MDEV-14849 CREATE + ALTER with user-invisible columns produce ...

Problem:-
  create or replace table t1 (pk int auto_increment primary key invisible, i int);
  alter table t1 modify pk int invisible;
 This last alter makes a invisible column which is not null and does not
 have default value.

Analysis:-
 This is caused because our error check for NOT_NULL_FLAG and
 NO_DEFAULT_VALUE_FLAG flag misses this sql_field , but this is not the fault
 of error check :).Actually this field come via mysql_prepare_alter_table
 and it does not have NO_DEFAULT_VALUE_FLAG flag turned on. (If it was create
 table NO_DEFAULT_VALUE_FLAG would have turned on Column_definition::check)
 and this would have generated error.

Solution:-
 I have moved the error check to kind last of mysql_prepare_create_table
 because upto this point we have applied NO_DEFAULT_VALUE_FLAG to required
 column.

mysql-test/r/invisible_field.result

@@ -26,7 +26,12 @@ ERROR 42000: You have an error in your SQL syntax; check the manual that corresp
 create table t1(a1 int primary key invisible ,a2 int unique invisible , a3 blob,a4 int not null invisible unique);
 ERROR HY000: Invisible column `a1` must have a default value
 create table t1(abc int not null invisible);
-ERROR HY000: Invisible column `abc` must have a default value
+ERROR 42000: A table must have at least 1 column
+MDEV-14849 CREATE + ALTER with user-invisible columns produce invalid table definition
+create or replace table t1 (pk int auto_increment primary key invisible, i int);
+alter table t1 modify pk int invisible;
+ERROR HY000: Invisible column `pk` must have a default value
+drop table t1;
 create table t1(a int invisible, b int);
 insert into t1 values(1);
 insert into t1(a) values(2);
@@ -439,7 +444,7 @@ d	int(11)	YES	UNI	NULL
 drop table t1;
 SHOW STATUS LIKE 'Feature_invisible_columns';
 Variable_name	Value
-Feature_invisible_columns	50
+Feature_invisible_columns	52
 #invisible is non reserved
 create table t1(a int unique , invisible int invisible, c int );
 desc t1;

mysql-test/t/invisible_field.test

@@ -11,8 +11,13 @@ create table t1(a1 int invisible);
 create table t1(a1 blob,invisible(a1));
 --error ER_INVISIBLE_NOT_NULL_WITHOUT_DEFAULT
 create table t1(a1 int primary key invisible ,a2 int unique invisible , a3 blob,a4 int not null invisible unique);
---error ER_INVISIBLE_NOT_NULL_WITHOUT_DEFAULT
+--error ER_TABLE_MUST_HAVE_COLUMNS
 create table t1(abc int not null invisible);
+--echo MDEV-14849 CREATE + ALTER with user-invisible columns produce invalid table definition
+create or replace table t1 (pk int auto_increment primary key invisible, i int);
+--error ER_INVISIBLE_NOT_NULL_WITHOUT_DEFAULT
+alter table t1 modify pk int invisible;
+drop table t1;
 create table t1(a int invisible, b int);
 #should automatically add null
 insert into t1 values(1);

sql/sql_table.cc

@@ -3593,14 +3593,6 @@ mysql_prepare_create_table(THD *thd, HA_CREATE_INFO *create_info,
       record_offset+= sql_field->pack_length;
     if (sql_field->flags & VERS_SYSTEM_FIELD)
       continue;
-    if (sql_field->invisible == INVISIBLE_USER &&
-        sql_field->flags & NOT_NULL_FLAG &&
-        sql_field->flags & NO_DEFAULT_VALUE_FLAG)
-    {
-      my_error(ER_INVISIBLE_NOT_NULL_WITHOUT_DEFAULT, MYF(0),
-                          sql_field->field_name.str);
-      DBUG_RETURN(TRUE);
-    }
   }
   /* Update virtual fields' offset and give error if
      All fields are invisible */
@@ -4244,6 +4236,14 @@ mysql_prepare_create_table(THD *thd, HA_CREATE_INFO *create_info,
       my_error(ER_INVALID_DEFAULT, MYF(0), sql_field->field_name.str);
       DBUG_RETURN(TRUE);
     }
+    if (sql_field->invisible == INVISIBLE_USER &&
+        sql_field->flags & NOT_NULL_FLAG &&
+        sql_field->flags & NO_DEFAULT_VALUE_FLAG)
+    {
+      my_error(ER_INVISIBLE_NOT_NULL_WITHOUT_DEFAULT, MYF(0),
+                          sql_field->field_name.str);
+      DBUG_RETURN(TRUE);
+    }
   }
 
   /* Check table level constraints */