macos x64: crossplatform native build

.github/actions/install-llvm-pgo-keg/action.yml

@@ -17,8 +17,17 @@ runs:
           echo "llvm-pgo keg already present"
           exit 0
         fi
-        # The published kegs are built for the standard prefixes only.
-        if [[ "$(uname -m)" == "arm64" ]]; then
+        # The published kegs are built for the standard prefixes only, and each one is
+        # tied to a prefix: /opt/homebrew is arm64, /usr/local is x86_64. Pick by prefix,
+        # not by `uname -m`, so the x86_64-on-arm64 cross runner (arm64 host, Intel brew
+        # at /usr/local) gets the Intel keg. Custom prefixes fall back to the host arch;
+        # those machines carry the keg already and returned above.
+        case "$BP" in
+          /usr/local)    KEG_ARCH=x86_64 ;;
+          /opt/homebrew) KEG_ARCH=arm64 ;;
+          *)             KEG_ARCH="$(uname -m)" ;;
+        esac
+        if [[ "$KEG_ARCH" == "arm64" ]]; then
           NEED=/opt/homebrew
           ASSET=llvm-pgo-22.1.8_2-arm64/llvm-pgo-22.1.8_2.arm64_opt-homebrew.tar.gz
           SHA=94f76fb55ec64490605d0e68115259426a428a78f269f7e9160726d90a22e197
@@ -38,15 +47,22 @@ runs:
     - name: Install the PGO ld64.lld into the keg
       shell: bash
       run: |
-        KEG="$(brew --prefix)/Cellar/llvm-pgo/22.1.8_2"
+        BP="$(brew --prefix)"
+        KEG="$BP/Cellar/llvm-pgo/22.1.8_2"
         # Homebrew has no `lld` bottle for Intel macOS since it became a Tier 3
         # configuration, and brew's llvm@22 carries no ld64.lld either, so the linker
         # comes from our own release. Next to clang++, which resolves `-fuse-ld=lld`
         # in its own directory before PATH.
         if [[ -x "$KEG/bin/ld64.lld" ]]; then
           echo "ld64.lld already in the keg"
         else
-          if [[ "$(uname -m)" == "arm64" ]]; then
+          # Match the keg's architecture, which follows the prefix (see above).
+          case "$BP" in
+            /usr/local)    KEG_ARCH=x86_64 ;;
+            /opt/homebrew) KEG_ARCH=arm64 ;;
+            *)             KEG_ARCH="$(uname -m)" ;;
+          esac
+          if [[ "$KEG_ARCH" == "arm64" ]]; then
             ASSET=ld64.lld-22.1.8-pgo.arm64-macos13
             SHA=8abf0ba324dea357ae4fbd8baee835353b560f62e9b1d001588a6df888755550
           else

.github/actions/install-macos-thirdparty/action.yml

@@ -104,6 +104,8 @@ runs:
         echo "brew-hash=$(printf %s "$BREW_PREFIX" | shasum -a 256 | cut -c1-16)" >> "$GITHUB_OUTPUT"
         echo "thirdparty-hash=$( {
           printf '%s\n' "$BREW_PREFIX"
+          # Discriminate the cross (x86_64) outputs from a same-instance native build.
+          if [ -n "${CMAKE_OSX_ARCHITECTURES}" ]; then printf 'osx-arch=%s\n' "${CMAKE_OSX_ARCHITECTURES}"; fi
           git ls-tree HEAD \
             thirdparty/googletest \
             thirdparty/OpenCTM-git \

.github/workflows/build-test-distribute.yml

@@ -177,6 +177,7 @@ jobs:
       upload_artifacts:      ${{ needs.config.outputs.upload_artifacts == 'true' }}
       upload_test_artifacts: ${{ needs.config.outputs.upload_test_artifacts == 'true' }}
       nuget_build_patch:     ${{ needs.config.outputs.build_enable_windows == 'true' && needs.config.outputs.upload_artifacts == 'true'}}
+      config_matrix:         ${{ needs.config.outputs.macos_config_matrix }}
     secrets: inherit
 
   update-win-version:
@@ -427,6 +428,7 @@ jobs:
       test_ubuntu_x64:   ${{ needs.config.outputs.build_enable_ubuntu_x64 == 'true' }}
       test_ubuntu_arm64: ${{ needs.config.outputs.build_enable_ubuntu_arm64 == 'true' }}
       test_macos:        ${{ needs.config.outputs.build_enable_macos == 'true' }}
+      test_macos_crossplatform: ${{ needs.config.outputs.build_enable_macos_crossplatform == 'true' }}
       test_windows:      ${{ needs.config.outputs.build_enable_windows == 'true' && needs.config.outputs.build-release-win == 'true' }}
     secrets:
       GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/build-test-macos.yml

