function DEFAULT(x) now works for expression defaults

mysql-test/r/default.result

@@ -413,11 +413,11 @@ ERROR 01000: Expression for field `a` is refering to uninitialized field `b`
 create or replace table t1 (a int default 1, b int as (c), c int as (a+1));
 ERROR 01000: Expression for field `b` is refering to uninitialized field `c`
 CREATE TABLE t1 (a INT DEFAULT (DEFAULT(a)));
-ERROR HY000: Field 'a' doesn't have a default value
+ERROR 01000: Expression for field `a` is refering to uninitialized field `a`
 CREATE TABLE t1 (a INT DEFAULT(DEFAULT(b)), b INT DEFAULT(DEFAULT(a)));
-ERROR HY000: Field 'b' doesn't have a default value
+ERROR 01000: Expression for field `a` is refering to uninitialized field `b`
 CREATE TABLE t1 (a INT DEFAULT(DEFAULT(b)) NOT NULL, b INT DEFAULT(DEFAULT(a)) NOT NULL);
-ERROR HY000: Field 'b' doesn't have a default value
+ERROR 01000: Expression for field `a` is refering to uninitialized field `b`
 #
 # Allow defaults to refer to not default fields
 #
@@ -1193,7 +1193,10 @@ a	b
 2	2
 6	1000
 select default(a),b from t1;
-ERROR HY000: Field 'a' doesn't have a default value
+default(a)	b
+6	1
+6	2
+6	1000
 select a,default(b) from t1;
 a	default(b)
 1	1000

mysql-test/r/func_default.result

@@ -21,3 +21,14 @@ INSERT INTO t1 VALUES (1, 'one'), (2, 'two'), (3, 'three');
 SELECT s, 32 AS mi FROM t1 GROUP BY s HAVING DEFAULT(mi) IS NULL;
 ERROR HY000: Field 'mi' doesn't have a default value
 DROP TABLE t1;
+set timestamp=unix_timestamp('2001-01-01 10:20:30.123456');
+create table t1 (a int default 1, b int default (a+1),
+c varchar(100) default 'foo', d text default 'bar',
+e timestamp default now(), f timestamp(6) default now(2));
+insert t1 () values ();
+insert t1 (a) values (10);
+select default(a),default(b),default(c),default(d),default(e),default(f) from t1;
+default(a)	default(b)	default(c)	default(d)	default(e)	default(f)
+1	2	foo	bar	2001-01-01 10:20:30	2001-01-01 10:20:30.123456
+1	11	foo	bar	2001-01-01 10:20:30	2001-01-01 10:20:30.123456
+drop table t1;

mysql-test/t/default.test

@@ -299,11 +299,11 @@ create or replace table t1 (a int default a);
 create or replace table t1 (a int default b, b int default (1+1));
 --error ER_EXPRESSION_REFERS_TO_UNINIT_FIELD
 create or replace table t1 (a int default 1, b int as (c), c int as (a+1));
---error ER_NO_DEFAULT_FOR_FIELD
+--error ER_EXPRESSION_REFERS_TO_UNINIT_FIELD
 CREATE TABLE t1 (a INT DEFAULT (DEFAULT(a)));
---error ER_NO_DEFAULT_FOR_FIELD
+--error ER_EXPRESSION_REFERS_TO_UNINIT_FIELD
 CREATE TABLE t1 (a INT DEFAULT(DEFAULT(b)), b INT DEFAULT(DEFAULT(a)));
---error ER_NO_DEFAULT_FOR_FIELD
+--error ER_EXPRESSION_REFERS_TO_UNINIT_FIELD
 CREATE TABLE t1 (a INT DEFAULT(DEFAULT(b)) NOT NULL, b INT DEFAULT(DEFAULT(a)) NOT NULL);
 
 --echo #
@@ -879,7 +879,6 @@ SHOW CREATE TABLE t1;
 insert into t1 values (1,1),(2,2);
 insert into t1 values (default,default);
 select * from t1;
---error ER_NO_DEFAULT_FOR_FIELD
 select default(a),b from t1;
 select a,default(b) from t1;
 drop table t1;

mysql-test/t/func_default.test

@@ -29,3 +29,15 @@ INSERT INTO t1 VALUES (1, 'one'), (2, 'two'), (3, 'three');
 SELECT s, 32 AS mi FROM t1 GROUP BY s HAVING DEFAULT(mi) IS NULL;
 DROP TABLE t1;
 
