Unreal Engine Issues and Bug Tracker (UE-42178)

Description

Adding a custom User Defined Struct code class to a project causes the Editor to crash whenever a hot reload is performed on that project. Removing the custom User Defined Struct class allows hot reloads to complete successfully.

REGRESSION:
No

Steps to Reproduce

Create a new Basic Code project.
Open the project in the Editor.
Add a new C++ class to the project that derives from UserDefinedStruct.

RESULT:
The Editor crashes while attempting to perform a hot reload after adding the new class. The Editor will also crash when performing any hot reload as long as the custom UserDefinedStruct class remains in the project, including when adding any additional code classes to the project.

EXPECTED:
The Editor continues to successfully complete hot reloads.

Callstack

Assertion failed: bPrepareCppStructOpsCompleted [File:D:\Main-Builds\Stream\Engine\Source\Runtime\CoreUObject\Public\UObject/Class.h] [Line: 1116] 
GetCppStructOps: PrepareCppStructOps() has not been called for class Default__MyUserDefinedStruct


UE4Editor_Core!FDebug::AssertFailed() [d:\main-builds\stream\engine\source\runtime\core\private\misc\assertionmacros.cpp:349]
UE4Editor_HotReload!FHotReloadModule::DoHotReloadInternal() [d:\main-builds\stream\engine\source\developer\hotreload\private\hotreload.cpp:914]
UE4Editor_HotReload!UE4Function_Private::TFunctionRefCaller<<lambda_845f9b2944b03bbc30be1e1f4a8d7f4b>,void __cdecl(TMap<FString,FString,FDefaultSetAllocator,TDefaultMapKeyFuncs<FString,FString,0> > const & __ptr64,bool,enum ECompilationResult::Type)>::Call() [d:\main-builds\stream\engine\source\runtime\core\public\templates\function.h:245]
UE4Editor_HotReload!FHotReloadModule::CheckForFinishedModuleDLLCompile() [d:\main-builds\stream\engine\source\developer\hotreload\private\hotreload.cpp:1916]
UE4Editor_HotReload!FHotReloadModule::RecompileModulesAsync() [d:\main-builds\stream\engine\source\developer\hotreload\private\hotreload.cpp:1551]
UE4Editor_HotReload!FHotReloadModule::RebindPackagesInternal() [d:\main-builds\stream\engine\source\developer\hotreload\private\hotreload.cpp:1163]
UE4Editor_HotReload!FHotReloadModule::RebindPackages() [d:\main-builds\stream\engine\source\developer\hotreload\private\hotreload.cpp:1107]
UE4Editor_GameProjectGeneration!GameProjectUtils::AddCodeToProject_Internal() [d:\main-builds\stream\engine\source\editor\gameprojectgeneration\private\gameprojectutils.cpp:3505]
UE4Editor_GameProjectGeneration!GameProjectUtils::AddCodeToProject() [d:\main-builds\stream\engine\source\editor\gameprojectgeneration\private\gameprojectutils.cpp:1105]
UE4Editor_GameProjectGeneration!SNewClassDialog::FinishClicked() [d:\main-builds\stream\engine\source\editor\gameprojectgeneration\private\snewclassdialog.cpp:1181]
UE4Editor_GameProjectGeneration!TBaseSPMethodDelegateInstance<0,SNewClassDialog,0,TTypeWrapper<void> __cdecl(void)>::Execute() [d:\main-builds\stream\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:327]
UE4Editor_GameProjectGeneration!TBaseSPMethodDelegateInstance<0,SNewClassDialog,0,void __cdecl(void)>::ExecuteIfSafe() [d:\main-builds\stream\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:433]
UE4Editor_AppFramework!SWizard::HandleFinishButtonClicked() [d:\main-builds\stream\engine\source\runtime\appframework\private\widgets\workflow\swizard.cpp:287]
