[AUCTeX] RefTeX not working well with Biblatex in class file

[Tristan Miller]

Dear all,

It seems that RefTeX does not work properly with Biblatex when the
latter is included via a class file rather than directly in the LaTeX
file being edited.  In such cases, C-[ doesn't provide the full
list of Biblatex citation commands, and searches only the first
bibliography resource for entries.

For example, consider the following four files:

=== foo.cls:
\NeedsTeXFormat{LaTeX2e}
\LoadClassWithOptions{article}
\ProvidesClass{foo}[2017/09/07 v0.1 test class]
\RequirePackage[backend=biber]{biblatex}

=== foo.tex:
\documentclass{foo}
\addbibresource{bar.bib}
\addbibresource{baz.bib}
\begin{document}
\end{document}

=== bar.bib:
@article{smith,
  author       = {John Smith},
  title        = {Smith's Article},
  year         = 2017,
  title        = {Smith's Journal},
}

=== baz.bib:
@article{smythe,
  author       = {Joan Smythe},
  title        = {Smythe's Article},
  year         = 2017,
  title        = {Smythe's Journal},
}


I open foo.tex (using Emacs 25.2 and AUCTeX 11.91) and hit C-[.  The
list of citation commands seems awfully short.  I hit enter.  I'm then
prompted for a regular expression. If I enter "smith" then everything
works fine and the citation is inserted. If I enter "smythe" then I get
the message "No matches found".

On the other hand, if I modify foo.tex so that it directly includes
biblatex with \usepackage, then C-[ gives me the full range of citation
commands, and the search is able to find both "smith" and "smythe".

Is this a known issue?  Any way of working around it, short of manually
copying the \RequirePackage[...]{biblatex} from the class file?

Regards,
Tristan

-- 
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                  Tristan Miller
Free Software developer, ferret herder, logologist
             https://logological.org/
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