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

[Roland Winkler]

On Tue May 25 2021 Lars Ingebrigtsen wrote:
> And this gets even more difficult to deal with for non-Latin scripts.
> 
> So I'm not sure anything here can be done programmatically...  the
> command could output a warning?  "Probably invalid key"?

The warning is a good idea.  Actually, the warning should be issued
if there are non-ascii characters anywhere in a BibTeX key because
(oldfashioned) BibTeX will choke on those no matter where they
appear.  So I'll add a new element for the user variable
bibtex-entry-format for this.  Then users can enable these warnings
if they use oldfashioned BibTeX.  (Those who use modern variants of
BibTeX need not enable these warnings.)

I believe that the real problem here lies in the fact that many
publishers of scientific journals let you download citation records
for their journal articles.  When they offer not only BibTeX-formatted
records but other formats, too, the BibTeX records are often
malformed, decorated with non-ascii characters that BibTeX (and
LaTeX) cannot handle and other things.  I have been fooled a number
of times by "invisible" non-ascii characters.  So I will enable the
new option for myself!