#num line directives suppress warnings in C code?

[Dara Hazeghi <dhazeghi@xxxxxxxxx>]

I've been dealing with a fair amount preprocessed C code, which includes directives that look like:
#0 "/usr/local/gcctrunk/lib/gcc/x86_64unknownlinuxgnu/4.9.0/include/stddef.h" 3


The problem I've encountered is that when I compile files with such code in them using gcc, the usual warnings from the compiler are suppressed.  I'm guessing that this is intended behavior?  If so, is there a way to disable it (re-enabling the warnings)?

For example the testcase below produces no warnings unless the first line is commented out.  Best,

Dara

------test.c-------
#0 "foo" 3

main ()
{
    printf ("%X\n");
}