Unreal Engine Issues and Bug Tracker (UE-46546)

Description

If the values of the elements in a Tmap are altered for a Tmap that is using a custom struct, the editor will crash on compile.

Steps to Reproduce

Open the editor
Create a new struct
Add two members
Save
Create new actor blueprint
Create a new Tmap based on the custom struct that was made
Set the other value to an integer
Add an element to the tmap
Change the values in the tmap element to anything other than the default (meaning the struct values in the element)
Add an element to the tmap
Change the values in the tmap element to anything other than the default (meaning the struct values in the element)
Compile

Result: The editor crashes when the blueprint in compiled
Expected: The blueprint would compile and accept the changes to the default values in the Tmap

Callstack

Assertion failed: CanWriteValueWithoutIdentifier() [File:D:\Build\++UE4+Release-4.16+Compile\Sync\Engine\Source\Runtime\Json\Public\Serialization/JsonWriter.h] [Line: 133] 



UE4Editor_Core!FDebug::AssertFailed() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\core\private\misc\assertionmacros.cpp:349]
UE4Editor_Kismet!TJsonWriter<wchar_t,TCondensedJsonPrintPolicy<wchar_t> >::WriteValue<double>() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\json\public\serialization\jsonwriter.h:134]
UE4Editor_Kismet!FJsonSerializer::Serialize<wchar_t,TCondensedJsonPrintPolicy<wchar_t> >() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\json\public\serialization\jsonserializer.h:279]
UE4Editor_Kismet!FJsonSerializer::Serialize<wchar_t,TCondensedJsonPrintPolicy<wchar_t> >() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\json\public\serialization\jsonserializer.h:103]
UE4Editor_Kismet!BlueprintSearchMetaDataHelpers::SaveVariableDescriptionToJson() [d:\build\++ue4+release-4.16+compile\sync\engine\source\editor\kismet\private\findinblueprintmanager.cpp:680]
UE4Editor_Kismet!FFindInBlueprintSearchManager::GatherBlueprintSearchMetadata() [d:\build\++ue4+release-4.16+compile\sync\engine\source\editor\kismet\private\findinblueprintmanager.cpp:1626]
UE4Editor_Kismet!FFindInBlueprintSearchManager::AddOrUpdateBlueprintSearchMetadata() [d:\build\++ue4+release-4.16+compile\sync\engine\source\editor\kismet\private\findinblueprintmanager.cpp:1750]
UE4Editor_UnrealEd!FKismetEditorUtilities::CompileBlueprint() [d:\build\++ue4+release-4.16+compile\sync\engine\source\editor\unrealed\private\kismet2\kismet2.cpp:783]
UE4Editor_Kismet!FBlueprintEditor::Compile() [d:\build\++ue4+release-4.16+compile\sync\engine\source\editor\kismet\private\blueprinteditor.cpp:3292]
UE4Editor_Kismet!TBaseSPMethodDelegateInstance<0,FBlueprintEditor,0,TTypeWrapper<void> __cdecl(void)>::Execute() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:327]
UE4Editor_Kismet!TBaseSPMethodDelegateInstance<0,FBlueprintEditor,0,void __cdecl(void)>::ExecuteIfSafe() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:434]
UE4Editor_Slate!FUICommandList::ExecuteAction() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\slate\private\framework\commands\uicommandlist.cpp:97]
UE4Editor_Slate!SToolBarButtonBlock::OnClicked() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\slate\private\framework\multibox\stoolbarbuttonblock.cpp:305]
UE4Editor_Slate!TMemberFunctionCaller<SToolBarButtonBlock,FReply (__cdecl SToolBarButtonBlock::*)(void) __ptr64>::operator()<>() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\core\public\delegates\delegateinstanceinterface.h:165]
UE4Editor_Slate!UE4Tuple_Private::TTupleImpl<TIntegerSequence<unsigned int> >::ApplyAfter<TMemberFunctionCaller<SToolBarButtonBlock,FReply (__cdecl SToolBarButtonBlock::*)(void) __ptr64> >() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\core\public\templates\tuple.h:497]
UE4Editor_Slate!TBaseSPMethodDelegateInstance<0,SToolBarButtonBlock,0,FReply __cdecl(void)>::Execute() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:327]
UE4Editor_Slate!TBaseDelegate<FReply>::Execute() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\core\public\delegates\delegatesignatureimpl.inl:537]
UE4Editor_Slate!SButton::OnMouseButtonUp() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\slate\private\widgets\input\sbutton.cpp:278]
UE4Editor_Slate!<lambda_8d0e9a1da76abd0a756a3a9d775f5ed1>::operator()() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5049]
UE4Editor_Slate!FEventRouter::Route<FReply,FEventRouter::FToLeafmostPolicy,FPointerEvent,<lambda_8d0e9a1da76abd0a756a3a9d775f5ed1> >() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:239]
UE4Editor_Slate!FSlateApplication::RoutePointerUpEvent() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5038]
UE4Editor_Slate!FSlateApplication::ProcessMouseButtonUpEvent() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5515]
UE4Editor_Slate!FSlateApplication::OnMouseUp() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5495]
UE4Editor_Core!FWindowsApplication::ProcessDeferredMessage() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:1704]
UE4Editor_Core!FWindowsApplication::DeferMessage() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:2127]
UE4Editor_Core!FWindowsApplication::ProcessMessage() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:867]
UE4Editor_Core!FWindowsApplication::AppWndProc() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:714]
user32
user32
UE4Editor_Core!FWindowsPlatformMisc::PumpMessages() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\core\private\windows\windowsplatformmisc.cpp:1009]
UE4Editor!FEngineLoop::Tick() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\launch\private\launchengineloop.cpp:3058]
UE4Editor!GuardedMain() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\launch\private\launch.cpp:166]
UE4Editor!GuardedMainWrapper() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:134]
UE4Editor!WinMain() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:210]
UE4Editor!__scrt_common_main_seh() [f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:253]
kernel32
ntdll

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Cannot Reproduce

Component	UE - Gameplay - Blueprint Compiler
Affects Versions	4.16.1

Created	Jun 27, 2017
Resolved	Jun 27, 2017
Updated	Apr 27, 2018

UE-46546

Crash when altering the values of a custom struct element in a Tmap

Crash when altering the values of a custom struct element in a Tmap

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