clang/test/Modules/Inputs/submodule-visibility/cycle1.h - llvm-project - Git at Google

 #ifndef CYCLE1
 #define CYCLE1

 #include "cycle2.h"

 struct C1 {};

 #endif
	#ifndef CYCLE1
	#define CYCLE1

	#include "cycle2.h"

	struct C1 {};

	#endif