hang in dummy natural join (no common columns) Bug #4807

mysql-test/r/join.result

@@ -283,6 +283,12 @@ ID	Value1	Value2
 SELECT * FROM t1 NATURAL JOIN t2 WHERE (Value1 = 'A' AND Value2 <> 'B') AND 1;
 ID	Value1	Value2
 drop table t1,t2;
+CREATE TABLE t1 (a int);
+CREATE TABLE t2 (b int);
+CREATE TABLE t3 (c int);
+SELECT * FROM t1 NATURAL JOIN t2 NATURAL JOIN t3;
+a	b	c
+DROP TABLE t1, t2, t3;
 create table t1 (i int);
 create table t2 (i int);
 create table t3 (i int);

mysql-test/t/join.test

@@ -284,6 +284,16 @@ SELECT * FROM t1 NATURAL JOIN t2 WHERE 1 AND Value1 = 'A' AND Value2 <> 'B';
 SELECT * FROM t1 NATURAL JOIN t2 WHERE (Value1 = 'A' AND Value2 <> 'B') AND 1;
 drop table t1,t2;
 
+#
+# dummy natural join (no common columns) Bug #4807
+#
+
+CREATE TABLE t1 (a int);
+CREATE TABLE t2 (b int);
+CREATE TABLE t3 (c int);
+SELECT * FROM t1 NATURAL JOIN t2 NATURAL JOIN t3;
+DROP TABLE t1, t2, t3;
+
 #
 # Test combination of join methods
 #

sql/sql_base.cc

@@ -2522,29 +2522,32 @@ int setup_conds(THD *thd,TABLE_LIST *tables,COND **conds)
       // to prevent natural join processing during PS re-execution
       table->natural_join= 0;
 
-      if (!table->outer_join)			// Not left join
+      if (cond_and->list.elements)
       {
-	*conds= and_conds(*conds, cond_and);
-	// fix_fields() should be made with temporary memory pool
-	if (stmt)
-	  thd->restore_backup_item_arena(stmt, &backup);
-	if (*conds && !(*conds)->fixed)
-	{
-	  if ((*conds)->fix_fields(thd, tables, conds))
-	    DBUG_RETURN(1);
-	}
-      }
-      else
-      {
-	table->on_expr= and_conds(table->on_expr, cond_and);
-	// fix_fields() should be made with temporary memory pool
-	if (stmt)
-	  thd->restore_backup_item_arena(stmt, &backup);
-	if (table->on_expr && !table->on_expr->fixed)
-	{
-	  if (table->on_expr->fix_fields(thd, tables, &table->on_expr))
-	   DBUG_RETURN(1);
-	}
+        if (!table->outer_join)			// Not left join
+        {
+          *conds= and_conds(*conds, cond_and);
+          // fix_fields() should be made with temporary memory pool
+          if (stmt)
+            thd->restore_backup_item_arena(stmt, &backup);
+          if (*conds && !(*conds)->fixed)
+          {
+            if ((*conds)->fix_fields(thd, tables, conds))
+              DBUG_RETURN(1);
+          }
+        }
+        else
+        {
+          table->on_expr= and_conds(table->on_expr, cond_and);
+          // fix_fields() should be made with temporary memory pool
+          if (stmt)
+            thd->restore_backup_item_arena(stmt, &backup);
+          if (table->on_expr && !table->on_expr->fixed)
+          {
+            if (table->on_expr->fix_fields(thd, tables, &table->on_expr))
+             DBUG_RETURN(1);
+          }
+        }
       }
     }
   }