Alternative fix to ticket [c8d3b9f0a750a529]: Prior to deleting or modifying

an Expr not that is referenced by an AggInfo, modify the AggInfo to get its
own copy of the original Expr.

FossilOrigin-Name: 7682d8a768fbccfe0cc956e9f6481637146e1ab9763b248ff11052761ce32e32

1 files changed, 61 insertions, 1 deletions

diff --git a/src/expr.c b/src/expr.c
index 496177a5c..631d71568 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -5710,6 +5710,66 @@ int sqlite3FunctionUsesThisSrc(Expr *pExpr, SrcList *pSrcList){
 }
 
 /*
+** This is a Walker expression node callback.
+**
+** For Expr nodes that contain pAggInfo pointers, make sure the AggInfo
+** object that is referenced does not refer directly to the Expr.  If
+** it does, make a copy.  This is done because the pExpr argument is
+** subject to change.
+**
+** The copy is stored on pParse->pConstExpr with a register number of 0.
+** This will cause the expression to be deleted automatically when the
+** Parse object is destroyed, but the zero register number means that it
+** will not generate any code in the preamble.
+*/
+static int agginfoPersistExprCb(Walker *pWalker, Expr *pExpr){
+  if( !ExprHasProperty(pExpr, EP_TokenOnly|EP_Reduced)
+   && pExpr->pAggInfo!=0
+  ){
+    AggInfo *pAggInfo = pExpr->pAggInfo;
+    int iAgg = pExpr->iAgg;
+    Parse *pParse = pWalker->pParse;
+    sqlite3 *db = pParse->db;
+    assert( pAggInfo->iAggMagic==AggInfoMagic );
+    assert( pExpr->op==TK_COLUMN || pExpr->op==TK_AGG_COLUMN
+            || pExpr->op==TK_FUNCTION || pExpr->op==TK_AGG_FUNCTION );
+    if( pExpr->op==TK_COLUMN || pExpr->op==TK_AGG_COLUMN ){
+      assert( iAgg>=0 && iAgg<pAggInfo->nColumn );
+      if( pAggInfo->aCol[iAgg].pExpr==pExpr ){
+        pExpr = sqlite3ExprDup(db, pExpr, 0);
+        if( pExpr ){
+          pAggInfo->aCol[iAgg].pExpr = pExpr;
+          pParse->pConstExpr = 
+             sqlite3ExprListAppend(pParse, pParse->pConstExpr, pExpr);
+        }
+      }
+    }else{
+      assert( iAgg>=0 && iAgg<pAggInfo->nFunc );
+      if( pAggInfo->aFunc[iAgg].pExpr==pExpr ){
+        pExpr = sqlite3ExprDup(db, pExpr, 0);
+        if( pExpr ){
+          pAggInfo->aFunc[iAgg].pExpr = pExpr;
+          pParse->pConstExpr = 
+             sqlite3ExprListAppend(pParse, pParse->pConstExpr, pExpr);
+        }
+      }
+    }
+  }
+  return WRC_Continue;
+}
+
+/*
+** Initialize a Walker object so that will persist AggInfo entries referenced
+** by the tree that is walked.
+*/
+void sqlite3AggInfoPersistWalkerInit(Walker *pWalker, Parse *pParse){
+  memset(pWalker, 0, sizeof(*pWalker));
+  pWalker->pParse = pParse;
+  pWalker->xExprCallback = agginfoPersistExprCb;
+  pWalker->xSelectCallback = sqlite3SelectWalkNoop;
+}
+
+/*
 ** Add a new element to the pAggInfo->aCol[] array.  Return the index of
 ** the new element.  Return a negative number if malloc fails.
 */
@@ -5739,7 +5799,7 @@ static int addAggInfoFunc(sqlite3 *db, AggInfo *pInfo){
        &i
   );
   return i;
-}    
+}
 
 /*
 ** This is the xExprCallback for a tree walker.  It is used to