-P   NOTE: Use of -P is strongly discouraged because of its inherent
            problems, including poor portability.

            This option causes your program to be run through the C preproces-
            sor before compilation by Perl.  Because both comments and cpp
            directives begin with the # character, you should avoid starting
            comments with any words recognized by the C preprocessor such as
            "if", "else", or "define".

            If you're considering using "-P", you might also want to look at
            the Filter::cpp module from CPAN.