Description

This is an early trending crash coming out of the 4.18 previews. It occurs on Mac, and all affected project names indicate it is related to AR. Users have not provided any descriptions of their actions when the crash occurred.

Callstack from log

LogMaterial: Missing cached shader map for material Material_3, compiling. 
LogMaterial: Warning: /Engine/Transient.Material_3 (no disk path found): Failed to compile Material for platform SF_METAL_SM5, Default Material will be used in game.
LogMaterial: 	(Node TextureObject) Texture Object> Requires valid texture
LogShaderCompilers: Warning: ShaderCompileWorker terminated unexpectedly!  Falling back to directly compiling which will be very slow.  Thread 2.
LogMac: Error: appError called: Assertion failed: 0 [File:/Users/build/Build/++UE4+Release-4.18+Compile/Sync/Engine/Source/Developer/Apple/MetalShaderFormat/Private/MetalBackend.cpp] [Line: 2810] 


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

LogMac: 0x032ed85b UE4Editor-Core.dylib!FGenericPlatformMisc::RaiseException(unsigned int)   [UnknownFile]) 
0x090f8f09 UE4Editor-ApplicationCore.dylib!FMacErrorOutputDevice::Serialize(wchar_t const*, ELogVerbosity::Type, FName const&)   [UnknownFile]) 
0x0359bf1d UE4Editor-Core.dylib!FOutputDevice::Logf(wchar_t const*, ...)   [UnknownFile]) 
0x035125ab UE4Editor-Core.dylib!FDebug::AssertFailed(char const*, char const*, int, wchar_t const*, ...)   [UnknownFile]) 
0x46cc5264 UE4Editor-MetalShaderFormat.dylib!FGenerateMetalVisitor::print_constant(ir_constant*, int)   [UnknownFile]) 
0x46cc0359 UE4Editor-MetalShaderFormat.dylib!FGenerateMetalVisitor::visit(ir_constant*)   [UnknownFile]) 
0x46cbc931 UE4Editor-MetalShaderFormat.dylib!FGenerateMetalVisitor::visit(ir_expression*)   [UnknownFile]) 
0x46cbd029 UE4Editor-MetalShaderFormat.dylib!FGenerateMetalVisitor::visit(ir_expression*)   [UnknownFile]) 
0x46cbfd0c UE4Editor-MetalShaderFormat.dylib!FGenerateMetalVisitor::visit(ir_assignment*)   [UnknownFile]) 
0x46cbb900 UE4Editor-MetalShaderFormat.dylib!FGenerateMetalVisitor::visit(ir_function_signature*)   [UnknownFile]) 
0x46cbbed5 UE4Editor-MetalShaderFormat.dylib!FGenerateMetalVisitor::visit(ir_function*)   [UnknownFile]) 
0x46c88e8f UE4Editor-MetalShaderFormat.dylib!FGenerateMetalVisitor::run(exec_list*)   [UnknownFile]) 
0x46c7fde4 UE4Editor-MetalShaderFormat.dylib!FMetalCodeBackend::GenerateCode(exec_list*, _mesa_glsl_parse_state*, EHlslShaderFrequency)   [UnknownFile]) 
0x46c2a410 UE4Editor-MetalShaderFormat.dylib!FHlslCrossCompilerContext::Run(char const*, char const*, FCodeBackend*, char**, char**)   [UnknownFile]) 
0x46c99d5f UE4Editor-MetalShaderFormat.dylib!FMetalShaderOutputCooker::Build(TArray<unsigned char, FDefaultAllocator>&)   [UnknownFile]) 
0x1b0456e1 UE4Editor-DerivedDataCache.dylib!FDerivedDataCache::FBuildAsyncWorker::DoWork()   [UnknownFile]) 
0x1b043839 UE4Editor-DerivedDataCache.dylib!FAsyncTask<FDerivedDataCache::FBuildAsyncWorker>::DoWork()   [UnknownFile]) 
0x1b0466da UE4Editor-DerivedDataCache.dylib!FAsyncTask<FDerivedDataCache::FBuildAsyncWorker>::Start(bool, FQueuedThreadPool*)   [UnknownFile]) 
0x1b03ba3d UE4Editor-DerivedDataCache.dylib!FDerivedDataCache::GetSynchronous(FDerivedDataPluginInterface*, TArray<unsigned char, FDefaultAllocator>&, bool*)   [UnknownFile]) 
0x46ca9c33 UE4Editor-MetalShaderFormat.dylib!CompileShader_Metal(FShaderCompilerInput const&, FShaderCompilerOutput&, FString const&)   [UnknownFile]) 
0x46cda174 UE4Editor-MetalShaderFormat.dylib!FMetalShaderFormat::CompileShader(FName, FShaderCompilerInput const&, FShaderCompilerOutput&, FString const&) const   [UnknownFile]) 
0x05b4142f UE4Editor-Engine.dylib!FShaderCompileThreadRunnable::CompileDirectlyThroughDll()   [UnknownFile]) 
0x05b426d7 UE4Editor-Engine.dylib!FShaderCompileThreadRunnable::CompilingLoop()   [UnknownFile]) 
0x05b3a099 UE4Editor-Engine.dylib!FShaderCompileThreadRunnableBase::Run()   [UnknownFile]) 
0x0337e12e UE4Editor-Core.dylib!FRunnableThreadPThread::Run()   [UnknownFile]) 
0x03328e77 UE4Editor-Core.dylib!FRunnableThreadPThread::_ThreadProc(void*)   [UnknownFile]) 
0x5a0766c1 libsystem_pthread.dylib!_pthread_body()   [UnknownFile]) 
0x5a07656d libsystem_pthread.dylib!_pthread_body()   [UnknownFile]) 
0x5a075c5d libsystem_pthread.dylib!thread_start()   [UnknownFile]) 
Steps to Reproduce

