From f030b376820102ff6cda49565c8b8173b2d44606 Mon Sep 17 00:00:00 2001
From: dan <dan@noemail.net>
Date: Fri, 22 Feb 2019 19:24:16 +0000
Subject: [PATCH] Internally, remove all references to a Window object that
 belongs to an expression in an ORDER BY clause if that expression is
 converted to an alias of a result-set expression. Fix for [4feb3159c6].

FossilOrigin-Name: 579b66eaa0816561c6e47ea116b46f229188f0fc84c1173bfe0d21df2dff9a9a
---
 src/resolve.c     | 49 ++++++++++++++++++++++++++++++++++-------------
 test/window1.test | 20 +++++++++++++++++++
 2 files changed, 56 insertions(+), 13 deletions(-)

diff --git a/src/resolve.c b/src/resolve.c
index 9410bc020..fd2cf539a 100644
--- a/src/resolve.c
+++ b/src/resolve.c
@@ -1243,6 +1243,38 @@ int sqlite3ResolveOrderGroupBy(
   return 0;
 }
 
+#ifndef SQLITE_OMIT_WINDOWFUNC
+/*
+** Walker callback for resolveRemoveWindows().
+*/
+static int resolveRemoveWindowsCb(Walker *pWalker, Expr *pExpr){
+  if( ExprHasProperty(pExpr, EP_WinFunc) ){
+    Window **pp;
+    for(pp=&pWalker->u.pSelect->pWin; *pp; pp=&(*pp)->pNextWin){
+      if( *pp==pExpr->y.pWin ){
+        *pp = (*pp)->pNextWin;
+        break;
+      }    
+    }
+  }
+  return WRC_Continue;
+}
+
+/*
+** Remove any Window objects owned by the expression pExpr from the
+** Select.pWin list of Select object pSelect.
+*/
+static void resolveRemoveWindows(Select *pSelect, Expr *pExpr){
+  Walker sWalker;
+  memset(&sWalker, 0, sizeof(Walker));
+  sWalker.xExprCallback = resolveRemoveWindowsCb;
+  sWalker.u.pSelect = pSelect;
+  sqlite3WalkExpr(&sWalker, pExpr);
+}
+#else
+# define resolveRemoveWindows(x,y)
+#endif
+
 /*
 ** pOrderBy is an ORDER BY or GROUP BY clause in SELECT statement pSelect.
 ** The Name context of the SELECT statement is pNC.  zType is either
@@ -1309,19 +1341,10 @@ static int resolveOrderGroupBy(
     }
     for(j=0; j<pSelect->pEList->nExpr; j++){
       if( sqlite3ExprCompare(0, pE, pSelect->pEList->a[j].pExpr, -1)==0 ){
-#ifndef SQLITE_OMIT_WINDOWFUNC
-        if( ExprHasProperty(pE, EP_WinFunc) ){
-          /* Since this window function is being changed into a reference
-          ** to the same window function the result set, remove the instance
-          ** of this window function from the Select.pWin list. */
-          Window **pp;
-          for(pp=&pSelect->pWin; *pp; pp=&(*pp)->pNextWin){
-            if( *pp==pE->y.pWin ){
-              *pp = (*pp)->pNextWin;
-            }    
-          }
-        }
-#endif
+        /* Since this expresion is being changed into a reference
+        ** to an identical expression in the result set, remove all Window
+        ** objects belonging to the expression from the Select.pWin list. */
+        resolveRemoveWindows(pSelect, pE);
         pItem->u.x.iOrderByCol = j+1;
       }
     }
diff --git a/test/window1.test b/test/window1.test
index 2c504205e..b3073985b 100644
--- a/test/window1.test
+++ b/test/window1.test
@@ -594,6 +594,26 @@
 } {
 }

+#-------------------------------------------------------------------------
+do_execsql_test 17.0 {
+  CREATE TABLE t8(a);
+  INSERT INTO t8 VALUES(1), (2), (3);
+}
+
+do_execsql_test 17.1 {
+  SELECT +sum(0) OVER () ORDER BY +sum(0) OVER ();
+} {0}
+
+do_execsql_test 17.2 {
+  select +sum(a) OVER () FROM t8 ORDER BY +sum(a) OVER () DESC;
+} {6 6 6}
+
+do_execsql_test 17.3 {
+  SELECT 10+sum(a) OVER (ORDER BY a)
+  FROM t8
+  ORDER BY 10+sum(a) OVER (ORDER BY a) DESC;
+} {16 13 11}
+
 # 2020-05-23
 # ticket 7a5279a25c57adf1
 #
-- 
2.39.2