Does gcc define anything when -g is specified?

Question

Shortly, I want to know if gcc (or g++. I need it in C, but also am curious about c++) defines any special symbols if -g is enabled. Does it? I

Answer 1

Running
g++ -E -dD -xc++ /dev/null
vs.
g++ -E -dD -g -xc++ /dev/null
shows me no extra defined symbols.

That, combined with the lack of any documentation stating that symbols get defined, should be enough to safely say that nothing gets defined.