When I built UE’s source(V4.21) in Xcode(the newest version). I got a error “Local variable ‘Out’ will be copied despite being returned by name”.
I cannot fix it. Who can help me ? Thanks a lot.
I have the same error and 12 others )) with UE4 21.1.2 release from github and XCode Version 10.2 (10E125).
I use this hot fixes =
…/UnrealEngine/Engine/Plugins/Experimental/RemoteSession/Source/RemoteSession/Private/MessageHandler/Messages.h
“fix” 
for 5 structures =
struct NoParamMsg, struct TwoParamMsg, struct ThreeParamMsg, struct FourParamMsg, struct FiveParamMsg
- return MemAr;
+ return MoveTemp(MemAr);
…/UnrealEngine/Engine/Plugins/FX/Niagara/Source/NiagaraEditor/Private/ViewModels/NiagaraScriptViewModel.cpp
LastCompileStatus = LastCompileStatus; - commented this string
// LastCompileStatus = LastCompileStatus;
…/UnrealEngine/Engine/Source/Editor/Kismet/Private/SBlueprintPalette.cpp
- else
- {
- ToolTipOut = ToolTipOut;
- }
+ // else
+ // {
+ // ToolTipOut = ToolTipOut;
+ // }
…/UnrealEngine/Engine/Source/Programs/UnrealHeaderTool/Private/CodeGenerator.cpp
- return Result;
+ return MoveTemp(Result);
…/UnrealEngine/Engine/Source/Programs/UnrealHeaderTool/Private/UnrealSourceFile.cpp
- return Out;
+ return MoveTemp(Out);
…/UnrealEngine/Engine/Source/Runtime/Engine/Private/Player.cpp
- return StrOut;
+ return MoveTemp(StrOut);
…/UnrealEngine/Engine/Source/Runtime/Engine/Private/TimerManager.cpp
- return Output;
+ return MoveTemp(Output);
…/UnrealEngine/Engine/Source/Runtime/Engine/Private/UnrealExporter.cpp
- return Output;
+ return MoveTemp(Output);
and
- return Archive;
+ return MoveTemp(Archive);
I don’t how it affected by engine but for me build looks like ok.