If a C/C++ source file of an Autotools project is opened in the editor window and a header file is subsequently opened by double-clicking in the Outline view, defined symbol and inclue path information is taken from the actual build parameters for the source file. This is extended to any subsequent header opened from that header etc.. If the Eclipse session is closed then reopened, the defined symbol and include path information is no longer known.
The cause of the problem is that the include chain was using a session property for the file which gets obliterated upon closing the session. A fix has been made to use a persistent property.