Incomplete reverse-BCP47

[viktoriasee]

There are cases where you wish to query the locale that is actually used.

MWE

\documentclass{article}
\usepackage[nswissgerman]{babel}
\BabelEnsureInfo

\begin{document}

\makeatletter
    \getlocaleproperty\mainlang
        {\bbl@main@language}
        {identification/tag.bcp47}
\makeatother

\typeout{THE MAIN LANGUAGE IS "\mainlang"}

Lorem ipsum.

\end{document}

This outputs «de». Tested under MikTeX and TexLife, XeTeX, LuaHBTeX and pdfTeX. It's not specific to Swiss German it happens to other languages as well.

Expected behaviour

Output should be «de-CH» or even «de-CH-1996» for the 1996 spelling reform.

[jbezos]

I assigned the <language type=".."> in the CLDR to tag.bcp47, which is clearly misleading. The locale actually loaded should be in tag.ini, but it seems it's not loaded correctly. I'll fix both issues.

[jbezos]

Fixed in 3.46. Now tag.bcp47 contains what it's name promises.