From 74a2ea6ee898cafff740267ee17cbb1a8d70b297 Mon Sep 17 00:00:00 2001
From: Carsten Dominik <carsten.dominik@gmail.com>
Date: Thu, 13 Nov 2008 09:54:30 +0100
Subject: [PATCH] Install a better error message for the "Before first heading"
 error.

Org sometimes hits a "Before first heading" error.  This error happens
when `outline-back-to-heading' is called before the first heading in a
buffer.  In normal use, this is something easy to fix, because of
course you know where you are and you can identify the problem.

However, when Org scans many different buffers, for example to collect
agenda entries, you may not be able to tell easily where this error
happened.  This patch introduces a wrapper around
`outline-back-to-heading', with improving the error message by
spelling out buffer and location.
---
 lisp/ChangeLog   |  8 ++++++++
 lisp/org-list.el |  2 +-
 lisp/org.el      | 12 +++++++++---
 3 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index ff298ed66..279fc3ee1 100755
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,5 +1,13 @@
 2008-11-13  Carsten Dominik  <carsten.dominik@gmail.com>
 
+	* org.el (org-up-heading-safe, org-forward-same-level): Always
+	call `org-back-to-heading' instead of `outline-back-to-heading'.
+	(org-back-to-heading): New wrapper around outline-back-to-heading,
+	with a useful error message telling where the error happened.
+
+	* org-list.el (org-update-checkbox-count): Always call
+	`org-back-to-heading' instead of `outline-back-to-heading'.
+
 	* org-exp.el (org-export-as-html): Make sure that each <img> tag
 	has an `alt' attribute, to ensure XHTML validation.
 
diff --git a/lisp/org-list.el b/lisp/org-list.el
index bd9d9bc3b..6726c5354 100644
--- a/lisp/org-list.el
+++ b/lisp/org-list.el
@@ -259,7 +259,7 @@ the whole buffer."
  (save-excursion
    (let* ((buffer-invisibility-spec (org-inhibit-invisibility)) ; Emacs 21
 	  (beg (condition-case nil
-		   (progn (outline-back-to-heading) (point))
+		   (progn (org-back-to-heading) (point))
 		 (error (point-min))))
 	  (end (move-marker (make-marker)
 			    (progn (outline-next-heading) (point))))
diff --git a/lisp/org.el b/lisp/org.el
index 47babccb9..e41cbeebb 100644
--- a/lisp/org.el
+++ b/lisp/org.el
@@ -14087,7 +14087,13 @@ plainly yank the text as it is.
 	(outline-invisible-p)
       (get-char-property (point) 'invisible))))
 
-(defalias 'org-back-to-heading 'outline-back-to-heading)
+(defun org-back-to-heading (invisible-ok)
+  "Call `outline-back-to-heading', but provide a better error message."
+  (condition-case nil
+      (outline-back-to-heading invisible-ok)
+    (error (error "Before first headline at position %d in buffer %s"
+		  (point) (current-buffer)))))
+
 (defalias 'org-on-heading-p 'outline-on-heading-p)
 (defalias 'org-at-heading-p 'outline-on-heading-p)
 (defun org-at-heading-or-item-p ()
@@ -14112,7 +14118,7 @@ headline found, or nil if no higher level is found."
   (let ((pos (point)) start-level level
 	(re (concat "^" outline-regexp)))
     (catch 'exit
-      (outline-back-to-heading t)
+      (org-back-to-heading t)
       (setq start-level (funcall outline-level))
       (if (equal start-level 1) (throw 'exit nil))
       (while (re-search-backward re nil t)
@@ -14188,7 +14194,7 @@ When ENTRY is non-nil, show the entire entry."
 Stop at the first and last subheadings of a superior heading.
 This is like outline-forward-same-level, but invisible headings are ok."
   (interactive "p")
-  (outline-back-to-heading t)
+  (org-back-to-heading t)
   (while (> arg 0)
     (let ((point-to-move-to (save-excursion
 			      (org-get-next-sibling))))
-- 
2.11.4.GIT