Concatenating proprocessor macro __FUNCTION__ with a string

Question

This should be trivial but I cannot seem to figure out how to concatenate __FUNCTION__ with strings especially on GCC -- although it works on VC++ (I'm porting some code to Linux)

#include <iostream>
#include <string>

#define KLASS_NAME  "Global"

int main()
{
    std::string msg = KLASS_NAME "::" __FUNCTION__;
    std::cout << msg << std::endl;
}

Online VC++ version

GCC error message

Test.cpp:9:36: error: expected ‘,’ or ‘;’ before ‘__FUNCTION__’
  std::string msg = KLASS_NAME "::" __FUNCTION__;

---

Update

Thanks to Chris, apparently adjacent string literals are concatenated [reference]. So VC++ may be correct in this case, until you consider that __FUNCTION__ is non-standard.

Answer 1

You need a concatenation operator and explicitly construct the string such that the right concatenation operator is found:

#include <iostream>
#include <string>

#define KLASS_NAME  "Global"

int main()
{
    std::string msg = std::string(KLASS_NAME) + "::" + __FUNCTION__;
    std::cout << msg << std::endl;
}

Live example: http://ideone.com/vn4yra