bug#23798: 25.0.90; Underscore for emphasis in Info?

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sat, 2 Jul 2016 13:59:54 -0700 (PDT)
> From: Drew Adams <drew.adams@oracle.com>
> Cc: 23798@debbugs.gnu.org
> 
> FWIW -
> 
> In my own code I'm using this regexp now (by default - a user option):
> 
> "_\\(\\(\\sw\\(\\s-\\|\\sw\\|\\s.\\)*\\)\\|\\(\\(\\s-\\|\\sw\\|\\s.\\)\\sw*\\)\\)_"
> 
> It matches word, punctuation, and whitespace chars, plus hyphens,
> with at least one word character.  Hyphen is included explicitly
> because it generally has symbol syntax in Info.
> 
> This seems to work pretty will.  But there are of course some
> places where it does not DTRT.
> 
> In my own code I also remove hiding of the enclosing `_' chars
> when emphasis highlighting is turned off:
> 
> (while (re-search-forward Info-emphasis-regexp nil t)
>   (let ((fn  (if Info-fontify-emphasis-flag
>                  #'add-text-properties
>                #'remove-text-properties)))
>      (funcall fn (match-beginning 0) (1+ (match-beginning 0))
>               '(invisible t front-sticky nil rear-nonsticky t))
>      (funcall fn (1- (match-end 0)) (match-end 0)
>               '(invisible t front-sticky nil rear-nonsticky t))
>      (funcall fn (match-beginning 1) (match-end 1)
>               '(font-lock-face info-emphasis))))

I hope one of the Info gurus will chime in at some point.

Thanks.