# Add an option to ignore all whitespace to ediff.
# Shortcut key is #b. The difference with ## is that by using #b,
# whitespace is fully ignored in the diff. (while ## will mark whitespace but skip over it.)
# This option was added to handle a few whitespace issues that are not handled correctly
# by emacs ediff.

--- lisp/vc/ediff-help.el.orig	2022-12-08 10:49:03.115864594 +0000
+++ lisp/vc/ediff-help.el	2022-12-07 17:40:28.404161562 +0000
@@ -67,7 +67,8 @@
 p,DEL -previous diff |     | -vert/horiz split   |a/b -copy A/B's region to B/A
 n,SPC -next diff     |     h -highlighting       | rx -restore buf X's old diff
     j -jump to diff  |     @ -auto-refinement    |  * -refine current region
-   gx -goto X's point|    ## -ignore whitespace  |  ! -update diff regions
+   gx -goto X's point|    ## -skip whitespace    |  ! -update diff regions
+                     |    #b -ignore whitespace  |
   C-l -recenter      |    #c -ignore case        |
   v/V -scroll up/dn  | #f/#h -focus/hide regions | wx -save buf X
   </> -scroll lt/rt  |     X -read-only in buf X | wd -save diff output

--- lisp/vc/ediff-diff.el.orig	2022-12-07 15:59:16.654660650 +0000
+++ lisp/vc/ediff-diff.el	2022-12-08 10:51:14.611610065 +0000
@@ -104,6 +104,18 @@
 GNU diff3 doesn't have such an option."
   :type 'string)
 
+;;; Ignore whitespace at the diff program level by specifying -Bbw,
+;;;   before the diff regions are generated.
+;;; This means that with this option active, ## (emacs built in ignore whitespace) has no effect.
+(defcustom ediff-ignore-whitespace-option "-Bbw"
+  "Option that causes the diff program to ignore whitespace."
+  :type 'string)
+
+(defcustom ediff-ignore-whitespace-option3 ""
+  "Option that causes the diff3 program to ignore whitespace.
+GNU diff3 doesn't have such an option."
+  :type 'string)
+
 ;; the actual options used in comparison
 (ediff-defvar-local ediff-actual-diff-options ediff-diff-options "")
 
@@ -153,7 +165,13 @@
 This variable can be set either in .emacs or toggled interactively.
 Use `setq-default' if setting it in .emacs")
 
-(ediff-defvar-local ediff-auto-refine-limit 14000
+(ediff-defvar-local ediff-ignore-whitespace nil
+  "If t, ignore all whitespace. This is done by passing options to ignore whitespace to the diff program
+before difference regions are calculated in emacs.
+This variable can be set either in .emacs or toggled interactively.
+Use `setq-default' if setting it in .emacs")
+
+(ediff-defvar-local ediff-auto-refine-limit 150000
   "Auto-refine only the regions of this size (in bytes) or less.")
 
 ;;; General
@@ -1433,14 +1451,30 @@
 
 
 (defun ediff-set-actual-diff-options ()
-  (if ediff-ignore-case
-      (setq ediff-actual-diff-options
-	    (concat ediff-diff-options " " ediff-ignore-case-option)
-	    ediff-actual-diff3-options
-	    (concat ediff-diff3-options " " ediff-ignore-case-option3))
-    (setq ediff-actual-diff-options ediff-diff-options
-	  ediff-actual-diff3-options ediff-diff3-options)
-    )
+  (let ((ediff-extra-diff-options "") (ediff-extra-diff3-options ""))
+
+    (if ediff-ignore-case
+        (setq ediff-extra-diff-options ediff-ignore-case-option
+	      ediff-extra-diff3-options ediff-ignore-case-option3)
+      )
+
+    (if ediff-ignore-whitespace
+        (setq ediff-extra-diff-options
+	      (concat ediff-extra-diff-options " " ediff-ignore-whitespace-option)
+	      ediff-extra-diff3-options
+	      (concat ediff-extra-diff3-options " " ediff-ignore-whitespace-option3))
+      )
+
+    (if (or ediff-ignore-whitespace ediff-ignore-case-option)
+        (setq ediff-actual-diff-options
+	      (concat ediff-diff-options " " ediff-extra-diff-options)
+	      ediff-actual-diff3-options
+	      (concat ediff-diff3-options " " ediff-extra-diff3-options))
+      (setq ediff-actual-diff-options ediff-diff-options
+	    ediff-actual-diff3-options ediff-diff3-options)
+      )
+  )
+
   (setq-default ediff-actual-diff-options ediff-actual-diff-options
 		ediff-actual-diff3-options ediff-actual-diff3-options)
   )

--- lisp/vc/ediff-util.el.orig	2022-12-07 15:59:29.911635997 +0000
+++ lisp/vc/ediff-util.el	2022-12-07 16:51:17.867825952 +0000
@@ -207,6 +207,7 @@
   (define-key ediff-mode-map "#c"  'ediff-toggle-ignore-case)
   (or ediff-word-mode
       (define-key ediff-mode-map "##"  'ediff-toggle-skip-similar))
+  (define-key ediff-mode-map "#b"  'ediff-toggle-ignore-whitespace)
   (define-key ediff-mode-map "o"   nil)
   (define-key ediff-mode-map "A"  'ediff-toggle-read-only)
   (define-key ediff-mode-map "B"  'ediff-toggle-read-only)
@@ -2270,6 +2271,21 @@
        "Skipping regions that differ only in white space & line breaks")
     (message "Skipping over white-space differences turned off")))
 
+(defun ediff-toggle-ignore-whitespace ()
+  "Toggle ignoring whitespace by specifying the relevant options to the diff program.
+This means that if this is active, whitespace differences are ignored
+before the diff regions are created in emacs, and so the ## option has no effect."
+  (interactive)
+  (ediff-barf-if-not-control-buffer)
+  (setq ediff-ignore-whitespace (not ediff-ignore-whitespace))
+  (ediff-set-actual-diff-options)
+  (if ediff-ignore-whitespace
+      (message "Ignoring all whitespace differences")
+    (message "Ignoring all whitespace differences turned off"))
+  (sit-for 1)
+  (ediff-update-diffs)
+  )
+
 (defun ediff-focus-on-regexp-matches (n)
   "Focus on diffs that match regexp `ediff-regexp-focus-A/B'.
 Regions to be ignored according to this function are those where