Cross compile against Unreal Engine 5

[iniside]

Default workflow for building unreal engine binaries (dedicated server), for linux is cross compilation. I'm trying to get the same process workig for SDK. After some fiddling and trying around I got aroud, cross compile AWS SDK from Windows Linux by using unreal provided tools. Here the bat file contents:

set ENGINE_ROOT=J:\SurvivalGame\Engine
set THIRDPARTY_ROOT=%ENGINE_ROOT%\Source\ThirdParty
set CMAKE_ADDITIONAL_ARGUMENTS=-DBUILD_SHARED_LIBS=0 -DENABLE_UNITY_BUILD=0 -DAUTORUN_UNIT_TESTS=0 -DENABLE_TESTING=0 -DENABLE_LIB_ONLY=ON -DENABLE_STATIC_LIB=ON -DCMAKE_FIND_USE_SYSTEM_ENVIRONMENT_PATH=OFF -DCMAKE_OBJECT_PATH_MAX=2048 -DTARGET_ARCH="LINUX"
set CMAKE_OPENSSL_ARGUMENTS=-DOPENSSL_CRYPTO_LIBRARY=%THIRDPARTY_ROOT%\OpenSSL\1.1.1n\lib\Unix\x86_64-unknown-linux-gnu\libcrypto.a -DOPENSSL_SSL_LIBRARY=%THIRDPARTY_ROOT%\OpenSSL\1.1.1n\lib\Unix\x86_64-unknown-linux-gnu\libssl.a -DOPENSSL_INCLUDE_DIR=%THIRDPARTY_ROOT%\OpenSSL\1.1.1n\include\Unix\x86_64-unknown-linux-gnu -DOPENSSL_USE_STATIC_LIBS=ON
set CMAKE_CRYPTO_ARGUMENTS=-Dcrypto_LIBRARY=J:/SurvivalGame/Engine/Source/ThirdParty/OpenSSL/1.1.1n/lib/Unix/x86_64-unknown-linux-gnu/libcrypto.a -Dcrypto_INCLUDE_DIR=J:/SurvivalGame/Engine/Source/ThirdParty/OpenSSL/1.1.1n/include/Unix/x86_64-unknown-linux-gnu
set CMAKE_ZLIB_ARGUMENTS=-DZLIB_LIBRARY=%THIRDPARTY_ROOT%\zlib\1.2.12\lib\Unix\x86_64-unknown-linux-gnu\Release\libz.a -DZLIB_INCLUDE_DIR=%THIRDPARTY_ROOT%\zlib\1.2.12\include
set CMAKE_CURL_ARGUMENTS=-DCURL_LIBRARY=J:/SurvivalGame/Engine/Source/ThirdParty/libcurl/7.83.1/lib/Unix/x86_64-unknown-linux-gnu/Release/libcurl.a -DCURL_INCLUDE_DIR=J:/SurvivalGame/Engine/Source/ThirdParty/libcurl/7.83.1/include
call "%ENGINE_ROOT%\Build\BatchFiles\RunUAT.bat" BuildCMakeLib -TargetPlatform=Unix -TargetArchitecture=x86_64-unknown-linux-gnu -TargetLib=aws-sdk-cpp-fork -TargetLibVersion=1.9.297 -TargetConfigs=Release -LibOutputPath=lib -CMakeGenerator=Makefile -CMakeAdditionalArguments="%CMAKE_ADDITIONAL_ARGUMENTS% %CMAKE_OPENSSL_ARGUMENTS% %CMAKE_ZLIB_ARGUMENTS% %CMAKE_CURL_ARGUMENTS% %CMAKE_CRYPTO_ARGUMENTS%" -SkipCreateChangelist -SkipSubmit || exit /b

It compiles fine, but when I try to link it against unreal project I get two errors:

aws\common\math.inl(191,5): Error : '_MSC_VER' is not defined, evaluates to 0 [-Werror,-Wundef]

This I fixed, and recompiled again (the if is trying to check for value instead if define exists).

