Build and publish macOS wheels via cibuildwheel

.github/scripts/cibw_before_all_macos.sh

@@ -0,0 +1,34 @@
+#!/usr/bin/env bash
+# One-time (per runner) setup for building macOS wheels with cibuildwheel.
+# Installs the non-Python-specific casacore dependencies via Homebrew and
+# downloads the sources that cibw_before_build_macos.sh compiles once per
+# Python version, mirroring docker/py_wheel.docker in the casacore repo.
+set -euxo pipefail
+
+source "$(dirname "${BASH_SOURCE[0]}")/cibw_env.sh"
+
+# bison: casacore needs >= 3 and macOS ships 2.3. flex ships with macOS.
+# No BLAS package: casacore links the Accelerate framework instead.
+brew install bison ccache cfitsio fftw gcc gsl hdf5 libdeflate wcslib
+ccache -M 1G
+
+mkdir -p "$CIBW_SRC"
+cd "$CIBW_SRC"
+
+# Boost source: Boost.Python must be compiled per Python version.
+boost_underscored=${CIBW_BOOST_VERSION//./_}
+curl -fsSL --retry 3 \
+    "https://archives.boost.io/release/${CIBW_BOOST_VERSION}/source/boost_${boost_underscored}.tar.bz2" \
+    -o boost.tar.bz2
+tar xjf boost.tar.bz2
+
+# casacore source: libcasa_python3 must be compiled per Python version.
+curl -fsSL --retry 3 \
+    "https://github.com/casacore/casacore/archive/refs/tags/v${CIBW_CASACORE_VERSION}.tar.gz" \
+    -o casacore.tar.gz
+tar xzf casacore.tar.gz
+
+# Measures data, bundled into the wheels; see CIBW_DATA in cibw_env.sh.
+mkdir -p "$CIBW_DATA"
+curl -fsSL --retry 3 https://www.astron.nl/iers/WSRT_Measures.ztar -o measures.tgz
+tar xzf measures.tgz -C "$CIBW_DATA"

