L10N USE_EXPAND variable replacing LINGUAS

Title: L10N USE_EXPAND variable replacing LINGUAS
Author: Mart Raudsepp <leio@gentoo.org>
Author: Ulrich Müller <ulm@gentoo.org>
Content-Type: text/plain
Posted: 2016-06-19
Revision: 1
News-Item-Format: 1.0

The L10N variable is replacing LINGUAS as a USE_EXPAND, to avoid a
conceptual clash with the standard gettext LINGUAS behaviour.

L10N controls which extra localization support will be installed.
This is commonly used for downloads of additional language packs.

If you have set LINGUAS in your make.conf, you most likely want to add
its entries also to L10N. Note that while the common two letter language
codes (like "de" or "fr") are identical, more complex entries have a
different syntax because L10N now uses IETF language tags. (For example,
"pt_BR" becomes "pt-BR" and "sr@latin" becomes "sr-Latn".) You can look
up the available codes in profiles/desc/l10n.desc in the gentoo tree.
A detailed description of language tags (aka BCP 47) can be found at:
https://www.w3.org/International/articles/language-tags/

After a transition time for packages to be converted, the LINGUAS
environment variable will maintain the standard gettext behaviour and
will work as expected with all package managers. It controls which
language translations are built and installed. An unset value means all
available, an empty value means none, and a value can be an unordered
list of gettext language codes, with or without country codes. Usually
two letter language codes suffice, but can be narrowed down by country
codes with a "ll_CC" formatting, where "ll" is the language code and
"CC" is the country code, e.g., "en_GB". Some rare languages also have
three letter language codes. Note that LINGUAS does not only affect
installed gettext catalog files (*.mo), but also lines of translations
in an always shipped file (e.g., *.desktop).

If you want English with a set LINGUAS, it is suggested to list it with
the desired country code, in case the default is not the usual "en_US".
It is also common to list "en" then, in case a package is natively
written in a different language, but does provide an English translation
for whichever country. A list of LINGUAS language codes is available at:
http://www.gnu.org/software/gettext/manual/gettext.html#Language-Codes

If you have per-package customizations of the LINGUAS USE_EXPAND, you
should also rename those. This typically means changing linguas_* to
l10n_*, and possibly updating the syntax as described above.

https://wiki.gentoo.org/wiki/Localization/Guide has also been updated to
reflect this change.