From 8cced1ac250078f2ea1cf1b82538c98621f7ca2f Mon Sep 17 00:00:00 2001
From: "Basil L. Contovounesios" <contovob@tcd.ie>
Date: Thu, 21 May 2020 23:18:33 +0100
Subject: [PATCH] Propertize all shr fragment IDs as shr-target-id

* lisp/net/shr.el (shr-descend, shr-tag-a): Display dummy anchor
characters as the empty string.  Give all relevant 'id' or 'name'
fragment identifier attributes the shr-target-id text property.
This ensures that cached content, such as tables, retains the
property across renders.  (Bug#40532)

* lisp/net/eww.el (eww-display-html): Adapt shr-target-id property
search accordingly.
---
 lisp/net/eww.el |  7 ++++---
 lisp/net/shr.el | 18 +++++++++---------
 2 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/lisp/net/eww.el b/lisp/net/eww.el
index a6c1abdbb1..b5780a6685 100644
--- a/lisp/net/eww.el
+++ b/lisp/net/eww.el
@@ -27,6 +27,7 @@
 (require 'cl-lib)
 (require 'format-spec)
 (require 'shr)
+(require 'text-property-search)
 (require 'url)
 (require 'url-queue)
 (require 'thingatpt)
@@ -543,10 +544,10 @@ eww-display-html
 	  (goto-char point))
 	 (shr-target-id
 	  (goto-char (point-min))
-	  (let ((point (next-single-property-change
-			(point-min) 'shr-target-id)))
+	  (let ((point (text-property-search-forward
+			'shr-target-id shr-target-id t)))
 	    (when point
-	      (goto-char point))))
+	      (goto-char (prop-match-beginning point)))))
 	 (t
 	  (goto-char (point-min))
 	  ;; Don't leave point inside forms, because the normal eww
diff --git a/lisp/net/shr.el b/lisp/net/shr.el
index 1f80ab74db..55c0c1d8ad 100644
--- a/lisp/net/shr.el
+++ b/lisp/net/shr.el
@@ -531,13 +531,13 @@ shr-descend
                (funcall function dom))
               (t
                (shr-generic dom)))
-	(when (and shr-target-id
-		   (equal (dom-attr dom 'id) shr-target-id))
+	(when-let* ((id (dom-attr dom 'id)))
 	  ;; If the element was empty, we don't have anything to put the
 	  ;; anchor on.  So just insert a dummy character.
 	  (when (= start (point))
-	    (insert "*"))
-	  (put-text-property start (1+ start) 'shr-target-id shr-target-id))
+	    (insert "*")
+	    (put-text-property (1- (point)) (point) 'display ""))
+	  (put-text-property start (1+ start) 'shr-target-id id))
 	;; If style is set, then this node has set the color.
 	(when style
 	  (shr-colorize-region
@@ -1497,14 +1497,14 @@ shr-tag-a
 	(start (point))
 	shr-start)
     (shr-generic dom)
-    (when (and shr-target-id
-	       (equal (dom-attr dom 'name) shr-target-id))
+    (when-let* ((id (unless (dom-attr dom 'id) ; Handled by `shr-descend'.
+                      (dom-attr dom 'name))))  ; Obsolete since HTML5.
       ;; We have a zero-length <a name="foo"> element, so just
       ;; insert...  something.
       (when (= start (point))
-	(shr-ensure-newline)
-	(insert " "))
-      (put-text-property start (1+ start) 'shr-target-id shr-target-id))
+	(insert " ")
+	(put-text-property (1- (point)) (point) 'display ""))
+      (put-text-property start (1+ start) 'shr-target-id id))
     (when url
       (shr-urlify (or shr-start start) (shr-expand-url url) title))))
 
-- 
2.26.2