Rmail trivia: give explicit errors for empty folders.

* mail/rmail.el (rmail-forward):
* mail/rmailkwd.el (rmail-set-label):
* mail/rmailout.el (rmail-output, rmail-output-as-seen)
(rmail-output-body-to-file): Give error if no message.

Fixes: debbugs:10082

4 files changed, 15 insertions, 1 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 54813759298..2a154b65890 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,5 +1,10 @@
 2011-11-23  Glenn Morris  <rgm@gnu.org>
 
+	* mail/rmail.el (rmail-forward):
+	* mail/rmailkwd.el (rmail-set-label):
+	* mail/rmailout.el (rmail-output, rmail-output-as-seen)
+	(rmail-output-body-to-file): Give error if no message.  (Bug#10082)
+
 	* mail/rmail.el (rmail-current-message): Doc fix.
 
 	* mail/rmail.el (rmail-message-filter): Mark as obsolete.  (Bug#2624)
diff --git a/lisp/mail/rmail.el b/lisp/mail/rmail.el
index 6e79c5c82b1..b920c065de5 100644
--- a/lisp/mail/rmail.el
+++ b/lisp/mail/rmail.el
@@ -3786,6 +3786,8 @@ which is an element of rmail-msgref-vector."
 With prefix argument, \"resend\" the message instead of forwarding it;
 see the documentation of `rmail-resend'."
   (interactive "P")
+  (if (zerop rmail-current-message)
+      (error "No message to forward"))
   (if resend
       (call-interactively 'rmail-resend)
     (let ((forward-buffer rmail-buffer)
diff --git a/lisp/mail/rmailkwd.el b/lisp/mail/rmailkwd.el
index 73542578bf6..472740aefd8 100644
--- a/lisp/mail/rmailkwd.el
+++ b/lisp/mail/rmailkwd.el
@@ -96,7 +96,8 @@ LABEL may be a symbol or string."
       (error "More than one label specified"))
   (with-current-buffer rmail-buffer
     (rmail-maybe-set-message-counters)
-    (or msg (setq msg rmail-current-message))
+    (if (zerop (or msg (setq msg rmail-current-message)))
+	(error "No message"))
     ;; Force recalculation of summary for this message.
     (aset rmail-summary-vector (1- msg) nil)
     (let (attr-index)
diff --git a/lisp/mail/rmailout.el b/lisp/mail/rmailout.el
index c168ca9d8f5..ad76a493483 100644
--- a/lisp/mail/rmailout.el
+++ b/lisp/mail/rmailout.el
@@ -468,6 +468,8 @@ from a non-Rmail buffer.  In this case, COUNT is ignored."
       (if rmail-buffer
 	  (set-buffer rmail-buffer)
 	(error "There is no Rmail buffer"))
+      (if (zerop rmail-total-messages)
+	  (error "No messages to output"))
       (let ((orig-count count)
 	    beg end)
 	(while (> count 0)
@@ -533,6 +535,8 @@ so you should call `rmail-output' directly in that case."
     (if rmail-buffer
 	(set-buffer rmail-buffer)
       (error "There is no Rmail buffer"))
+    (if (zerop rmail-total-messages)
+	(error "No messages to output"))
     (let ((orig-count count)
 	  (cur (current-buffer)))
       (while (> count 0)
@@ -594,6 +598,8 @@ than appending to it.  Deletes the message after writing if
 	(expand-file-name file-name
 			  (and rmail-default-body-file
 			       (file-name-directory rmail-default-body-file))))
+  (if (zerop rmail-current-message)
+      (error "No message to output"))
   (save-excursion
     (goto-char (point-min))
     (search-forward "\n\n")