bug#47455: 27.1; bibtex mode - citation key generation - non-ascii characters

[Arash Esbati <arash@gnu.org>]

Brian Elmegaard via "Bug reports for GNU Emacs, the Swiss army knife of
text editors" <bug-gnu-emacs@gnu.org> writes:

> Thanks for looking into this.
> I understand your reasoning about this being an issue with the tools
> used.  In auctex I can also enter \newcommand{\ü}{u} without being
> warned that it will not work with latex.

It's not about LaTeX as the macro package, it's about the underlying
engine.  This example

    \documentclass[10pt]{article}
    \newcommand\ü{foo}
    \begin{document}
    \ü bar
    \end{document}

works when your run lualatex on it, but chokes with pdflatex.  The
reason is described in ltnews30.pdf:

    Improving Unicode handling in pdfTEX

    [...]  What is not possible when using an 8-bit engine such as
    pdfTEX is to use characters other than ascii letters as part of a
    command name. This is due to the fact that all other characters in
    such engines are not single character tokens, but in fact consist of
    a sequence of bytes and this is not supported in command names.

So yes, it about the tools used :-)

Best, Arash