Unreal Engine Issues

UE-14113

Crash with for loop and TArray in constructor to generate multiple StaticMeshComponents

Crash with for loop and TArray in constructor to generate multiple StaticMeshComponents

Developer Notes

New Item must be added to array before accessing it.

PuzzlePieces[Piece] = ObjectInitializer.CreateDefaultSubobject<...>(...);
This should be replaced with:
PuzzlePieces.Add(ObjectInitializer.CreateDefaultSubobject<...>(...));

UDN
Description

Using a TArray to store multiple components being setup inside a for loop of a constructor will crash on project open.

Crash Reporter:

[Link Removed]

Steps to Reproduce

1. Open UE4 Editor (any project)
2. Add code to project based on Actor (MyActor)
3. Add the following to the constructor declaration

 (const FObjectInitializer &ObjectInitialIzer)

4.. In the header file add the following:

UPROPERTY(VisibleAnywhere, BlueprintReadWrite, Category = Puzzle)
		int32 PuzzleWidth;

	UPROPERTY(VisibleAnywhere, BlueprintReadWrite, Category = Puzzle)
		int32 PuzzleHeight;

	UPROPERTY(VisibleAnywhere, BlueprintReadWrite, Category = Puzzle)
	float PieceWidth;
	
	UPROPERTY(VisibleAnywhere, BlueprintReadWrite, Category = Puzzle)
	int32 TotalPieces;

	UPROPERTY(VisibleAnywhere, BlueprintReadWrite, Category = Puzzle)
	USceneComponent* Root;

	UPROPERTY(VisibleAnywhere, BlueprintReadWrite, Category = Puzzle)
		TArray<UStaticMeshComponent*> PuzzlePieces;

5. In the source file add the following to the constructor:

PuzzleWidth = 3;
	PuzzleHeight = 3;
	PieceWidth = 2.f;
	TotalPieces = PuzzleHeight * PuzzleWidth;

	Root = ObjectInitializer.CreateDefaultSubobject<USceneComponent>(this, TEXT("Root"));

	for (int32 Piece = 0; Piece < TotalPieces; Piece++)
	{
		FString PieceName = "PieceMesh" + FString::FromInt(Piece);

		PuzzlePieces[Piece] = ObjectInitializer.CreateDefaultSubobject<UStaticMeshComponent>(this, FName(*PieceName));
		PuzzlePieces[Piece]->AttachParent = RootComponent;
		PuzzlePieces[Piece]->AttachSocketName = FName(*PieceName);
	}

6. Compile
7. Open the project

Result:
Editor will crash on open. Running in debug causes breakpoint during loading process

Callstack
MachineId:9FA88CA44B7C623122B0039D6C8BA1B0

Unknown exception - code 00000001 (first/second chance not available)

"Assertion failed: (Index >= 0) & (Index < ArrayNum) [File:D:\Builds\Main\UE4\Engine\Source\Runtime\Core\Public\Containers\Array.h] [Line: 678] 
Array index out of bounds: 0 fr

KERNELBASE
UE4Editor_Core!FOutputDeviceWindowsError::Serialize() [d:\builds\main\ue4\engine\source\runtime\core\private\windows\windowsplatformoutputdevices.cpp:95]
UE4Editor_Core!FOutputDevice::Logf__VA() [d:\builds\main\ue4\engine\source\runtime\core\private\misc\outputdevice.cpp:144]
UE4Editor_Core!FDebug::AssertFailed() [d:\builds\main\ue4\engine\source\runtime\core\private\misc\outputdevice.cpp:360]
UE4Editor_ForLoopBreakTEST
UE4Editor_CoreUObject!UClass::CreateDefaultObject() [d:\builds\main\ue4\engine\source\runtime\coreuobject\private\uobject\class.cpp:2538]
UE4Editor_CoreUObject!UObjectLoadAllCompiledInDefaultProperties() [d:\builds\main\ue4\engine\source\runtime\coreuobject\private\uobject\uobjectbase.cpp:680]
UE4Editor_CoreUObject!ProcessNewlyLoadedUObjects() [d:\builds\main\ue4\engine\source\runtime\coreuobject\private\uobject\uobjectbase.cpp:768]
UE4Editor_CoreUObject!TBaseStaticDelegateInstance<void __cdecl(void)>::ExecuteIfSafe() [d:\builds\main\ue4\engine\source\runtime\core\public\delegates\delegateinstancesimpl_variadics.inl:921]
UE4Editor_Core!TBaseMulticastDelegate<void>::Broadcast() [d:\builds\main\ue4\engine\source\runtime\core\public\delegates\delegatesignatureimpl_variadics.inl:1031]
UE4Editor_Core!FModuleManager::LoadModuleWithFailureReason() [d:\builds\main\ue4\engine\source\runtime\core\private\modules\modulemanager.cpp:413]
UE4Editor_Projects!FModuleDescriptor::LoadModulesForPhase() [d:\builds\main\ue4\engine\source\runtime\projects\private\moduledescriptor.cpp:370]
UE4Editor_Projects!FProjectManager::LoadModulesForProject() [d:\builds\main\ue4\engine\source\runtime\projects\private\projectmanager.cpp:53]
UE4Editor!FEngineLoop::LoadStartupModules() [d:\builds\main\ue4\engine\source\runtime\launch\private\launchengineloop.cpp:1903]
UE4Editor!FEngineLoop::PreInit() [d:\builds\main\ue4\engine\source\runtime\launch\private\launchengineloop.cpp:1425]
UE4Editor!GuardedMain() [d:\builds\main\ue4\engine\source\runtime\launch\private\launch.cpp:110]
UE4Editor!GuardedMainWrapper() [d:\builds\main\ue4\engine\source\runtime\launch\private\windows\launchwindows.cpp:126]
UE4Editor!WinMain() [d:\builds\main\ue4\engine\source\runtime\launch\private\windows\launchwindows.cpp:249]

Have Comments or More Details?

There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-14113 in the post.

0
Login to Vote
By Design
ComponentUE - Foundation - Core
Affects Versions4.8
Target Fix4.9
CreatedApr 20, 2015
ResolvedApr 22, 2015
UpdatedFeb 5, 2017
View Jira Issue