Fixed bug mdev-5078.

For aggregated fields from views/derived tables the possible adjustment
of thd->lex->in_sum_func->max_arg_level in the function Item_field::fix_fields
must be done before we leave the function.

mysql-test/r/derived_view.result

@@ -2205,6 +2205,24 @@ DROP VIEW v1;
 DROP TABLE t1,t2;
 set optimizer_switch=@save_optimizer_switch;
 #
+# mdev-5078: sum over a view/derived table
+#
+CREATE TABLE t1 (a int);
+INSERT INTO t1 (a) VALUES (1), (2);
+CREATE TABLE t2 (b int(11));
+INSERT INTO t2 (b) VALUES (1), (2);
+CREATE VIEW v AS SELECT b as c FROM t2;
+SELECT a, (SELECT SUM(a + c) FROM v) FROM t1;
+a	(SELECT SUM(a + c) FROM v)
+1	5
+2	7
+SELECT a, (SELECT SUM(a + c) FROM (SELECT b as c FROM t2) AS v1) FROM t1;
+a	(SELECT SUM(a + c) FROM (SELECT b as c FROM t2) AS v1)
+1	5
+2	7
+DROP VIEW v;
+DROP TABLE t1,t2;
+#
 # end of 5.3 tests
 #
 set optimizer_switch=@exit_optimizer_switch;

mysql-test/t/derived_view.test

@@ -1545,6 +1545,25 @@ DROP TABLE t1,t2;
 set optimizer_switch=@save_optimizer_switch;
 
 
+--echo #
+--echo # mdev-5078: sum over a view/derived table
+--echo #
+
+CREATE TABLE t1 (a int);
+INSERT INTO t1 (a) VALUES (1), (2);
+
+CREATE TABLE t2 (b int(11));
+INSERT INTO t2 (b) VALUES (1), (2);
+
+CREATE VIEW v AS SELECT b as c FROM t2;
+
+SELECT a, (SELECT SUM(a + c) FROM v) FROM t1;
+
+SELECT a, (SELECT SUM(a + c) FROM (SELECT b as c FROM t2) AS v1) FROM t1;
+
+DROP VIEW v;
+DROP TABLE t1,t2;
+
 --echo #
 --echo # end of 5.3 tests
 --echo #

sql/item.cc

@@ -4746,6 +4746,11 @@ bool Item_field::fix_fields(THD *thd, Item **reference)
         goto mark_non_agg_field;
     }
 
+    if (thd->lex->in_sum_func &&
+        thd->lex->in_sum_func->nest_level == 
+        thd->lex->current_select->nest_level)
+      set_if_bigger(thd->lex->in_sum_func->max_arg_level,
+                    thd->lex->current_select->nest_level);
     /*
       if it is not expression from merged VIEW we will set this field.
 
@@ -4762,11 +4767,6 @@ bool Item_field::fix_fields(THD *thd, Item **reference)
       return FALSE;
 
     set_field(from_field);
-    if (thd->lex->in_sum_func &&
-        thd->lex->in_sum_func->nest_level == 
-        thd->lex->current_select->nest_level)
-      set_if_bigger(thd->lex->in_sum_func->max_arg_level,
-                    thd->lex->current_select->nest_level);
   }
   else if (thd->mark_used_columns != MARK_COLUMNS_NONE)
   {