#include <iostream>
#include <string>
#include <experimental/source_location>
 
void log(std::string message,
         const std::experimental::source_location& location = std::experimental::source_location::current())
{
    std::cout << "info:"
              << location.function_name() << ":"
              << location.file_name() << ":"
              << location.line() << ":"
              << location.column() << " "
              << message << '\n';
}
 
int main()
{
    log("Hello world!");
}