Generate compiler messages from code

Hi

I just wonder, if its possible to add some pragma's or other syntaxs in the C files, that would generate custom compiler errors or warnings when build?

Just something like this

#ifdef _OLD_HW <COMPILE WARN>: "Building for old Hardware"
#endif

Then when its compiled, the message "Building for old Hardware" is shown in the compiler output windows.
This could be very usefull in automatic build environment etc.

Thomas