.github/scripts/cibw_before_build_macos.sh

@@ -0,0 +1,95 @@
+#!/usr/bin/env bash
+# Per-Python-version build of Boost.Python and casacore for macOS wheels.
+# cibuildwheel runs this before building each wheel, with the target Python
+# first on PATH as `python`. It is the macOS analogue of docker/py_wheel.docker
+# in the casacore repo: libcasa_python3 embeds the CPython ABI, so both
+# libraries are rebuilt per Python version into CIBW_PREFIX, where the
+# python-casacore build finds them via CMAKE_PREFIX_PATH.
+#
+# As in the Linux wheel images, libcasa_python3 must not link a real
+# libpython, or the wheels would only work with one specific interpreter:
+# Python3_LIBRARY is pointed at Boost.Python and Python symbols are left
+# undefined, to be resolved from the host interpreter at import time.
+set -euxo pipefail
+
+source "$(dirname "${BASH_SOURCE[0]}")/cibw_env.sh"
+
+BREW_PREFIX=$(brew --prefix)
+export PATH="$BREW_PREFIX/opt/bison/bin:$PATH"
+NCPU=$(sysctl -n hw.ncpu)
+
+PYTHON=$(command -v python)
+PY_VER=$("$PYTHON" -c 'import sys; print("%d.%d" % sys.version_info[:2])')
+PY_XY=${PY_VER//./}
+PY_INCLUDE=$("$PYTHON" -c 'import sysconfig; print(sysconfig.get_path("include"))')
+
+rm -rf "$CIBW_PREFIX"
+
+# ---- Boost.Python against the target Python ------------------------------
+# numpy is installed only afterwards, so that b2 skips boost_numpy, matching
+# the build order in docker/py_wheel.docker.
+cd "$CIBW_SRC/boost_${CIBW_BOOST_VERSION//./_}"
+b2_args=()
+if command -v ccache >/dev/null; then
+    # Route b2 through ccache too, via the darwin toolset so Boost.Python
+    # keeps its macOS-specific linking (no libpython; see the header).
+    echo "using darwin : : ccache clang++ ;" > user-config.jam
+    b2_args=(--user-config=user-config.jam)
+fi
+./bootstrap.sh --prefix="$CIBW_PREFIX" \
+    --with-libraries=python \
+    --with-python="$PYTHON" \
+    --with-python-version="$PY_VER"
+# b2 cannot derive the include dir from a virtualenv Python; the same
+# workaround as in docker/py_wheel.docker.
+./b2 -j"$NCPU" "${b2_args[@]}" cxxflags="-fPIC -I$PY_INCLUDE" install
+
+# ---- casacore against the target Python ----------------------------------
+"$PYTHON" -m pip install numpy
+
+# Flags taken from casacore's own recipes: docker/py_wheel.docker and its
+# Homebrew formulae.
+casacore_args=(
+    -DCMAKE_BUILD_TYPE=Release
+    -DCMAKE_INSTALL_PREFIX="$CIBW_PREFIX"
+    -DBUILD_TESTING=OFF
+    -DBUILD_PYTHON=OFF
+    -DBUILD_PYTHON3=ON
+    -DPython3_EXECUTABLE="$PYTHON"
+    -DPython3_INCLUDE_DIR="$PY_INCLUDE"
+    # Boost.Python stands in for libpython; see the header comment.
+    -DPython3_LIBRARY="$CIBW_PREFIX/lib/libboost_python${PY_XY}.dylib"
+    -DPORTABLE=TRUE
+    -DUSE_PCH=FALSE
+    -DUSE_OPENMP=OFF
+    -DUSE_FFTW3=ON
+    -DUSE_HDF5=ON
+    -DDATA_DIR="$CIBW_DATA"
+)
+
+# macOS-specific additions, not present in the casacore recipes.
+macos_args=(
+    # Find the Homebrew-installed dependencies.
+    -DCMAKE_PREFIX_PATH="$BREW_PREFIX"
+    # Find the per-Python Boost built above.
+    -DBoost_ROOT="$CIBW_PREFIX"
+    # Allow undefined symbols, so that Python symbols resolve from the host
+    # interpreter at import time. ELF linkers allow this by default, which is
+    # why the Linux recipe needs no such flag.
+    -DCMAKE_SHARED_LINKER_FLAGS="-Wl,-undefined,dynamic_lookup"
+)
+
+# ccache makes the repeated casacore builds cheap after the first.
+CCACHE_ARGS=()
+if command -v ccache >/dev/null; then
+    CCACHE_ARGS=(
+        -DCMAKE_C_COMPILER_LAUNCHER=ccache
+        -DCMAKE_CXX_COMPILER_LAUNCHER=ccache
+    )
+fi
+
+rm -rf "$CIBW_SRC/casacore-build"
+cmake -S "$CIBW_SRC/casacore-$CIBW_CASACORE_VERSION" -B "$CIBW_SRC/casacore-build" \
+    "${casacore_args[@]}" "${macos_args[@]}" "${CCACHE_ARGS[@]}"
+cmake --build "$CIBW_SRC/casacore-build" --parallel "$NCPU"
+cmake --install "$CIBW_SRC/casacore-build"

.github/scripts/cibw_env.sh

@@ -0,0 +1,20 @@
+#!/usr/bin/env bash
+# Shared configuration for the macOS cibuildwheel scripts. On Linux the
+# equivalent values are frozen into the per-Python wheel images built from
+# docker/py_wheel.docker in the casacore repo; macOS has no such images, so
+# the before-* scripts build the dependencies at CI time.
+
+# Dependency versions.
+export CIBW_BOOST_VERSION="1.91.0"
+export CIBW_CASACORE_VERSION="3.8.1"
+
+# Everything under one root, so a single CMAKE_PREFIX_PATH finds both installs.
+# CIBW_PREFIX, CIBW_DATA and CCACHE_DIR are duplicated as literals in
+# pyproject.toml; CCACHE_DIR also appears in build_release.yml.
+export CIBW_ROOT="$HOME/cibw"
+export CIBW_SRC="$CIBW_ROOT/src"        # extracted boost + casacore sources
+export CIBW_PREFIX="$CIBW_ROOT/local"   # install prefix for boost + casacore
+export CCACHE_DIR="$CIBW_ROOT/ccache"   # persisted across CI runs
+# The leaf directory must be named "data": python-casacore installs it into
+# the wheel by basename, and casacore/__init__.py expects casacore/data.
+export CIBW_DATA="$CIBW_ROOT/measures/data"

