Re: [gentoo-user] Re: gcc upgrade

[Alan McKinnon]

On Monday 12 July 2010 10:18:48 ZekeyG@×××××.com wrote:
> In linux.gentoo.user, you wrote:
> > On Saturday 10 July 2010 02:57:42 Nikos Chantziaras wrote:
> >> On 07/10/2010 04:16 AM, Valmor de Almeida wrote:
> >> > Hello,
> >> >
> >> > I just updated the portage tree and gcc was upgraded. I have set gcc
> >> > to the newer version
> >> >
> >> > ->  gcc-config -l
> >> >
> >> >   [1] i686-pc-linux-gnu-4.3.4
> >> >   [2] i686-pc-linux-gnu-4.4.3 *
> >> >
> >> > and I am trying to rebuild the whole system with
> >> >
> >> >   emerge -e system
> >> >   emerge -e world
> >> >
> >> > assuming this all goes without trouble (will take a while), should I
> >> > unmerge version 4.3.4?
> >>
> >> There's no reason to.  Unless you don't need it anymore.
> >
> > And why is the OP rebuilding world at all? There's no reason to do that
> > either, there's no API/ABI break between 4.3.4 and 4.3.3
>
> The difference is between 4.3.4 and 4.4.3, not 4.3.3.

Typo.

> Gentoo has the new GCC slotted and the handbook

Of course is slotted. gcc has been slotted since the dawn of time so that you 
can install mutiple compilers and use any one you feel like at any point. 
Tools exists to switch the current compiler in use

> http://www.gentoo.org/doc/en/gcc-upgrading.xml
>
> Suggests emerge -e system and emerge -e world in the "General Upgrade
> Instructions.

It "suggests", it does not say it is mandatory with description of why.

Periodically on this list this topic comes up and we re-hash again, for the 
unmpteenth time, why the docs are misleading. That doc was apparently written 
by someone who was looking for ways to minimize the amount of mail he gets. If 
he says to rebuild system and world, then most of the questions he gets asked 
just go away. Can't fault the dev for that....

This is all in the mail archives. Most of the whinging done by me actually

> If you think the handbook is wrong or my interpretation of it wrong
> then *please* tell me. I would prefer *not* to go through this nightmare
> whenever GCC does a major version bump.

You do not have to do what the handbook tells you, you just have to realise 
what the handbook hopes to achieve. As hinted above, the intended result 
appears to be least hassle for the gentoo devs and document writers with 
maximal guarantee that your box will work afterwards regardless fo how long it 
takes or number of cpu cycles burnt. It's not necessarily the most convenient 
way.

I have not had to rebuild world due to a compiler upgrade since sometime 
around the late 3 series (there was a C++ ABI change).

-- 
alan dot mckinnon at gmail dot com