Add support for iOS

.github/workflows/wheels-dependencies.sh

@@ -1,31 +1,86 @@
 #!/bin/bash
 
-# Setup that needs to be done before multibuild utils are invoked
-PROJECTDIR=$(pwd)
-if [[ "$(uname -s)" == "Darwin" ]]; then
-    # Safety check - macOS builds require that CIBW_ARCHS is set, and that it
-    # only contains a single value (even though cibuildwheel allows multiple
-    # values in CIBW_ARCHS).
+# Safety check - Pillow builds require that CIBW_ARCHS is set, and that it only
+# contains a single value (even though cibuildwheel allows multiple values in
+# CIBW_ARCHS). This check doesn't work on Linux because of how the CIBW_ARCHS
+# variable is exposed.
+function check_cibw_archs {
     if [[ -z "$CIBW_ARCHS" ]]; then
-        echo "ERROR: Pillow macOS builds require CIBW_ARCHS be defined."
+        echo "ERROR: Pillow builds require CIBW_ARCHS be defined."
         exit 1
     fi
     if [[ "$CIBW_ARCHS" == *" "* ]]; then
-        echo "ERROR: Pillow macOS builds only support a single architecture in CIBW_ARCHS."
+        echo "ERROR: Pillow builds only support a single architecture in CIBW_ARCHS."
         exit 1
     fi
+}
+
+# Setup that needs to be done before multibuild utils are invoked. Process
+# potential cross-build platforms before native platforms to ensure that we pick
+# up the cross environment.
+PROJECTDIR=$(pwd)
+if [[ "$CIBW_PLATFORM" == "ios" ]]; then
+    check_cibw_archs
+    # On iOS, CIBW_ARCHS is actually a multi-arch - arm64_iphoneos,
+    # arm64_iphonesimulator or x86_64_iphonesimulator. Split into the CPU
+    # platform, and the iOS SDK.
+    PLAT=$(echo $CIBW_ARCHS | sed "s/\(.*\)_\(.*\)/\1/")
+    IOS_SDK=$(echo $CIBW_ARCHS | sed "s/\(.*\)_\(.*\)/\2/")
+
+    # Build iOS builds in `build/iphoneos` or `build/iphonesimulator/`
+    # (depending on the build target). Install them into `build/deps/iphoneos`
+    # or `build/deps/iphonesimulator`
+    WORKDIR=$(pwd)/build/$IOS_SDK
+    BUILD_PREFIX=$(pwd)/build/deps/$IOS_SDK
+    PATCH_DIR=$(pwd)/patches/iOS
+
+    # GNU tooling insists on using aarch64 rather than arm64
+    if [[ $PLAT == "arm64" ]]; then
+        GNU_ARCH=aarch64
+    else
+        GNU_ARCH=x86_64
+    fi
+
+    IOS_SDK_PATH=$(xcrun --sdk $IOS_SDK --show-sdk-path)
+    CMAKE_SYSTEM_NAME=iOS
+    if [[ "$IOS_SDK" == "iphonesimulator" ]]; then
+        IOS_HOST_TRIPLE=$PLAT-apple-ios$IPHONEOS_DEPLOYMENT_TARGET-simulator
+    else
+        IOS_HOST_TRIPLE=$PLAT-apple-ios$IPHONEOS_DEPLOYMENT_TARGET
+    fi
+
+    # GNU Autotools doesn't recognize the existence of arm64-apple-ios-simulator
+    # as a valid host. However, the only difference between arm64-apple-ios and
+    # arm64-apple-ios-simulator is the choice of sysroot, and that is
+    # coordinated by CC,CFLAGS etc. From the perspective of configure, the two
+    # platforms are identical, so we can use arm64-apple-ios consistently.
+    # This (mostly) avoids us needing to patch config.sub in dependency sources.
+    HOST_CONFIGURE_FLAGS="--disable-shared --enable-static --host=$GNU_ARCH-apple-ios --build=$GNU_ARCH-apple-darwin"
+
+    # Cmake has native support for iOS. However, most of that support is based
+    # on using the Xcode builder, which isn't very helpful for most of Pillow's
+    # dependencies. Therefore, we lean on the OSX configurations, plus CC/CFLAGS
+    # etc to ensure the right sysroot is selected.
+    HOST_CMAKE_FLAGS="-DCMAKE_SYSTEM_NAME=$CMAKE_SYSTEM_NAME -DCMAKE_SYSTEM_PROCESSOR=$GNU_ARCH -DCMAKE_OSX_DEPLOYMENT_TARGET=$IPHONEOS_DEPLOYMENT_TARGET -DCMAKE_OSX_SYSROOT=$IOS_SDK_PATH -DBUILD_SHARED_LIBS=NO"
 
