

• Add a pyproject.toml that declares a modern backend and build requirements.

Minimal example:

[build-system]
requires = [
  "setuptools>=70",  # ensures setuptools’ vendored distutils
  "wheel",
  "cython>=3.0",
  "numpy>=2.0",
]
build-backend = "setuptools.build_meta"

[project]
name = "Pillow-SIMD"
dynamic = ["version", "description"]  # or set explicitly
requires-python = ">=3.8"

[tool.setuptools]
# if using src/ layout, otherwise omit/change
# package-dir = {"" = "src"}

• Ensure pyproject.toml is included in the sdist.
• Optionally, publish cp312 wheels for manylinux_2_17 (manylinux2014) to avoid source builds on common glibc baselines.

Workarounds (not ideal)

• Install with --no-build-isolation and SETUPTOOLS_USE_DISTUTILS=local.
• Use stock pillow when wheels aren’t available.

Acceptance criteria

• pip wheel --use-pep517 pillow-simd==<new-version> succeeds on Python 3.12+ in a clean venv.
• Building from sdist works without relying on stdlib distutils.
• New sdist includes pyproject.toml; wheels are built with the declared backend.

Reference: https://github.com/uploadcare/pillow-simd