UE4Editor_AppFramework!TMemberFunctionCaller<SWizard,FReply (__cdecl SWizard::*)(void) __ptr64>::operator()<>() [d:\main-builds\stream\engine\source\runtime\core\public\delegates\delegateinstanceinterface.h:165]
UE4Editor_AppFramework!TTupleImpl<TIntegerSequence<unsigned int> >::ApplyAfter<TMemberFunctionCaller<SWizard,FReply (__cdecl SWizard::*)(void) __ptr64> >() [d:\main-builds\stream\engine\source\runtime\core\public\delegates\tuple.h:134]
UE4Editor_AppFramework!TBaseSPMethodDelegateInstance<0,SWizard,0,FReply __cdecl(void)>::Execute() [d:\main-builds\stream\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:327]
UE4Editor_Slate!TBaseDelegate<FReply>::Execute() [d:\main-builds\stream\engine\source\runtime\core\public\delegates\delegatesignatureimpl.inl:537]
UE4Editor_Slate!SButton::OnMouseButtonUp() [d:\main-builds\stream\engine\source\runtime\slate\private\widgets\input\sbutton.cpp:278]
UE4Editor_Slate!<lambda_8d0e9a1da76abd0a756a3a9d775f5ed1>::operator()() [d:\main-builds\stream\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5013]
UE4Editor_Slate!FEventRouter::Route<FReply,FEventRouter::FToLeafmostPolicy,FPointerEvent,<lambda_8d0e9a1da76abd0a756a3a9d775f5ed1> >() [d:\main-builds\stream\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:239]
UE4Editor_Slate!FSlateApplication::RoutePointerUpEvent() [d:\main-builds\stream\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5002]
UE4Editor_Slate!FSlateApplication::ProcessMouseButtonUpEvent() [d:\main-builds\stream\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5469]
UE4Editor_Slate!FSlateApplication::OnMouseUp() [d:\main-builds\stream\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5446]
UE4Editor_Core!FWindowsApplication::ProcessDeferredMessage() [d:\main-builds\stream\engine\source\runtime\core\private\windows\windowsapplication.cpp:1698]
UE4Editor_Core!FWindowsApplication::DeferMessage() [d:\main-builds\stream\engine\source\runtime\core\private\windows\windowsapplication.cpp:2120]
UE4Editor_Core!FWindowsApplication::ProcessMessage() [d:\main-builds\stream\engine\source\runtime\core\private\windows\windowsapplication.cpp:867]
UE4Editor_Core!FWindowsApplication::AppWndProc() [d:\main-builds\stream\engine\source\runtime\core\private\windows\windowsapplication.cpp:714]
user32
user32
UE4Editor_Core!FWindowsPlatformMisc::PumpMessages() [d:\main-builds\stream\engine\source\runtime\core\private\windows\windowsplatformmisc.cpp:980]
UE4Editor!FEngineLoop::Tick() [d:\main-builds\stream\engine\source\runtime\launch\private\launchengineloop.cpp:3008]
UE4Editor!GuardedMain() [d:\main-builds\stream\engine\source\runtime\launch\private\launch.cpp:166]
UE4Editor!GuardedMainWrapper() [d:\main-builds\stream\engine\source\runtime\launch\private\windows\launchwindows.cpp:134]
UE4Editor!WinMain() [d:\main-builds\stream\engine\source\runtime\launch\private\windows\launchwindows.cpp:210]
UE4Editor!__scrt_common_main_seh() [f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:264]
kernel32
ntdll

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Fixed

Component	UE - Foundation - Core
Affects Versions	4.14.3, 4.15, 4.16
Target Fix	4.16

Fix Commit	3318919
Main Commit	3345747

Created	Feb 20, 2017
Resolved	Feb 23, 2017
Updated	Apr 27, 2018

View Jira Issue

UE-42178

Editor crashes when a hot reload is performed on a project that contains a custom User Defined Struct code class

Editor crashes when a hot reload is performed on a project that contains a custom User Defined Struct code class

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