error : ‘ptrdiff_t’ does not name a type

external/gtest/src/../include/gtest/internal/gtest-param-util.h:122:11: error: ‘ptrdiff_t’ does not name a type 


external/gtest/src/../include/gtest/internal/gtest-param-util.h 파일 수정


======================================================
#include <vector>
+          #include <cstddef>
#include <gtest/internal/gtest-port.h> 
======================================================

위와 같이 cstddef include 추가