[RN][iOS] Fix symbol not found _jump_fcontext with use_frameworks!

[cipolleschi]

Summary:

While developing Xcode 15, Apple reimplemented the linker.
In Xcode 15.0, the linker was making old iOS (< 15) crash when they were built using Xcode 15.

To fix that, we make Apple create new compiler flags (-ld_classic) to have a backward compatible linker.

In Xcode 15.1, Apple fixed that behavior, so the flags should not be required anymore.
But now, if we pass -ld_classic to the linker and we have an app that is using use_framworks!, that app crashes at startup.

This change remove the flags if the Xcode that is used is 15.1 or greater.

Note: The previous change added the flags to Hermes as well. I tested this fix in a configuration where Hermes has the flags and React Native does not, and it works. So we are removing the flags only from React Native.

Changelog:

[Internal] - Do not add the -ld_classic flag if the app is built with Xcode 15.1 or greater.

Test Plan:

Tested locally that a new app with use_frameworks! is not crashing.
Tested on Firebase Testlab that a new app built with Xcode 15.2 and running on iOS <15 is not crashing at startup.

[floydkim]

Thank you for resolving the issue. 😄 👍
And also, the explanation of -ld_classic was very informative for me.

I created a patch-package diff with the changes in the PR. (react-native 0.71.15)

react-native+0.71.15.patch

diff --git a/node_modules/react-native/scripts/cocoapods/utils.rb b/node_modules/react-native/scripts/cocoapods/utils.rb
index 154ba3e..25968c2 100644
--- a/node_modules/react-native/scripts/cocoapods/utils.rb
+++ b/node_modules/react-native/scripts/cocoapods/utils.rb
@@ -160,7 +160,7 @@ class ReactNativePodsUtils

                 # fix for weak linking
                 self.safe_init(config, other_ld_flags_key)
-                if self.is_using_xcode15_or_greter(:xcodebuild_manager => xcodebuild_manager)
+                if self.is_using_xcode15_0(:xcodebuild_manager => xcodebuild_manager)
                     self.add_value_to_setting_if_missing(config, other_ld_flags_key, xcode15_compatibility_flags)
                 else
                     self.remove_value_from_setting_if_present(config, other_ld_flags_key, xcode15_compatibility_flags)
@@ -299,7 +299,7 @@ class ReactNativePodsUtils
         end
     end

-    def self.is_using_xcode15_or_greter(xcodebuild_manager: Xcodebuild)
+    def self.is_using_xcode15_0(xcodebuild_manager: Xcodebuild)
         xcodebuild_version = xcodebuild_manager.version

         # The output of xcodebuild -version is something like
@@ -310,7 +310,8 @@ class ReactNativePodsUtils
         regex = /(\d+)\.(\d+)(?:\.(\d+))?/
         if match_data = xcodebuild_version.match(regex)
             major = match_data[1].to_i
-            return major >= 15
+            minor = match_data[2].to_i
+            return major == 15 && minor == 0
         end

         return false

When I ran the pod install on a machine with Xcode 15.2,
I see a minor blemish and want to inform you.

it produces " " value to OTHER_LDFLAGS. (all configurations)

it looks wierd but build is OK.