Eigen/src/ThreadPool/InternalHeaderCheck.h - eigen - Git at Google

 #ifndef EIGEN_THREADPOOL_MODULE_H
 #error \
     "Please include unsupported/Eigen/CXX11/ThreadPool instead of including headers inside the src directory directly."
 #endif
	#ifndef EIGEN_THREADPOOL_MODULE_H
	#error \
	"Please include unsupported/Eigen/CXX11/ThreadPool instead of including headers inside the src directory directly."
	#endif