bug#13480: 24.3.50; `C-w' from Isearch should translate newlines to spaces

[Drew Adams]

> > 2. It is less surprising and more clean to me to see in the 
> > echo area exactly the text I'm supplying, without translations
> > of any kind.
> 
> Well, OTOH it makes a lot of sense to think of the text displayed in
> the echo area (during Isearch) not necessarily as the raw search
> string, but as its "canonical form", according to the current matching
> behavior (which the user should be able to alter on-the-fly).
> 
> Definitely that would be a nice behavior, and not only for the laxity
> in whitespace matching, but also in other ones discussed recently like
> those related to accented.

Yes, it would be good, if possible, for a user to be able to toggle between a
raw search string that Isearch uses under the covers and its effective or more
visually convenient representation.

This can be useful in regexp searching, of course.  And it can be useful if a
user switches from plain search to regexp and wants to retrieve the underlying
regexp and tweak it.

We discussed this a couple of times, IIRC.  In connection with letting `.' match
also newlines, letting SPC represent a more complex whitespace regexp, and maybe
in connection with accents etc.  E.g., a regexp or other pattern that matches
any char including newlines or any whitespace or the chars in an equivalence
class ignoring diacritics.

Sorry, I don't have references to the discussions.