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

Question

How can I tell where g++ was able to find an include file? Basically if I

#include <foo.h>

g++ will scan the search path, using any include options to add or alter the path. But, at the end of days, is there a way I can tell the absolute path of foo.h that g++ chose to compile? Especially relevant if there is more than one foo.h in the myriad of search paths.

Short of a way of accomplishing that... is there a way to get g++ to tell me what its final search path is after including defaults and all include options?

Answer 1

g++ -H ...

will also print the full path of include files in a format which shows which header includes which