Remove RCT_HERMES_V1_ENABLED from CocoaPods infrastructure (#56735)

Summary:
Pull Request resolved: #56735

  - Remove `RCT_HERMES_V1_ENABLED` environment variable from `react_native_pods.rb`
  - Simplify `jsengine.rb` to always use `.hermesversion` tag file
  - Remove conditional `HERMES_V1_ENABLED=1` preprocessor definition from `utils.rb`
  - Simplify `hermes-engine.podspec`: always read `HERMES_VERSION_NAME`, use V1 source files, remove legacy inspector subspecs
  - Simplify `hermes-utils.rb`: remove `hermes_v1_enabled()` function, always use `250829098.0.0-stable` branch, always use `.hermesversion` tag file

## Changelog:
[iOS][Removed] - Remove the RCT_HERMES_V1_ENABLED from Cocoapods

  ## Test plan
  - [x] iOS: `bundle exec pod install` — success
  - [x] iOS: `xcodebuild` rn-tester on iPhone 16 Pro simulator — BUILD SUCCEEDED

Differential Revision: D104247277

Reviewed By: cortinico

Author: Riccardo Cipolleschi

packages/react-native/scripts/cocoapods/jsengine.rb

@@ -13,7 +13,7 @@ def setup_hermes!(react_native_path: "../node_modules/react-native")
     react_native_dir = Pod::Config.instance.installation_root.join(react_native_path)
     # This `:tag => hermestag` below is only to tell CocoaPods to update hermes-engine when React Native version changes.
     # We have custom logic to compute the source for hermes-engine. See sdks/hermes-engine/*
-    hermestag_file_name = ENV['RCT_HERMES_V1_ENABLED'] == "1" ? ".hermesv1version" : ".hermesversion"
+    hermestag_file_name = ".hermesv1version"
     hermestag_file = File.join(react_native_dir, "sdks", hermestag_file_name)
     hermestag = File.exist?(hermestag_file) ? File.read(hermestag_file).strip : ''
     pod 'hermes-engine', :podspec => "#{react_native_path}/sdks/hermes-engine/hermes-engine.podspec", :tag => hermestag

packages/react-native/scripts/cocoapods/utils.rb

@@ -45,13 +45,10 @@ def self.has_pod(installer, name)
     end
 
     def self.set_gcc_preprocessor_definition_for_React_hermes(installer)
-        if ENV['RCT_HERMES_V1_ENABLED'] == "1"
-            self.add_build_settings_to_pod(installer, "GCC_PREPROCESSOR_DEFINITIONS", "HERMES_ENABLE_DEBUGGER=1 HERMES_V1_ENABLED=1", "React-hermes", :debug)
-            self.add_build_settings_to_pod(installer, "GCC_PREPROCESSOR_DEFINITIONS", "HERMES_ENABLE_DEBUGGER=1 HERMES_V1_ENABLED=1", "React-RuntimeHermes", :debug)
-        else
-            self.add_build_settings_to_pod(installer, "GCC_PREPROCESSOR_DEFINITIONS", "HERMES_ENABLE_DEBUGGER=1", "React-hermes", :debug)
-            self.add_build_settings_to_pod(installer, "GCC_PREPROCESSOR_DEFINITIONS", "HERMES_ENABLE_DEBUGGER=1", "React-RuntimeHermes", :debug)
-        end
+        # HERMES_V1_ENABLED=1 is set unconditionally to stay aligned with the Android/CMake build,
+        # where react-native-flags.cmake always defines HERMES_V1_ENABLED=1.
+        self.add_build_settings_to_pod(installer, "GCC_PREPROCESSOR_DEFINITIONS", "HERMES_ENABLE_DEBUGGER=1 HERMES_V1_ENABLED=1", "React-hermes", :debug)
+        self.add_build_settings_to_pod(installer, "GCC_PREPROCESSOR_DEFINITIONS", "HERMES_ENABLE_DEBUGGER=1 HERMES_V1_ENABLED=1", "React-RuntimeHermes", :debug)
 
         self.add_build_settings_to_pod(installer, "GCC_PREPROCESSOR_DEFINITIONS", "HERMES_ENABLE_DEBUGGER=1", "hermes-engine", :debug)
     end

packages/react-native/scripts/react_native_pods.rb

@@ -95,13 +95,11 @@ def use_react_native! (
   # excluding the legacy arch unless the user turns this flag off explicitly.
   ENV['RCT_REMOVE_LEGACY_ARCH'] = ENV['RCT_REMOVE_LEGACY_ARCH'] == '0' ? '0' : '1'
 
-  # Enable Hermes V1 by default.
-  # Users can still turn it off and use legacy hermes by setting the RCT_HERMES_V1_ENABLED
-  # environment variable to '0'.
-  ENV['RCT_HERMES_V1_ENABLED']= ENV['RCT_HERMES_V1_ENABLED'] == '0' ? '0' : '1'
-
   ReactNativePodsUtils.check_minimum_required_xcode()
 
