Update: On OpenSolaris 2008.11 I used the following (after having intalled gcc packages from blastwave):
../gcc-4.3.2/configure --with-gnu-as --with-as=/usr/sfw/bin/gas --without-gnu-ld --with-ld=/usr/ccs/bin/ld --enable-shared --enable-languages=c,c++,objc,fortran --with-mpfr=/opt/csw --with-gmp=/opt/csw --with-libiconv-prefix=/opt/csw --prefix=/usr/local && gmake -j4
I got a new laptop (my old one was 2 1/2 years old, huge, and prone to overheating - but other than that still not a bad machine). The new laptop is a Dell Inspiron E1505N, shipped with Ubuntu. I removed Ubuntu immediately as my experiences have never been good with it. Vista was installed and removed the next day as well. I'm now happily running (for the most part) Windows XP 64 edition and Solaris Developer edition on the machine. Perhaps a full review of Solaris will be in order later, but for now, I wanted to show how to build GCC 4.2.0 on Solaris.
It is rather simple once you know the tricks.... I leave it to the reader to deduce why all this works, as much of it was just trial and error. Note: I never got gcj to work and I didn't bother with ada. There were several bugs in boehm-gc with which I ran out of patience. Please let me know if you have better success =) I'm new to Solaris still; I've primarily been a user of Linux for the past few years.
Here is the path that was used to build GCC:
bash-3.00$ echo $PATH
(make sure you have mpfr and gmp installed - I installed the packages from blastwave)
And the command to build:
../gcc-4.2.0/configure --with-as=/opt/csw/bin/gas --with-gnu-as --with-ld=/usr/ccs/bin/ld --without-gnu-ld --enable-threads=posix --enable-multilib --enable-nls --with-included-gettext --with-system-zlib --with-mpfr=/opt/csw --with-gmp=/opt/csw --enable-languages=c,c++,objc,fortran --enable-shared --with-libiconv-prefix=/opt/csw && gmake -j 4
bash-3.00$ gcc -v
Reading specs from /opt/csw/gcc4/lib/gcc/i386-pc-solaris2.8/4.0.2/specs
Configured with: ../sources/gcc-4.0.2/configure --prefix=/opt/csw/gcc4 --with-local-prefix=/opt/csw --with-gnu-as --with-as=/opt/csw/bin/gas --without-gnu-ld --with-ld=/usr/ccs/bin/ld --enable-threads=posix --enable-shared --enable-multilib --enable-nls --with-included-gettext --with-libiconv-prefix=/opt/csw --with-x --enable-java-awt=xlib --with-system-zlib --enable-languages=c,c++,f95,java,objc,ada
Thread model: posix
gcc version 4.0.2