+#
+# 10.2 tests
+#
+
+set timestamp=unix_timestamp('2001-01-01 10:20:30.123456');
+create table t1 (a int default 1, b int default (a+1),
+  c varchar(100) default 'foo', d text default 'bar',
+  e timestamp default now(), f timestamp(6) default now(2));
+insert t1 () values ();
+insert t1 (a) values (10);
+select default(a),default(b),default(c),default(d),default(e),default(f) from t1;
+drop table t1;

sql/item.cc

@@ -8211,8 +8211,7 @@ bool Item_default_value::fix_fields(THD *thd, Item **items)
   }
 
   field_arg= (Item_field *)real_arg;
-  if ((field_arg->field->flags & NO_DEFAULT_VALUE_FLAG) ||
-      field_arg->field->default_value)
+  if ((field_arg->field->flags & NO_DEFAULT_VALUE_FLAG))
   {
     my_error(ER_NO_DEFAULT_FOR_FIELD, MYF(0), field_arg->field->field_name);
     goto error;
@@ -8225,6 +8224,12 @@ bool Item_default_value::fix_fields(THD *thd, Item **items)
                                (def_field->table->s->default_values -
                                 def_field->table->record[0]));
   set_field(def_field);
+  if (field->default_value)
+  {
+    if (field->default_value->expr_item) // it's NULL during CREATE TABLE
+      field->default_value->expr_item->walk(&Item::register_field_in_read_map, 1, 0);
+    IF_DBUG(def_field->is_stat_field=1,); // a hack to fool ASSERT_COLUMN_MARKED_FOR_WRITE_OR_COMPUTED
+  }
   return FALSE;
 
 error:
@@ -8245,10 +8250,53 @@ void Item_default_value::print(String *str, enum_query_type query_type)
   str->append(')');
 }
 
+void Item_default_value::calculate()
+{
+  if (field->default_value || field->has_insert_default_function())
+    field->set_default();
+}
+
+String *Item_default_value::val_str(String *str)
+{
+  calculate();
+  return Item_field::val_str(str);
+}
+
+double Item_default_value::val_real()
+{
+  calculate();
+  return Item_field::val_real();
+}
+
+longlong Item_default_value::val_int()
+{
+  calculate();
+  return Item_field::val_int();
+}
+
+my_decimal *Item_default_value::val_decimal(my_decimal *decimal_value)
+{
+  calculate();
+  return Item_field::val_decimal(decimal_value);
+}
+
+bool Item_default_value::get_date(MYSQL_TIME *ltime,ulonglong fuzzydate)
+{
+  calculate();
+  return Item_field::get_date(ltime, fuzzydate);
+}
+
+bool Item_default_value::send(Protocol *protocol, String *buffer)
+{
+  calculate();
+  return Item_field::send(protocol, buffer);
+}
 
 int Item_default_value::save_in_field(Field *field_arg, bool no_conversions)
 {
-  if (!arg)
+  if (arg)
+    calculate();
+  else
   {
     TABLE *table= field_arg->table;
     THD *thd= table->in_use;

sql/item.h

@@ -4877,6 +4877,7 @@ class Cached_item_field :public Cached_item
 
 class Item_default_value : public Item_field
 {
+  void calculate();
 public:
   Item *arg;
   Item_default_value(THD *thd, Name_resolution_context *context_arg)
@@ -4890,7 +4891,13 @@ class Item_default_value : public Item_field
   enum Type type() const { return DEFAULT_VALUE_ITEM; }
   bool eq(const Item *item, bool binary_cmp) const;
   bool fix_fields(THD *, Item **);
-  virtual void print(String *str, enum_query_type query_type);
+  void print(String *str, enum_query_type query_type);
+  String *val_str(String *str);
+  double val_real();
+  longlong val_int();
+  my_decimal *val_decimal(my_decimal *decimal_value);
+  bool get_date(MYSQL_TIME *ltime,ulonglong fuzzydate);
+  bool send(Protocol *protocol, String *buffer);
   int save_in_field(Field *field_arg, bool no_conversions);
   table_map used_tables() const { return (table_map)0L; }