gcc/libgomp/testsuite/libgomp.c/examples-4/task_dep-2.c

/* { dg-do run } */

#include <stdlib.h>
int main()
{
   int x = 1;
   #pragma omp parallel
   #pragma omp single
   {
      #pragma omp task shared(x) depend(in: x)
        if (x != 1)
          abort ();
      #pragma omp task shared(x) depend(out: x)
        x = 2;
   }
   return 0;
}