MinGW support

.github/workflows/ci.yaml

@@ -7,7 +7,7 @@ jobs:
     runs-on: ${{ matrix.os }}-latest
     strategy:
       matrix:
-        os: [ubuntu, macos]
+        os: [ubuntu, macos, windows]
         python-version: ['3.8', '3.9', '3.10', '3.11', '3.12', '3.13', '3.14']
         exclude:
           # Avoid spurious "upgrade pip" error annotation
@@ -19,7 +19,8 @@ jobs:
         uses: actions/checkout@v5
 
       - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v6
+        uses: actions/setup-python@v5
+        id: setup-python
         with:
           python-version: ${{ matrix.python-version }}
 
@@ -37,9 +38,41 @@ jobs:
         run: |
           brew unlink xz || true  # Remove brewed liblzma as it is not multiarch
 
+      - name: Install MSYS2 build prerequisites
+        id: msys2
+        if: runner.os == 'Windows'
+        uses: msys2/setup-msys2@v2
+        with:
+          msystem: ucrt64
+          update: true
+          install: >-
+            base-devel
+            mingw-w64-ucrt-x86_64-binutils
+            mingw-w64-ucrt-x86_64-headers-git
+            mingw-w64-ucrt-x86_64-gcc
+            mingw-w64-ucrt-x86_64-libmangle-git
+            mingw-w64-ucrt-x86_64-winpthreads-git
+            mingw-w64-ucrt-x86_64-make
+            mingw-w64-ucrt-x86_64-pkgconf
+            mingw-w64-ucrt-x86_64-tools-git
+            mingw-w64-ucrt-x86_64-curl
+            mingw-w64-ucrt-x86_64-libdeflate
+            mingw-w64-ucrt-x86_64-bzip2
+            mingw-w64-ucrt-x86_64-zlib
+            mingw-w64-ucrt-x86_64-xz
+            mingw-w64-ucrt-x86_64-openssl
+            mingw-w64-ucrt-x86_64-libsystre
+            mingw-w64-ucrt-x86_64-libiconv
+
       - name: Build (directly from checkout)
+        if: runner.os != 'Windows'
         run:  python setup.py build
 
+      - name: Build (directly from checkout)
+        if: runner.os == 'Windows'
+        shell: msys2 {0}
+        run:  sh -c '$(cygpath "${{ steps.setup-python.outputs.python-path }}") setup.py build'
+
       - name: Install test prerequisites
         run: |
           case $RUNNER_OS in

setup.cfg

@@ -1,6 +1,9 @@
 [bdist_wheel]
 universal = 0
 
+[build_ext]
+compiler = mingw32
+
 [tool:pytest]
 # -s: do not capture stdout, conflicts with pysam.dispatch
 # -v: verbose output