@@ -31,52 +31,24 @@ on:
         default: false
         required: false
         type: boolean
+      config_matrix:
+        # JSON `{"include":[...]}` selected by config.yml from
+        # .github/workflows/matrix/macos-config.json.
+        required: true
+        type: string
 
 jobs:
   macos-build-test:
+    # Legs live in .github/workflows/matrix/macos-config.json; config.yml drops the
+    # self-hosted x64-cross leg when the disable-build-macos-crossplatform label is
+    # set, so a down runner can't hang macOS CI. arm64/Release is pinned to macos-14
+    # to share the mrbind cache with pip-build.yml.
+    name: macos-build-test (${{ matrix.arch }}, ${{ matrix.config }})
     timeout-minutes: 100
     runs-on: ${{ matrix.runner }}
     strategy:
       fail-fast: false
-      matrix:
-        arch: [ x64, arm64 ]
-        config: [ Debug, Release ]
-        exclude:
-          - arch: x64
-            config: Debug
-        include:
-          - arch: x64
-            config: Release
-            compiler: AppleClang
-            cxx-compiler-template: /usr/bin/clang++
-            c-compiler-template: /usr/bin/clang
-            # mrbind and the bindings use the PGO keg fetched from
-            # MeshInspector/toolchains releases; the app stays on AppleClang.
-            llvm-prefix-template: BREW_PREFIX/Cellar/llvm-pgo/22.1.8_2
-            # https://docs.github.com/en/actions/using-github-hosted-runners/about-github-hosted-runners/about-github-hosted-runners
-            runner: macos-15-intel # github hosted
-            instance: macos-15-intel
-          - arch: arm64
-            config: Release
-            compiler: AppleClang
-            cxx-compiler-template: /usr/bin/clang++
-            c-compiler-template: /usr/bin/clang
-            # mrbind and the bindings use the PGO keg fetched from
-            # MeshInspector/toolchains releases; the app stays on AppleClang.
-            llvm-prefix-template: BREW_PREFIX/Cellar/llvm-pgo/22.1.8_2
-            # Pinned to the same image pip-build.yml uses so the mrbind cache is shared.
-            runner: macos-14
-            instance: macos-14
-          - arch: arm64
-            config: Debug
-            compiler: brew-llvm22
-            # The -O3+PGO+ThinLTO keg, built on each runner via the local/pgo
-            # tap (llvm.rb with ENV.O3, installed with --build-bottle).
-            llvm-prefix-template: BREW_PREFIX/Cellar/llvm-pgo/22.1.8_2
-            cxx-compiler-template: BREW_PREFIX/Cellar/llvm-pgo/22.1.8_2/bin/clang++
-            c-compiler-template: BREW_PREFIX/Cellar/llvm-pgo/22.1.8_2/bin/clang
-            runner: [ self-hosted, macos, arm64, build ] #  any macos version
-            instance: self-hosted-arm
+      matrix: ${{ fromJSON(inputs.config_matrix) }}
     permissions:
       id-token: write # This is required for requesting the JWT
       contents: read  # This is required for actions/checkout
@@ -88,6 +60,44 @@ jobs:
       - name: macOS Diagnostics
         uses: ./.github/actions/macos-diagnostics
 
