From 9d693d807fbd77761cf1c35de1bcbcfc91d690e4 Mon Sep 17 00:00:00 2001
From: Stefan Monnier <monnier@iro.umontreal.ca>
Date: Fri, 24 Aug 2007 14:39:25 +0000
Subject: [PATCH] (byte-optimize-if): Don't presume `clause' is a list.

---
 lisp/ChangeLog              | 9 +++++++--
 lisp/emacs-lisp/byte-opt.el | 4 +++-
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index a97ee9a2621..4601d4a6d76 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,8 @@
+2007-08-24  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+	* emacs-lisp/byte-opt.el (byte-optimize-if): Don't presume `clause' is
+	a list.
+
 2007-08-24  Thien-Thi Nguyen  <ttn@gnuvola.org>
 
 	* progmodes/hideshow.el (hs-match-data): Delete alias.
@@ -39,8 +44,8 @@
 
 2007-08-23  Masatake YAMATO  <jet@gyve.org>
 
-	* progmodes/cc-fonts.el (gtkdoc-font-lock-doc-comments): Highlight
-	name of parameters in document body.
+	* progmodes/cc-fonts.el (gtkdoc-font-lock-doc-comments):
+	Highlight name of parameters in document body.
 
 2007-08-23  Stefan Monnier  <monnier@iro.umontreal.ca>
 
diff --git a/lisp/emacs-lisp/byte-opt.el b/lisp/emacs-lisp/byte-opt.el
index b4eaf4ff5eb..80a6ad595b2 100644
--- a/lisp/emacs-lisp/byte-opt.el
+++ b/lisp/emacs-lisp/byte-opt.el
@@ -1020,7 +1020,9 @@
   ;; (if <test> nil <else...>) ==> (if (not <test>) (progn <else...>))
   ;; (if <test> <then> nil) ==> (if <test> <then>)
   (let ((clause (nth 1 form)))
-    (cond ((eq (car clause) 'progn)
+    (cond ((and (eq (car-safe clause) 'progn)
+                ;; `clause' is a proper list.
+                (null (cdr (last clause))))
            (if (null (cddr clause))
                ;; A trivial `progn'.
                (byte-optimize-if `(if ,(cadr clause) ,@(nthcdr 2 form)))
-- 
2.39.5