What to recompile when moving to a new version of gcc?

juanbobo · n00b Joined: 22 Sep 2007 Posts: 39

When changing your default version of gcc are there any general guidelines for what you should recompile to ensure you don't have any linking or runtime incompatibilities? I've run into issues before, sometimes needing to recompile kdelibs, but as I have not tested all software on my system I can't know what is potentially broken. What does fix_libtool_files.sh actually solve?

Sade · Posted: Tue Dec 15, 2009 8:03 pm Post subject:

short story, run emerge -DuNav world and you are probably fine.

intermediate story: Gentoo GCC upgrade guide

long story
But please note that hielvc himself posts on page nine that his tool is not really needed.
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figueroa · Posted: Sun Jan 17, 2010 8:19 pm Post subject:

The answer "emerge -DuNav" seems to be seriously in conflict with the gcc upgrade guide which says:

d2_racing · Posted: Sun Jan 17, 2010 8:23 pm Post subject:

For my concern, each time that there is a new gcc version, I always run this :

figueroa · Posted: Sun Jan 17, 2010 8:33 pm Post subject:

Thank you.

Rats! I was afraid that was the real answer. :-)

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DaggyStyle · Watchman Joined: 22 Mar 2006 Posts: 5909

krinn · Watchman Joined: 02 May 2003 Posts: 7470

the good way for a clean toolochain is
- emerge gcc && emerge glibc && emerge gcc and you'll end up with a gcc link to latest glibc build by itself.

this is why people may argue "emerge sysstem && emerge world" (as gcc is in system and glibc too) would be the best, but i don't think it is:

1/ building system to get a new gcc won't build the new gcc with the new glibc, only one or the other
2/ rebuilding twice others tools (because world include system) is just a lost of time. As you don't even change your gcc version, you're just recompiling the thing you already have link to your new glibc but still with the old gcc (emerge gcc won't switch your gcc profile to the new gcc)

in fact it could be even worst if you build "system then world" because in case a new glibc is out, you can even bork your own toolchain by
- building system might build new gcc (notice building the new gcc won't change the compiler to use that newly create gcc), build a new glibc, in that case you'll end up with new gcc build for an old glibc. For minor version emerge will even remove the old glibc version (that should be safe, but "should" isn't always safe)
To try to be clearer, let's say you have gcc1 and glibc1 and there's a new gcc2 and glibc2: emerge system will produce a gcc2 build by gcc1 that is build against gblic1 AND a glibc2 that is build with the gcc1.

So: emerge system && emerge world won't produce what you wish as you will just build a new gcc and rebuild all your programs twice with the old one AND you may bork your toolchain and rebuild these programs in a random state.

If you're really lazy, i think emerge gcc && emerge glibc && switching to new gcc && emerge world would do what you wish in a easier way.

Mike Hunt · Watchman Joined: 19 Jul 2009 Posts: 5287

New bookmark: Best explanation ever for building new gcc version.

krinn · Watchman Joined: 02 May 2003 Posts: 7470

if you follow the explain closely you'll see i'm wrong

it should be emerge gcc && switch to it && emerge glibc && emerge gcc (or world for lazy version)

It wasn't a wanted mistake, i'm just tired.

pianosaurus · l33t Joined: 19 Apr 2004 Posts: 944 Location: Bash$

d2_racing · Posted: Mon Jan 18, 2010 1:07 am Post subject:

I wrote that a while ago and it was the resume of the big thread at the time :

http://gentoo-quebec.org/wiki/index.php/Recompilation_Toolchain

It seems that we can run this :