+      # Before `Resolve LLVM prefix` and every other `brew --prefix`: the shim makes
+      # them resolve the x86_64 /usr/local brew whose bottles this target links.
+      - name: Configure native x86_64 cross-build environment
+        if: ${{ matrix.cross-osx-arch == 'x86_64' }}
+        run: |
+          PYVER=3.10
+          SHIM="$RUNNER_TEMP/x86_64-cross-shim"
+          mkdir -p "$SHIM"
+          # The native arm64 Homebrew prefix varies across the self-hosted fleet
+          # (/opt/homebrew, ~/.homebrew, ...); find it by its arm64 cmake so build
+          # tools run natively, not the x86_64 copies under /usr/local (which would
+          # drag clang into Rosetta). Fail loudly rather than dangle shim symlinks.
+          ARM_BREW=""
+          for p in /opt/homebrew "$HOME/.homebrew"; do
+            if file -b "$p/bin/cmake" 2>/dev/null | grep -q arm64; then ARM_BREW="$p"; break; fi
+          done
+          [ -n "$ARM_BREW" ] || { echo "::error::x86_64 cross setup: no arm64 Homebrew cmake found"; exit 1; }
+          for t in "$ARM_BREW/bin/cmake" "$ARM_BREW/bin/ninja" \
+                   "/usr/local/bin/python$PYVER" "/usr/local/bin/python$PYVER-config" /usr/local/bin/brew; do
+            [ -x "$t" ] || { echo "::error::x86_64 cross setup: missing $t"; exit 1; }
+          done
+          ln -sf "$ARM_BREW/bin/cmake" "$SHIM/cmake"
+          ln -sf "$ARM_BREW/bin/ninja" "$SHIM/ninja"
+          ln -sf "/usr/local/bin/python$PYVER" "$SHIM/python$PYVER"
+          ln -sf "/usr/local/bin/python$PYVER-config" "$SHIM/python$PYVER-config"
+          # A symlink-to-a-symlink breaks Homebrew's self-location, so wrap brew.
+          printf '#!/bin/bash\nexec /usr/local/bin/brew "$@"\n' > "$SHIM/brew"
+          chmod +x "$SHIM/brew"
+          echo "$SHIM" >> "$GITHUB_PATH"
+          {
+            echo "CMAKE_OSX_ARCHITECTURES=${{ matrix.cross-osx-arch }}"
+            echo "CMAKE_MAKE_PROGRAM=$ARM_BREW/bin/ninja"
+            echo "CMAKE_PREFIX_PATH=/usr/local"
+            echo "MESHLIB_HOMEBREW_PREFIX=/usr/local"
+            echo "HOMEBREW_DIR=/usr/local"
+            echo "PKG_CONFIG_PATH=$(/usr/local/bin/brew --prefix python@$PYVER)/lib/pkgconfig${PKG_CONFIG_PATH:+:$PKG_CONFIG_PATH}"
+          } >> "$GITHUB_ENV"
+
       # LLVM_PREFIX selects the LLVM keg for the build and the mrbind scripts;
       # resolved per machine since the self-hosted label set spans runners
       # with different homebrew prefixes.
@@ -168,6 +178,11 @@ jobs:
             -DMR_CXX_STANDARD=23
             -DMESHLIB_BUILD_GENERATED_C_BINDINGS=OFF
             -DMR_PCH_USE_EXTRA_HEADERS=ON
+            ${{ matrix.cross-osx-arch == 'x86_64' && '-DMR_PLATFORM=APPLE_x86_64' || '' }}
+
+      - name: Verify x86_64 output
+        if: ${{ matrix.cross-osx-arch == 'x86_64' }}
+        run: lipo -archs build/${{ matrix.config }}/bin/libMRMesh.dylib | grep -qx x86_64
 
       - name: Wait for C bindings
         if: ${{ inputs.mrbind_c }}
@@ -330,8 +345,10 @@ jobs:
           artifact_glob: meshlib_${{matrix.arch}}.pkg
           stats_file_suffix: -${{ steps.collect-runner-stats.outputs.job_id }}
 
+      # NuGet consumes the exact artifact name DotNetPatchArchiveMacOs-x64, so the
+      # x64-cross leg's copy would only be uploaded and then deleted; skip it there.
       - name: Create and fix fake Wheel for NuGet
-        if: ${{ inputs.nuget_build_patch && matrix.config == 'Release' }}
+        if: ${{ inputs.nuget_build_patch && matrix.config == 'Release' && matrix.arch != 'x64-cross' }}
         shell: bash
         run: |
           python3 -m venv ./wheel_venv
@@ -341,7 +358,7 @@ jobs:
           ./scripts/nuget_patch/fix_macos_rpath.sh ./patched_content/libMeshLibC2.dylib
 
       - name: Upload NuGet files to Artifacts
-        if: ${{ inputs.nuget_build_patch && matrix.config == 'Release' }}
+        if: ${{ inputs.nuget_build_patch && matrix.config == 'Release' && matrix.arch != 'x64-cross' }}
         uses: actions/upload-artifact@v7
         with:
           name: DotNetPatchArchiveMacOs-${{ matrix.arch }}

