[gentoo-user] multiple gcc versions

[gentoo-user] multiple gcc versions

[Matthias Langer]

I'm mainly in x86 and thus using gcc-3.3.6. However, as i do some 
programming, i want to know if it is without greater problems possible, 
to install gcc-3.4.4 additionally, so that i can make sure that the code 
i'm writing is accepted by gcc-3.4.x too [i know that i can't expect my 
code to work, as it is c++ stuff and the libs i'm using are compiled 
with 3.3.6 - i only want to be sure that the code compiles cleanly].

Thanks,
Matthias Langer
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Re: [gentoo-user] multiple gcc versions

[Peter O'Connor]

Matthias Langer wrote:
> I'm mainly in x86 and thus using gcc-3.3.6. However, as i do some 
> programming, i want to know if it is without greater problems possible, 
> to install gcc-3.4.4 additionally, so that i can make sure that the code 
> i'm writing is accepted by gcc-3.4.x too [i know that i can't expect my 
> code to work, as it is c++ stuff and the libs i'm using are compiled 
> with 3.3.6 - i only want to be sure that the code compiles cleanly].
> 
> Thanks,
> Matthias Langer

It shouldn't be too much of a problem since they are different branches 
of gcc and should be default install side by side. I run 3.4.4-r1 and 
when I pretend to install 3.3.6

# emerge -p =gcc-3.3.6
[ebuild  NS   ] sys-devel/gcc-3.3.6

	(from man emerge)	
               N = new, (not yet installed)
               S = new, slot installation (side-by-side versions)

First of all you would need to make the 3.4.4 version available

echo "sys-devel/gcc ~x86" >> /etc/portage/package.keywords

Then try # emerge -p gcc to test how it will install the new version. If 
it shows NS, it won't remove 3.3.6 at all. Otherwise you may want to 
hold off installing.

Use gcc-config -l to check what version it is using after the install 
and make sure it's set for 3.3.6, otherwise change it (that is assuming 
you are still wanting 3.3.6 as default).

Depending on how you compile your programs you can use the gcc-3.4.4 and 
  g++-3.4.4 (ie g++-3.4.4 -o foo foo.cc) commands if you do it manually.

Or else you can use gcc-config to set 3.4.4 before compiling your code 
to test if it compiles and then change back to 3.3.6 when you're done.
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