+    # Meson needs to be pointed at a cross-platform configuration file
+    # This will be generated once CC etc have been evaluated.
+    HOST_MESON_FLAGS="--cross-file $WORKDIR/meson-cross.txt -Dprefer_static=true -Ddefault_library=static"
+
+elif [[ "$(uname -s)" == "Darwin" ]]; then
+    check_cibw_archs
     # Build macOS dependencies in `build/darwin`
     # Install them into `build/deps/darwin`
+    PLAT="${CIBW_ARCHS:-$AUDITWHEEL_ARCH}"
     WORKDIR=$(pwd)/build/darwin
     BUILD_PREFIX=$(pwd)/build/deps/darwin
 else
     # Build prefix will default to /usr/local
+    PLAT="${CIBW_ARCHS:-$AUDITWHEEL_ARCH}"
     WORKDIR=$(pwd)/build
     MB_ML_LIBC=${AUDITWHEEL_POLICY::9}
     MB_ML_VER=${AUDITWHEEL_POLICY:9}
 fi
-PLAT="${CIBW_ARCHS:-$AUDITWHEEL_ARCH}"
 
 # Define custom utilities
 source wheels/multibuild/common_utils.sh
@@ -36,7 +91,9 @@ fi
 
 ARCHIVE_SDIR=pillow-depends-main
 
-# Package versions for fresh source builds
+# Package versions for fresh source builds. Version numbers with "Patched"
+# annotations have a source code patch that is required for some platforms. If
+# you change those versions, ensure the patch is also updated.
 FREETYPE_VERSION=2.13.3
 HARFBUZZ_VERSION=11.2.1
 LIBPNG_VERSION=1.6.49
@@ -47,31 +104,57 @@ TIFF_VERSION=4.7.0
 LCMS2_VERSION=2.17
 ZLIB_VERSION=1.3.1
 ZLIB_NG_VERSION=2.2.4
-LIBWEBP_VERSION=1.5.0
+LIBWEBP_VERSION=1.5.0  # Patched
 BZIP2_VERSION=1.0.8
 LIBXCB_VERSION=1.17.0
-BROTLI_VERSION=1.1.0
+BROTLI_VERSION=1.1.0  # Patched
 
