bug#31796: 27.1; dired-do-find-regexp-and-replace fails to find multiline regexps

[Eli Zaretskii]

> Cc: abela@chalmers.se, 31796@debbugs.gnu.org
> From: Dmitry Gutov <dgutov@yandex.ru>
> Date: Sun, 29 Nov 2020 04:30:14 +0200
> 
> For instance, a number of character classes in Emacs regexps are 
> dependent on the syntax table. Like [:word:], for instance.
> 
> Even [:space:] is dependent on syntax, while it matches a fixed set of 
> characters in Grep. So when searching across different file types we 
> can't even "expand" such constructs into concrete characters to search for.

It isn't clear to me which interpretation users will want.  I don't
think there's a single answer.

> Someone should try it, but it's a fair amount of work to handle all 
> supported constructs, and to catch all (most?) the regexps which we 
> can't support in this mode.

FWIW, I think this is much less important than the embedded newline
support.