Rmail summary fixes for empty summaries.

* lisp/mail/rmailsum.el (rmail-summary, rmail-new-summary)
(rmail-new-summary-1): Allow empty summaries. 
(rmail-new-summary): Remember that rmail-summary-buffer is buffer-local.

Fixes: debbugs:9964

2 files changed, 15 insertions, 12 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 8f28e033419..676c0c6b180 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,9 @@
+2011-11-14  Glenn Morris  <rgm@gnu.org>
+
+	* mail/rmailsum.el (rmail-summary, rmail-new-summary)
+	(rmail-new-summary-1): Allow empty summaries.  (Bug#9964)
+	(rmail-new-summary): Remember that rmail-summary-buffer is buffer-local.
+
 2011-11-12  Martin Rudalics  <rudalics@gmx.at>
 
 	* window.el (window-resize, delete-window): Use window-splits
diff --git a/lisp/mail/rmailsum.el b/lisp/mail/rmailsum.el
index 8e28201e31f..b95651d3b69 100644
--- a/lisp/mail/rmailsum.el
+++ b/lisp/mail/rmailsum.el
@@ -269,7 +269,8 @@ Setting this option to nil might speed up the generation of summaries."
   "Display a summary of all messages, one line per message."
   (interactive)
   (rmail-new-summary "All" '(rmail-summary) nil)
-  (unless (get-buffer-window rmail-buffer)
+  (unless (or (zerop (buffer-size))		; empty summary
+	      (get-buffer-window rmail-buffer))
     (rmail-summary-beginning-of-message)))
 
 ;;;###autoload
@@ -404,13 +405,13 @@ nil for FUNCTION means all messages."
   (message "Computing summary lines...")
   (unless rmail-buffer
     (error "No RMAIL buffer found"))
-  (let (mesg was-in-summary)
+  (let (mesg was-in-summary sumbuf)
     (if (eq major-mode 'rmail-summary-mode)
 	(setq was-in-summary t))
     (with-current-buffer rmail-buffer
-      (if (zerop (setq mesg rmail-current-message))
-	  (error "No messages to summarize"))
-      (setq rmail-summary-buffer (rmail-new-summary-1 desc redo func args)))
+      (setq rmail-summary-buffer (rmail-new-summary-1 desc redo func args)
+	    ;; r-s-b is buffer-local.
+	    sumbuf rmail-summary-buffer))
     ;; Now display the summary buffer and go to the right place in it.
     (unless was-in-summary
       (if (and (one-window-p)
@@ -420,13 +421,12 @@ nil for FUNCTION means all messages."
 	  (progn
 	    (split-window (selected-window) rmail-summary-window-size)
 	    (select-window (next-window (frame-first-window)))
-	    (rmail-pop-to-buffer rmail-summary-buffer)
+	    (rmail-pop-to-buffer sumbuf)
 	    ;; If pop-to-buffer did not use that window, delete that
 	    ;; window.  (This can happen if it uses another frame.)
-	    (if (not (eq rmail-summary-buffer
-			 (window-buffer (frame-first-window))))
+	    (if (not (eq sumbuf (window-buffer (frame-first-window))))
 		(delete-other-windows)))
-	(rmail-pop-to-buffer rmail-summary-buffer))
+	(rmail-pop-to-buffer sumbuf))
       (set-buffer rmail-buffer)
       ;; This is how rmail makes the summary buffer reappear.
       ;; We do this here to make the window the proper size.
@@ -490,9 +490,6 @@ message."
     ;; Temporarily, while summary buffer is unfinished,
     ;; we "don't have" a summary.
     (setq rmail-summary-buffer nil)
-    (unless summary-msgs
-      (kill-buffer sumbuf)
-      (error "Nothing to summarize"))
     ;; I have not a clue what this clause is doing.  If you read this
     ;; chunk of code and have a clue, then please email that clue to
     ;; pmr@pajato.com