From c8f4f52409e4d7b3d65b2e0672cb9340f5cb33c1 Mon Sep 17 00:00:00 2001
From: yamaoka <yamaoka>
Date: Fri, 26 Dec 2003 05:46:28 +0000
Subject: [PATCH] Synch to Gnus 200312260545.

---
 lisp/ChangeLog    |    6 ++++++
 lisp/dgnushack.el |   37 +++++++++++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+)

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index be20d47..a69d4c8 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,9 @@
+2003-12-26  Katsumi Yamaoka  <yamaoka@jpl.org>
+
+	* dgnushack.el: Add an advice to byte-optimize-form-code-walker to
+	avoid the warning ``...called for effect'' for the pop form when
+	running Emacs 21.3.
+
 2003-12-26  Jesper Harder  <harder@ifa.au.dk>
 
 	* mm-bodies.el (mm-body-encoding): Don't use 7bit if the body
diff --git a/lisp/dgnushack.el b/lisp/dgnushack.el
index acbe183..97670f4 100644
--- a/lisp/dgnushack.el
+++ b/lisp/dgnushack.el
@@ -99,6 +99,43 @@
 ;  (cons 'progn (cdr form)))
 ;(defalias 'byte-compile-file-form-defsubst 'byte-compile-file-form-defun)
 
+(when (and (not (featurep 'xemacs))
+	   (= emacs-major-version 21)
+	   (= emacs-minor-version 3)
+	   (condition-case code
+	       (let ((byte-compile-error-on-warn t))
+		 (byte-optimize-form (quote (pop x)) t)
+		 nil)
+	     (error (string-match "called for effect"
+				  (error-message-string code)))))
+  (defadvice byte-optimize-form-code-walker (around silence-warn-for-pop
+						    (form for-effect)
+						    activate)
+    "Silence the warning \"...called for effect\" for the `pop' form.
+It is effective only when the `pop' macro is defined by cl.el rather
+than subr.el."
+    (let (tmp)
+      (if (and (eq (car-safe form) 'car)
+	       for-effect
+	       (setq tmp (get 'car 'side-effect-free))
+	       (not byte-compile-delete-errors)
+	       (not (eq tmp 'error-free))
+	       (eq (car-safe (cadr form)) 'prog1)
+	       (let ((var (cadr (cadr form)))
+		     (last (nth 2 (cadr form))))
+		 (and (symbolp var)
+		      (null (nthcdr 3 (cadr form)))
+		      (eq (car-safe last) 'setq)
+		      (eq (cadr last) var)
+		      (eq (car-safe (nth 2 last)) 'cdr)
+		      (eq (cadr (nth 2 last)) var))))
+	  (progn
+	    (put 'car 'side-effect-free 'error-free)
+	    (unwind-protect
+		ad-do-it
+	      (put 'car 'side-effect-free tmp)))
+	ad-do-it))))
+
 (when (boundp 'MULE)
   (let (current-load-list)
     ;; Make the function to be silent at compile-time.
-- 
1.7.10.4