bug#43702: Emacs master: Incorrect highlighting in regexp isearch.

[Juri Linkov]

>> >> I suppose you agree that the previous color palette in isearch
>> >> with a color gradient is not suitable for highlighting of group matches
>> >> because while looking at highlighted matches it's quite impossible to
>> >> say which color corresponds to which group number.
>> >
>> > And with the current implementation on master it is possible?  If so,
>> > how?
>>
>> With only 2 default group faces it's possible to see that one of them
>> isearch-group-1 is brighter than the default isearch face, and another
>> isearch-group-2 is darker than the default isearch face.
>
> No, I meant to ask if it's possible to say which color corresponds to
> which group number.

The default two colors work well for simple regexps,
but degrade with increase of regexp complexity.
And defining more colors with same color gradations
doesn't help.  Even the color scheme designed by Drew
has problems.  So users and theme authors need to decide
themselves how many and what colors they want to use.