Create wheels on Windows (#1015)

* Create wheels on Windows

* Statically link run-time libraries on Windows for Python 2.7

* Remove condition in CMakeLists.txt for hiding C++ symbols

* Simplify Python 2.7 Windows wheels build.

.github/workflows/python-package.yml

@@ -66,29 +66,36 @@ jobs:
         fail_ci_if_error: true
 
   package_wheels:
-    name: Package wheels on ${{ matrix.os }}
     needs: build
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-latest, macOS-latest]
+        os: [ubuntu-latest, macos-latest, windows-latest]
         python-build: [cp27*, cp37*, cp38*]
-
     steps:
       - uses: actions/checkout@v2
 
-      # Used to host cibuildwheel
-      - uses: actions/setup-python@v2
-
-      - name: Install cibuildwheel
-        run: python -m pip install cibuildwheel==1.10.0
+      # cibuildwheel 1.12.0 gates Python 2.7 wheels builds
+      # by using two environment variables, DISTUTILS_USE_SDK and MSSdk.
+      # https://cibuildwheel.readthedocs.io/en/1.x/cpp_standards/#windows-and-python-27
+      # Note that normally these are used by setuptools/distutils, but in our case
+      # they are really just used for cibuildwheel as we don't use any of the
+      # setuptools/distutils build tools. Our builds are entirely handled
+      # by CMake. CMake is able to find the right toolchain, thanks to
+      # the -A argument that we specify in the setup.py to set the
+      # target platform (x86, x64, etc).
+      - name: Set Windows Python 2.7 environment variables
+        if: matrix.python-build == 'cp27*' && runner.os == 'Windows'
+        shell: bash
+        run: |
+          echo "DISTUTILS_USE_SDK=1" >> $GITHUB_ENV
+          echo "MSSdk=1" >> $GITHUB_ENV
 
       - name: Build wheels
-        run: python -m cibuildwheel --output-dir wheelhouse
-        # TODO: Solve for the 32-bit errors in windows python 2.7:
-        #   https://github.com/pybind/cmake_example/blob/master/.github/workflows/wheels.yml#L66
+        uses: pypa/cibuildwheel@v1.12.0
+        with:
+          output-dir: wheelhouse
         env:
-          CIBW_SKIP: cp27-win*
           CIBW_BUILD: ${{ matrix.python-build }}
 
       - uses: actions/upload-artifact@v2

CMakeLists.txt

@@ -103,10 +103,23 @@ if(OTIO_SHARED_LIBS)
 else()
     message(STATUS "Building static libs")
     set(OTIO_SHARED_OR_STATIC_LIB "STATIC")
-    if (OTIO_PYTHON_INSTALL AND NOT MSVC)
+    if (OTIO_PYTHON_INSTALL)
         # If we're compiling for pybind, we can hide all our symbols, they'll only be called from pybind
-        set(CMAKE_CXX_VISIBILITY_PRESET hidden) 
+        # Note that this has no effect on Windows.
+        set(CMAKE_CXX_VISIBILITY_PRESET hidden)
         set(CMAKE_VISIBILITY_INLINES_HIDDEN 1)
+
+        if(MSVC AND Python_VERSION_MAJOR VERSION_LESS 3)
+            # Statically link run-time library (vcruntime and msvcp)
+            # See https://docs.microsoft.com/en-us/cpp/build/reference/md-mt-ld-use-run-time-library?view=msvc-160
+            # This allows us to compile OTIO bindings with a newer MSVC version
+            # than the one used by the interpreter where OTIO will be installed.
+            # This is only required for Python < 3 because only these are
+            # compiled with an older compiler (9.0). CPython 3.5+ uses at least
+            # Visual C++ 14.X.
+            # See https://wiki.python.org/moin/WindowsCompilers#Which_Microsoft_Visual_C.2B-.2B-_compiler_to_use_with_a_specific_Python_version_.3F
+            add_compile_options(/MT)
+        endif()
     endif()
 endif()
 

setup.py

@@ -27,6 +27,10 @@
 
 SOURCE_DIR = os.path.abspath(os.path.dirname(__file__))
 
+PLAT_TO_CMAKE = {
+    "win32": "Win32",
+    "win-amd64": "x64",
+}
 
 INSTALL_REQUIRES = [
     'pyaaf2~=1.4.0',
@@ -103,8 +107,7 @@ def generate_cmake_arguments(self):
         ]
 
         if platform.system() == "Windows":
-            if sys.maxsize > 2**32:
-                cmake_args += ['-A', 'x64']
+            cmake_args += ["-A", PLAT_TO_CMAKE[self.plat_name]]
 
         cxx_coverage = bool(os.environ.get("OTIO_CXX_COVERAGE_BUILD"))
         if cxx_coverage and not os.environ.get("OTIO_CXX_BUILD_TMP_DIR"):