Tests/FindOpenMP/Test/main.c - third_party/github.com/Kitware/CMake - Git at Google

 #include <omp.h>
 int main(void)
 {
 #ifndef _OPENMP
   breaks_on_purpose
 #endif
 }
	#include <omp.h>
	int main(void)
	{
	#ifndef _OPENMP
	breaks_on_purpose
	#endif
	}