Fixed bug #24345.

This bug appeared after the patch for bug 21390 that had added some code
to handle outer joins with no matches after substitution of a const
table in an efficient way. That code as it is cannot be applied to the case
of nested outer join operations. Being applied to the queries with
nested outer joins the code can cause crashes or wrong result sets.
The fix blocks row substitution for const inner tables of an outer join
if the inner operand is not a single table.  


mysql-test/r/join_nested.result:
  Added a test case for bug #24345.
mysql-test/t/join_nested.test:
  Added a test case for bug #24345.

mysql-test/r/join_nested.result

@@ -1562,3 +1562,46 @@ id	ngroupbynsa
 2	1
 2	1
 DROP TABLE t1,t2,t3,t4,t5;
+CREATE TABLE t1 (
+id int NOT NULL PRIMARY KEY,
+ct int DEFAULT NULL,
+pc int DEFAULT NULL,
+INDEX idx_ct (ct),
+INDEX idx_pc (pc)
+);
+INSERT INTO t1 VALUES  
+(1,NULL,NULL),(2,NULL,NULL),(3,NULL,NULL),(4,NULL,NULL),(5,NULL,NULL);
+CREATE TABLE t2 (
+id int NOT NULL PRIMARY KEY,
+sr int NOT NULL,
+nm varchar(255) NOT NULL,
+INDEX idx_sr (sr)
+);
+INSERT INTO t2 VALUES
+(2441905,4308,'LesAbymes'),(2441906,4308,'Anse-Bertrand');
+CREATE TABLE t3 (
+id int NOT NULL PRIMARY KEY,
+ct int NOT NULL,
+ln int NOT NULL,
+INDEX idx_ct (ct),
+INDEX idx_ln (ln)
+);
+CREATE TABLE t4 (
+id int NOT NULL PRIMARY KEY,
+nm varchar(255) NOT NULL
+);
+INSERT INTO t4 VALUES (4308,'Guadeloupe'),(4309,'Martinique');
+SELECT t1.*
+FROM t1 LEFT JOIN
+(t2 LEFT JOIN t3 ON t3.ct=t2.id AND t3.ln='5') ON t1.ct=t2.id
+WHERE t1.id='5';
+id	ct	pc
+5	NULL	NULL
+SELECT t1.*, t4.nm
+FROM t1 LEFT JOIN
+(t2 LEFT JOIN t3 ON t3.ct=t2.id AND t3.ln='5') ON t1.ct=t2.id
+LEFT JOIN t4 ON t2.sr=t4.id
+WHERE t1.id='5';
+id	ct	pc	nm
+5	NULL	NULL	NULL
+DROP TABLE t1,t2,t3,t4;

mysql-test/t/join_nested.test

@@ -994,3 +994,54 @@ SELECT t1.id1 AS id, t5.id1 AS ngroupbynsa
 
 DROP TABLE t1,t2,t3,t4,t5;
 
+#
+# Test for bug #24345: crash with nested left outer join when outer table is substituted
+#                      for a row that happens to have a null value for the join attribute.
+#
+
+CREATE TABLE t1 (
+  id int NOT NULL PRIMARY KEY,
+  ct int DEFAULT NULL,
+  pc int DEFAULT NULL,
+  INDEX idx_ct (ct),
+  INDEX idx_pc (pc)
+);
+INSERT INTO t1 VALUES  
+ (1,NULL,NULL),(2,NULL,NULL),(3,NULL,NULL),(4,NULL,NULL),(5,NULL,NULL);
+
+CREATE TABLE t2 (
+  id int NOT NULL PRIMARY KEY,
+  sr int NOT NULL,
+  nm varchar(255) NOT NULL,
+  INDEX idx_sr (sr)
+);
+INSERT INTO t2 VALUES
+  (2441905,4308,'LesAbymes'),(2441906,4308,'Anse-Bertrand');
+
+CREATE TABLE t3 (
+  id int NOT NULL PRIMARY KEY,
+  ct int NOT NULL,
+  ln int NOT NULL,
+  INDEX idx_ct (ct),
+  INDEX idx_ln (ln)
+);
+
+CREATE TABLE t4 (
+  id int NOT NULL PRIMARY KEY,
+  nm varchar(255) NOT NULL
+);
+
+INSERT INTO t4 VALUES (4308,'Guadeloupe'),(4309,'Martinique');
+
+SELECT t1.*
+  FROM t1 LEFT JOIN
+       (t2 LEFT JOIN t3 ON t3.ct=t2.id AND t3.ln='5') ON t1.ct=t2.id
+    WHERE t1.id='5';
+
+SELECT t1.*, t4.nm
+  FROM t1 LEFT JOIN
+      (t2 LEFT JOIN t3 ON t3.ct=t2.id AND t3.ln='5') ON t1.ct=t2.id
+          LEFT JOIN t4 ON t2.sr=t4.id
+    WHERE t1.id='5';
+
+DROP TABLE t1,t2,t3,t4;

sql/sql_select.cc

@@ -2306,8 +2306,18 @@ make_join_statistics(JOIN *join, TABLE_LIST *tables, COND *conds,
         substitution of a const table the key value happens to be null
         then we can state that there are no matches for this equi-join.
       */  
-      if ((keyuse= s->keyuse) && *s->on_expr_ref)
+      if ((keyuse= s->keyuse) && *s->on_expr_ref && !s->embedding_map)
       {
+        /* 
+          When performing an outer join operation if there are no matching rows
+          for the single row of the outer table all the inner tables are to be
+          null complemented and thus considered as constant tables.
+          Here we apply this consideration to the case of outer join operations 
+          with a single inner table only because the case with nested tables
+          would require a more thorough analysis.
+          TODO. Apply single row substitution to null complemented inner tables
+          for nested outer join operations. 
+	*/              
         while (keyuse->table == table)
         {
           if (!(keyuse->val->used_tables() & ~join->const_table_map) &&