Fix for tickets #3378 and #3381 that preserves the aliasing optimization.

And yet, this fix feels uncomfortable.  Seeking an alternative... (CVS 5712)

FossilOrigin-Name: f8b759f1977915c314be874840ebf18e6bc69b57

src/expr.c

@@ -12,7 +12,7 @@
 ** This file contains routines used for analyzing expressions and
 ** for generating VDBE code that evaluates expressions in SQLite.
 **
-** $Id: expr.c,v 1.393 2008/09/16 18:02:47 drh Exp $
+** $Id: expr.c,v 1.394 2008/09/17 00:13:12 drh Exp $
 */
 #include "sqliteInt.h"
 #include <ctype.h>
@@ -2456,7 +2456,7 @@ int sqlite3ExprCodeExprList(
   Parse *pParse,     /* Parsing context */
   ExprList *pList,   /* The expression list to be coded */
   int target,        /* Where to write results */
-  int doHardCopy     /* Call sqlite3ExprHardCopy on each element if true */
+  int doHardCopy     /* Make a hard copy of every element */
 ){
   struct ExprList_item *pItem;
   int i, n;
@@ -2464,17 +2464,16 @@ int sqlite3ExprCodeExprList(
   assert( target>0 );
   n = pList->nExpr;
   for(pItem=pList->a, i=0; i<n; i++, pItem++){
-#if 0  /* Remove temporarily for tickets #3378 and #3381 */
     if( pItem->iAlias ){
       int iReg = codeAlias(pParse, pItem->iAlias, pItem->pExpr);
       Vdbe *v = sqlite3GetVdbe(pParse);
       sqlite3VdbeAddOp2(v, OP_SCopy, iReg, target+i);
-    }else
-#endif
-    {
+    }else{
       sqlite3ExprCode(pParse, pItem->pExpr, target+i);
     }
-    if( doHardCopy ) sqlite3ExprHardCopy(pParse, target, n);
+    if( doHardCopy ){
+      sqlite3ExprHardCopy(pParse, target, n);
+    }
   }
   return n;
 }