[gentoo-user] Upgrading gcc from 6.4 to 7.3

[gevisz]

After updating portage tree today, portage
suggested to upgrade gcc from 6.4 to 7.3
version what I have done just now.

Nevertheless,
# gcc-config --list-profiles
[1] x86_64-pc-linux-gnu-6.4.0 *
[2] x86_64-pc-linux-gnu-7.3.0
shows that I still have version 6.4 as a default.

As https://wiki.gentoo.org/wiki/Upgrading_GCC
still do not have any specific instructions on
switching to gcc version 7.3, I am still afread
of switching to gcc version 7.3 and would like
to ask if anybody encountered some problem
after switching to gcc version 7.3 and which
packages should be rebuild after such switching.

Thank you in advance for your help.

[Mick]

On Wednesday, 20 June 2018 11:43:32 BST gevisz wrote:
> After updating portage tree today, portage
> suggested to upgrade gcc from 6.4 to 7.3
> version what I have done just now.
>
> Nevertheless,
> # gcc-config --list-profiles
> [1] x86_64-pc-linux-gnu-6.4.0 *
> [2] x86_64-pc-linux-gnu-7.3.0
> shows that I still have version 6.4 as a default.

I'm on gcc-7.3.0-r3 and have not noticed any problems on 3 boxen so far.

> As https://wiki.gentoo.org/wiki/Upgrading_GCC
> still do not have any specific instructions on
> switching to gcc version 7.3, I am still afread
> of switching to gcc version 7.3 and would like
> to ask if anybody encountered some problem
> after switching to gcc version 7.3 and which
> packages should be rebuild after such switching.
>
> Thank you in advance for your help.

I didn't have to rebuild anything, but if you have reasons to fear breakage
you can rebuild your toolchain:

1. Use gcc-config to select x86_64-pc-linux-gnu-7.3.0
2. Re-source /etc/profile by running in your current console/terminal:
. /etc/profile
3. Re-emerge libtool:
emerge -1 sys-devel/libtool
4. Re-emerge the following packages in this order:
emerge -1 sys-devel/gcc-7.3.0-r3
emerge -1 sys-devel/binutils
emerge -1 sys-libs/glibc
5. You could if you want re-emerge your entire system, 'emerge -e @world' or
if you would rather conserve electricity wait as different packages come up
for an update over time.

If my experience to date holds true and for a general purpose desktop none of
the above rebuilds are necessary, other than switching your gcc to 7.3.0.

--
Regards,
Mick

[gevisz]

Thank you for your reply. I do not want to rebuild gcc-7.3 for the second time
today (as far as the temperature in my room is already +30°C). So, I will stick
to your last advice: I will just switch the default gcc version to 7.3
and wait for
problems to appear. :)

[gevisz]

Just have rebuilt libtool and llvm, to have less problems. :)

[Andreas K. Huettel]

> As https://wiki.gentoo.org/wiki/Upgrading_GCC
> still do not have any specific instructions on
> switching to gcc version 7.3, I am still afread

> of switching to gcc version 7.3 ...

You won't see any specific information for a new GCC version there unless
something specific needs to be done. Which isn't the case for this particular
update... So, no worry.

Also, you have to imagine that all ~arch users and all developers have now
been using gcc 7 for ages. So once it becomes stable, it should really be
rock-solid. :)

(/me looks forward to testing gcc 8 now... :)

--
Andreas K. Hüttel
dilf...@gentoo.org
Gentoo Linux developer
(council, toolchain, perl, libreoffice, comrel)

[gevisz]

Just today vlc failed to compile because libebml have been compiled
with gcc-6.4.0.
(Thanks to Alexander Kapshuk for the tip.)

So, libebml should be added to the list of packages that have to be
recompiled with gcc-7.3
(namely, to libtool and llvm), and recompiling everything twice after
updating major version
of gcc does not seem to be so bad idea for me any more. :)

[gevisz]

2018-06-20 14:16 GMT+03:00 Mick <michael...@gmail.com>:

You forgot the 6th item:

6. Recompile the kernel.

Just today, virtualbox-modules refused to compile because of this.
Thanks to Michael Orlitzky for the tip how to interpret portage messages.

[gevisz]

By the way, this recommendation is absent from Gentoo wiki on updating gcc.

[Thomas]

Whenever you compile your kernel, you will need to run 

emerge @module-rebuild

Otherwise, you can always install all the modules manually. 

https://wiki.gentoo.org/wiki/Kernel/Upgrade#Reinstalling_external_kernel_modules