Support enable ARC in modules

#jira UE-107891
#review @Sam.Zamani @Bertrand.Carre @Chris.Varnsverry @Roman.Dzieciol @Josh.Adams  @Jack.Porter
#preflight

[CL 23133821 by Rafa Lecina in ue5-main branch]

Engine/Source/Programs/UnrealBuildTool/Configuration/ModuleRules.cs

@@ -720,6 +720,13 @@ namespace UnrealBuildTool
 		/// </summary>
 		public bool bEnableObjCExceptions = false;
 
+		/// <summary>
+		/// Enable objective C automatic reference counting (ARC)
+		/// If you set this to true you should not use shared PCHs for this module. The engine won't be extensively using ARC in the short term  
+		/// Not doing this will result in a compile errors because shared PCHs were compiled with different flags than consumer
+		/// </summary>
+		public bool bEnableObjCAutomaticReferenceCounting = false;
+		
 		/// <summary>
 		/// How to treat shadow variable warnings
 		/// </summary>

Engine/Source/Programs/UnrealBuildTool/Configuration/UEBuildModuleCPP.cs

@@ -1558,6 +1558,7 @@ namespace UnrealBuildTool
 			Result.bBuildLocallyWithSNDBS = Rules.bBuildLocallyWithSNDBS;
 			Result.bEnableExceptions |= Rules.bEnableExceptions;
 			Result.bEnableObjCExceptions |= Rules.bEnableObjCExceptions;
+			Result.bEnableObjCAutomaticReferenceCounting = Rules.bEnableObjCAutomaticReferenceCounting;
 			Result.ShadowVariableWarningLevel = Rules.ShadowVariableWarningLevel;
 			Result.UnsafeTypeCastWarningLevel = Rules.UnsafeTypeCastWarningLevel;
 			Result.bDisableStaticAnalysis = Rules.bDisableStaticAnalysis;

Engine/Source/Programs/UnrealBuildTool/System/CppCompileEnvironment.cs

@@ -228,6 +228,13 @@ namespace UnrealBuildTool
 		/// </summary>
 		public bool bEnableObjCExceptions = false;
 
+		/// <summary>
+		/// Enable objective C automatic reference counting (ARC)
+		/// If you set this to true you should not use shared PCHs for this module. The engine won't be extensively using ARC in the short term  
+		/// Not doing this will result in a compile errors because shared PCHs were compiled with different flags than consumer
+		/// </summary>
+		public bool bEnableObjCAutomaticReferenceCounting = false;
+		
 		/// <summary>
 		/// How to treat any warnings in the code
 		/// </summary>
@@ -526,6 +533,7 @@ namespace UnrealBuildTool
 			bRetainFramePointers = Other.bRetainFramePointers;
 			bEnableExceptions = Other.bEnableExceptions;
 			bEnableObjCExceptions = Other.bEnableObjCExceptions;
+			bEnableObjCAutomaticReferenceCounting = Other.bEnableObjCAutomaticReferenceCounting;
 			DefaultWarningLevel = Other.DefaultWarningLevel;
 			DeprecationWarningLevel = Other.DeprecationWarningLevel;
 			ShadowVariableWarningLevel = Other.ShadowVariableWarningLevel;

Engine/Source/Programs/UnrealBuildTool/ToolChain/AppleToolChain.cs

@@ -254,6 +254,16 @@ namespace UnrealBuildTool
 			return Definition.Contains("\"") ? Definition.Replace("\"", "\\\"") : Definition;
 		}
 
+		protected override void GetCppStandardCompileArgument(CppCompileEnvironment CompileEnvironment, List<string> Arguments)
+		{
+			if (CompileEnvironment.bEnableObjCAutomaticReferenceCounting)
+			{
+				Arguments.Add("-fobjc-arc");
+			}
+
+			base.GetCppStandardCompileArgument(CompileEnvironment, Arguments);
+		}
+
 		protected override void GetCompileArguments_CPP(CppCompileEnvironment CompileEnvironment, List<string> Arguments)
 		{
 			Arguments.Add("-x objective-c++");