Specifying out-of-tree include paths

Hello,

Thank you for GNU Global.  It's really quite nice.

I have a question:

1) How do I specify out-of-tree include paths in the case of a C++ project?  Ie, I have files included like

#include "file.h"

which are not reachable recursively from the directory where the project sources are kept (which is where I run gtags).

I would expect that there is an option (like the -I flag to a C compiler) to specify such directories manually (otherwise these include files, often specifying different interfaces, will be unparsed!)


Regards,

Tobias Gerdin