[cfe-dev] Newbie question: source locations

[Christian Convey]

I'm dealing with the clang AST for the first time, and I'm having
trouble understanding from the doxygen docs how the various flavors of
source locations relate to each other.  Can anyone point me to a good
explanation?

I *think* I'm pretty clear on spelling locations.  But I'm definitely
confused about "presumed location" and "getImmediateExpansionRange"