[CrashReport] Mac/Metal crash due to enabling Metal 2.0 on 10.12.6

Assertion failed:  [File:/Users/build/Build/++UE4+Release-4.18+Compile/Sync/Engine/Source/Runtime/Apple/MetalRHI/Private/MetalPipeline.cpp] [Line: 729] 
Failed to generate a render pipeline state object:

 Function Main_00001026_9738d51b is using language version 2.0 which is incompatible with this OS.

 === Critical error: ===
SIGSEGV: invalid attempt to access memory at address 0x3

0x09430dbb UE4Editor-Core.dylib!FGenericPlatformMisc::RaiseException(unsigned int)   [UnknownFile]) 
0x0f26ec09 UE4Editor-ApplicationCore.dylib!FMacErrorOutputDevice::Serialize(wchar_t const*, ELogVerbosity::Type, FName const&)   [UnknownFile]) 
0x096decfd UE4Editor-Core.dylib!FOutputDevice::Logf(wchar_t const*, ...)   [UnknownFile]) 
0x0965531b UE4Editor-Core.dylib!FDebug::AssertFailed(char const*, char const*, int, wchar_t const*, ...)   [UnknownFile]) 
0x2d4c8b5a UE4Editor-MetalRHI.dylib!CreateMTLRenderPipeline(FGraphicsPipelineStateInitializer const&, EMetalIndexType)   [UnknownFile]) 
0x2d453d7a UE4Editor-MetalRHI.dylib!FMetalGraphicsPipelineState::FMetalGraphicsPipelineState(FGraphicsPipelineStateInitializer const&)   [UnknownFile]) 
0x2d454375 UE4Editor-MetalRHI.dylib!FMetalDynamicRHI::RHICreateGraphicsPipelineState(FGraphicsPipelineStateInitializer const&)   [UnknownFile]) 
0x0ef4dc57 UE4Editor-RHI.dylib!GetAndOrCreateGraphicsPipelineState(FRHICommandList&, FGraphicsPipelineStateInitializer const&, EApplyRendertargetOption)   [UnknownFile]) 
0x0ef4f0c8 UE4Editor-RHI.dylib!SetGraphicsPipelineState(FRHICommandList&, FGraphicsPipelineStateInitializer const&, EApplyRendertargetOption)   [UnknownFile]) 
0x0f82039f UE4Editor-UtilityShaders.dylib!IssueScalableLongGPUTask(FRHICommandListImmediate&, int)   [UnknownFile]) 
0x0f82199e UE4Editor-UtilityShaders.dylib!MeasureLongGPUTaskExecutionTime(FRHICommandListImmediate&)   [UnknownFile]) 
0x09348cce UE4Editor!TGraphTask<FEngineLoop::Tick()::EURCMacro_MeasureLongGPUTaskExecutionTimeCmd>::ExecuteTask(TArray<FBaseGraphTask*, FDefaultAllocator>&, ENamedThreads::Type)   [UnknownFile]) 
0x0944d33c UE4Editor-Core.dylib!FNamedTaskThread::ProcessTasksNamedThread(int, bool)   [UnknownFile]) 
0x0944c3e8 UE4Editor-Core.dylib!FNamedTaskThread::ProcessTasksUntilQuit(int)   [UnknownFile]) 
0x094484ce UE4Editor-Core.dylib!FTaskGraphImplementation::ProcessThreadUntilRequestReturn(ENamedThreads::Type)   [UnknownFile]) 
0x0eebc2a1 UE4Editor-RenderCore.dylib!RenderingThreadMain(FEvent*)   [UnknownFile]) 
0x0eed0d17 UE4Editor-RenderCore.dylib!FRenderingThread::Run()   [UnknownFile]) 
0x094c169e UE4Editor-Core.dylib!FRunnableThreadPThread::Run()   [UnknownFile]) 
0x0946c3e7 UE4Editor-Core.dylib!FRunnableThreadPThread::_ThreadProc(void*)   [UnknownFile]) 
0xbd32f93b libsystem_pthread.dylib!_pthread_body()   [UnknownFile]) 
0xbd32f887 libsystem_pthread.dylib!_pthread_body()   [UnknownFile]) 
0xbd32f08d libsystem_pthread.dylib!thread_start()   [UnknownFile]) 

SEGV_MAPERR at 0x3

UE4Editor-MetalRHI.dylib!CreateMTLRenderPipeline()
UE4Editor-MetalRHI.dylib!FMetalGraphicsPipelineState::FMetalGraphicsPipelineState()
UE4Editor-MetalRHI.dylib!FMetalDynamicRHI::RHICreateGraphicsPipelineState()
UE4Editor-RHI.dylib!GetAndOrCreateGraphicsPipelineState()
UE4Editor-RHI.dylib!SetGraphicsPipelineState()
UE4Editor-UtilityShaders.dylib!IssueScalableLongGPUTask()
UE4Editor-UtilityShaders.dylib!MeasureLongGPUTaskExecutionTime()
UE4Editor!TGraphTask<FEngineLoop::Tick()::EURCMacro_MeasureLongGPUTaskExecutionTimeCmd>::ExecuteTask()
UE4Editor-Core.dylib!FNamedTaskThread::ProcessTasksNamedThread()
UE4Editor-Core.dylib!FNamedTaskThread::ProcessTasksUntilQuit()
UE4Editor-Core.dylib!FTaskGraphImplementation::ProcessThreadUntilRequestReturn()
UE4Editor-RenderCore.dylib!RenderingThreadMain()
UE4Editor-RenderCore.dylib!FRenderingThread::Run()
UE4Editor-Core.dylib!FRunnableThreadPThread::Run()
UE4Editor-Core.dylib!FRunnableThreadPThread::_ThreadProc()
libsystem_pthread.dylib!<Unknown>
libsystem_pthread.dylib!<Unknown>
libsystem_pthread.dylib!<Unknown>