Gentoo Archives: gentoo-dev

From: "Michał Górny" <mgorny@g.o>
To: gentoo-dev@l.g.o
Cc: qa@g.o
Subject: [gentoo-dev] [RFC] Masterplan for solving LINGUAS problems
Date: Tue, 31 May 2016 12:49:45
Message-Id: 20160531144926.4937d77a.mgorny@gentoo.org
Hello, everyone.

Since the previous thread doesn't seem to have brought any good
solution to the problem other than stopping to (ab)use LINGUAS
as USE_EXPAND, I would like to start a RFC on a draft solution that
I'd like afterwards to propose to the Council.


Rationale
---------

The direct reason for this is that LINGUAS is treated as non-standard
special variable by multiple build systems. This includes the following
problems:

1. no localizations are installed if it is set to an empty value (which
happens in EAPI 5 when the ebuild does not use the flags),

2. there were historical cases where order of LINGUAS mattered.

Those problems can't be reasonably solved within the scope of
USE_EXPAND. Furthermore, the use of flags to control localizations is
causing the following problems:

a. maintaining correct flag list is a serious maintenance burden,
especially that differences in build systems make it hard to figure out
the 'most correct' set automatically,

b. missing flags result in localizations being silently dropped, with
no clear way (i.e. for QA check) to detect that,

c. large number of additional USE flags make it pretty much impossible
to limit localizations this way when using binary packages.


The plan
--------

1. Get approval on INSTALL_MASK GLEP [1] and finish implementing it
in Portage.

2. Introduce a new USE_EXPAND that can be used to control localizations
whenever this is really required (dependencies, large files, etc.).
Let's use L10N as a draft name for it.

3. Fix all packages using LINGUAS as USE_EXPAND, either by converting
to L10N or by removing the needless flags.

4. Remove LINGUAS from USE_EXPAND, therefore removing the special EAPI
rules from the variable.

5. Release a news item explaining the users the change,
and the necessary action. Request changing LINGUAS to L10N
in make.conf, and make LINGUAS considered an 'advanced variable' for
implicit localization control (i.e. passed through to build systems).
Recommend clean INSTALL_MASK solution instead.

The example 'new' make.conf would probably look like:

  # controlling e.g. langpacks
  L10N="en_US pl"
  # stripping unneeded files
  INSTALL_MASK="@linguas -@linguas_pl"


Your thoughts?


[1]:https://wiki.gentoo.org/wiki/User:MGorny/GLEP:INSTALL_MASK

-- 
Best regards,
Michał Górny
<http://dev.gentoo.org/~mgorny/>

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