.github/workflows/build_release.yml

@@ -33,14 +33,29 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-latest] #, macos-latest]
+        os: [ubuntu-latest, macos-15] # macos-15 is Sequoia, arm64
 
     steps:
       - uses: actions/checkout@v7
         with:
           # Needed for `setuptools-scm`
           fetch-depth: 0
 
+      - name: Cache compiler output from the casacore builds
+        if: runner.os == 'macOS'
+        uses: actions/cache@v6
+        with:
+          # CCACHE_DIR in .github/scripts/cibw_env.sh
+          path: ~/cibw/ccache
+          key: ccache-${{ matrix.os }}-${{ hashFiles('.github/scripts/cibw_env.sh') }}
+          restore-keys: ccache-${{ matrix.os }}-
+
+      # We're using Homebrew for deps, so we can only build
+      # wheels targeting the runner's macOS version
+      - name: Match wheel deployment target to the runner
+        if: runner.os == 'macOS'
+        run: echo "MACOSX_DEPLOYMENT_TARGET=$(sw_vers -productVersion | cut -d. -f1).0" >> "$GITHUB_ENV"
+
       - name: Build wheels
         uses: pypa/cibuildwheel@v4.1
 

pyproject.toml

@@ -51,23 +51,41 @@ Homepage = "https://github.com/casacore/python-casacore"
 #########################
 
 [tool.cibuildwheel]
-build = "cp3{10,11,12,13,14}-*_x86_64"
+# Each runner builds only its native architecture: x86_64 on Linux,
+# arm64 on the macOS runner.
+build = "cp3{10,11,12,13,14}-*"
 build-verbosity = 1
-environment = """ \
-    CXXFLAGS="-I/usr/include/cfitsio" \
-    LD_LIBRARY_PATH=/opt/boost/lib \
-"""
 test-command = "cd {package}/tests && pytest"
 test-requires = "pytest"
 
 [tool.cibuildwheel.macos]
+# before-build compiles Boost.Python and casacore against each Python version,
+# the macOS analogue of the per-Python Linux images below; see the script for
+# details.
+before-all = "bash {project}/.github/scripts/cibw_before_all_macos.sh"
+before-build = "bash {project}/.github/scripts/cibw_before_build_macos.sh"
+# cibuildwheel cannot source cibw_env.sh, so these are literals. Keep the
+# paths in sync with CIBW_PREFIX, CIBW_DATA and CCACHE_DIR there. CMAKE_ARGS
+# routes the extension build through the same ccache as the dependencies.
+environment = """ \
+    CMAKE_PREFIX_PATH=$HOME/cibw/local \
+    CASACORE_DATA=$HOME/cibw/measures/data \
+    CCACHE_DIR=$HOME/cibw/ccache \
+    CMAKE_ARGS="-DCMAKE_C_COMPILER_LAUNCHER=ccache -DCMAKE_CXX_COMPILER_LAUNCHER=ccache" \
+"""
 repair-wheel-command = """\
-    DYLD_LIBRARY_PATH=${BOOST_INSTALL_DIR}/lib delocate-wheel \
+    source {project}/.github/scripts/cibw_env.sh && \
+    DYLD_LIBRARY_PATH=$CIBW_PREFIX/lib delocate-wheel \
     --require-archs {delocate_archs} -w {dest_dir} -v {wheel}\
 """
 
 [tool.cibuildwheel.linux]
 skip = ["*-musllinux_*"]
+# These paths exist inside the prebuilt wheel images selected below.
+environment = """ \
+    CXXFLAGS="-I/usr/include/cfitsio" \
+    LD_LIBRARY_PATH=/opt/boost/lib \
+"""
 
 [[tool.cibuildwheel.overrides]]
 select="cp310-*"