I stumbled upon some "Unable to resolve Identifier" issues while using the Boost libraries. I boiled the problem down to the following snippet:

#include <iostream>

namespace first {
    namespace second {
    };
    using namespace second;
    namespace second {
        namespace third {

            void third_print() {
                std::cout << "BAM \n";
            }
        }

    }

}

int main(int argc, char** argv) {


    first::third::third_print();          // Unable to resolve identifier third
    first::second::third::third_print();  // Works

    return 0;
}