+  # Enable Hermes V1 by default. Keep the env var setup for backward compatibility.
+  ENV['RCT_HERMES_V1_ENABLED'] = '1'
+
   # Current target definition is provided by Cocoapods and it refers to the target
   # that has invoked the `use_react_native!` function.
   ReactNativePodsUtils.detect_use_frameworks(current_target_definition)

packages/react-native/sdks/hermes-engine/hermes-engine.podspec

@@ -56,15 +56,7 @@ Pod::Spec.new do |spec|
 
     spec.subspec 'Pre-built' do |ss|
       ss.preserve_paths = ["destroot/bin/*"].concat(["**/*.{h,c,cpp}"])
-      if ENV["RCT_HERMES_V1_ENABLED"] == "0"
-        ss.source_files = "destroot/include/hermes/**/*.h"
-      else
-        # Hermes v1 is shipping a jsi/hermes.h header which is imported by the hermes.h header
-        # and that file is not present in React Native's JSI
-        # (see https://github.com/facebook/react-native/tree/main/packages/react-native/ReactCommon/jsi/jsi/ where there is
-        # hermes-interface.h but not hermes.h)
-        ss.source_files = ["destroot/include/hermes/**/*.h", "destroot/include/jsi/hermes.h"]
-      end
+      ss.source_files = ["destroot/include/hermes/**/*.h", "destroot/include/jsi/hermes.h"]
       ss.header_mappings_dir = "destroot/include"
       ss.ios.vendored_frameworks = "destroot/Library/Frameworks/universal/hermesvm.xcframework"
       ss.visionos.vendored_frameworks = "destroot/Library/Frameworks/universal/hermesvm.xcframework"
@@ -127,20 +119,6 @@ Pod::Spec.new do |spec|
       ss.header_dir = 'hermes/Public'
     end
 
-    if ENV['RCT_HERMES_V1_ENABLED'] == "0"
-      spec.subspec 'inspector' do |ss|
-        ss.source_files = ''
-        ss.public_header_files = 'API/hermes/inspector/*.h'
-        ss.header_dir = 'hermes/inspector'
-      end
-
-      spec.subspec 'inspector_chrome' do |ss|
-        ss.source_files = ''
-        ss.public_header_files = 'API/hermes/inspector/chrome/*.h'
-        ss.header_dir = 'hermes/inspector/chrome'
-      end
-    end
-
     hermesc_path = "${PODS_ROOT}/hermes-engine/build_host_hermesc"
 
     if ENV.has_key?('HERMES_OVERRIDE_HERMESC_PATH') && File.exist?(ENV['HERMES_OVERRIDE_HERMESC_PATH']) then

packages/react-native/sdks/hermes-engine/hermes-utils.rb

@@ -85,10 +85,6 @@ def hermes_commit_envvar_defined()
     return ENV.has_key?('HERMES_COMMIT')
 end
 
-def hermes_v1_enabled()
-    return ENV['RCT_HERMES_V1_ENABLED'] != "0"
-end
-
 def force_build_from_tag(react_native_path)
     return ENV[ENV_BUILD_FROM_SOURCE] === 'true' && File.exist?(hermestag_file(react_native_path))
 end
@@ -175,16 +171,12 @@ def podspec_source_build_from_github_commit()
 def podspec_source_build_from_github_tag(react_native_path)
     tag = File.read(hermestag_file(react_native_path)).strip
 
-    if hermes_v1_enabled()
-        hermes_log("Using tag defined in sdks/.hermesv1version: #{tag}")
-    else
-        hermes_log("Using tag defined in sdks/.hermesversion: #{tag}")
-    end
+    hermes_log("Using tag defined in sdks/.hermesv1version: #{tag}")
     return {:git => HERMES_GITHUB_URL, :tag => tag}
 end
 
 def podspec_source_build_from_github_main()
-    branch = hermes_v1_enabled() ? "250829098.0.0-stable" : "main"
+    branch = "250829098.0.0-stable"
     hermes_log("Using the latest commit from #{branch}.")
     return {:git => HERMES_GITHUB_URL, :commit => `git ls-remote #{HERMES_GITHUB_URL} #{branch} | cut -f 1`.strip}
 end
@@ -210,11 +202,7 @@ def artifacts_dir()
 end
 
 def hermestag_file(react_native_path)
-    if hermes_v1_enabled()
-        return File.join(react_native_path, "sdks", ".hermesv1version")
-    else
-        return File.join(react_native_path, "sdks", ".hermesversion")
-    end
+    return File.join(react_native_path, "sdks", ".hermesv1version")
 end
 
 def release_tarball_url(version, build_type)