bug#13041: 24.2; diacritic-fold-search

[Juri Linkov]

> If I correctly understand Juri, I next have to deal with things like
>
> (get-char-code-property #xff59 'decomposition)
>
> and related issues we might unearth in the course of this.

Only until bug#13084 is fixed that is a separate problem.

> Also, while currently sorting is stable in the sense that with respect
> to diacritics text remains unchanged from the original order, this is
> not nice for sorting larger pieces of text.  So I'd rather have to use
> the second list element returned by `get-char-code-property' to make
> sure that, for example, "e" gets always sorted before "è" before "é".

In principle, you could do this by let-binding a new variable
`sort-decomposition' to non-nil for stable sorting.

And later to let-bind `sort-decomposition' to nil for
last-resort comparison where equal lines
(equal according to non-nil `sort-decomposition')
will be sorted without regard to decomposition.