[CI] Build release binaries for Apple Silicon

These binaries are not added to releases yet, in case the new configuration
doesn't work out of the box. Later this will be used to replace the internal
Apple Silicon build.

Author: fhanau

.github/workflows/release.yml

@@ -62,12 +62,18 @@ jobs:
             os: ubuntu-20.04
             bazel-config: release_linux
             target-arch: X64
+          # Based on runner availability, we build both Apple Silicon and (cross-compiled) x86
+          # release binaries on the macos-15 runner.
           - os-name: macOS
             # This configuration is used for cross-compiling – macos-15 is Apple Silicon-based but
             # we use it to compile the x64 release.
             os: macos-15
             bazel-config: release_macos
             target-arch: X64
+          - os-name: macOS-arm64
+            os: macos-15
+            bazel-config: release_macos
+            target-arch: ARM64
           - os-name: windows
             os: windows-2022
             bazel-config: release_windows
@@ -104,10 +110,13 @@ jobs:
           # exist from an older pre-installed LLVM version on the runner image.
           brew install lld
           sudo ln -s -f $(brew --prefix lld)/bin/ld64.lld /usr/local/bin/ld64.lld
-          # Cross-compile so that we can use the latest Xcode version for the Intel Mac binary
-          echo "build:macos --config=macos-cross-x86_64" >> .bazelrc
           # Enable lld identical code folding to significantly reduce binary size.
           echo "build:macos --config=macos_lld_icf" >> .bazelrc
+      - name: Setup macOS (cross)
+        if: ${{ matrix.os-name }} == 'macOS'
+        run: |
+          # Cross-compile so that we can use the latest Xcode version for the Intel Mac binary
+          echo "build:macos --config=macos-cross-x86_64" >> .bazelrc
       - name: Setup Windows
         if: runner.os == 'Windows'
         run: |
@@ -146,6 +155,11 @@ jobs:
             name: Linux-X64
           - arch: darwin-64
             name: macOS-X64
+          # TODO(soon): After verifying that Apple Silicon artifacts are being built and uploaded
+          # properly, decommission the internal build and add them to the tagged release instead of
+          # using the internal build.
+          # - arch: darwin-arm64
+          #   name: macOS-ARM64
           - arch: windows-64
             name: Windows-X64
     steps: