I'm building a library that was originally written to be compiled with gcc (I'm using MSVC). Most of the functions look something like this:-

void the_function_name ()
  assert ( <whatever> );

  if (DEBUG (BUFFER)) {
    // Dump some Debug information

  // Rest of the function
I looked through the header files and discovered that one of them re-defines DEBUG - like so:-

#define DEBUG_LEVEL(WHAT, LEVEL) (_hb_debug ((LEVEL), HB_DEBUG_##WHAT))
If I build a Debug version I see the expected warning from MSVC:-

warning C4005: 'DEBUG' : macro redefinition
That in itself doesn't worry me unduly. What worries me more is that there's no guard around the above re-definition. So I'm worried in case DEBUG will now be defined for my Release builds as well as my Debug builds. I contacted the author who said that this won't happen because the compiler will optimize everything away when building a Release version. Does anyone know if that's true, either for gcc or MSVC?