share/cmake-3.23/Modules/CheckIncludeFile.c.in - platform/prebuilts/cmake/windows-x86 - Git at Google

 #include <${CHECK_INCLUDE_FILE_VAR}>

 #ifdef __CLASSIC_C__
 int main()
 {
   return 0;
 }
 #else
 int main(void)
 {
   return 0;
 }
 #endif
	#include <${CHECK_INCLUDE_FILE_VAR}>

	#ifdef __CLASSIC_C__
	int main()
	{
	return 0;
	}
	#else
	int main(void)
	{
	return 0;
	}
	#endif