 function build_pkg_config {
     if [ -e pkg-config-stamp ]; then return; fi
-    # This essentially duplicates the Homebrew recipe
-    CFLAGS="$CFLAGS -Wno-int-conversion" build_simple pkg-config 0.29.2 https://pkg-config.freedesktop.org/releases tar.gz \
+    # This essentially duplicates the Homebrew recipe.
+    # On iOS, we need a binary that can be executed on the build machine; but we
+    # can create a host-specific pc-path to store iOS .pc files. To ensure a
+    # macOS-compatible build, we temporarily clear environment flags that set
+    # iOS-specific values.
+    if [[ -n "$IOS_SDK" ]]; then
+        ORIGINAL_HOST_CONFIGURE_FLAGS=$HOST_CONFIGURE_FLAGS
+        ORIGINAL_IPHONEOS_DEPLOYMENT_TARGET=$IPHONEOS_DEPLOYMENT_TARGET
+        unset HOST_CONFIGURE_FLAGS
+        unset IPHONEOS_DEPLOYMENT_TARGET
+    fi
+
+    CFLAGS="$CFLAGS -Wno-int-conversion" CPPFLAGS="" build_simple pkg-config 0.29.2 https://pkg-config.freedesktop.org/releases tar.gz \
         --disable-debug --disable-host-tool --with-internal-glib \
         --with-pc-path=$BUILD_PREFIX/share/pkgconfig:$BUILD_PREFIX/lib/pkgconfig \
         --with-system-include-path=$(xcrun --show-sdk-path --sdk macosx)/usr/include
+
+    if [[ -n "$IOS_SDK" ]]; then
+        HOST_CONFIGURE_FLAGS=$ORIGINAL_HOST_CONFIGURE_FLAGS
+        IPHONEOS_DEPLOYMENT_TARGET=$ORIGINAL_IPHONEOS_DEPLOYMENT_TARGET
+    fi;
+
     export PKG_CONFIG=$BUILD_PREFIX/bin/pkg-config
     touch pkg-config-stamp
 }
 
 function build_zlib_ng {
     if [ -e zlib-stamp ]; then return; fi
+    # zlib-ng uses a "configure" script, but it's not a GNU autotools script, so
+    # it doesn't honor the usual flags. Temporarily disable any
+    # cross-compilation flags.
+    ORIGINAL_HOST_CONFIGURE_FLAGS=$HOST_CONFIGURE_FLAGS
+    unset HOST_CONFIGURE_FLAGS
+
     build_github zlib-ng/zlib-ng $ZLIB_NG_VERSION --zlib-compat
 
-    if [ -n "$IS_MACOS" ]; then
+    HOST_CONFIGURE_FLAGS=$ORIGINAL_HOST_CONFIGURE_FLAGS
+
+    if [ -n "$IS_MACOS" ] && [ -z "$IOS_SDK" ]; then
         # Ensure that on macOS, the library name is an absolute path, not an
         # @rpath, so that delocate picks up the right library (and doesn't need
         # DYLD_LIBRARY_PATH to be set). The default Makefile doesn't have an
-        # option to control the install_name.
+        # option to control the install_name. This isn't needed on iOS, as iOS
+        # only builds the static library.
         install_name_tool -id $BUILD_PREFIX/lib/libz.1.dylib $BUILD_PREFIX/lib/libz.1.dylib
     fi
     touch zlib-stamp
@@ -81,18 +164,19 @@ function build_brotli {
     if [ -e brotli-stamp ]; then return; fi
     local out_dir=$(fetch_unpack https://github.com/google/brotli/archive/v$BROTLI_VERSION.tar.gz brotli-$BROTLI_VERSION.tar.gz)
     (cd $out_dir \
-        && cmake -DCMAKE_INSTALL_PREFIX=$BUILD_PREFIX -DCMAKE_INSTALL_LIBDIR=$BUILD_PREFIX/lib -DCMAKE_INSTALL_NAME_DIR=$BUILD_PREFIX/lib . \
+        && cmake -DCMAKE_INSTALL_PREFIX=$BUILD_PREFIX -DCMAKE_INSTALL_LIBDIR=$BUILD_PREFIX/lib -DCMAKE_INSTALL_NAME_DIR=$BUILD_PREFIX/lib $HOST_CMAKE_FLAGS  . \
         && make install)
     touch brotli-stamp
 }
 
 function build_harfbuzz {
     if [ -e harfbuzz-stamp ]; then return; fi
+
     python3 -m pip install meson ninja
 
