bug#15166: 24.3.50; Isearch for an octal code

[Drew Adams]

> > Why is C-q SPC obsolete?
> 
> The problem is that C-q SPC has limited applicability -
> it works only in regexp isearch, and has no effect in
> normal non-regexp isearch.  This might be too confusing
> to users when typing the same key sequence unexpectedly
> works differently in different isearch modes.
> 
> Initially C-q SPC was intended only for regexp isearch,
> but after introduction of isearch-lax-whitespace mode
> it can't be used in non-regexp mode because the C-q SPC
> feature was based on regexps.
> 
> I don't propose to remove it now, keeping it for users
> that rely on it in regexp search.  But to remove mentions
> from documentation to not confuse users about the feature
> that doesn't work in non-regexp mode.

What doesn't work?  Can you please elaborate?

It's not clear to me what you mean by C-q SPC not working
for non-regexp isearch.  I can only guess that you mean that,
although C-q SPC does in fact add a SPC char to the search
string, that does not cause non-regexp isearch to search
for only one SPC (per SPC char added to the search string).

If that's what you mean then I don't see that as a problem.
At least not a problem wrt C-q SPC.  (The confusion is elsewhere.)

In that case, C-q SPC still does its job.  Anything confusing
coming from the result is confusion coming from the fact that
isearch now interprets any number of contiguous SPC chars in
the search string - including, in particular, just one SPC
char - as an arbitrarily long sequence of whitespace chars to
match.

I was not particularly in favor of that change to Emacs, as
you know, but so be it.

The point here is that given that change there is AFAICT
nothing broken, unexpected, or confusing about the behavior
of C-q SPC.  (As far as I can see.)

Perhaps you can give a recipe showing the confusion you
have in mind, if it is different from what I am supposing,
and if it is in fact something directly related to C-q SPC.
Thx.