[ci] [python-package] add arm64 macOS wheels

.ci/test.sh

@@ -174,8 +174,7 @@ elif [[ $TASK == "bdist" ]]; then
         if [[ $ARCH == "x86_64" ]]; then
             PLATFORM="macosx_10_15_x86_64.macosx_11_6_x86_64.macosx_12_5_x86_64"
         else
-            echo "ERROR: macos wheels not supported yet on architecture '${ARCH}'"
-            exit 1
+            PLATFORM="macosx_14_0_arm64"
         fi
         mv \
             ./dist/tmp.whl \

.github/workflows/python_package.yml

@@ -36,6 +36,10 @@ jobs:
             python_version: '3.8'
           - os: macos-13
             task: if-else
+            python_version: '3.9'
+          - os: macos-14
+            task: bdist
+            method: wheel
             python_version: '3.10'
           # We're currently skipping MPI jobs on macOS, see https://github.com/microsoft/LightGBM/pull/6425
           # for further details.
@@ -63,7 +67,11 @@ jobs:
           export TASK="${{ matrix.task }}"
           export METHOD="${{ matrix.method }}"
           export PYTHON_VERSION="${{ matrix.python_version }}"
-          if [[ "${{ matrix.os }}" == "macos-13" ]]; then
+          if [[ "${{ matrix.os }}" == "macos-14" ]]; then
+              # use clang when creating macOS release artifacts
+              export COMPILER="clang"
+              export OS_NAME="macos"
+          elif [[ "${{ matrix.os }}" == "macos-13" ]]; then
               export COMPILER="gcc"
               export OS_NAME="macos"
           elif [[ "${{ matrix.os }}" == "ubuntu-latest" ]]; then
@@ -75,6 +83,12 @@ jobs:
           export PATH=${CONDA}/bin:${PATH}
           $GITHUB_WORKSPACE/.ci/setup.sh || exit 1
           $GITHUB_WORKSPACE/.ci/test.sh || exit 1
+      - name: upload wheels
+        if: ${{ matrix.method == 'wheel' && matrix.os == 'macos-14' }}
+        uses: actions/upload-artifact@v4
+        with:
+          name: macosx-arm64-wheel
+          path: dist/*.whl
   test-oldest-versions:
     name: Python - oldest supported versions (ubuntu-latest)
     runs-on: ubuntu-latest

CMakeLists.txt

@@ -707,6 +707,61 @@ if(__BUILD_FOR_PYTHON)
     set(CMAKE_INSTALL_PREFIX "lightgbm")
 endif()
 
+# The macOS linker puts an absolute path to linked libraries in lib_lightgb.dylib.
+# This block overrides that information for LightGBM's OpenMP dependency, to allow
+# finding that library in more places.
+#
+# This reduces the risk of runtime issues resulting from multiple libomp.dylib being loaded.
+#
+if(APPLE AND USE_OPENMP)
+  # store path to libomp found at build time in a variable
+  get_target_property(
+    OpenMP_LIBRARY_LOCATION
+    OpenMP::OpenMP_CXX
+    INTERFACE_LINK_LIBRARIES
+  )
+  # get just the filename of that path
+  # (to deal with the possibility that it might be 'libomp.dylib' or 'libgomp.dylib' or 'libiomp.dylib')
+  get_filename_component(
+    OpenMP_LIBRARY_NAME
+    ${OpenMP_LIBRARY_LOCATION}
+    NAME
+  )
+  # get directory of that path
+  get_filename_component(
+    OpenMP_LIBRARY_DIR
+    ${OpenMP_LIBRARY_LOCATION}
+    DIRECTORY
+  )
+  # Override the absolute path to OpenMP with a relative one using @rpath.
+  #
+  # This also ensures that if a libomp.dylib has already been loaded, it'll just use that.
+  add_custom_command(
+    TARGET _lightgbm
+    POST_BUILD
+      COMMAND
+        install_name_tool
+        -change
+        ${OpenMP_LIBRARY_LOCATION}
+        "@rpath/${OpenMP_LIBRARY_NAME}"
+        "${PROJECT_SOURCE_DIR}/lib_lightgbm.dylib"
+      WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+      COMMENT "Replacing hard-coded OpenMP install_name with '@rpath/${OpenMP_LIBRARY_NAME}'..."
+  )
+  # add RPATH entries to ensure the loader looks in the following, in the following order:
+  #
+  #   - /opt/homebrew/opt/libomp/lib (where 'brew install' / 'brew link' puts libomp.dylib)
+  #   - ${OpenMP_LIBRARY_DIR}        (wherever find_package(OpenMP) found OpenMP at build time)
+  #
+  set_target_properties(
+    _lightgbm
+    PROPERTIES
+      BUILD_WITH_INSTALL_RPATH TRUE
+      INSTALL_RPATH "/opt/homebrew/opt/libomp/lib;${OpenMP_LIBRARY_DIR}"
+      INSTALL_RPATH_USE_LINK_PATH FALSE
+  )
+endif()
+
 install(
   TARGETS _lightgbm
   RUNTIME DESTINATION ${CMAKE_INSTALL_PREFIX}/bin