Re: Upcoming loss of usability of Emacs source files and Emacs.

[Eli Zaretskii <eliz@gnu.org>]

> Date: Thu, 18 Jun 2015 07:27:37 +0200
> From: Ulrich Mueller <ulm@gentoo.org>
> Cc: eggert@cs.ucla.edu, rms@gnu.org, Nicolas Petton <nicolas@petton.fr>,
> 	emacs-devel@gnu.org, Tassilo Horn <tsdh@gnu.org>, acm@muc.de,
> 	stephen@xemacs.org
> 
> ;; Ignore accent and umlaut marks when searching.
> ;; Works for Emacs 19.30 and later.
> (let ((eqv-list '("aAàÀáÁâÂãÃäÄåÅ"
> 		  "cCçÇ"
> 		  "eEèÈéÉêÊëË"
> 		  "iIìÌíÍîÎïÏ"
> 		  "nNñÑ"
> 		  "oOòÒóÓôÔõÕöÖøØ"
> 		  "uUùÙúÚûÛüÜ"
> 		  "yYýÝÿ"))
>       (table (standard-case-table))
>       canon)
>   (setq canon (copy-sequence table))
>   (mapcar (lambda (s)
> 	    (mapcar (lambda (c) (aset canon c (aref s 0))) s))
> 	  eqv-list)
>   (set-char-table-extra-slot table 1 canon)
>   (set-char-table-extra-slot table 2 nil)
>   (set-standard-case-table table))

This means you cannot search for, say, å, even if you want to find
only it and not the other "equivalents", right?  That's not how Emacs
works now wrt letter-case.  At the very least, this folding of
diacriticals should offer the same flexibility, i.e. if the user types
'a', she should be able to find all the variants, but if she types 'å',
should find only that character.

Also, this doesn't handle decomposed characters, as in 'å'.  So this
is not really Unicode-compliant, it's a half-measure of sorts.