why didn't my g++ and gcc version get upgraded?

I am on a Mac. I updated my OSx to Yosemite. I updated my xcode to version 6. I downloaded the command line tools.

And still, whenever I type in g++ --version, I get:

# g++ --version
couldn't understand kern.osversion `14.1.0'
i686-apple-darwin11-llvm-g++-4.2 (GCC) 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2336.11.00)
Copyright (C) 2007 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

meaning, I am still using the old version of g++ and gcc.

Why wasn't it upgraded? I am interested in using c++0x in Eclipse, and for that I need a newer g++/gcc compiler.