feat: include macOS slice in Hermes xcframework

- Make HERMES_PATH overridable via environment variable so CI can point
  to a separately cloned Hermes repo
- Add CMAKE_OSX_DEPLOYMENT_TARGET to build_host_hermesc to fix
  -Werror=unguarded-availability-new failures in LLVM cmake checks
- Add macOS deployment target support via get_mac_deployment_target

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Saadnajmi

packages/react-native/sdks/hermes-engine/utils/build-apple-framework.sh

@@ -12,7 +12,7 @@ CURR_SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd -P)"
 IMPORT_HERMESC_PATH=${HERMES_OVERRIDE_HERMESC_PATH:-$PWD/build_host_hermesc/ImportHermesc.cmake}
 BUILD_TYPE=${BUILD_TYPE:-Debug}
 
-HERMES_PATH="$CURR_SCRIPT_DIR/.."
+HERMES_PATH=${HERMES_PATH:-"$CURR_SCRIPT_DIR/.."}
 REACT_NATIVE_PATH=${REACT_NATIVE_PATH:-$CURR_SCRIPT_DIR/../../..}
 
 NUM_CORES=$(sysctl -n hw.ncpu)
@@ -60,7 +60,12 @@ function get_mac_deployment_target {
 function build_host_hermesc {
   echo "Building hermesc"
   pushd "$HERMES_PATH" > /dev/null || exit 1
-    cmake -S . -B build_host_hermesc -DJSI_DIR="$JSI_PATH"
+    # Set a deployment target to prevent -Werror=unguarded-availability-new
+    # failures in LLVM's check_symbol_exists tests (macOS SDK headers contain
+    # availability annotations that error without a deployment target).
+    cmake -S . -B build_host_hermesc \
+      -DJSI_DIR="$JSI_PATH" \
+      -DCMAKE_OSX_DEPLOYMENT_TARGET:STRING="${MAC_DEPLOYMENT_TARGET:-10.15}"
     cmake --build ./build_host_hermesc --target hermesc -j "${NUM_CORES}"
   popd > /dev/null || exit 1
 }

packages/react-native/sdks/hermes-engine/utils/build-ios-framework.sh

@@ -10,7 +10,7 @@ fi
 set -e
 
 # Given a specific target, retrieve the right architecture for it
-# $1 the target you want to build. Allowed values: iphoneos, iphonesimulator, catalyst, xros, xrsimulator
+# $1 the target you want to build. Allowed values: iphoneos, iphonesimulator, catalyst, macosx, xros, xrsimulator
 function get_architecture {
     if [[ $1 == "iphoneos" || $1 == "xros" ]]; then
       echo "arm64"
@@ -20,7 +20,7 @@ function get_architecture {
       echo "arm64"
     elif [[ $1 == "appletvsimulator" ]]; then
       echo "x86_64;arm64"
-    elif [[ $1 == "catalyst" ]]; then
+    elif [[ $1 == "catalyst" || $1 == "macosx" ]]; then
       echo "x86_64;arm64"
     else
       echo "Error: unknown architecture passed $1"
@@ -29,7 +29,9 @@ function get_architecture {
 }
 
 function get_deployment_target {
-    if [[ $1 == "xros" || $1 == "xrsimulator" ]]; then
+    if [[ $1 == "macosx" ]]; then
+      echo "$(get_mac_deployment_target)"
+    elif [[ $1 == "xros" || $1 == "xrsimulator" ]]; then
       echo "$(get_visionos_deployment_target)"
     else # tvOS and iOS use the same deployment target
       echo "$(get_ios_deployment_target)"
@@ -53,7 +55,7 @@ function build_framework {
 # group the frameworks together to create a universal framework
 function build_universal_framework {
     if [ ! -d destroot/Library/Frameworks/universal/hermes.xcframework ]; then
-        create_universal_framework "iphoneos" "iphonesimulator" "catalyst" "xros" "xrsimulator" "appletvos" "appletvsimulator"
+        create_universal_framework "macosx" "iphoneos" "iphonesimulator" "catalyst" "xros" "xrsimulator" "appletvos" "appletvsimulator"
     else
         echo "Skipping; Clean \"destroot\" to rebuild".
     fi
@@ -63,6 +65,7 @@ function build_universal_framework {
 # this is used to preserve backward compatibility
 function create_framework {
     if [ ! -d destroot/Library/Frameworks/universal/hermes.xcframework ]; then
+        build_framework "macosx"
         build_framework "iphoneos"
         build_framework "iphonesimulator"
         build_framework "appletvos"