     local out_dir=$(fetch_unpack https://github.com/harfbuzz/harfbuzz/releases/download/$HARFBUZZ_VERSION/harfbuzz-$HARFBUZZ_VERSION.tar.xz harfbuzz-$HARFBUZZ_VERSION.tar.xz)
     (cd $out_dir \
-        && meson setup build --prefix=$BUILD_PREFIX --libdir=$BUILD_PREFIX/lib --buildtype=minsize -Dfreetype=enabled -Dglib=disabled -Dtests=disabled)
+        && meson setup build --prefix=$BUILD_PREFIX --libdir=$BUILD_PREFIX/lib --buildtype=minsize -Dfreetype=enabled -Dglib=disabled -Dtests=disabled $HOST_MESON_FLAGS)
     (cd $out_dir/build \
         && meson install)
     touch harfbuzz-stamp
@@ -110,19 +194,19 @@ function build {
     fi
 
     build_simple xcb-proto 1.17.0 https://xorg.freedesktop.org/archive/individual/proto
-    if [ -n "$IS_MACOS" ]; then
+    if [[ -n "$IS_MACOS" ]]; then
         build_simple xorgproto 2024.1 https://www.x.org/pub/individual/proto
         build_simple libXau 1.0.12 https://www.x.org/pub/individual/lib
         build_simple libpthread-stubs 0.5 https://xcb.freedesktop.org/dist
     else
-        sed s/\${pc_sysrootdir\}// $BUILD_PREFIX/share/pkgconfig/xcb-proto.pc > $BUILD_PREFIX/lib/pkgconfig/xcb-proto.pc
+        sed "s/\${pc_sysrootdir\}//" $BUILD_PREFIX/share/pkgconfig/xcb-proto.pc > $BUILD_PREFIX/lib/pkgconfig/xcb-proto.pc
     fi
     build_simple libxcb $LIBXCB_VERSION https://www.x.org/releases/individual/lib
 
     build_libjpeg_turbo
-    if [ -n "$IS_MACOS" ]; then
+    if [[ -n "$IS_MACOS" ]]; then
         # Custom tiff build to include jpeg; by default, configure won't include
-        # headers/libs in the custom macOS prefix. Explicitly disable webp,
+        # headers/libs in the custom macOS/iOS prefix. Explicitly disable webp,
         # libdeflate and zstd, because on x86_64 macs, it will pick up the
         # Homebrew versions of those libraries from /usr/local.
         build_simple tiff $TIFF_VERSION https://download.osgeo.org/libtiff tar.gz \
@@ -146,14 +230,44 @@ function build {
 
     build_brotli
 
-    if [ -n "$IS_MACOS" ]; then
+    if [[ -n "$IS_MACOS" ]]; then
         # Custom freetype build
         build_simple freetype $FREETYPE_VERSION https://download.savannah.gnu.org/releases/freetype tar.gz --with-harfbuzz=no
     else
         build_freetype
     fi
 
-    build_harfbuzz
+    if [[ -z "$IOS_SDK" ]]; then
+        # On iOS, there's no vendor-provided raqm, and we can't ship it due to
+        # licensing, so there's no point building harfbuzz.
+        build_harfbuzz
+    fi
+}
+
+function create_meson_cross_config {
+    cat << EOF > $WORKDIR/meson-cross.txt
+[binaries]
+pkg-config = '$BUILD_PREFIX/bin/pkg-config'
+cmake = '$(which cmake)'
+c = '$CC'
+cpp = '$CXX'
+strip = '$STRIP'
+
+[built-in options]
+c_args = '$CFLAGS -I$BUILD_PREFIX/include'
+cpp_args = '$CXXFLAGS -I$BUILD_PREFIX/include'
+c_link_args = '$CFLAGS -L$BUILD_PREFIX/lib'
+cpp_link_args = '$CFLAGS -L$BUILD_PREFIX/lib'
+
+[host_machine]
+system = 'darwin'
+subsystem = 'ios'
+kernel = 'xnu'
+cpu_family = '$(uname -m)'
+cpu = '$(uname -m)'
+endian = 'little'
+
+EOF
 }
 
