ci(gpui): cross-compile the macOS x86_64 release on Apple Silicon

.github/workflows/voltage-buzz-gpui-release.yml

@@ -130,10 +130,14 @@ jobs:
         include:
           - runner: macos-14
             arch: arm64
-          - runner: macos-15-intel
+          # Cross-compiled on Apple Silicon: the Intel runner took about
+          # 51 minutes to build what macos-14 builds in 17.
+          - runner: macos-14
             arch: x86_64
+            rust-target: x86_64-apple-darwin
     env:
       BUZZ_GPUI_RELEASE_VERSION: ${{ needs.version.outputs.version }}
+      BUZZ_GPUI_MACOS_ARCH: ${{ matrix.arch }}
       # The root rust-toolchain.toml pins block/buzz's Rust, and rustup reads
       # it from apps/buzz-gpui too, so name the GPUI toolchain explicitly.
       RUSTUP_TOOLCHAIN: 1.98.1
@@ -149,9 +153,15 @@ jobs:
       - uses: dtolnay/rust-toolchain@683b588c487a69d01f6c6ddf40f036ff682cc2c8 # master
         with:
           toolchain: 1.98.1
+          targets: ${{ matrix.rust-target }}
+      # The x86_64 checks run the bundled Node and provider under Rosetta.
+      - if: matrix.arch == 'x86_64'
+        run: sudo softwareupdate --install-rosetta --agree-to-license
       - uses: Swatinem/rust-cache@e18b497796c12c097a38f9edb9d0641fb99eee32 # v2.9.1
         with:
           workspaces: apps/buzz-gpui
+          # Both architectures now share a runner image; keep their caches apart.
+          key: ${{ matrix.arch }}
           save-if: ${{ github.ref == 'refs/heads/main' }}
           # Keep the release build when packaging fails after it.
           cache-on-failure: true

apps/buzz-gpui/scripts/build-package.sh

@@ -5,6 +5,9 @@ here="$(cd "$(dirname "$0")/.." && pwd)"
 repo="$(cd "$here/../.." && pwd)"
 cd "$here"
 target="${CARGO_TARGET_DIR:-$here/target}"
+# Cargo puts a cross build (CARGO_BUILD_TARGET) under target/<triple>/.
+out=release
+if [ -n "${CARGO_BUILD_TARGET:-}" ]; then out="$CARGO_BUILD_TARGET/release"; fi
 features=()
 if [ "${BUZZ_GPUI_VOLTAGE:-0}" = 1 ]; then
   features=(--features voltage-sandbox)
@@ -15,5 +18,5 @@ cargo build --locked --release -p buzz-gpui "${features[@]}" "$@"
 if [ "${BUZZ_GPUI_VOLTAGE:-0}" = 1 ]; then
   suffix=""
   if [ "${OS:-}" = Windows_NT ]; then suffix=.exe; fi
-  cp "$target/voltage-provider/release/buzz-backend-relay$suffix" "$target/release/"
+  cp "$target/voltage-provider/$out/buzz-backend-relay$suffix" "$target/$out/"
 fi

apps/buzz-gpui/scripts/package-macos.sh

@@ -1,6 +1,7 @@
 #!/usr/bin/env bash
 # Builds an ad-hoc signed Buzz.app and wraps it in a .dmg. Runs on macOS,
-# for the architecture of the machine it runs on. The app carries the
+# for the machine's architecture or BUZZ_GPUI_MACOS_ARCH (arm64 or x86_64),
+# which it cross-compiles; the checks then run an x86_64 build under Rosetta. The app carries the
 # GStreamer it plays media with, copied from the official GStreamer
 # framework (the runtime and development .pkg installers from
 # gstreamer.freedesktop.org), so users need not install GStreamer.
@@ -31,15 +32,29 @@ export RUSTFLAGS="${RUSTFLAGS:-} -C link-arg=-Wl,-headerpad_max_install_names"
 
