Nixpkgs: Upgrade default gcc to 6.x

[edolstra]

Title says all. This will be nice to have for 17.03.

We should set up a branch+jobset with gcc 6 to see how much breaks.

http://hydra.nixos.org/jobset/nixos/gcc-6

[copumpkin]

Out of curiosity, why not LLVM+clang? Are there any major blockers for that left nowadays?

[edolstra]

That's a separate issue really.

[groxxda]

Do we really need a separate branch with all the merge work it implies?
Wouldn't it be possible to only have a jobset that overrides gcc = gcc6 but uses master?

If we _fix_ a package for gcc6, it should not break gcc5.

[vcunat]

I don't think it will need much "merge work".

[vcunat]

There's a new problem with -isystem: https://lists.fedoraproject.org/archives/list/[email protected]/thread/Q5SWCUUMWQ4EMS7CU2CBOZHV3WZYOOTT/

On Hydra it currently shows up with openjdk but I've already seen another instance (EDIT: qt5.qtbase and qt4 are important instances).

[domenkozar]

How far is this work?

[vcunat]

In this branch I can't see any commits towards fixing the general problem from my last comment (and I didn't work on it since then).

[vcunat]

Hmm, I guess we might skip gcc-6 default, as gcc-7 is expected in about a month. We've done at least one similar leap already, some time with 5.x.

[copumpkin]

Looks like gcc 7 is out. Anyone still looking at this?

[edolstra]

Yes, I am. GCC 7 is probably too bleeding edge for the next release, so GCC 6 would be better. I'd like to merge the gcc-6 branch into staging soon.

[copumpkin]

Awesome, thanks!

On Fri, Jun 30, 2017 at 9:47 AM, Eelco Dolstra [e-mail]
wrote:

Yes, I am. GCC 7 is probably too bleeding edge for the next release, so
GCC 6 would be better. I'd like to merge the gcc-6 branch into staging soon.

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[vcunat]

GCC 7.1 is from May and the next NixOS release is planned for September, so it might not be that bad, but it seems safer and perfectly OK to wait after that.

[edolstra]

FYI, I've changed the nixos/gcc-6 jobset (as well as the nixos/staging jobset) to build on x86_64-linux only. Otherwise evaluation kept barfing with a Boehm out-of-memory error. (No idea why, given that master does evaluate...)

http://hydra.nixos.org/eval/1378105

The last eval (from > a month ago) showed only a handful of major failing dependencies (mostly clucene-core and akonadi, breaking a lot of KDE, and gnome-control-center, breaking some of Gnome). So I think we should fix those and then merge this into staging in a few days. Remaining failures can be dealt with as part of a ZHF push for 17.09.

@fpletz

[vcunat]

@edolstra: any particular reason why you haven't staged this yet?

[edolstra]

@vcunat Sorry, I've been on vacation. I've merged gcc-6 into staging now.

[fpletz]

Thanks!