gcc/testsuite/gcc.dg/gomp/macro-4.c

/* PR preprocessor/27746 */
/* { dg-do compile } */
/* { dg-options "-fopenmp -Wunknown-pragmas" } */

#define p		_Pragma ("omp parallel")
#define omp_p		_Pragma ("omp p")

void bar (void);

void
foo (void)
{
#pragma omp p		/* { dg-warning "-:ignoring '#pragma omp _Pragma'" } */
    bar ();
  omp_p			/* { dg-warning "-:ignoring '#pragma omp _Pragma'" } */
    bar ();
}

#define parallel	serial
#define omp_parallel	_Pragma ("omp parallel")

void
baz (void)
{
#pragma omp parallel	/* { dg-warning "-:ignoring '#pragma omp serial'" } */
    bar ();
  omp_parallel		/* { dg-warning "-:ignoring '#pragma omp serial'" } */
    bar ();
}