 version="$(cargo metadata --no-deps --format-version 1 \
   | python3 -c 'import json,sys; print(next(p["version"] for p in json.load(sys.stdin)["packages"] if p["name"] == "buzz-gpui"))')"
-arch="$(uname -m)"
+host_arch="$(uname -m)"
+arch="${BUZZ_GPUI_MACOS_ARCH:-$host_arch}"
+out=release
+if [ "$arch" != "$host_arch" ]; then
+  case "$arch" in
+    arm64) triple=aarch64-apple-darwin ;;
+    x86_64) triple=x86_64-apple-darwin ;;
+    *) echo "Cannot build for $arch." >&2; exit 1 ;;
+  esac
+  export CARGO_BUILD_TARGET="$triple"
+  # pkg-config refuses a cross build unless told; the universal framework
+  # carries this architecture's libraries.
+  export PKG_CONFIG_ALLOW_CROSS=1
+  out="$triple/release"
+fi
 bash scripts/build-package.sh
 
 work="$(mktemp -d)"
 app="$work/Buzz.app"
 mkdir -p "$app/Contents/MacOS" "$app/Contents/Resources" dist
-cp target/release/buzz-gpui "$app/Contents/MacOS/"
+cp "target/$out/buzz-gpui" "$app/Contents/MacOS/"
 if [ "${BUZZ_GPUI_VOLTAGE:-0}" = 1 ]; then
-  cp target/release/buzz-backend-relay "$app/Contents/MacOS/"
+  cp "target/$out/buzz-backend-relay" "$app/Contents/MacOS/"
 fi
 
 iconset="$work/buzz.iconset"

apps/buzz-gpui/scripts/test-package-build.py

@@ -9,7 +9,7 @@
 
 
 class PackageBuild(unittest.TestCase):
-    def run_build(self, voltage, windows=False, fail=False):
+    def run_build(self, voltage, windows=False, fail=False, cross=None):
         temporary = tempfile.TemporaryDirectory()
         self.addCleanup(temporary.cleanup)
         root = Path(temporary.name)
@@ -29,7 +29,7 @@ def run_build(self, voltage, windows=False, fail=False):
 if provider and os.environ.get("FAIL_PROVIDER") == "1":
     sys.exit(9)
 target = pathlib.Path(args[args.index("--target-dir")+1] if provider else os.environ["CARGO_TARGET_DIR"])
-release = target / "release"
+release = target / os.environ.get("CARGO_BUILD_TARGET", "") / "release"
 release.mkdir(parents=True, exist_ok=True)
 name = "buzz-backend-relay" if provider else "buzz-gpui"
 if os.environ.get("OS") == "Windows_NT":
@@ -41,11 +41,22 @@ def run_build(self, voltage, windows=False, fail=False):
                    CALLS=str(root/"calls.jsonl"), CARGO_TARGET_DIR=str(root/"build"),
                    BUZZ_GPUI_VOLTAGE="1" if voltage else "0",
                    OS="Windows_NT" if windows else "Linux", FAIL_PROVIDER="1" if fail else "0")
+        env.pop("CARGO_BUILD_TARGET", None)
+        if cross:
+            env["CARGO_BUILD_TARGET"] = cross
         result = subprocess.run(["bash", str(scripts/"build-package.sh")],
                                 env=env, capture_output=True, text=True, timeout=10)
         calls = [json.loads(line) for line in (root/"calls.jsonl").read_text().splitlines()]
         return root, result, calls
 
+    def test_cross_build_stages_the_provider_beside_the_cross_built_app(self):
+        root, result, calls = self.run_build(True, cross="x86_64-apple-darwin")
+        self.assertEqual(result.returncode, 0, result.stderr)
+        self.assertEqual(len(calls), 2)
+        staged = root/"build"/"x86_64-apple-darwin"/"release"/"buzz-backend-relay"
+        self.assertEqual(staged.read_text(), "fresh buzz-backend-relay")
+        self.assertFalse((root/"build"/"release"/"buzz-backend-relay").exists())
+
     def test_voltage_build_enables_remote_ui_and_stages_the_same_builds_provider(self):
         for windows in [False, True]:
             with self.subTest(windows=windows):