repro steps currently unknown.

Callstack
SEGV_MAPERR at 0x3

UE4Editor-ApplicationCore.dylib!FMacErrorOutputDevice::Serialize()
UE4Editor-MetalShaderFormat.dylib!FGenerateMetalVisitor::print_constant()
UE4Editor-MetalShaderFormat.dylib!FGenerateMetalVisitor::visit()
UE4Editor-MetalShaderFormat.dylib!FGenerateMetalVisitor::visit()
UE4Editor-MetalShaderFormat.dylib!FGenerateMetalVisitor::visit()
UE4Editor-MetalShaderFormat.dylib!FGenerateMetalVisitor::visit()
UE4Editor-MetalShaderFormat.dylib!FGenerateMetalVisitor::visit()
UE4Editor-MetalShaderFormat.dylib!FGenerateMetalVisitor::visit()
UE4Editor-MetalShaderFormat.dylib!FGenerateMetalVisitor::run()
UE4Editor-MetalShaderFormat.dylib!FMetalCodeBackend::GenerateCode()
UE4Editor-MetalShaderFormat.dylib!FHlslCrossCompilerContext::Run()
UE4Editor-MetalShaderFormat.dylib!FMetalShaderOutputCooker::Build()
UE4Editor-DerivedDataCache.dylib!FDerivedDataCache::FBuildAsyncWorker::DoWork()
UE4Editor-DerivedDataCache.dylib!FAsyncTask<FDerivedDataCache::FBuildAsyncWorker>::DoWork()
UE4Editor-DerivedDataCache.dylib!FAsyncTask<FDerivedDataCache::FBuildAsyncWorker>::Start()
UE4Editor-DerivedDataCache.dylib!FDerivedDataCache::GetSynchronous()
UE4Editor-MetalShaderFormat.dylib!CompileShader_Metal()
UE4Editor-MetalShaderFormat.dylib!FMetalShaderFormat::CompileShader()
UE4Editor-Engine.dylib!FShaderCompileThreadRunnable::CompileDirectlyThroughDll()
UE4Editor-Engine.dylib!FShaderCompileThreadRunnable::CompilingLoop()
UE4Editor-Engine.dylib!FShaderCompileThreadRunnableBase::Run()
UE4Editor-Core.dylib!FRunnableThreadPThread::Run()
UE4Editor-Core.dylib!FRunnableThreadPThread::_ThreadProc()
libsystem_pthread.dylib!<Unknown>
libsystem_pthread.dylib!<Unknown>
libsystem_pthread.dylib!<Unknown>

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Fixed
ComponentUE - Graphics Features
Affects Versions4.18
Target Fix4.18
Fix Commit3660129
Main Commit3661409
Release Commit3660129
CreatedSep 22, 2017
ResolvedSep 23, 2017
UpdatedApr 27, 2018