DI_problem.cpp

#include <iostream>

namespace ModuleA
{
    struct Config
    {
        static unsigned char ( * get_next_byte_function)(void);
    };
    unsigned char (*Config::get_next_byte_function)(void)
            = []()-> unsigned char{ return '\0';};
}
//// Other src file ////
namespace ModuleB
{
    struct Config
    {
        static unsigned char (* get_next_byte_function)(void);
    };
    unsigned char (*Config::get_next_byte_function)(void)
            = []()-> unsigned char{ return '\0';};
}                             

//// Other src file ////
namespace ModuleUtilities
{
    unsigned char get_next_byte()
    {
        std::cout << "3";
        return '3';
    };
}

/// Main/Logic file ///

int main()
{
    ModuleA::Config::get_next_byte_function = &ModuleUtilities::get_next_byte;
    ModuleB::Config::get_next_byte_function = &ModuleUtilities::get_next_byte;
    ModuleB::Config::get_next_byte_function();
    ModuleB::Config::get_next_byte_function();
}