bug#49534: [External] : bug#49534: 26.3; Isearch should support using filter predicates with empty search hits

[Juri Linkov]

>> What would be better: to remember its result in a let-bound variable,
>> or to use save-match-data?  Probably, save-match-data:
>
> Yes, that's probably the right thing; good catch.
> ___
>
> [On the other hand, a filter predicate can really
> do more than just act as a predicate (it can
> perform useful side effects).  There could
> presumably be reasons we'd want to let it change
> the match data.
>
> No, I don't have any concrete use case in mind;
> and yes, without some other changes, that could
> mess up code that follows using the predicate.
> I just wonder about further restricting the
> predicate.  The point of this bug fix was to
> _remove_ an unnecessary restriction, but now
> we're adding another restriction. ;-)]

If you want to mess with the match data,
you can use own isearch-search-fun-function.