LNK2019 error but Intellisense works fine

Question

I have a native C++ unit test project that is throwing a LNK2019 error for every function call in the project under test. Surprisingly though, IntelliSense works just fine!

The project under test is a static library (.lib) comprised of a single public static function (type and member names have been changed to protect the innocent):

Type.h

#pragma once

#include <string>

using namespace std;

namespace N
{
    enum class ResultCode { Undefined, A, B, C}; 

    class MyType
    {
    public:
        static void GetResult(string id, string metadata, ResultCode result);
    };
}

Type.cpp

#include "pch.h"
#include "Type.h"

namespace N
{
    void MyType::GetResult(string id, string metadata, N::ResultCode result)
    {
        // implementation
    }
}

My unit test project (a .dll) does not use a header file for the tests. I'm using the google test framework. Here is the source:

Test.cpp

#include <pch.h>
#include <gtest/gtest.h>
#include <gtesthelpers/gtesthelpers.h>
#include <MyType.h>

class MyTypeUnitTests : public testing::Test {};

TEST(MyTypeUnitTests, Foo)
{
    std::string metadata; 
    N::ResultCode result = N::ResultCode::Undefined;
    N::MyType::GetResult("1234", metadata, result);
    ASSERT_TRUE(result == N::ResultCode::A);
}

When I compile MyType, everything is just fine. And when I wrote Test, IntelliSense provided me with the signature for GetResult. But when I compile:

Test.obj : error LNK2019: unresolved external symbol "public: static void __cdecl N:MyType:GetResult(class std::basic_string,class std::allocator >,class std::basic_string,class std::allocator >, enum N::ResultCode)" ... referenced in function ...

I have modified the test project properties so that:

• VC++ Directories > Include Directories includes a reference to the directory containing MyType.h;
• VC++ Directories > Reference Directories includes a reference to the directory containing MyType.lib;

I have also confirmed that under Project Dependencies for the test project, the project under test is checked. I also used undname to verify that the function name specified in the error matches the name in the .h and .cpp.

Finally I created a new static parameterless function in MyType, and tried calling that from the test (so as to rule out a problem with the enum parameter) but no dice. I have followed the instructions on the MSDN page that I linked to above, and I'm out of ideas.

How can I go about resolving this?

EDIT: Showing the namespace block in the cpp.

Answer 1

I resolved this by adding a reference to my library in the test project properties at Configuration Properties > Linker > Input > Additional Dependencies. No path, just "Type.lib".

Answer 2

This is your problem:

using namespace N;

void MyType::GetResult(string id, string metadata, N::ResultCode result)
{
    // implementation
}

You should actually wrap the definition into a namespace:

namespace N
{

void MyType::GetResult(string id, string metadata, N::ResultCode result)
{
    // implementation
}

}