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unresolved external symbol Aws::Malloc #23

Wylie-Modro opened this issue Oct 9, 2019 · 1 comment


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@Wylie-Modro Wylie-Modro commented Oct 9, 2019

Hi everyone,

I followed these wonderful tutorials to get a game session running on AWS GameLift and got clients to connect to it successfully.
I did have to rollback the GameLift Client SDK commit to the one in the video (commit 14), as I encountered something similar to this issue
I am on Windows using Unreal 4.21.

However I have hit what appears to be a missing some dependencies within the Client SDK. I was trying to use Aws::Vector which is part of AWSCore but upon build I get the following linker errors:

error LNK2019: unresolved external symbol "void * __cdecl Aws::Malloc(char const *,unsigned __int64)" (?Malloc@Aws@@YAPEAXPEBD_K@Z) referenced in function "private: bool __cdecl std::vector<class Aws::GameLift::Model::GameSessionQueueDestination,class Aws::Allocator<class Aws::GameLift::Model::GameSessionQueueDestination> >::_Buy(unsigned __int64)" (?_Buy@?$vector@VGameSessionQueueDestination@Model@GameLift@Aws@@V?$Allocator@VGameSessionQueueDestination@Model@GameLift@Aws@@@4@@std@@AEAA_N_K@Z)

error LNK2019: unresolved external symbol "void __cdecl Aws::Free(void *)" (?Free@Aws@@YAXPEAX@Z) referenced in function "public: __cdecl std::vector<class Aws::GameLift::Model::GameSessionQueueDestination,class Aws::Allocator<class Aws::GameLift::Model::GameSessionQueueDestination> >::~vector<class Aws::GameLift::Model::GameSessionQueueDestination,class Aws::Allocator<class Aws::GameLift::Model::GameSessionQueueDestination> >(void)" (??1?$vector@VGameSessionQueueDestination@Model@GameLift@Aws@@V?$Allocator@VGameSessionQueueDestination@Model@GameLift@Aws@@@4@@std@@QEAA@XZ)

These linker errors are usually encountered when the linker cannot find the correct function definition for a used function declaration. The Client SDKs that I cloned has the AWSCore header files and I also have the aws-cpp-sdk-core dll and lib files in Plugins\GameLiftClientSDK\ThirdParty\GameLiftClientSDK\Win64, like the tutorial instructed, so it should have the correct function definitions.

AWS::Vector is using AWS::Allocator, which is then using Malloc and Free.

template< typename T > using Vector = std::vector< T, Aws::Allocator< T > >;

typename Base::pointer allocate(size_type n, const void *hint = nullptr)
return reinterpret_cast<typename Base::pointer>(Malloc("AWSSTL", n * sizeof(T)));

AWS_CORE_API void* Malloc(const char* allocationTag, size_t allocationSize);

In the aws-cpp-sdk github repo I can see the AWSMemory.cpp file

I can see that it has a #include <aws/common/common.h> from the aws-c-common library, but I believe that was only added recently and since I am using an older commit of the client sdk I dont think I should have encountered this error. AWS says ." "Starting from version 1.7.0, we added several third party dependencies, including aws-c-common, aws-checksums and aws-c-event-stream

Either way, in attempt to solve this I added AWSMemory.cpp to AWSCore, then downloaded aws-c-common, built it, copied its lib and dll to ThirdParty and added all the headers to AWSCore/Public/common. Then edited AWSCore.Build.cs and AWSCoreModule.h/.cpp to add the lib and dll dependencies, but I end up hitting a wall of macro error like:

aws/common/assert.h(57): error C4668: '__clang_analyzer__' is not defined as a preprocessor macro, replacing with '0' for '#if/#elif'
aws/common/predicates.h(21): error C4668: 'AWS_DEEP_CHECKS' is not defined as a preprocessor macro, replacing with '0' for '#if/#elif'
AWSMemory.cpp(129): error C4668: '__GNUC__' is not defined as a preprocessor macro, replacing with '0' for '#if/#elif'

I have also tried to build aws-c-common from source as a new unreal module, but ended up with even more errors.

I just want to use a damn AWS::Vector.
Anyone know if I am missing something or is there a defect with the client sdk?

@chris-gong, did you ever encounter this?


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@Wylie-Modro Wylie-Modro commented Oct 13, 2019

Just a note: I updated the AWS CPP SDK binaries and still get the same error.
Any ideas @ryanjon2040?

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