Unresolved externals no matter what compile option I use

[j2inet]

I've got a simple C++ program that uses that AWS CPP SDK. Here is the entirity of the source code.

#include <iostream>
#define USE_IMPORT_EXPORT
#include <aws/core/Aws.h>
#pragma comment(lib, "aws-cpp-sdk-core.lib")
int main()
{
    Aws::SDKOptions options;
    Aws::InitAPI(options);
    Aws::ShutdownAPI(options);
}

In addition to this source code, I have also added the folder that has the compiled libs that were installed from the SDK compilation to the additional lib folders setting for the project, and I've added the include folder from the aws cpp installation to the additional include folder settings.

In the above, I have a #define and undef for USE_IMPORT_EXPORT. I'm getting the least amount of unresolved errors when I have USE_IMPORT_EXPORT uncommented. I've tried both with different compilation options for the SDK with nothing leading to 100% success.

This is the error output for the shortest set of errors that I got.

Build started at 4:19 PM...
1>------ Build started: Project: AWSFailureTest, Configuration: Debug x64 ------
1>AWSFailureTest.cpp
1>AWSFailureTest.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) void __cdecl Aws::InitAPI(struct Aws::SDKOptions const &)" (__imp_?InitAPI@Aws@@YAXAEBUSDKOptions@1@@Z) referenced in function main
1>AWSFailureTest.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) void __cdecl Aws::ShutdownAPI(struct Aws::SDKOptions const &)" (__imp_?ShutdownAPI@Aws@@YAXAEBUSDKOptions@1@@Z) referenced in function main
1>C:\Users\Joel\source\repos\AWSFailureTest\x64\Debug\AWSFailureTest.exe : fatal error LNK1120: 2 unresolved externals
1>Done building project "AWSFailureTest.vcxproj" -- FAILED.
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
========== Build completed at 4:19 PM and took 00.964 seconds ==========

To compile the SDK I made a batch file. This ensures that I am compiling it the same way on any machine that I try. Here is what I did to compile the SDK.

@ECHO OFF
pushd
SET startTime=%date% %time%
set CloneDrive=c:
set CloneFolder=%CloneDrive%\shares\projects\amazon
set InstallDrive=c:
set InstallFolder=%InstallDrive%\shares\projects\amazon\aws-cpp-sdk-lib

%InstallDrive%
mkdir %InstallFolder%
%CloneDrive%
mkdir %CloneFolder%
cd %CloneFolder%

git clone --recurse-submodules https://github.com/aws/aws-sdk-cpp
cd aws-sdk-cpp
mkdir sdk_build
cd sdk_build
cmake ".." -DCMAKE_BUILD_TYPE=Debug  -G "Visual Studio 17 2022" -DBUILD_SHARED_LIBS=OFF -A x64 -DENABLE_TESTING="OFF" -DFORCE_SHARED_CRT=ON -DCMAKE_INSTALL_PREFIX=%InstallFolder%
cmake --build . --config=Debug
cmake --install . --config=Debug

SET endTime=%date% %time%

ECHO For more information on this procedure, see https://docs.aws.amazon.com/sdk-for-cpp/
ECHO Start Time : %startTime%
ECHO End Time:  %endTime%

If the settings BUILD_SHARED_LIBS and FORCE_SHARED_CRT, I've tried changing which one of these mutually exclusive settings gets set to ON

Can anyone tell me what is going on here? Why is it that the SDK is never able to resolve these externals? If I reference other libraries, some of those libraries have this issue, some do not.

[DmitriyMusatkin]

You are compiling SDK statically, but then trying to import symbols from dll. You likely dont need USE_IMPORT_EXPORT as thats what defines the dllimport symbol

[j2inet]

I've documented how I compiled the AWS C++ SDK and provided a batch file that will do most of what needs to be done. From a Visual Studio developer console with admin level privileges, I have a batch file that I run that clones the SDK and compiles 4 variations of it. Debug-Shared, Debug-Static, Release-Shared, Release-Static. You can find more on that here.
https://blog.j2i.net/2025/03/25/compiling-and-linking-to-the-aws-c-sdk/

The resolution to my issue was that there were many other DLLs that I needed to link to. I hadn't realized there were dependencies on these DLLs from the ones I was linking with. I'm using Visual C++'s #pragma comment(lib, "whatever.lib") to link to the DLLs. To link to all the one's that I needed, the following was added to my program.

#pragma comment(lib, "aws-cpp-sdk-core.lib")
#pragma comment(lib, "aws-c-auth.lib")
#pragma comment(lib, "aws-c-cal.lib")
#pragma comment(lib, "aws-c-common.lib")
#pragma comment(lib, "aws-c-compression.lib")
#pragma comment(lib, "aws-c-event-stream.lib")
#pragma comment(lib, "aws-checksums.lib")
#pragma comment(lib, "aws-c-http.lib")
#pragma comment(lib, "aws-c-io.lib")
#pragma comment(lib, "aws-c-mqtt.lib")
#pragma comment(lib, "aws-cpp-sdk-core.lib")
#pragma comment(lib, "aws-crt-cpp.lib")
#pragma comment(lib, "aws-c-s3.lib")
#pragma comment(lib, "aws-c-sdkutils.lib")
 
#pragma comment(lib, "aws-c-s3.lib")
#pragma comment(lib, "aws-c-common.lib")
#pragma comment(lib, "aws-crt-cpp.lib")
#pragma comment(lib, "aws-cpp-sdk-s3.lib")
#pragma comment(lib, "aws-cpp-sdk-s3-encryption.lib")
#pragma comment(lib, "aws-cpp-sdk-s3-crt.lib")
#pragma comment(lib, "aws-cpp-sdk-transfer.lib")

More information on how I arrived at this is in the link posted above. The script I used for compiling the SDK can be found at https://github.com/j2inet/DevSetup/blob/main/aws-cpp/aws-cpp-sdk-setup.cmd

[DmitriyMusatkin]

note you are mixing up shared (.dll) and static (.lib) objects. if you compile cpp sdk to a shared object (i.e. dll, which we consider a typical flow), then you dont need to bother with any of its dependencies and can just import whatever you need from dll). But in the static object case you do need to link every single dep of cpp sdk, since its gonna be built into your final binary.