BibTeX-mode: Key generation when latin-1 characters appear in author field

[Christian Schlauer]

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Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:

I create the following entry in a BibTeX file -- the critical thing is
that the name of the author contains an umlaut. (This is okay, as the
BibTeX versions that nowadays come with TeX distributions are 8-bit
capable, which means that I can enter umlauts in the .bib file
directly instead of using \"o or something similar -- I just have to
specify \usepackage[latin1]{inputenc} in the document preamble as
well):

@Article{,
  author =       {B. Blöd},
  title =        {Test},
  journal =      {A},
  year =         {2005},
  OPTkey =       {},
  OPTvolume =    {},
  OPTnumber =    {},
  OPTpages =     {},
  OPTmonth =     {},
  OPTnote =      {},
  OPTannote =    {}
}

Now, press `C-c C-c' inside the entry -- Emacs suggests `blöd05:_test'
as the key to use -- and hit RET: Emacs writes in the minibuffer `New
inserted entry yields duplicate key'.

To my surprise, the umlaut in the reference key does not cause
trouble, it seems -- the following document could be processed with
latex/bibtex/latex/latex:

\documentclass{article}
\bibliographystyle{unsrt}
\begin{document}
A reference \cite{blöd05:_test}.
\bibliography{test}
\end{document}

I don't know what is right, but I think BibTeX-mode should either
change umlauts to their `nearest ordinary ASCII character', here ö ->
o, or it shouldn't issue that `duplicate key' message in the
minibuffer: there is only one key in the .bib file, so what has been
duplicated? It seems to me that the conversion of funny characters to
ASCII characters is probably safer.

In GNU Emacs 22.0.50.1 (powerpc-apple-darwin7.7.2)
 of 2005-04-02 on tesla.local
Distributor `Apple Computers', version 10.3.8
configured using `configure '--without-x' '--prefix=/usr/local''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: nil
  locale-coding-system: nil
  default-enable-multibyte-characters: t

Major mode: BibTeX

Minor modes in effect:
  encoded-kbd-mode: t
  tooltip-mode: t
  tool-bar-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  unify-8859-on-encoding-mode: t
  utf-translate-cjk-mode: t
  line-number-mode: t

Recent input:
M-x s e t - l <backspace> k e z <backspace> y <tab> 
<return> m a c - r o m a n <return> C-x C-f t e s t 
. b i b <return> <help-echo> <menu-bar> <Entry-Types> 
<Article in Journal> B . SPC B l ö d C-j T e s t 
C-j A C-j 2 0 0 5 C-c C-c <return> M-x r e p o r t 
<tab> <return>

Recent messages:
Loading bibtex...
Loading easymenu...done
Loading regexp-opt...done
Loading bibtex...done
Author1 [and Author2 ...] [and others]
Title of the article (BibTeX converts it to lowercase)
Name of the journal (use string, remove braces)
Year of publication
bibtex-clean-entry: New inserted entry yields duplicate key
Loading emacsbug...done