From 647e09dc4c414f4889af01ecdcd39e89a30f1ff7 Mon Sep 17 00:00:00 2001
From: Riccardo Cipolleschi <cipolleschi@meta.com>
Date: Mon, 18 Sep 2023 06:11:10 -0700
Subject: [PATCH] Add ld_classic flag to Hermes when building for Xcode 15
 (#39516)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/39516

With Xcode15, Apple rewrote the C++ linker.
This is a breaking change that does not work with weak symbols.
As a workaround, apple is suggesting to add `-ld_classic` to the linker in order to readd support for weak symbols. The flag does not exists for Xcode 14.3 or lower, so we need to add it conditionally.

With this change, we introduce a couple of checks in the Hermes build logic:
1. Detect the version of Xcode that is used
2. Add the new flag to `HERMES_EXTRA_LINKER_FLAGS` if Xcode version is 15.

[Internal] - Make hermes build properly with Xcode 15

Reviewed By: cortinico, dmytrorykun

Differential Revision: D49368675

fbshipit-source-id: 62d8ed81855c426f56ed94b6a2d6da2eb882b355
---
 sdks/hermes-engine/utils/build-apple-framework.sh | 9 ++++++++-
 sdks/hermes-engine/utils/build-hermes-xcode.sh    | 8 ++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/sdks/hermes-engine/utils/build-apple-framework.sh b/sdks/hermes-engine/utils/build-apple-framework.sh
index 87faae6cb69..caae918e8e3 100755
--- a/sdks/hermes-engine/utils/build-apple-framework.sh
+++ b/sdks/hermes-engine/utils/build-apple-framework.sh
@@ -52,7 +52,7 @@ function build_host_hermesc {
 
 # Utility function to configure an Apple framework
 function configure_apple_framework {
-  local build_cli_tools enable_bitcode enable_debugger cmake_build_type
+  local build_cli_tools enable_bitcode enable_debugger cmake_build_type xcode_15_flags xcode_major_version
 
   if [[ $1 == iphoneos || $1 == catalyst ]]; then
     enable_bitcode="true"
@@ -77,8 +77,15 @@ function configure_apple_framework {
     cmake_build_type="MinSizeRel"
   fi
 
+  xcode_15_flags=""
+  xcode_major_version=$(xcodebuild -version | grep -oE '[0-9]*' | head -n 1)
+  if [[ $xcode_major_version -ge 15 ]]; then
+    xcode_15_flags="LINKER:-ld_classic"
+  fi
+
   pushd "$HERMES_PATH" > /dev/null || exit 1
     cmake -S . -B "build_$1" \
+      -DHERMES_EXTRA_LINKER_FLAGS="$xcode_15_flags" \
       -DHERMES_APPLE_TARGET_PLATFORM:STRING="$1" \
       -DCMAKE_OSX_ARCHITECTURES:STRING="$2" \
       -DCMAKE_OSX_DEPLOYMENT_TARGET:STRING="$3" \
diff --git a/sdks/hermes-engine/utils/build-hermes-xcode.sh b/sdks/hermes-engine/utils/build-hermes-xcode.sh
index 37faee32506..fa2ebe91bbc 100755
--- a/sdks/hermes-engine/utils/build-hermes-xcode.sh
+++ b/sdks/hermes-engine/utils/build-hermes-xcode.sh
@@ -33,6 +33,13 @@ if [ -z "$deployment_target" ]; then
   deployment_target=${MACOSX_DEPLOYMENT_TARGET}
 fi
 
+xcode_15_flags=""
+xcode_major_version=$(xcodebuild -version | grep -oE '[0-9]*' | head -n 1)
+if [[ $xcode_major_version -ge 15 ]]; then
+  echo "########### Using LINKER:-ld_classic ###########"
+  xcode_15_flags="LINKER:-ld_classic"
+fi
+
 architectures=$( echo "$ARCHS" | tr  " " ";" )
 
 echo "Configure Apple framework"
@@ -40,6 +47,7 @@ echo "Configure Apple framework"
 "$CMAKE_BINARY" \
   -S "${PODS_ROOT}/hermes-engine" \
   -B "${PODS_ROOT}/hermes-engine/build/${PLATFORM_NAME}" \
+  -DHERMES_EXTRA_LINKER_FLAGS="$xcode_15_flags" \
   -DHERMES_APPLE_TARGET_PLATFORM:STRING="$PLATFORM_NAME" \
   -DCMAKE_OSX_ARCHITECTURES:STRING="$architectures" \
   -DCMAKE_OSX_DEPLOYMENT_TARGET:STRING="$deployment_target" \