items for functions which is converted to constants internally to support its correct printing added (BUG#4663)

mysql-test/r/view.result:
  test of functions in VIEW which is converted to constants internally
mysql-test/t/view.test:
  test of functions in VIEW which is converted to constants internally
sql/item.h:
  items for functions which is converted to constants internally to support its correct printing
sql/item_create.cc:
  items for functions which is converted to constants internally to support its correct printing

mysql-test/r/view.result

@@ -1053,3 +1053,8 @@ create index i1 on v1 (col1);
 ERROR HY000: 'test.v1' is not BASIC TABLE
 drop view v1;
 drop table t1;
+CREATE VIEW v1 (f1,f2,f3,f4) AS SELECT connection_id(), pi(), current_user(), version();
+SHOW CREATE VIEW v1;
+Table	Create Table
+v1	CREATE VIEW test.v1 AS select sql_no_cache connection_id() AS `f1`,pi() AS `f2`,current_user() AS `f3`,version() AS `f4`
+drop view v1;

mysql-test/t/view.test

@@ -997,3 +997,10 @@ create view v1 as select * from t1;
 create index i1 on v1 (col1);
 drop view v1;
 drop table t1;
+
+#
+# connection_id(), pi(), current_user(), version() representation test
+#
+CREATE VIEW v1 (f1,f2,f3,f4) AS SELECT connection_id(), pi(), current_user(), version();
+SHOW CREATE VIEW v1;
+drop view v1;

sql/item.h

@@ -669,6 +669,17 @@ public:
 };
 
 
+class Item_static_int_func :public Item_int
+{
+  const char *func_name;
+public:
+  Item_static_int_func(const char *str_arg, longlong i, uint length)
+    :Item_int(NullS, i, length), func_name(str_arg)
+  {}
+  void print(String *str) { str->append(func_name); }
+};
+
+
 class Item_uint :public Item_int
 {
 public:
@@ -724,6 +735,18 @@ public:
 };
 
 
+class Item_static_real_func :public Item_real
+{
+  const char *func_name;
+public:
+  Item_static_real_func(const char *str, double val_arg, uint decimal_par,
+                        uint length)
+    :Item_real(NullS, val_arg, decimal_par, length), func_name(str)
+  {}
+  void print(String *str) { str->append(func_name); }
+};
+
+
 class Item_float :public Item_real
 {
 public:
@@ -803,6 +826,20 @@ public:
   void cleanup() {}
 };
 
+
+class Item_static_string_func :public Item_string
+{
+  const char *func_name;
+public:
+  Item_static_string_func(const char *name_par, const char *str, uint length,
+                          CHARSET_INFO *cs,
+                          Derivation dv= DERIVATION_COERCIBLE)
+    :Item_string(NullS, str, length, cs, dv), func_name(name_par)
+  {}
+  void print(String *str) { str->append(func_name); }
+};
+
+
 /* for show tables */
 
 class Item_datetime :public Item_string

sql/item_create.cc

@@ -73,12 +73,13 @@ Item *create_func_connection_id(void)
 {
   THD *thd=current_thd;
   thd->lex->safe_to_cache_query= 0;
-  return new Item_int(NullS,(longlong)
-                      ((thd->slave_thread) ?
-                       thd->variables.pseudo_thread_id :
-                       thd->thread_id),
-                      10);
-} 
+  return new Item_static_int_func("connection_id()",
+                                  (longlong)
+                                  ((thd->slave_thread) ?
+                                   thd->variables.pseudo_thread_id :
+                                   thd->thread_id),
+                                  10);
+}
 
 Item *create_func_conv(Item* a, Item *b, Item *c)
 {
@@ -293,7 +294,7 @@ Item *create_func_period_diff(Item* a, Item *b)
 
 Item *create_func_pi(void)
 {
-  return new Item_real("pi()",M_PI,6,8);
+  return new Item_static_real_func("pi()", M_PI, 6, 8);
 }
 
 Item *create_func_pow(Item* a, Item *b)
@@ -309,8 +310,9 @@ Item *create_func_current_user()
 
   length= (uint) (strxmov(buff, thd->priv_user, "@", thd->priv_host, NullS) -
 		  buff);
-  return new Item_string(NullS, thd->memdup(buff, length), length,
-			 system_charset_info);
+  return new Item_static_string_func("current_user()",
+                                     thd->memdup(buff, length), length,
+                                     system_charset_info);
 }
 
 Item *create_func_radians(Item *a)
@@ -434,7 +436,7 @@ Item *create_func_uuid(void)
 
 Item *create_func_version(void)
 {
-  return new Item_string(NullS,server_version, 
+  return new Item_static_string_func("version()", server_version,
 			 (uint) strlen(server_version),
 			 system_charset_info, DERIVATION_IMPLICIT);
 }