Created attachment 171267 [details]
(Preliminary) Patch to solve the problem with example.

Example:

test.cpp:

#include <iostream>
using namespace std;

#define FUNC1

void func1(int test)
{
        cout << "func1: Hallo" << endl;
}
void func2(int test)
{
        cout << "func2: Hallo" << endl;
}

int main() {

#ifdef FUNC1
        func1(0);
#else
        func2(0);
#endif

        return 0;
}


Doxygen produces something like this for the main function when
generating xml output:

<references refid="test_8cpp_1a5d7f916959f4f32d1f8d38816c20fbef"
compoundref="test_8cpp" startline="7" endline="10">func1</references>
<references refid="test_8cpp_1af40a1280e9eecc3ea5aa6e37a4b41f65"
compoundref="test_8cpp" startline="11" endline="14">func2</references>

But the second function (func2) gets never called.