Problem with gcc 4.6 installation on ubuntu - gcc

Question

I am trying to install gcc 4.6 (mainly for having C++0x better supported) in my ubuntu 9.10 (via virtualbox). I referred to previous questions, but I am getting a different error.
I am referring this link for the installation. Now, I have done till the ./gcc-xx/configure ... step. Though it was giving some flex package related error. Mostly due to that make is also failing with below errors:
build/gengtype.o: In function
adjust_field_rtx_def':
/home/milind/ubuntu_shared/GCC/build/gcc/../../gcc-4.6-20110610/gcc/gengtype.c:978:
undefined reference tolexer_line'
/home/milind/ubuntu_shared/GCC/build/gcc/../../gcc-4.6-20110610/gcc/gengtype.c:1032:
undefined reference to lexer_line'
/home/milind/ubuntu_shared/GCC/build/gcc/../../gcc-4.6-20110610/gcc/gengtype.c:1042:
undefined reference tolexer_line' ...............
Now this is giving me a hard time figuring it out because I have already flex/bison latest versions installed. I searched over internet for 2 days almost but no luck. Any help would be really appreciated. Also note that, I already have gcc 4.4 installed in /usr/bin/gcc and I have unzipped the gcc 4.6 tar in my home directory local folder.
[Note: I am also ok with installing ubuntu 11.10 too (which has gcc 4.6) as last resort. But I don't know if its .iso image is available.]

Answer 1

I got this fixed. I followed following procedure:
[Note: run all the commands with sudo, if you are not login as root. e.g. sudo ls -ltr; sudo make install;
As mentioned in the link in my
question, download the gcc4.6...tar
file in a temporary place
Now find the place where current
gcc is stored. e.g. My earlier
gcc4.4 was stored in
/usr/lib/gcc/i486-linux-gnu. Which
has a folder called 4.4, 4.4.1
Create a folder named 4.6 (or
4.6.1/2/3 etc.) and put that
.tar file inside it. Untar the
file as shown in link.
Follow all the procedure as per the
link. Use nohup <command> & to
track the logs. i.e. nohup make
clean all & followed by tail -f
nohup.out
If some error comes, it means some
package is missing. Mostly those
package will be present in your
current gcc version. You can
install them there itself. For
example, in my case zlib was
missing. I ran sudo apt-get install
zlib1g-dev libssl-dev and it worked
fine. Otherwise download from internet and install it.
Once your gcc is installed, you
can simply check it using type
gcc-4.6. In my case it showed that
it's stored as
/usr/local/bin/g++-4.6.
Either you can use the same path to
compile or you can put an alias in
your bash/tcsh/ksh. e.g.
/usr/local/bin/g++-4.6 -std=c++0x
-Wall test.cpp

Answer 2

FWIW Debian testing and unstable have gcc-4.6 as a standard package. So you can simply install that distro inside of virtualbox or, as I've done on my Ubuntu 11.04 server at home, via kvm. In the past, I also used to use dchroot build environments.
There may also be prepackaged gcc-4.6 binaries at launchpad.