But this I the error I have no idea what to do about:

J:\SurvivalGame\Engine\Source\ThirdParty\Unix\LibCxx\include\c++\v1\locale(1216,18): Error  : member reference type 'int' is not a pointer
            if (!isdigit_l(*__ns, _LIBCPP_GET_C_LOCALE))
                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
C:\UnrealToolchains\v20_clang-13.0.1-centos7\x86_64-unknown-linux-gnu\usr\include\ctype.h(328,26): note: expanded from macro 'isdigit_l'
#  define isdigit_l(c,l)        __isdigit_l ((c), (l))
                                ^~~~~~~~~~~~~~~~~~~~~~
C:\UnrealToolchains\v20_clang-13.0.1-centos7\x86_64-unknown-linux-gnu\usr\include\ctype.h(309,28): note: expanded from macro '__isdigit_l'
#  define __isdigit_l(c,l)      __isctype_l((c), _ISdigit, (l))
                                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
C:\UnrealToolchains\v20_clang-13.0.1-centos7\x86_64-unknown-linux-gnu\usr\include\ctype.h(263,14): note: expanded from macro '__isctype_l'
  ((locale)->__ctype_b[(int) (c)] & (unsigned short int) type)
   ~~~~~~~~  ^

And I'm stuck. At that point I don't really know what to do to push it any further.

[jmklix]

There is a newish blog created on How to Integrate the AWS C++ SDK with Unreal Engine. Please let us know if you are still running into any problems with cross compiling this sdk

[smg-daniell]

Hi I was trying to integrate AWS SDK with Unreal Engine 5.1.0 source on Linux (Amazon Linux 2) and I received the following error while linking. The error looks like AWS SDK was linked with libstdc++ and UE is trying to link with libc++. Is there any way to work around this issue?

I have tried to follow the instructions provided in the link above to build the sdk and also tried to follow the instructions on the sdk's github page to build it. But both result in similar errors.

>>> referenced by DefaultEndpointProvider.h:76 (/Plugins/Test/Source/Test/Include/aws/core/endpoint/DefaultEndpointProvider.h:76)
>>>               /Intermediate/Build/Linux/B4D820EA/UnrealEditor/Development/App/Module.App.30_of_37.cpp.o:(Aws::Endpoint::DefaultEndpointProvider<Aws::Client::GenericClientConfiguration<true>, Aws::Endpoint::BuiltInParameters, Aws::Endpoint::ClientContextParameters>::ResolveEndpoint(std::__1::vector<Aws::Endpoint::EndpointParameter, std::__1::allocator<Aws::Endpoint::EndpointParameter> > const&) const)
ld.lld: error: undefined symbol: Aws::Endpoint::BuiltInParameters::OverrideEndpoint(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, Aws::Http::Scheme const&)
>>> referenced by DefaultEndpointProvider.h:99 (/Plugins/Test/Source/Test/Include/aws/core/endpoint/DefaultEndpointProvider.h:99)
>>>               /Intermediate/Build/Linux/B4D820EA/UnrealEditor/Development/App/Module.App.30_of_37.cpp.o:(Aws::Endpoint::DefaultEndpointProvider<Aws::Client::GenericClientConfiguration<true>, Aws::Endpoint::BuiltInParameters, Aws::Endpoint::ClientContextParameters>::OverrideEndpoint(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&))
ld.lld: error: undefined symbol: std::_Rb_tree_insert_and_rebalance(bool, std::_Rb_tree_node_base*, std::_Rb_tree_node_base*, std::_Rb_tree_node_base&)
>>> referenced by AmazonWebServiceRequest.cpp
>>>               AmazonWebServiceRequest.cpp.o:(Aws::AmazonWebServiceRequest::SetAdditionalCustomHeaderValue(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)) in archive /Plugins/Test/Source/Test/Binaries/Linux/libaws-cpp-sdk-core.a
>>> referenced by URI.cpp
>>>               URI.cpp.o:(InsertValueOrderedParameter(std::multimap<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::less<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::pair<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)) in archive /Plugins/Test/Source/AwsSdk/Binaries/Linux/libaws-cpp-sdk-core.a
>>> referenced by URI.cpp
>>>               URI.cpp.o:(InsertValueOrderedParameter(std::multimap<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::less<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::pair<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)) in archive /Plugins/Test/Source/Test/Binaries/Linux/libaws-cpp-sdk-core.a
>>> referenced 27 more times

[jmklix]

We don't fully support Unreal Engine so I have created a feature request here.

[github-actions[bot]]

Hello! Reopening this discussion to make it searchable.