From 887d14add7ac21ae466f37208f347f860db33765 Mon Sep 17 00:00:00 2001
From: Lars Magne Ingebrigtsen <larsi@gnus.org>
Date: Fri, 1 Jul 2011 01:19:45 +0200
Subject: [PATCH] textmodes/flyspell.el (flyspell-word): Consider words that
 differ only in case as potential doublons (bug#5687).

---
 lisp/ChangeLog             | 3 +++
 lisp/textmodes/flyspell.el | 9 ++++++---
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index c1c213d1440..1ce1eb61f14 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,5 +1,8 @@
 2011-06-30  Lars Magne Ingebrigtsen  <larsi@gnus.org>
 
+	* textmodes/flyspell.el (flyspell-word): Consider words that
+	differ only in case as potential doublons (bug#5687).
+
 	* net/soap-client.el (soap-invoke, soap-wsdl-resolve-references):
 	Remove two rather uninteresting debugging-like messages to make
 	debbugs.el more silent.
diff --git a/lisp/textmodes/flyspell.el b/lisp/textmodes/flyspell.el
index bc8644be786..7bb3323eb17 100644
--- a/lisp/textmodes/flyspell.el
+++ b/lisp/textmodes/flyspell.el
@@ -993,14 +993,17 @@ Mostly we check word delimiters."
 ;;*---------------------------------------------------------------------*/
 ;;*    flyspell-word-search-backward ...                                */
 ;;*---------------------------------------------------------------------*/
-(defun flyspell-word-search-backward (word bound)
+(defun flyspell-word-search-backward (word bound &optional ignore-case)
   (save-excursion
     (let ((r '())
 	  (inhibit-point-motion-hooks t)
 	  p)
       (while (and (not r) (setq p (search-backward word bound t)))
 	(let ((lw (flyspell-get-word)))
-	  (if (and (consp lw) (string-equal (car lw) word))
+	  (if (and (consp lw)
+		   (if ignore-case
+		       (equalp (car lw) word)
+		     (string-equal (car lw) word)))
 	      (setq r p)
 	    (goto-char p))))
       r)))
@@ -1069,7 +1072,7 @@ misspelling and skips redundant spell-checking step."
 			      (- end start)
 			      (- (skip-chars-backward " \t\n\f"))))
 			  (p (when (>= bound (point-min))
-			       (flyspell-word-search-backward word bound))))
+			       (flyspell-word-search-backward word bound t))))
 		     (and p (/= p start)))))
 	    ;; yes, this is a doublon
 	    (flyspell-highlight-incorrect-region start end 'doublon)