iflang Warning: Mismatch between \language (patterns) and and setting of \languagename

Question

I am currently writing a class and there I need to test the current language. Therefore I use the package iflang. A strange warning pops up when I change the default language, consider:

\documentclass{article}
\usepackage{polyglossia}
\setdefaultlanguage{english}
\usepackage{iflang}
\begin{document}
\makeatletter
\noindent PATT: \the\l@dutch \\
LANG: \the\language
\makeatother
\end{document}

The code does not produce any warnings, but if I change the code to \setdefaultlanguage{dutch}, the package iflang produces a warning:

Package iflang Warning: Mismatch between \language (patterns)
(iflang)                and setting of \languagename.

despite the two variables having the same value. Is this a bug in the package?

Answer 1

After

\usepackage{polyglossia}
\setdefaultlanguage{dutch}

the language name is dutch, but the language setting is still the default language 0 (USenglish). Thus the warning is correct. Package polyglossia sets the language later in \begin{document}.

The warning can be avoided:

• Loading the package later, when polyglossia has set the language:

  \usepackage{polyglossia}
  \setdefaultlanguage{dutch}
  \AtBeginDocument{\usepackage{iflang}}
  

• Or explicit setting of the language:

  \usepackage{polyglossia}
  \setdefaultlangauge{dutch}
  \selectlanguage{dutch}
  \usepackage{iflang}
  

• Or loading package iflang earlier:

  \usepackage{iflang}
  \usepackage{polyglossia}
  \setdefaultlanguage{dutch}