setup.py: fix macos arm64 wheel builds.

- Move cibuildwheel config to pyproject.toml to support local builds.
- Building arm64 instead of universal2 for macos.
- Passing --host argument to libusb configure when building under cibuildwheel and the ARCHFLAGS env var is set. The cross-compile architecture is set to the one specified in ARCHFLAGS.
- Cleaning libusb before build to force a fresh build.

Author: flit

.github/workflows/build-wheels.yml

@@ -22,6 +22,7 @@ on:
   workflow_dispatch:
 
 jobs:
+  # Note: cibuildwheel configuration comes from pyproject.toml instead of env vars!
   build_wheels:
     name: Build wheels on ${{ matrix.os }}
     runs-on: ${{ matrix.os }}
@@ -32,14 +33,6 @@ jobs:
           - ubuntu-latest
           - macos-latest
           - windows-latest
-    env:
-      CIBW_ARCHS_LINUX: auto aarch64
-      CIBW_ARCHS_MACOS: x86_64 universal2
-      CIBW_ARCHS_WINDOWS: auto
-      CIBW_SKIP: "cp27-* cp34-* cp35-* pp*"
-      CIBW_BEFORE_BUILD: "python -m pip install --upgrade pip wheel setuptools setuptools_scm"
-      CIBW_BEFORE_BUILD_MACOS: "brew install autoconf automake libtool m4"
-      CIBW_BUILD_VERBOSITY: 1
 
     steps:
       - uses: actions/checkout@v2

pyproject.toml

@@ -13,3 +13,17 @@ fallback_version = "1.0.0.0"
 [tool.mypy]
 files = "src/libusb_package"
 ignore_missing_imports = true
+
+[tool.cibuildwheel]
+before-build = "python -m pip install --upgrade pip wheel setuptools setuptools_scm"
+build-verbosity = 1
+
+[tool.cibuildwheel.linux]
+archs = ["auto", "aarch64"]
+
+[tool.cibuildwheel.macos]
+archs = ["x86_64", "arm64"]
+before-build = "brew install autoconf automake libtool m4"
+
+[tool.cibuildwheel.windows]
+archs = ["auto"]

setup.py

@@ -115,15 +115,35 @@ def run(self):
                     "-Wredundant-decls",
                     "-Wswitch-enum",
                     ]
+                extra_configure_args = []
+
+                # Special conditions when cibuildwheel is building us.
+                if os.environ.get('CIBUILDWHEEL') == '1':
+                    if sys.platform == 'darwin':
+                        # Support arm64 cross-compile builds from x86-64 on macOS from cibuildwheel.
+                        archflags = os.environ.get('ARCHFLAGS', '')
+                        if archflags:
+                            # Wrap in exception handler just in case something goes unexpectedly wrong, it
+                            # won't totally break all builds.
+                            try:
+                                arch = archflags.split()[-1]
+                                cflags += [archflags]
+                                extra_configure_args = [f'--host={arch}-apple-darwin']
+                            except Exception as err:
+                                print(f"Warning: failure to extract architecture from ARCHFLAGS='{archflags}' ({err})")
+                    else:
+                        # Don't include libudev (for now) on Linux since it isn't in the CI runner image.
+                        extra_configure_args = ['--disable-udev']
 
                 os.environ['CFLAGS'] = ' '.join(cflags)
 
                 # Run bootstrap.sh, configure, and make.
-
                 try:
+                    self.spawn(['env']) # Dump environment for debugging purposes.
                     self.spawn(['bash', str(BOOTSTRAP_SCRIPT)])
-                    self.spawn(['bash', str(CONFIGURE_SCRIPT), '--disable-udev'])
-                    self.spawn(['make', f'-j{os.cpu_count() or 4}'])
+                    self.spawn(['bash', str(CONFIGURE_SCRIPT), *extra_configure_args])
+                    self.spawn(['make', 'clean'])
+                    self.spawn(['make', f'-j{os.cpu_count() or 4}', 'all'])
                 except Exception as err:
                     # Exception is caught here and reraised as our specific Exception class because the actual
                     # DistutilsExecError class raised on exceptions appears to be difficult to import to use in