Merge pull request #358 from henryiii/henryiii/pep517

Adding PEP 518 test, fix 3.5 Python on Windows

cibuildwheel/windows.py

@@ -5,6 +5,7 @@ import sys
 import tempfile
 from pathlib import Path
 from zipfile import ZipFile
+import toml
 
 from typing import Dict, List, Optional, NamedTuple
 
@@ -153,6 +154,31 @@ def setup_python(python_configuration: PythonConfiguration, dependency_constrain
     return env
 
 
+def pep_518_cp35_workaround(package_dir: Path, env: Dict[str, str]) -> None:
+    """
+    Python 3.5 PEP 518 hack (see https://github.com/pypa/pip/issues/8392#issuecomment-639563494)
+    Basically, nuget's Python is an embedded Python distribution, which is not supported by pip.
+    Before version 3.6, there was no way to disable the "embedded" behavior, including the ignoring
+    of environment variables, including the ones pip uses to setup PEP 518 builds.
+
+    The fix here is as suggested in that issue; we manually setup the PEP 518 requirements. Since we
+    are in a fresh environment (except for pinned cibuildweel dependencies), the build is already
+    mostly "isolated".
+    """
+
+    pyproject_path = package_dir / 'pyproject.toml'
+
+    if pyproject_path.exists():
+        data = toml.load(pyproject_path)
+        requirements = (
+            data['build-system'].get('requires', [])
+            if 'build-system' in data
+            else []
+        )
+        if requirements:
+            shell(['pip', 'install'] + requirements, env=env)
+
+
 def build(options: BuildOptions) -> None:
     temp_dir = Path(tempfile.mkdtemp(prefix='cibuildwheel'))
     built_wheel_dir = temp_dir / 'built_wheel'
@@ -183,6 +209,11 @@ def build(options: BuildOptions) -> None:
             before_build_prepared = prepare_command(options.before_build, project='.', package=options.package_dir)
             shell([before_build_prepared], env=env)
 
+        # activate the PEP 518 patch if on Windows Python 3.5
+        # (will only have an effect if PEP 517 builds are used):
+        if config.version.startswith('3.5'):
+            pep_518_cp35_workaround(options.package_dir, env)
+
         # build the wheel
         if built_wheel_dir.exists():
             shutil.rmtree(built_wheel_dir)

setup.py

@@ -12,7 +12,7 @@ long_description = (this_directory / 'README.md').read_text(encoding='utf-8')
 setup(
     name='cibuildwheel',
     version='1.4.2',
-    install_requires=['bashlex!=0.13'],
+    install_requires=['bashlex!=0.13', 'toml'],
     description="Build Python wheels on CI with minimal configuration.",
     long_description=long_description,
     long_description_content_type='text/markdown',

test/test_pep518.py

@@ -0,0 +1,44 @@
+import textwrap
+from . import test_projects
+from . import utils
+
+basic_project = test_projects.new_c_project(
+    setup_py_add=textwrap.dedent(
+        """
+        # Will fail if PEP 518 does work
+        import requests
+        assert requests.__version__ == "2.23.0", "Requests found but wrong version ({0})".format(requests.__version__)
+
+        # Just making sure environment is still set
+        import os
+        if os.environ.get("CIBUILDWHEEL", "0") != "1":
+            raise Exception("CIBUILDWHEEL environment variable is not set to 1")
+        """
+    )
+)
+
+basic_project.files[
+    "pyproject.toml"
+] = """
+[build-system]
+requires = [
+    "setuptools>=42",
+    "wheel",
+    "requests==2.23.0"
+]
+
+build-backend = "setuptools.build_meta"
+"""
+
+
+def test_pep518(tmp_path):
+
+    project_dir = tmp_path / "project"
+    basic_project.generate(project_dir)
+
+    # build the wheels
+    actual_wheels = utils.cibuildwheel_run(project_dir)
+
+    # check that the expected wheels are produced
+    expected_wheels = utils.expected_wheels("spam", "0.1.0")
+    assert set(actual_wheels) == set(expected_wheels)