.github/workflows/config.yml

@@ -41,6 +41,9 @@ on:
       windows_x64_config_matrix:
         description: "Config matrix for Windows builds"
         value: ${{ jobs.prepare-config.outputs.windows_x64_config_matrix }}
+      macos_config_matrix:
+        description: "Config matrix for macOS builds; the self-hosted x64-cross leg is dropped when disabled"
+        value: ${{ jobs.prepare-config.outputs.macos_config_matrix }}
       update_doc:
         description:
         value: ${{ jobs.prepare-config.outputs.tag-update-doc == 'true' || jobs.prepare-config.outputs.tag-update-doc-only == 'true' }}
@@ -78,6 +81,9 @@ on:
       build_enable_macos:
         description:
         value: ${{ !( jobs.prepare-config.outputs.tag-update-doc-only == 'true' || jobs.prepare-config.outputs.tag-disable-macos == 'true' ) }}
+      build_enable_macos_crossplatform:
+        description: "macOS native x86_64 cross leg (label disable-build-macos-crossplatform); also off whenever macOS is disabled. Gates its distro test; the build leg itself is dropped from macos_config_matrix"
+        value: ${{ !( jobs.prepare-config.outputs.tag-update-doc-only == 'true' || jobs.prepare-config.outputs.tag-disable-macos == 'true' || jobs.prepare-config.outputs.tag-disable-macos-crossplatform == 'true' ) }}
       build_enable_emscripten:
         description:
         value: ${{ !( jobs.prepare-config.outputs.tag-update-doc-only == 'true' || jobs.prepare-config.outputs.tag-disable-emscripten == 'true' ) }}
@@ -93,6 +99,7 @@ jobs:
       ubuntu_arm64_config_matrix: ${{ steps.set-ubuntu-arm64-matrix.outputs.matrix }}
       ubuntu_x64_config_matrix: ${{ steps.set-ubuntu-x64-matrix.outputs.matrix }}
       windows_x64_config_matrix: ${{ steps.set-windows-x64-matrix.outputs.matrix }}
+      macos_config_matrix:      ${{ steps.set-macos-matrix.outputs.matrix }}
       vcpkg-docker-image-tag:   ${{ steps.select-vcpkg-docker-image-tag.outputs.image_tag }}
       windows-changes:          ${{ steps.windows-changes.outputs.src }}
       # Read PR labels live; github.event.pull_request.labels is a
@@ -113,6 +120,7 @@ jobs:
       tag-disable-ubuntu-arm64:   ${{ steps.live-labels.outputs.tag-disable-ubuntu-arm64 }}
       tag-disable-linux-vcpkg:    ${{ steps.live-labels.outputs.tag-disable-linux-vcpkg }}
       tag-disable-macos:          ${{ steps.live-labels.outputs.tag-disable-macos }}
+      tag-disable-macos-crossplatform: ${{ steps.live-labels.outputs.tag-disable-macos-crossplatform }}
       tag-disable-emscripten:     ${{ steps.live-labels.outputs.tag-disable-emscripten }}
 
     runs-on: ubuntu-latest
@@ -351,3 +359,15 @@ jobs:
             "$MATRIX_FILE" > tmp.json
 
           echo "matrix=$(jq -c . tmp.json)" >> $GITHUB_OUTPUT
+
+      - name: Set matrix for macos builds
+        id: set-macos-matrix
+        run: |
+          # The x64-cross leg needs the self-hosted crossplatform-build runner; drop it
+          # (never scheduled) when the disable-build-macos-crossplatform label is set.
+          if [[ "${{ steps.live-labels.outputs.tag-disable-macos-crossplatform }}" == "true" ]]; then
+            FILTER='del(.include[] | select(.arch == "x64-cross"))'
+          else
+            FILTER='.'
+          fi
+          echo "matrix=$(jq -c "$FILTER" .github/workflows/matrix/macos-config.json)" >> "$GITHUB_OUTPUT"

