Can't gem install json -v '1.7.3'
Use which gcc and create a symlink to it in /usr/bin/gcc-4.2. e.g.
sudo ln -s /usr/bin/gcc /usr/bin/gcc-4.2
Use which gcc and create a symlink to it in /usr/bin/gcc-4.2. e.g.
sudo ln -s /usr/bin/gcc /usr/bin/gcc-4.2