Attempting to compile using "gcc -traditional" gives errors
about header files. Compile this file for example:

#include <limits.h>

main()
{
}

If you use "gcc -traditional test.c" you get the following.
(I have tried this on two different machines now.)

In file included from /usr/lib/gcc-lib/i386-redhat-
linux/2.7.2.3/include/limits.
h:112,
                 from /usr/lib/gcc-lib/i386-redhat-
linux/2.7.2.3/include/syslimi
ts.h:7,
                 from /usr/lib/gcc-lib/i386-redhat-
linux/2.7.2.3/include/limits.
h:11,
                 from test.c:2:
/usr/include/limits.h:42: undefined or invalid # directive
/usr/include/limits.h:44: undefined or invalid # directive
/usr/include/limits.h:45: undefined or invalid # directive
/usr/include/limits.h:52: undefined or invalid # directive
/usr/include/limits.h:53: undefined or invalid # directive