rt_gccstream/gcc/testsuite/gcc.dg/cpp/cmdlne-dU-6.c

/* { dg-do preprocess } */
/* { dg-options "-P -dU" } */
/* { dg-final { scan-file cmdlne-dU-6.i "^\n*#undef A\n+#define A *\n*$" } } */
#ifdef A
#endif
#define A
#ifdef A
#endif