Re: strange behaviour of `isearch-forward-regexp'

[Paul Pogonyshev]

I wrote:
> While searching for " ?t" regular expression, letter 't' in word
> "reset" doesn't match.  This is very strange since searching for
> "t?t" and even "^I?t" does match the letter.  Is it "a feature"
> or a bug somewhere in Emacs?

Kevin Rodgers wrote:

> It's a feature, though it doesn't appear to be documented in the Emacs manual:
>
> | search-whitespace-regexp's value is "\\s-+"
> |
> | Documentation:
> | *If non-nil, regular expression to match a sequence of whitespace chars.
> | This applies to regular expression incremental search.
> | You might want to use something like "[ \t\r\n]+" instead.
> | In the Customization buffer, that is `[' followed by a space,
> | a tab, a carriage return (control-M), a newline, and `]+'.
>
> You need to type `C-s C-q SPC ? t', or set search-whitespace-regexp to nil.

Wouldn't it solve the problem if `search-whitespacec-regexp' was set
to "\\(\\s-+\\)" by default?  Or would it break something match group
related?

And, btw, i'm not subscribed to the list.  Could you please CC answers
to me?

Paul Pogonyshev