c++ - How to tell where a header file is included from? -

how can tell g++ able find include file? if i

#include <foo.h> 

g++ scan search path, using include options add or alter path. but, @ end of days, there way can tell absolute path of foo.h g++ chose compile? relevant if there more 1 foo.h in myriad of search paths.

short of way of accomplishing that... there way g++ tell me final search path after including defaults , include options?

this give make dependencies list absolute paths of include files:

gcc  -m showtime.c 

if don't want system includes (i.e. #include <something.h>) use:

gcc  -mm showtime.c