CXXSources-- what are they?

I'm new to compiling C/C++ with the aid of make. I downloaded an open source project and noticed that there is in the make file CXXSources and CXXObjects. I think I understand roughly what the make file is doing with them but...

I don't have any of the source files listed under CXXSources. Are these like dependences I'm supposed to know how to find? Is there any custom as to what CXXSource is versus just Source?

Added link to project: http://www.fim.uni-passau.de/en/fim/faculty/chairs/theoretische-informatik/projects.html

More specifically, the GML parser, eg. http://www.fim.uni-passau.de/fileadmin/files/lehrstuhl/brandenburg/projekte/gml/gm开发者_开发技巧l-parser.tar.gz

It seems to be getting stuck on the line:

gml_to_graph : $(CXXOBJECTS) gml_scanner.o gml_parser.o $(CXX) -o gml_to_graph_demo $(CXXOBJECTS) gml_parser.o gml_scanner.o -L$(LEDADIR)/lib -lG -lL -lm

The $CXXObjects is defined by

CXXSOURCES = gml_to_graph.cc gml_to_graph_demo.cc CXXOBJECTS = $(CXXSOURCES:.cc=.o)

So I need gml_to_graph.cc, it seems. Or maybe I'm wrong?

Usually, the variables are set before the point where you see them. This could be

(a) via the environment (b) before including the quoted makefile (c) in the quoted makefile, but preceding the location quoted

To see (verbosely) what GNU make takes into account, do:

make -Bn

(it will show everything that _would get executed)

Even more verbose:

make -p all

It will show you all the internal variable expansions.

If you post a link or more information, we will be able to come up with less generic (and hence possibly less confusing) answers