tools/build/feature/test-setns.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 #define _GNU_SOURCE
 #include <sched.h>

 int main(void)
 {
 	return setns(0, 0);
 }
 #undef _GNU_SOURCE
	// SPDX-License-Identifier: GPL-2.0
	#define _GNU_SOURCE
	#include <sched.h>

	int main(void)
	{
	return setns(0, 0);
	}
	#undef _GNU_SOURCE