Check-in [a9657c87c53c1922] is wrong: the IndexedExpr.bMaybeNullRow flag is

required for virtual columns if they are part of an outer join.  Add a
test case (derived from dbsqlfuzz b9e65e2f110df998f1306571fae7af6c01e4d92b)
to prove it.

Author: D. Richard Hipp

src/where.c

@@ -5948,16 +5948,10 @@ static SQLITE_NOINLINE void whereAddIndexedExpr(
   for(i=0; i<pIdx->nColumn; i++){
     Expr *pExpr;
     int j = pIdx->aiColumn[i];
-    int bMaybeNullRow;
     if( j==XN_EXPR ){
       pExpr = pIdx->aColExpr->a[i].pExpr;
-      testcase( pTabItem->fg.jointype & JT_LEFT );
-      testcase( pTabItem->fg.jointype & JT_RIGHT );
-      testcase( pTabItem->fg.jointype & JT_LTORJ );
-      bMaybeNullRow = (pTabItem->fg.jointype & (JT_LEFT|JT_LTORJ|JT_RIGHT))!=0;
     }else if( j>=0 && (pTab->aCol[j].colFlags & COLFLAG_VIRTUAL)!=0 ){
       pExpr = sqlite3ColumnExpr(pTab, &pTab->aCol[j]);
-      bMaybeNullRow = 0;
     }else{
       continue;
     }
@@ -5989,7 +5983,7 @@ static SQLITE_NOINLINE void whereAddIndexedExpr(
     p->iDataCur = pTabItem->iCursor;
     p->iIdxCur = iIdxCur;
     p->iIdxCol = i;
-    p->bMaybeNullRow = bMaybeNullRow;
+    p->bMaybeNullRow = (pTabItem->fg.jointype & (JT_LEFT|JT_LTORJ|JT_RIGHT))!=0;
     if( sqlite3IndexAffinityStr(pParse->db, pIdx) ){
       p->aff = pIdx->zColAff[i];
     }

test/joinH.test

@@ -309,4 +309,36 @@ do_execsql_test 12.3 {
   SELECT * FROM t1 LEFT JOIN t2 ON true RIGHT JOIN t3 ON d2=e3 WHERE c2 BETWEEN NULL AND a1;
 }
 
+#-------------------------------------------------------------------------
+# 2024-04-05 dbsqlfuzz b9e65e2f110df998f1306571fae7af6c01e4d92b
+reset_db
+do_execsql_test 13.1 {
+  CREATE TABLE t1(a INT AS (b), b INT);
+  INSERT INTO t1(b) VALUES(123);
+  CREATE TABLE t2(a INT, c INT);
+  SELECT a FROM t2 NATURAL RIGHT JOIN t1;
+} {123}
+do_execsql_test 13.2 {
+  CREATE INDEX t1a ON t1(a);
+  SELECT a FROM t2 NATURAL RIGHT JOIN t1;
+} {123}
+# Further tests of the same logic (indexes on expressions
+# used by RIGHT JOIN) from check-in ffe23af73fcb324d and
+# forum post https://sqlite.org/forum/forumpost/9b491e1debf0b67a.
+db null NULL
+do_execsql_test 13.3 {
+  CREATE TABLE t3(a INT, b INT);
+  CREATE UNIQUE INDEX t3x ON t3(a, a+b);
+  INSERT INTO t3(a,b) VALUES(1,2),(4,8),(16,32),(4,80),(1,-300);
+  CREATE TABLE t4(x INT, y INT);
+  INSERT INTO t4(x,y) SELECT a, b FROM t3;
+  INSERT INTO t4(x,y) VALUES(99,99);
+  SELECT a1.a, sum( a1.a+a1.b ) FROM t3 AS a1 RIGHT JOIN t4 ON a=x
+   GROUP BY a1.a ORDER BY 1;
+} {NULL NULL 1 -592 4 192 16 48}
+do_execsql_test 13.4 {
+  SELECT sum( a1.a+a1.b ) FROM t3 AS a1 RIGHT JOIN t3 ON true
+   GROUP BY a1.a ORDER BY 1;
+} {-1480 240 480}
+
 finish_test