Add CI support for publishing Windows ARM64 wheels

.github/workflows/build-wheels.yml

@@ -17,7 +17,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest, windows-latest, macos-14, macos-15-intel]
+        os: [ubuntu-latest, windows-latest, windows-11-arm, macos-14, macos-15-intel]
 
     steps:
       - name: Checkout code
@@ -34,20 +34,33 @@ jobs:
         run: |
           echo "MACOSX_DEPLOYMENT_TARGET=$(sw_vers -productVersion | cut -d '.' -f 1-2)" >> $GITHUB_ENV
           # This does not work inside CIBW_BEFORE_ALL_MACOS; Without it, the wheel repair fails.
-
-      - name: Windows - Set up pkg-config and CMake
-        if: runner.os == 'windows'
+      
+      - name: Windows - Install CMake & pkgconfig
+        if: runner.os == 'Windows'
         shell: bash
         run: |
           choco install cmake --version=3.31.5 --allow-downgrade -y --no-progress
           choco install -y --no-progress --stoponfirstfailure pkgconfiglite
+
+      - name: Windows - Set x86-64 PKG_CONFIG_PATH 
+        if: runner.os == 'Windows' && runner.arch == 'X64'
+        shell: bash
+        run: |
           echo "PKG_CONFIG_PATH=C:/mingw64/lib/pkgconfig" >> $GITHUB_ENV
 
+      - name: Windows ARM64 - Set up compilers and OpenBLAS
+        if: runner.os == 'Windows' && runner.arch == 'ARM64'
+        shell: pwsh
+        run: |
+          $VsVars = 'C:\Program Files\Microsoft Visual Studio\18\Enterprise\VC\Auxiliary\Build\vcvarsarm64.bat'
+          cmd /c "`"$VsVars`" && set" > "$env:RUNNER_TEMP\vcvars.txt"
+          ./cibw-scripts/setup_windows_arm64.ps1
+
       - name: Build wheels
         uses: pypa/cibuildwheel@v3.4.1
         env:
           # All cibuildwheel options are here (nothing "hidden" in pyproject.toml)
-          CIBW_SKIP: "*-win32 *i686 cp3??t-*"
+          CIBW_SKIP: "*-win32 *i686 cp3??t-* cp310-win_arm64"
           CIBW_BUILD_FRONTEND: build
           CIBW_BUILD_VERBOSITY: 3
           CIBW_TEST_REQUIRES: pytest scipy
@@ -65,6 +78,14 @@ jobs:
             pip install delvewheel
           CIBW_REPAIR_WHEEL_COMMAND_WINDOWS: |
             bash ./cibw-scripts/repair_wheel_command_windows.sh {wheel} {dest_dir}
+          CIBW_ENVIRONMENT_PASS_WINDOWS: >
+            CC
+            CXX
+            FC
+            AR
+            PKG_CONFIG_PATH
+            OPENBLAS_DIR
+            ODRPACK_WIN_ARM64
 
       - name: Upload wheels 
         uses: actions/upload-artifact@v6
@@ -127,4 +148,4 @@ jobs:
 
 #       - uses: pypa/gh-action-pypi-publish@release/v1
 #         with:
-#           repository-url: https://test.pypi.org/legacy/
+#           repository-url: https://test.pypi.org/legacy/

cibw-scripts/before_all_windows.sh

@@ -1,5 +1,17 @@
+#!/bin/bash
 set -xe
 
+# ARM64: compilers (CC/CXX/FC) and OpenBLAS are already set up by
+# cibw-scripts/setup_windows_arm64.ps1, so there is nothing to install here.
+if [[ -n "${ODRPACK_WIN_ARM64:-}" ]]; then
+    clang-cl --version
+    flang-new --version
+    pkg-config --modversion openblas
+    exit 0
+fi
+
+# x86-64: install OpenBLAS via MSYS2/MinGW.
+
 # Verify active compiler locations
 which gcc
 which gfortran

cibw-scripts/setup_windows_arm64.ps1

@@ -0,0 +1,56 @@
+$ErrorActionPreference = 'Stop'
+$ProgressPreference = 'SilentlyContinue'
+$LlvmVersion = '22.1.8'
+$LlvmBin = 'C:\Program Files\LLVM\bin'
+$LlvmInstaller = "$env:RUNNER_TEMP\LLVM-22.1.8-woa64.exe"
+$LlvmUrl = "https://github.com/llvm/llvm-project/releases/download/llvmorg-$LlvmVersion/LLVM-$LlvmVersion-woa64.exe"
+Invoke-WebRequest $LlvmUrl -UseBasicParsing -OutFile $LlvmInstaller
+Start-Process -FilePath $LlvmInstaller -ArgumentList '/S' -Wait
+$env:PATH = "$LlvmBin;$env:PATH"
+$LlvmBin | Out-File -FilePath $env:GITHUB_PATH -Encoding utf8 -Append
+$LlvmRuntime = "$LlvmBin\..\lib\clang\22.1.8\lib\windows"
+$FlangRuntime = "$LlvmBin\..\lib\clang\22\lib\aarch64-pc-windows-msvc"
+$env:LIB = "$FlangRuntime;$LlvmRuntime;$env:LIB"
+"LIB=$env:LIB" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append
+@(
+    'CC=clang-cl'
+    'CXX=clang-cl'
+    'FC=flang-new'
+    'AR=llvm-ar'
+    'ODRPACK_WIN_ARM64=1'
+) | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append
+
+$OpenBlasVersion = '0.3.34'
+$OpenBlasDir = 'C:\openblas'
+$zip = "$env:RUNNER_TEMP\openblas.zip"
+$tmp = "$env:RUNNER_TEMP\openblas_extract"
+$url = "https://github.com/OpenMathLib/OpenBLAS/releases/download/v$OpenBlasVersion/OpenBLAS-$OpenBlasVersion-woa64-64-dll.zip"
+Invoke-WebRequest -Uri $url -OutFile $zip -UseBasicParsing
+
+# Extract to a temp dir, then flatten the top-level OpenBLAS folder
+Expand-Archive -LiteralPath $zip -DestinationPath $tmp -Force
+Move-Item "$tmp\OpenBLAS" $OpenBlasDir
+
+$pkgConfigDir = "$OpenBlasDir\lib\pkgconfig"
+$prefix = $OpenBlasDir.Replace('\', '/')
+
+@"
+libdir=$prefix/lib
+libnameprefix=
+libnamesuffix=
+libsuffix=
+includedir=$prefix/include/openblas
+
+Name: OpenBLAS
+Description: OpenBLAS is an optimized BLAS library based on GotoBLAS2 1.13 BSD version
+Version: $OpenBlasVersion
+URL: https://github.com/OpenMathLib/OpenBLAS
+Libs: -L`${libdir} -l`${libnameprefix}openblas`${libnamesuffix}`${libsuffix}
+Cflags: -I`${includedir}
+"@ | Set-Content -LiteralPath "$pkgConfigDir\openblas.pc" -Encoding ASCII
+@(
+    "PKG_CONFIG_PATH=$($pkgConfigDir.Replace('\', '/'))"
+    "OPENBLAS_DIR=$OpenBlasDir"
+) | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append
+
+"$OpenBlasDir\bin" | Out-File -FilePath $env:GITHUB_PATH -Encoding utf8 -Append