Avoid coding unindexed WHERE constraints if an equivalent transitive term has already been coded by an outer loop.

FossilOrigin-Name: 644bb77f8bb2c3499db7c280440c92fd2649a98ce714ae0d5d690eabfdc04326

test/unionall2.test

@@ -35,5 +35,24 @@ do_execsql_test 1.1 {
   SELECT 1 FROM vA, vA, vA, vA, vA, vA, vA, vA, vA, vA
 }
 
+#-------------------------------------------------------------------------
+
+do_execsql_test 2.1 {
+  CREATE TABLE y1(a INTEGER, b);
+  CREATE TABLE y2(c INTEGER, d);
+
+  CREATE TABLE x3_a(a INTEGER PRIMARY KEY, b TEXT);
+  CREATE TABLE x3_b(c INTEGER PRIMARY KEY, d TEXT);
+}
+
+do_execsql_test 2.2 {
+
+  SELECT * FROM y1 CROSS JOIN y2 WHERE y1.a=y2.c AND y2.c IN (
+    SELECT a FROM x3_a UNION ALL
+    SELECT c FROM x3_b ORDER BY 1
+  )
+}
+
+
 
 finish_test