Re: [gentoo-dev] Migrate away from python-2 or not

[Philip Webb]

191124 Benda Xu wrote:
> Bug 684962 (dev-python/ipython-7.5.0: package conflicts) has demonstrated
> a painful consequence when upstream start to release python3 only versions.
> Upstream has dropped python-2.7 support in dev-python/ipython-7.5.0,
> thus there is no python_targets_python2_7 USE flag for the ebuild.
> dev-python/qtconsole, a dependant of dev-python/ipython,
> still supports python-2.7.  When qtconsole get emerged
> with USE="python_targets_python2_7 python_targets_python3_6" for example,
> old dev-python/ipython-5.8.0-r1 is drawn, resulting in conflict
> against dev-python/ipython-7.5.0.  USE=python_targets_python2_7
> had to be removed from dev-python/qtconsole to avoid it.
> If one package drops python-2.7, all its dependants
> have to drop python-2.7 even if they can work with python-2.7.
> Given the python-2 countdown deadline being 2020-01-01, a month away,
> shall we get rid of python-2?

As a user, I wb delighted to see the end of it.
It's a constant hindrance when updating some pkgs.

> If the answer is yes,
> we will need to decide on the following python-2-only packages.
>
> ,----
> | $ comm -23 <(equery -qC h python_targets_python2_7 | sort ) <(equery -qC h python_targets_python3_6 | sort)
> | dev-lang/yasm-1.3.0
> | dev-libs/libxslt-1.1.33-r1
> | dev-python/backports-functools-lru-cache-1.5
> | dev-python/enum34-1.1.6-r1
> | dev-python/functools32-3.2.3
> | dev-python/futures-3.2.0
> | dev-python/pygobject-2.28.6-r55
> | dev-python/pygtk-2.24.0-r4
> | dev-python/subprocess32-3.2.7
> | dev-util/boost-build-1.70.0
> | dev-vcs/subversion-1.12.2
> | gnome-base/libglade-2.6.4-r2
> | net-analyzer/nmap-7.70
> | sys-devel/clang-8.0.1
> | x11-wm/xpra-2.4.3
> `----

On my system, I get

  root:588 portage> emerge -cpv python:2.7

  Calculating dependencies... done!
  dev-lang/python-2.7.15 pulled in by:
    dev-lang/spidermonkey-60.5.2_p0-r2 requires >=dev-lang/python-2.7.5-r2:2.7[ncurses,sqlite,ssl,threads]
    dev-qt/qtwebkit-5.212.0_pre20190629 requires >=dev-lang/python-2.7.5-r2:2.7
    net-libs/nodejs-8.12.0 requires >=dev-lang/python-2.7.5-r2:2.7[threads]
    net-mail/fetchmail-6.3.26-r4 requires >=dev-lang/python-2.7.5-r2:2.7[tk]
    sys-devel/clang-8.0.1 requires >=dev-lang/python-2.7.5-r2:2.7
    sys-devel/llvm-8.0.1 requires >=dev-lang/python-2.7.5-r2:2.7
    www-client/firefox-68.2.0 requires dev-lang/python:2.7[ncurses,sqlite,ssl,threads(+)]

Is there eg an easy replacement for Fetchmail ?
Is there an easy way to avoid the other requirements ?

> If the answer is no, to avoid holding back new versions having only python3,
> such as bug 671796 for dev-python/matplotlib bump,
> old versions with python_targets_python2_7 and new versions without
> should be co-installable into different SLOTs.

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