Recompute the set of columns used for each table when the table is

involved in query flattening.

FossilOrigin-Name: a9bb71ba708ba72255ba8d18c9856e38ddf53eae2d61c8435149354fb2b2459e

1 files changed, 10 insertions, 9 deletions

diff --git a/src/walker.c b/src/walker.c
index 5733210c4..48d7ddbf3 100644
--- a/src/walker.c
+++ b/src/walker.c
@@ -156,15 +156,16 @@ int sqlite3WalkSelectFrom(Walker *pWalker, Select *p){
   struct SrcList_item *pItem;
 
   pSrc = p->pSrc;
-  assert( pSrc!=0 );
-  for(i=pSrc->nSrc, pItem=pSrc->a; i>0; i--, pItem++){
-    if( pItem->pSelect && sqlite3WalkSelect(pWalker, pItem->pSelect) ){
-      return WRC_Abort;
-    }
-    if( pItem->fg.isTabFunc
-     && sqlite3WalkExprList(pWalker, pItem->u1.pFuncArg)
-    ){
-      return WRC_Abort;
+  if( pSrc ){
+    for(i=pSrc->nSrc, pItem=pSrc->a; i>0; i--, pItem++){
+      if( pItem->pSelect && sqlite3WalkSelect(pWalker, pItem->pSelect) ){
+        return WRC_Abort;
+      }
+      if( pItem->fg.isTabFunc
+       && sqlite3WalkExprList(pWalker, pItem->u1.pFuncArg)
+      ){
+        return WRC_Abort;
+      }
     }
   }
   return WRC_Continue;