.github/workflows/matrix/macos-config.json

@@ -0,0 +1,45 @@
+{
+  "include": [
+    {
+      "arch": "x64",
+      "config": "Release",
+      "compiler": "AppleClang",
+      "cxx-compiler-template": "/usr/bin/clang++",
+      "c-compiler-template": "/usr/bin/clang",
+      "llvm-prefix-template": "BREW_PREFIX/Cellar/llvm-pgo/22.1.8_2",
+      "runner": ["macos-15-intel"],
+      "instance": "macos-15-intel"
+    },
+    {
+      "arch": "arm64",
+      "config": "Release",
+      "compiler": "AppleClang",
+      "cxx-compiler-template": "/usr/bin/clang++",
+      "c-compiler-template": "/usr/bin/clang",
+      "llvm-prefix-template": "BREW_PREFIX/Cellar/llvm-pgo/22.1.8_2",
+      "runner": ["macos-14"],
+      "instance": "macos-14"
+    },
+    {
+      "arch": "arm64",
+      "config": "Debug",
+      "compiler": "brew-llvm22",
+      "cxx-compiler-template": "BREW_PREFIX/Cellar/llvm-pgo/22.1.8_2/bin/clang++",
+      "c-compiler-template": "BREW_PREFIX/Cellar/llvm-pgo/22.1.8_2/bin/clang",
+      "llvm-prefix-template": "BREW_PREFIX/Cellar/llvm-pgo/22.1.8_2",
+      "runner": ["self-hosted", "macos", "arm64", "build"],
+      "instance": "self-hosted-arm"
+    },
+    {
+      "arch": "x64-cross",
+      "config": "Release",
+      "compiler": "AppleClang",
+      "cxx-compiler-template": "/usr/bin/clang++",
+      "c-compiler-template": "/usr/bin/clang",
+      "llvm-prefix-template": "BREW_PREFIX/Cellar/llvm-pgo/22.1.8_2",
+      "runner": ["self-hosted", "macos", "arm64", "crossplatform-build"],
+      "instance": "self-hosted-arm-x64-native",
+      "cross-osx-arch": "x86_64"
+    }
+  ]
+}

.github/workflows/test-distribution.yml

@@ -15,6 +15,10 @@ on:
       test_macos:
         required: true
         type: boolean
+      test_macos_crossplatform:
+        # The *x64-cross.pkg exists only when the self-hosted cross build ran.
+        required: true
+        type: boolean
       test_windows:
         required: true
         type: boolean
@@ -35,6 +39,9 @@ on:
       test_macos:
         type: boolean
         default: false
+      test_macos_crossplatform:
+        type: boolean
+        default: false
       test_windows:
         type: boolean
         default: false
@@ -244,29 +251,19 @@ jobs:
     timeout-minutes: 30
     strategy:
       fail-fast: false
-      matrix:
-        include:
-          - arch: arm64
-            runner: macos-13
-            pkg_pattern: '*arm64.pkg'
-          - arch: arm64
-            runner: macos-14
-            pkg_pattern: '*arm64.pkg'
-          - arch: arm64
-            runner: macos-15
-            pkg_pattern: '*arm64.pkg'
-          - arch: arm64
-            runner: macos-26
-            pkg_pattern: '*arm64.pkg'
-          - arch: x64
-            runner: macos-12-intel
-            pkg_pattern: '*x64.pkg'
-          - arch: x64
-            runner: macos-15-intel
-            pkg_pattern: '*x64.pkg'
-          - arch: x64
-            runner: macos-26-intel
-            pkg_pattern: '*x64.pkg'
+      # One leg per (runner, pkg). The x64-cross leg is appended only when that build
+      # ran, else `gh release download` finds no *x64-cross.pkg. An include-only matrix
+      # can't be trimmed with `exclude` (include is applied after it), hence the JSON.
+      matrix: >-
+        ${{ fromJSON(format('{{"include":[{0}{1}]}}',
+        '{"arch":"arm64","runner":"macos-13","pkg_pattern":"*arm64.pkg"},
+        {"arch":"arm64","runner":"macos-14","pkg_pattern":"*arm64.pkg"},
+        {"arch":"arm64","runner":"macos-15","pkg_pattern":"*arm64.pkg"},
+        {"arch":"arm64","runner":"macos-26","pkg_pattern":"*arm64.pkg"},
+        {"arch":"x64","runner":"macos-12-intel","pkg_pattern":"*x64.pkg"},
+        {"arch":"x64","runner":"macos-15-intel","pkg_pattern":"*x64.pkg"},
+        {"arch":"x64","runner":"macos-26-intel","pkg_pattern":"*x64.pkg"}',
+        inputs.test_macos_crossplatform && ',{"arch":"x64-cross","runner":"macos-15-intel","pkg_pattern":"*x64-cross.pkg"}' || '')) }}
     steps:
       - name: Checkout
         uses: actions/checkout@v7