I was about to report "cpp dies if stdin is a terminal" when I remembered
that, last time I reported it, my /usr/bin/cpp was a 44 character
shell script that just ran cat.  Sure enough.

It looks very much like the shell script "cppstdin" distributed with perl.

Does anyone know that perl is installing a cpp over /usr/bin/cpp under
any likely circumstances?  I last saw this right after installing perl,
and I see it now just after installing a new perl.

-s