 # Perform all dependency builds in the build subfolder.
@@ -172,24 +286,40 @@ if [[ ! -d $WORKDIR/pillow-depends-main ]]; then
 fi
 
 if [[ -n "$IS_MACOS" ]]; then
-    # Homebrew (or similar packaging environments) install can contain some of
-    # the libraries that we're going to build. However, they may be compiled
-    # with a MACOSX_DEPLOYMENT_TARGET that doesn't match what we want to use,
-    # and they may bring in other dependencies that we don't want. The same will
-    # be true of any other locations on the path. To avoid conflicts, strip the
-    # path down to the bare minimum (which, on macOS, won't include any
-    # development dependencies).
-    export PATH="$BUILD_PREFIX/bin:$(dirname $(which python3)):/usr/bin:/bin:/usr/sbin:/sbin:/Library/Apple/usr/bin"
-    export CMAKE_PREFIX_PATH=$BUILD_PREFIX
-
     # Ensure the basic structure of the build prefix directory exists.
     mkdir -p "$BUILD_PREFIX/bin"
     mkdir -p "$BUILD_PREFIX/lib"
 
-    # Ensure pkg-config is available
+    # Ensure pkg-config is available. This is done *before* setting CC, CFLAGS
+    # etc to ensure that the build is *always* a macOS build, even when building
+    # for iOS.
     build_pkg_config
-    # Ensure cmake is available
+
+    # Ensure cmake is available, and that the default prefix used by CMake is
+    # the build prefix
     python3 -m pip install cmake
+    export CMAKE_PREFIX_PATH=$BUILD_PREFIX
+
+    if [[ -n "$IOS_SDK" ]]; then
+        export AR="$(xcrun --find --sdk $IOS_SDK ar)"
+        export CPP="$(xcrun --find --sdk $IOS_SDK clang) -E"
+        export CC=$(xcrun --find --sdk $IOS_SDK clang)
+        export CXX=$(xcrun --find --sdk $IOS_SDK clang++)
+        export LD=$(xcrun --find --sdk $IOS_SDK ld)
+        export STRIP=$(xcrun --find --sdk $IOS_SDK strip)
+
+        CPPFLAGS="$CPPFLAGS --sysroot=$IOS_SDK_PATH"
+        CFLAGS="-target $IOS_HOST_TRIPLE --sysroot=$IOS_SDK_PATH -mios-version-min=$IPHONEOS_DEPLOYMENT_TARGET"
+        CXXFLAGS="-target $IOS_HOST_TRIPLE --sysroot=$IOS_SDK_PATH -mios-version-min=$IPHONEOS_DEPLOYMENT_TARGET"
+
+        # Having IPHONEOS_DEPLOYMENT_TARGET in the environment causes problems
+        # with some cross-building toolchains, because it introduces implicit
+        # behavior into clang.
+        unset IPHONEOS_DEPLOYMENT_TARGET
+
+        # Now that we know CC etc, we can create a meson cross-configuration file
+        create_meson_cross_config
+    fi
 fi
 
 wrap_wheel_builder build

.github/workflows/wheels-test.ps1

@@ -23,7 +23,7 @@ cd $pillow
 if (!$?) { exit $LASTEXITCODE }
 & $venv\Scripts\$python selftest.py
 if (!$?) { exit $LASTEXITCODE }
-& $venv\Scripts\$python -m pytest -vx Tests\check_wheel.py
+& $venv\Scripts\$python -m pytest -vx checks\check_wheel.py
 if (!$?) { exit $LASTEXITCODE }
 & $venv\Scripts\$python -m pytest -vx Tests
 if (!$?) { exit $LASTEXITCODE }

.github/workflows/wheels-test.sh

@@ -25,8 +25,6 @@ else
     yum install -y fribidi
 fi
 
-python3 -m pip install numpy
-
 if [ ! -d "test-images-main" ]; then
     curl -fsSL -o pillow-test-images.zip https://github.com/python-pillow/test-images/archive/main.zip
     unzip pillow-test-images.zip
@@ -35,5 +33,5 @@ fi
 
 # Runs tests
 python3 selftest.py
-python3 -m pytest Tests/check_wheel.py
+python3 -m pytest checks/check_wheel.py
 python3 -m pytest