Help disabling GNU extensions in output of the C preprocessor

["Jose Miguel de la Rosa Trevin" <delarosatrevin@xxxxxxxxx>]

Hi all,

I need to write a 2nd C pre-processor that run after the
pre-processor, in the following way:
> gcc -E test.c > i_test.c
>./mypreprocessor i_test.c > ii_test.c
> gcc ii_test.c -o test

but my grammar fails due some
extensions like:

__extension__
__attribute__
__const

and others, there are any way of disable this in the output of the preprocessor?

Thanks in advance.
Jose Miguel.