When the sqlite3WindowRewrite() routine detects and error, have it convert

the SELECT statement into just "SELECT null" so that it does not leave the
parse tree in a goofy state that can cause problems with subsequent code
before the stack has a chance to unwind and report the error.
Ticket [d87336c81c7d0873]

FossilOrigin-Name: fa58aad48a788802b13a819e49f9b8787f713bbe395c46c7295e821c52c81738

src/expr.c

@@ -594,6 +594,7 @@ static void codeVectorCompare(
   int addrDone = sqlite3VdbeMakeLabel(pParse);
   int isCommuted = ExprHasProperty(pExpr,EP_Commuted);
 
+  if( pParse->nErr ) return;
   if( nLeft!=sqlite3ExprVectorSize(pRight) ){
     sqlite3ErrorMsg(pParse, "row value misused");
     return;
@@ -2686,8 +2687,10 @@ static char *exprINAffinity(Parse *pParse, Expr *pExpr){
 **   "sub-select returns N columns - expected M"
 */   
 void sqlite3SubselectError(Parse *pParse, int nActual, int nExpect){
-  const char *zFmt = "sub-select returns %d columns - expected %d";
-  sqlite3ErrorMsg(pParse, zFmt, nActual, nExpect);
+  if( pParse->nErr==0 ){
+    const char *zFmt = "sub-select returns %d columns - expected %d";
+    sqlite3ErrorMsg(pParse, zFmt, nActual, nExpect);
+  }
 }
 #endif
 

src/select.c

@@ -84,7 +84,10 @@ struct SortCtx {
 
 /*
 ** Delete all the content of a Select structure.  Deallocate the structure
-** itself only if bFree is true.
+** itself depending on the value of bFree
+**
+** If bFree==1, call sqlite3DbFree() on the p object.
+** If bFree==0, Leave the first Select object unfreed
 */
 static void clearSelect(sqlite3 *db, Select *p, int bFree){
   while( p ){
@@ -188,6 +191,20 @@ void sqlite3SelectDelete(sqlite3 *db, Select *p){
   if( OK_IF_ALWAYS_TRUE(p) ) clearSelect(db, p, 1);
 }
 
+/*
+** Delete all the substructure for p, but keep p allocated.  Redefine
+** p to be a single SELECT where every column of the result set has a
+** value of NULL.
+*/
+void sqlite3SelectReset(Parse *pParse, Select *p){
+  if( ALWAYS(p) ){
+    clearSelect(pParse->db, p, 0);
+    memset(&p->iLimit, 0, sizeof(Select) - offsetof(Select,iLimit));
+    p->pEList = sqlite3ExprListAppend(pParse, 0,
+                     sqlite3ExprAlloc(pParse->db,TK_NULL,0,0));
+  }
+}
+
 /*
 ** Return a pointer to the right-most SELECT statement in a compound.
 */
@@ -2711,9 +2728,9 @@ static int multiSelect(
         ** it is that we currently need.
         */
         assert( unionTab==dest.iSDParm || dest.eDest!=priorOp );
-        if( dest.eDest!=priorOp ){
+        assert( p->pEList || db->mallocFailed );
+        if( dest.eDest!=priorOp && db->mallocFailed==0 ){
           int iCont, iBreak, iStart;
-          assert( p->pEList );
           iBreak = sqlite3VdbeMakeLabel(pParse);
           iCont = sqlite3VdbeMakeLabel(pParse);
           computeLimitRegisters(pParse, p, iBreak);
@@ -5738,7 +5755,9 @@ int sqlite3Select(
   }
 
 #ifndef SQLITE_OMIT_WINDOWFUNC
-  if( sqlite3WindowRewrite(pParse, p) ){
+  rc = sqlite3WindowRewrite(pParse, p);
+  if( rc ){
+    assert( pParse->nErr>0 );
     goto select_end;
   }
 #if SELECTTRACE_ENABLED

src/sqliteInt.h

@@ -2918,13 +2918,13 @@ struct Upsert {
 ** sequences for the ORDER BY clause.
 */
 struct Select {
-  ExprList *pEList;      /* The fields of the result */
   u8 op;                 /* One of: TK_UNION TK_ALL TK_INTERSECT TK_EXCEPT */
   LogEst nSelectRow;     /* Estimated number of result rows */
   u32 selFlags;          /* Various SF_* values */
   int iLimit, iOffset;   /* Memory registers holding LIMIT & OFFSET counters */
   u32 selId;             /* Unique identifier number for this SELECT */
   int addrOpenEphm[2];   /* OP_OpenEphem opcodes related to this select */
+  ExprList *pEList;      /* The fields of the result */
   SrcList *pSrc;         /* The FROM clause */
   Expr *pWhere;          /* The WHERE clause */
   ExprList *pGroupBy;    /* The GROUP BY clause */
@@ -4092,6 +4092,7 @@ int sqlite3Select(Parse*, Select*, SelectDest*);
 Select *sqlite3SelectNew(Parse*,ExprList*,SrcList*,Expr*,ExprList*,
                          Expr*,ExprList*,u32,Expr*);
 void sqlite3SelectDelete(sqlite3*, Select*);
+void sqlite3SelectReset(Parse*, Select*);
 Table *sqlite3SrcListLookup(Parse*, SrcList*);
 int sqlite3IsReadOnly(Parse*, Table*, int);
 void sqlite3OpenTable(Parse*, int iCur, int iDb, Table*, int);

src/window.c

@@ -1021,6 +1021,9 @@ int sqlite3WindowRewrite(Parse *pParse, Select *p){
       pSub->selFlags |= SF_Expanded;
       pTab2 = sqlite3ResultSetOfSelect(pParse, pSub, SQLITE_AFF_NONE);
       if( pTab2==0 ){
+        /* Might actually be some other kind of error, but in that case
+        ** pParse->nErr will be set, so if SQLITE_NOMEM is set, we will get
+        ** the correct error message regardless. */
         rc = SQLITE_NOMEM;
       }else{
         memcpy(pTab, pTab2, sizeof(Table));
@@ -1039,9 +1042,12 @@ int sqlite3WindowRewrite(Parse *pParse, Select *p){
     sqlite3DbFree(db, pTab);
   }
 
-  if( rc && pParse->nErr==0 ){
-    assert( pParse->db->mallocFailed );
-    return sqlite3ErrorToParser(pParse->db, SQLITE_NOMEM);
+  if( rc ){
+    if( pParse->nErr==0 ){
+      assert( pParse->db->mallocFailed );
+      sqlite3ErrorToParser(pParse->db, SQLITE_NOMEM);
+    }
+    sqlite3SelectReset(pParse, p);
   }
   return rc;
 }