> Maybe that should be regarded as a bug in cpp, but it can be useful at 
> times if the preprocessor just ignores things it doesn't understand, 
> especially inside #if{,def} sequences that are false.

Yeah, and it can also screw you by silently accepting code that produces
buggy output!

I've seen OMF incompatibilities introduced into a shipping toolchain because
no one noticed the "preprocessor directive #elsse unknown, ignored" message
until it was Too Late.

Todd Whitesel
toddpw @ best.com