unc1.c

this is a gcc file, you can download it and learn its usetility, for further detail please look at t

/* Tests for un-terminated conditionals: 1.  */
/* { dg-do preprocess } */

#if 1  /* { dg-error "unterminated" "unterminated #if" } */

#ifdef notdef /* { dg-bogus "unterminated" "nested terminated #ifdef" } */

blah blah blah

#endif

more text

/* oops! */