Unreal Engine Issues and Bug Tracker (UE-35629)

Description

Defining a FRuntimeFloatCurve inside a code based struct causes the editor to crash if the struct is added as a local variable to a blueprint function and the "Create External Curve" button is pressed.

This crash only occurs if the struct is a local variable of a function.

Steps to Reproduce

Open UE4 Editor
Add code to project based on Actor (MyActor)

Add the following include to MyActor.h:

#include "Runtime/Engine/Classes/Curves/CurveFloat.h"

Add the following struct to MyActor.h between include statements and UCLASS() macro:

USTRUCT(BlueprintType, Blueprintable)
struct MYPROJECT11_API FMyCustomCurve
{
	GENERATED_BODY()
public:
	
		UPROPERTY(config,BlueprintReadWrite, EditAnywhere, meta = (
			DisplayName = "Custom Tween Curve",
			XAxisName = "Alpha", YAxisName = "Value"))
		FRuntimeFloatCurve CustomCurve;
};

Compile
Create Blueprint based on MyActor (MyActorBP)
Create a function inside blueprint
Add local variable to BP function
Set Local Variable type to My Custom Curve
Compile BP
With variable selected, expand Default Value dropdowns and click Create External Curve button

Result:
Editor crashes with the shown callstack

Expected:
Window for "Choose Location for External Curve Asset" opens when button is clicked.

Callstack

MachineId:7156C35640F86204E61B8383F45DEE17
EpicAccountId:e8c7fa630b6440f69a25a2c64d6c482c

Access violation - code c0000005 (first/second chance not available)

UE4Editor_CoreUObject!UObjectBaseUtility::GetName() [d:\build\++ue4+release-4.13+compile\sync\engine\source\runtime\coreuobject\public\uobject\uobjectbaseutility.h:345]
UE4Editor_DetailCustomizations!FCurveStructCustomization::OnCreateButtonClicked() [d:\build\++ue4+release-4.13+compile\sync\engine\source\editor\detailcustomizations\private\curvestructcustomization.cpp:268]
UE4Editor_DetailCustomizations!TMemberFunctionCaller<FCurveStructCustomization,FReply (__cdecl FCurveStructCustomization::*)(void) __ptr64>::operator()<>() [d:\build\++ue4+release-4.13+compile\sync\engine\source\runtime\core\public\delegates\delegateinstanceinterface.h:161]
UE4Editor_DetailCustomizations!TTupleImpl<TIntegerSequence<unsigned int> >::ApplyAfter<TMemberFunctionCaller<FCurveStructCustomization,FReply (__cdecl FCurveStructCustomization::*)(void) __ptr64> >() [d:\build\++ue4+release-4.13+compile\sync\engine\source\runtime\core\public\delegates\tuple.h:115]
UE4Editor_DetailCustomizations!TBaseSPMethodDelegateInstance<0,FCurveStructCustomization,0,FReply __cdecl(void)>::Execute() [d:\build\++ue4+release-4.13+compile\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:317]
UE4Editor_Slate!TBaseDelegate<FReply>::Execute() [d:\build\++ue4+release-4.13+compile\sync\engine\source\runtime\core\public\delegates\delegatesignatureimpl.inl:521]
UE4Editor_Slate!SButton::OnMouseButtonUp() [d:\build\++ue4+release-4.13+compile\sync\engine\source\runtime\slate\private\widgets\input\sbutton.cpp:278]
UE4Editor_Slate!<lambda_8d0e9a1da76abd0a756a3a9d775f5ed1>::operator()() [d:\build\++ue4+release-4.13+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:4901]
UE4Editor_Slate!FEventRouter::Route<FReply,FEventRouter::FToLeafmostPolicy,FPointerEvent,<lambda_8d0e9a1da76abd0a756a3a9d775f5ed1> >() [d:\build\++ue4+release-4.13+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:215]
UE4Editor_Slate!FSlateApplication::RoutePointerUpEvent() [d:\build\++ue4+release-4.13+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:4890]
UE4Editor_Slate!FSlateApplication::ProcessMouseButtonUpEvent() [d:\build\++ue4+release-4.13+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5348]
UE4Editor_Slate!FSlateApplication::OnMouseUp() [d:\build\++ue4+release-4.13+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5328]
UE4Editor_Core!FWindowsApplication::ProcessDeferredMessage() [d:\build\++ue4+release-4.13+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:1584]
UE4Editor_Core!FWindowsApplication::DeferMessage() [d:\build\++ue4+release-4.13+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:1930]
UE4Editor_Core!FWindowsApplication::ProcessMessage() [d:\build\++ue4+release-4.13+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:747]
UE4Editor_Core!FWindowsApplication::AppWndProc() [d:\build\++ue4+release-4.13+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:669]
user32
user32
UE4Editor_Core!FWindowsPlatformMisc::PumpMessages() [d:\build\++ue4+release-4.13+compile\sync\engine\source\runtime\core\private\windows\windowsplatformmisc.cpp:905]
UE4Editor!FEngineLoop::Tick() [d:\build\++ue4+release-4.13+compile\sync\engine\source\runtime\launch\private\launchengineloop.cpp:2788]
UE4Editor!GuardedMain() [d:\build\++ue4+release-4.13+compile\sync\engine\source\runtime\launch\private\launch.cpp:156]
UE4Editor!GuardedMainWrapper() [d:\build\++ue4+release-4.13+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:126]
UE4Editor!WinMain() [d:\build\++ue4+release-4.13+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:202]
UE4Editor!__scrt_common_main_seh() [f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:264]
kernel32
ntdll

Community References

[Crash] BP LocalVar crash when try to Create External Curve

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Fixed

Component	UE - Gameplay - Blueprint
Affects Versions	4.13
Target Fix	4.16

Fix Commit	3253983
Main Commit	3255791

Created	Sep 6, 2016
Resolved	Jan 11, 2017
Updated	Feb 5, 2017

UE-35629

Creating External Curve for a function's local struct variable causes editor to crash

Creating External Curve for a function's local struct variable causes editor to crash

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