@FRidh, thanks for your PR! By analyzing the history of the files in this pull request, we identified @NeQuissimus, @peti and @micxjo to be potential reviewers.

http://hydra.nixos.org/jobset/nixpkgs/python3 builds python packages only, but I guess we should rebuild the whole nixpkgs? I'll change to that.

Done. error: undefined variable ‘pythonPackages’ at /nix/store/2m6xrym9ch7j7j7a0jqsvsazhhp22cnp-git-export/pkgs/development/arduino/ino/default.nix:15:36

Hydra job: http://hydra.nixos.org/eval/1297631?compare=staging

Failures relative to staging:
http://hydra.nixos.org/eval/1297676?compare=staging#tabs-now-fail

I think I've fixed about half of those by now.

latest evaluation
http://hydra.nixos.org/eval/1297698?compare=staging

@domenkozar could we merge this into staging? There are still some important failures, but as far as I can see no more rebuilds. Then on staging we can fix the final issues that prevent merging into master.

Two issues merging this:

• it compares to staging evaluation that was mostly canceled, so there might be more failures
• we still have to run all nixos tests before it's merged to staging. It's important to not break everything as that will block others from using staging

it compares to staging evaluation that was mostly canceled, so there might be more failures

Indeed, there's a bit more failures http://hydra.nixos.org/eval/1297698?compare=1297372

There's also the list of errors to consider. This list will include packages that could not be build because a Python dependency is disabled.
http://hydra.nixos.org/jobset/nixpkgs/python3#tabs-errors

That's a looooong list.

Does the LLVM stuff still work? That's the main thing I care about for Darwin purposes.

I've merged into staging everything except the actual switch to Python 3.

@copumpkin all llvm except for 3.4 were building fine.

correction: llvm 3.7 needed python 2 because of a bytes - str issue.

Some packages are not available for Python 3. Therefore, any package that depends on this one should use Python 2.

• gyp (see also https://codereview.chromium.org/1454433002/)
• pygame (although the 1.9.2 alpha with patching could be made to work)
• pygtk

I tried merging this into staging and building the darwin stdenv and I didn't notice any difference during the bootstrap. Is LLVM pulling in python2 explicitly?

My system now runs on this branch, and I haven't encountered any issues so far. Judging from the tests I think there's only one issue remaining, and that would be fixing kde 4. Aside from that there's a bunch of lesser important packages that need to be fixed but I'll leave that for the maintainers.

If we want to have Python 3.5 as default some fixes are going to be needed. If I recall correctly Python 3 builds or packages are not yet deterministic. I won't have much time to work on this or Nixpkgs in general the coming months (final phase of PhD).

cc release manager @globin

Do you see this being ready for the branch-off at the end of February?

@globin unless someone else picks it up, no. I won't have any time to work on this. Migrating the final packages to Python 3 (or letting them remain at 2) shouldn't be too much work I think.

I'll include a link to this PR in the timeline announcement, hoping someone will pick this up.

As was discussed on the mailing list some are against simply staging python = python3; and want to replace all occurrences of python with python3. I'm not interested in doing that work so I'm closing this PR.