Make universal2 wheels on macos

Author: ankith26

.github/workflows/build-macos.yml

@@ -57,41 +57,29 @@ jobs:
       #     path: ${{ github.workspace }}/pygame_mac_deps_${{ matrix.macarch }}
 
   build:
-    name: ${{ matrix.macarch }}
+    name: universal2
     needs: deps
-    runs-on: ${{ matrix.os }}
-    strategy:
-      fail-fast: false  # if a particular matrix build fails, don't skip the rest
-      matrix:
-        include:
-          - { macarch: arm64, os: macos-15 }
-          - { macarch: x86_64, os: macos-15 }
+    runs-on: macos-15
 
     env:
-      MAC_ARCH: ${{ matrix.macarch }}
-
       # Explicitly tell CIBW what the wheel arch deployment target should be
       # There seems to be no better way to set this than this env
       # We need this because our minimum is 10.11, different from default
       # of 10.9 on x86s
       # Related issue: https://github.com/pypa/cibuildwheel/issues/952
-      _PYTHON_HOST_PLATFORM: ${{ matrix.macarch == 'x86_64' && 'macosx-10.11-x86_64' || 'macosx-11.0-arm64'}}
+      _PYTHON_HOST_PLATFORM: 'macosx-10.11-universal2'
 
       # Similarly, we need to tell CIBW that the wheel's linking steps
       # should be for 10.11 on x86
-      MACOSX_DEPLOYMENT_TARGET: ${{ matrix.macarch == 'x86_64' && '10.11' || '11.0' }}
+      MACOSX_DEPLOYMENT_TARGET: '10.11'
 
-      CIBW_ARCHS: ${{ matrix.macarch }}
+      CIBW_ARCHS: universal2
 
       # Setup macOS dependencies
       CIBW_BEFORE_ALL: |
         cd buildconfig/macdependencies
-        cp -r ${{ github.workspace }}/pygame_mac_deps_${{ matrix.macarch }} ${{ github.workspace }}/pygame_mac_deps
         bash ./install_mac_deps.sh
 
-      CIBW_BEFORE_BUILD: |
-        cp -r ${{ github.workspace }}/pygame_mac_deps_${{ matrix.macarch }} ${{ github.workspace }}/pygame_mac_deps
-
       # To remove any speculations about the wheel not being self-contained
       CIBW_BEFORE_TEST: rm -rf ${{ github.workspace }}/pygame_mac_deps
 
@@ -104,12 +92,18 @@ jobs:
           path: ~/Library/Caches/pip  # This cache path is only right on mac
           key: pip-cache-${{ matrix.macarch }}-${{ matrix.os }}
 
-      - name: Fetch Mac deps
-        id: macdep-cache
+      - name: Fetch Mac deps (x86_64)
         uses: actions/cache@v4.3.0
         with:
-          path: ${{ github.workspace }}/pygame_mac_deps_${{ matrix.macarch }}
-          key: macdep-${{ hashFiles('buildconfig/manylinux-build/**') }}-${{ hashFiles('buildconfig/macdependencies/*.sh') }}-${{ matrix.macarch }}
+          path: ${{ github.workspace }}/pygame_mac_deps_x86_64
+          key: macdep-${{ hashFiles('buildconfig/manylinux-build/**') }}-${{ hashFiles('buildconfig/macdependencies/*.sh') }}-x86_64
+          fail-on-cache-miss: true
+
+      - name: Fetch Mac deps (arm64)
+        uses: actions/cache@v4.3.0
+        with:
+          path: ${{ github.workspace }}/pygame_mac_deps_arm64
+          key: macdep-${{ hashFiles('buildconfig/manylinux-build/**') }}-${{ hashFiles('buildconfig/macdependencies/*.sh') }}-arm64
           fail-on-cache-miss: true
 
       - name: Install uv for speed

buildconfig/macdependencies/install_mac_deps.py

@@ -3,6 +3,7 @@
 """
 
 import shutil
+import subprocess
 import sys
 from pathlib import Path
 
@@ -30,6 +31,38 @@ def rmpath(path: Path, verbose: bool = False):
         shutil.rmtree(path)
 
 
+def merge_dylibs(out_dir: Path, x86_dir: Path, arm_dir: Path, verbose: bool = False):
+    """
+    Merge .dylib files from x86_64 into a copy of arm64 folder.
+    - Moves arm_dir to out_dir.
+    - For each .dylib in x86_dir, merges it with the arm64 one if present,
+      otherwise just copies it over.
+    - Deletes x86_dir after merging.
+    """
+    shutil.move(arm_dir, out_dir)
+    if verbose:
+        print(f"- Moved {arm_dir} -> {out_dir}")
+
+    for x86_file in x86_dir.rglob("*.dylib"):
+        rel_path = x86_file.relative_to(x86_dir)
+        out_file = out_dir / rel_path
+        if out_file.exists():
+            subprocess.run(
+                ["lipo", "-create", "-output", out_file, out_file, x86_file], check=True
+            )
+            if verbose:
+                print(f"- Merged: {rel_path}")
+        else:
+            out_file.parent.mkdir(parents=True, exist_ok=True)
+            shutil.copy2(x86_file, out_file)
+            if verbose:
+                print(f"- Copied x86-only: {rel_path}")
+
+    shutil.rmtree(x86_dir)
+    if verbose:
+        print(f"- Deleted {x86_dir}")
+
+
 def symtree(srcdir: Path, destdir: Path, verbose: bool = False):
     """
     This function creates symlinks pointing to srcdir, from destdir, such that
@@ -57,5 +90,7 @@ def symtree(srcdir: Path, destdir: Path, verbose: bool = False):
 
             destpath.symlink_to(path)
 
-
-symtree(Path(sys.argv[1]), Path("/usr/local"), verbose=True)
+if __name__ == "__main__":
+    out_dir, x86_dir, arm_dir = map(Path, sys.argv[1:])
+    merge_dylibs(out_dir, x86_dir, arm_dir, verbose=True)
+    symtree(out_dir, Path("/usr/local"), verbose=True)

buildconfig/macdependencies/install_mac_deps.sh

@@ -2,4 +2,6 @@
 set -e -x
 
 bash ./clean_usr_local.sh
-sudo python3 install_mac_deps.py ${GITHUB_WORKSPACE}/pygame_mac_deps_${MAC_ARCH}
+sudo python3 install_mac_deps.py ${GITHUB_WORKSPACE}/pygame_mac_deps \
+    ${GITHUB_WORKSPACE}/pygame_mac_deps_x86_64 \
+    ${GITHUB_WORKSPACE}/pygame_mac_deps_arm64