Re: search-default-mode char-fold-to-regexp and Greek Extended block characters

[Juri Linkov]

> This is an offshoot of the discussion in Bug#36717.
>
> I have
>
> (setq search-default-mode 'char-fold-to-regexp)
>
> In a buffer containing
>
> 1. ί (\u03af GREEK SMALL LETTER IOTA WITH TONOS)
> 2. ί (\u1f77 GREEK SMALL LETTER IOTA WITH OXIA)
>
> I do C-s C-x 8 RET 03b9
>
> isearch will find the iota with tonos, but not the iota with oxia,
> even though the decomposition of the decomposition of the latter
> contains iota. Is that expected?

Decomposition of GREEK SMALL LETTER IOTA WITH TONOS is
GREEK SMALL LETTER IOTA + COMBINING ACUTE ACCENT, whereas
decomposition of GREEK SMALL LETTER IOTA WITH OXIA is
GREEK SMALL LETTER IOTA WITH TONOS, i.e. it's just an alias,
but so far several levels of indirection (from GREEK SMALL LETTER IOTA
to GREEK SMALL LETTER IOTA WITH OXIA via GREEK SMALL LETTER IOTA WITH TONOS)
was unsupported in char-fold.el.  This should be fixed in bug#35689.