bug#22991: 25.0.92: C-u C-s does not display "Regexp I-search:" in the echo area

[Eli Zaretskii <eliz@gnu.org>]

> From: Michael Heerdegen <michael_heerdegen@web.de>
> Cc: Kaushal Modi <kaushal.modi@gmail.com>,  22991@debbugs.gnu.org,  bruce.connor.am@gmail.com
> Date: Sat, 12 Mar 2016 13:33:09 +0100
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > Second, I don't agree with Michael, so if we want to allow such a
> > different behavior, I will insist on a user option.
> 
> I mean especially, if I end up with the default mode and the literal
> search mode both show the same prompt, that would not be good.

This could only happen if the literal search is the default.  If the
default is different, a literal search should show some non-empty
prefix.

> Would it make sense to you to decide what to show in the prompt based on
> the fact whether `search-default-mode' has a buffer local binding -
> instead of introducing a new option (which seems a bit of overkill to
> me)?  I.e., if there is a buffer local binding that differs from the
> global value, do what I want - else, do what you prefer.

I'm not sure I understand how the fact of the binding being local has
any relevance to what we show in the prompt.