(Command-line option to suppress warning: -w-obs) 

Issues a warning upon usage for any "C" linkage function that has been specified. This will warn about functions that are "obsolete". 

Here's an example of it's usage:

#ifdef __cplusplus
extern "C" {
#endif
void my_func(void);
#ifdef __cplusplus
}
#endif
#pragma obsolete my_func
main()
{
my_func();   // Generates warning about obsolete function
}