Make language-data available in MediaWiki core

[winstonsung]

We would like to bring language-data to MediaWiki core.

Questions

Should we move this repository to Gerrit/GitLab?

Reason for Gerrit:

• We could easily make the list of users with CR +2 rights the same with mediawiki/core on Gerrit.
• ~~It would be hard for integration of Depends-On on different platforms.~~
  (There's no CI injection/dependency feature for libraries in Wikimedia Gerrit.)

Reason for GitLab: Contributors aren't required to accept third party privacy policies.

---

The reason it should be under Gerrit instead of GitLab is due to the decision of the project layout.

This repository shold fall under mediawiki/libs (i.e., named as mediawiki/libs/LanguageData and included in /vendor in mediawiki/core) as it should contain PHP codes, and all mediawiki/libs/ projects were on Gerrit while none of them were on GitLab.

• Wikimedia Gerrit - All of them
• Wikimedia GitLab - No /libs

https://www.mediawiki.org/wiki/GitLab/Migration_status

---

Should composer.json be exported?

Looks like we need composer.json to be exported, should it be removed from .gitattributes export-ignore?

https://gerrit.wikimedia.org/r/c/mediawiki/vendor/+/1056254

Nikki wrote:

The language-data format doesn't support all the data they have (multiple scripts, Wikidata IDs, English names, parent language/families, etc), and requires data that is hard to get (autonyms), I think it would need big changes if it's ever going to be useful for things other than selecting a MediaWiki interface language.

Considerations

• BCP 47 Language/script/region/variant subtags
• ISO codes
  • NOTE: This is actually different from BCP 47 subtags.
• MediaWiki internal language codes
• Wikidata IDs
• WikiLambda ZID
• Autonyms (language name written in its local writing system)
• The script in which a language is written
  • Multiple scripts
• The regions in which the language is spoken/written
• Translations of language names
  • English names
• Language fallback chains
• Parent language/families
• The writing mode of the text
  • The directionality of the text
  • The writing-mode property of the text
• Time formats

Bug: T190129