From GCC Package maintainer Peter Felecan :
The first release of the new GNU Compiler Collection is available.
This is the branch 4 of the GNU compiler suite. The branch 4 is
new. My recommendation is to not use it in a production
environment. If you wish to use a stable and well tested version of
the GNU compiler suite you can use the branch 3; for this, look for
the gcc3 related packages. There is also the branch 2 which is still
used and sometimes preferred for some products. If you are in this
situation look for the gcc2 related packages.