rospack export does not list all include directories

edit

Suppose I'd like to retrieve all the build flags to be able to integrate syntax checking into my favorite editor for the package my_vision. I'd need to add a check-syntax target to the cmake.mk file according to something like this:

.PHONY: check-syntax
check-syntax:
        gcc -Wall -fsyntax-only $(shell rospack export --lang=cpp --attrib=cflags) $(CHK_SOURCES)

rospack export does not list /home/me/ros/my_vision/include as a include directory, even though the headers I've place here will still be found during compilation. So:

1. How does the ROS build system find my custom header files?

2. Can I also use this functionality in the cmake.mk file?