bug#23057: 25.0.92; shr wrongly adds two newlines to div element

[Stephen Berman <stephen.berman@gmx.net>]

On Fri, 18 Mar 2016 22:10:37 +0100 Stephen Berman <stephen.berman@gmx.net> wrote:

> The following patch fixes this display problem for me, but I'm not
> familiar enough either with shr or with all the details of HTML block
> elements to be sure this is a sufficient or even correct fix.
>
> diff --git a/lisp/net/shr.el b/lisp/net/shr.el
> index e943132..d9dcda3 100644
> --- a/lisp/net/shr.el
> +++ b/lisp/net/shr.el
> @@ -812,6 +812,9 @@ shr-ensure-paragraph
>  						    (line-end-position))
>  		       (line-end-position)))))
>  	(delete-region (match-beginning 0) (match-end 0)))
> +       ((eq (dom-tag dom) 'div)
> +	;; <div> contains no block element; do nothing.
> +	)
>         (t
>  	(insert "\n\n"))))))

Oops, I overlooked that `dom' is unbound here; it's dynamically bound
when called from shr-tag-div, but that may be a problem elsewhere.
Here's a cleaner alternative, but it's probably too ad hoc for a real
fix:

diff --git a/lisp/net/shr.el b/lisp/net/shr.el
index e943132..6350dfb 100644
--- a/lisp/net/shr.el
+++ b/lisp/net/shr.el
@@ -786,7 +786,7 @@ shr-ensure-newline
   (unless (zerop (current-column))
     (insert "\n")))
 
-(defun shr-ensure-paragraph ()
+(defun shr-ensure-paragraph (&optional dom)
   (unless (bobp)
     (let ((prefix (get-text-property (line-beginning-position)
 				     'shr-prefix-length)))
@@ -812,6 +812,10 @@ shr-ensure-paragraph
 						    (line-end-position))
 		       (line-end-position)))))
 	(delete-region (match-beginning 0) (match-end 0)))
+       ((and dom
+             (eq (dom-tag dom) 'div))
+	;; <div> contains no block element; do nothing.
+	)
        (t
 	(insert "\n\n"))))))
 
@@ -1206,7 +1210,7 @@ shr-tag-p
   (shr-ensure-paragraph))
 
 (defun shr-tag-div (dom)
-  (shr-ensure-paragraph)
+  (shr-ensure-paragraph dom)
   (shr-generic dom)
   (shr-ensure-newline))