Re: Questions about isearch

[Eli Zaretskii]

> Date: Wed, 25 Nov 2015 20:14:06 +0000
> From: Artur Malabarba <address@hidden>
> Cc: emacs-devel <address@hidden>
> 
> > 1. Character folding doesn't catch ligatures, such as æ (should it match
> > the two characters "ae")?
> 
> I've no idea. It would be easy to add. 

No, I meant to ask why it doesn't work already.  AFAIU, the
decomposition of ff is "ff":

  (get-char-code-property ?ff 'decomposition)
    => (compat 102 102)

but searching for 'f' doesn't match the ligature.  (æ doesn't have a
decomposition in the Unicode database, so maybe it's a different
case.)

> Those who use ligatures need to tell us whether that makes sense.

I thought we used decomposition data automatically, no?

> > 2. It also doesn't match ä (a single character) with ä (2 characters,
> > which Emacs correctly composes into 1 grapheme cluster). Should it?
> 
> Possibly. Since they look the same, might make things easier on users. But I
> wouldn't know as I've never seen the second version used anywhere. 

Once again, the decomposition attribute says we should match them:

  (get-char-code-property ?ä 'decomposition)
    => (97 776)

and the second character in ä is U+0308 = 776.  Doesn't that say we
should have matched them?