Use ediff interactive merge to help conflict resolution.

Idea from smerge code, adapted to git, new key binding on "e"

magit.el

@@ -1104,6 +1104,7 @@ Many Magit faces inherit from this one by default."
     (define-key map (kbd "B") 'magit-create-branch)
     (define-key map (kbd "m") 'magit-manual-merge)
     (define-key map (kbd "M") 'magit-automatic-merge)
+    (define-key map (kbd "e") 'magit-interactive-resolve-item)
     (define-key map (kbd "N r") 'magit-svn-rebase)
     (define-key map (kbd "N c") 'magit-svn-dcommit)
     (define-key map (kbd "R") 'magit-rebase-step)
@@ -1167,6 +1168,7 @@ Many Magit faces inherit from this one by default."
     ["Create branch" magit-create-branch t]
     ["Merge" magit-automatic-merge t]
     ["Merge (no commit)" magit-manual-merge t]
+    ["Interactive resolve" magit-interactive-resolve-item t]
     ["Rebase" magit-rebase-step t]
     ("Git SVN"
      ["Rebase" magit-svn-rebase (magit-svn-enabled)]
@@ -2865,4 +2867,58 @@ Prefix arg means justify as well."
     (erase-buffer)
     (shell-command (concat magit-git-executable " branch -va") t t)))
 
+(defvar magit-ediff-file)
+(defvar magit-ediff-windows)
+
+(defun magit-interactive-resolve (file)
+  (let ((merge-status (magit-git-string "ls-files -u -- %s" file))
+	(base-buffer (generate-new-buffer (concat file ".base")))
+	(our-buffer (generate-new-buffer (concat file ".ours")))
+	(their-buffer (generate-new-buffer (concat file ".theirs")))
+	(windows (current-window-configuration)))
+    (if (null merge-status)
+	(error "Cannot resolge %s" file))
+    (with-current-buffer base-buffer
+      (if (string-match "^[0-9]+ [0-9a-f]+ 1" merge-status)
+	  (insert (magit-git-string "cat-file blob :1:%s" file))))
+    (with-current-buffer our-buffer
+      (if (string-match "^[0-9]+ [0-9a-f]+ 2" merge-status)
+	  (insert (magit-git-string "cat-file blob :2:%s" file))))
+    (with-current-buffer their-buffer
+      (if (string-match "^[0-9]+ [0-9a-f]+ 3" merge-status)
+	  (insert (magit-git-string "cat-file blob :3:%s" file))))
+    ;; We have now created the 3 buffer with ours, theirs and the ancestor files
+    (with-current-buffer (ediff-merge-buffers-with-ancestor our-buffer their-buffer base-buffer)
+      (make-local-variable 'magit-ediff-file)
+      (setq magit-ediff-file file)
+      (make-local-variable 'magit-ediff-windows)
+      (setq magit-ediff-windows windows)
+      (make-local-variable 'ediff-quit-hook)
+      (add-hook 'ediff-quit-hook
+		(lambda ()
+		  (let ((buffer-A ediff-buffer-A)
+			(buffer-B ediff-buffer-B)
+			(buffer-C ediff-buffer-C)
+			(buffer-Ancestor ediff-ancestor-buffer)
+			(file magit-ediff-file)
+			(windows magit-ediff-windows))
+		    (ediff-cleanup-mess)
+		    (find-file file)
+		    (erase-buffer)
+		    (insert-buffer-substring buffer-C)
+		    (kill-buffer buffer-A)
+		    (kill-buffer buffer-B)
+		    (kill-buffer buffer-C)
+		    (when (bufferp buffer-Ancestor) (kill-buffer buffer-Ancestor))
+		    (set-window-configuration windows)
+		    (message "Conflict resolution finished; you may save the buffer")))))))
+
+
+(defun magit-interactive-resolve-item ()
+  (interactive)
+  (magit-section-action (item info "resolv")
+    ((diff)
+     (magit-interactive-resolve (cadr info)))))
+
+
 (provide 'magit)

magit.texi

@@ -452,10 +452,10 @@ one parent).  If you want to abort a manual merge, just do a hard
 reset to HEAD with @kbd{X}.
 
 Merges can fail if the two branches you merge want to introduce
-conflicting changes.  In that case, the automatic merge stops before
+conflicting changes.  In that case, the automatic merge stops before the
-the commit, essentially falling back to a manual merge.  You need to
+commit, essentially falling back to a manual merge.  You need to resolve
-resolve the conflicts and stage the resolved files, for example with
+the conflicts for example with @kbd{e} and stage the resolved files, for
-@kbd{S}.
+example with @kbd{S}.
 
 You can not stage individual hunks one by one as you resolve them, you
 can only stage whole files once all conflicts in them have been