From 18acc9d5b7202bf3bfac081ab094119957f15ee4 Mon Sep 17 00:00:00 2001
From: Ludovic Jacomme <alliance-cvs@asim.lip6.fr>
Date: Fri, 2 Aug 2002 13:33:09 +0000
Subject: [PATCH] dupablexpr

---
 alliance/src/abl/src/abldup.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/alliance/src/abl/src/abldup.c b/alliance/src/abl/src/abldup.c
index 8620b343..3466c725 100644
--- a/alliance/src/abl/src/abldup.c
+++ b/alliance/src/abl/src/abldup.c
@@ -87,6 +87,11 @@ ablexpr *dupablexpr( Expr )
   ablexpr *ExprDup;
   ablexpr *ExprQueue;
 
+  if ( Expr == (ablexpr *)0 )
+  {
+    return ( Expr );
+  }
+
   if ( ABL_ATOM( Expr ) )
   {
     return( addchain( (ablexpr *)0, ABL_CAR( Expr ) ) );