MDEV-11117 CHECK constraint fails on intermediate step of ALTER

Fixed the bug by failing the statement with an error message that explains
that an auto-increment column may not be used in an expression for a
check constraint.
Added a test case in check_constraint.test.
Updated existing tests and results.

mysql-test/r/check_constraint.result

@@ -140,6 +140,8 @@ create table t1 (a int, b int, check(a>0));
 alter table t1 drop column a;
 ERROR 42S22: Unknown column 'a' in 'CHECK'
 drop table t1;
+create or replace table t1( c1 int auto_increment primary key, check( c1 > 0 or c1 is null ) );
+ERROR HY000: Function or expression 'AUTO_INCREMENT' cannot be used in the CHECK clause of `c1`
 create table t1 (a int check (@b in (select user from mysql.user)));
 ERROR HY000: Function or expression 'select ...' cannot be used in the CHECK clause of `a`
 create table t1 (a int check (a > @b));

mysql-test/suite/gcol/inc/gcol_column_def_options.inc

@@ -198,7 +198,7 @@ drop table t1;
 create table t1 (a int, b int generated always as(-b) virtual, c int generated always as (b + 1) virtual);
 --error ER_EXPRESSION_REFERS_TO_UNINIT_FIELD
 create table t1 (a int, b int generated always as(-c) virtual, c int generated always as (b + 1) virtual);
---error ER_EXPRESSION_REFERS_TO_UNINIT_FIELD
+--error ER_GENERATED_COLUMN_FUNCTION_IS_NOT_ALLOWED
 create table t1 (pk int auto_increment primary key, col_int_nokey int generated always as (pk + col_int_key) stored, col_int_key int);
 
 --echo # Bug#20339347: FAIL TO USE CREATE ....SELECT STATEMENT TO CREATE A NEW TABLE

mysql-test/suite/gcol/r/gcol_column_def_options_innodb.result

@@ -259,7 +259,7 @@ ERROR 01000: Expression for field `b` is refering to uninitialized field `b`
 create table t1 (a int, b int generated always as(-c) virtual, c int generated always as (b + 1) virtual);
 ERROR 01000: Expression for field `b` is refering to uninitialized field `c`
 create table t1 (pk int auto_increment primary key, col_int_nokey int generated always as (pk + col_int_key) stored, col_int_key int);
-ERROR 01000: Expression for field `col_int_nokey` is refering to uninitialized field `pk`
+ERROR HY000: Function or expression 'AUTO_INCREMENT' cannot be used in the GENERATED ALWAYS AS clause of `pk`
 # Bug#20339347: FAIL TO USE CREATE ....SELECT STATEMENT TO CREATE A NEW TABLE
 create table t1 (a int, b int generated always as(-a) virtual, c int generated always as (b + 1) stored);
 insert into t1(a) values(1),(2);

mysql-test/suite/gcol/r/gcol_column_def_options_myisam.result

@@ -259,7 +259,7 @@ ERROR 01000: Expression for field `b` is refering to uninitialized field `b`
 create table t1 (a int, b int generated always as(-c) virtual, c int generated always as (b + 1) virtual);
 ERROR 01000: Expression for field `b` is refering to uninitialized field `c`
 create table t1 (pk int auto_increment primary key, col_int_nokey int generated always as (pk + col_int_key) stored, col_int_key int);
-ERROR 01000: Expression for field `col_int_nokey` is refering to uninitialized field `pk`
+ERROR HY000: Function or expression 'AUTO_INCREMENT' cannot be used in the GENERATED ALWAYS AS clause of `pk`
 # Bug#20339347: FAIL TO USE CREATE ....SELECT STATEMENT TO CREATE A NEW TABLE
 create table t1 (a int, b int generated always as(-a) virtual, c int generated always as (b + 1) stored);
 insert into t1(a) values(1),(2);

mysql-test/t/check_constraint.test

@@ -87,6 +87,12 @@ create table t1 (a int, b int, check(a>0));
 alter table t1 drop column a;
 drop table t1;
 
+#
+# MDEV-11117 CHECK constraint fails on intermediate step of ALTER
+#
+-- error ER_GENERATED_COLUMN_FUNCTION_IS_NOT_ALLOWED
+create or replace table t1( c1 int auto_increment primary key, check( c1 > 0 or c1 is null ) );
+
 #
 # MDEV-12421 Check constraint with query crashes server and renders DB unusable
 #

sql/field.h

@@ -563,7 +563,10 @@ inline bool is_temporal_type_with_time(enum_field_types type)
 enum enum_vcol_info_type
 {
   VCOL_GENERATED_VIRTUAL, VCOL_GENERATED_STORED,
-  VCOL_DEFAULT, VCOL_CHECK_FIELD, VCOL_CHECK_TABLE
+  VCOL_DEFAULT, VCOL_CHECK_FIELD, VCOL_CHECK_TABLE,
+  /* Additional types should be added here */
+  /* Following is the highest value last   */
+  VCOL_TYPE_NONE = 127 // Since the 0 value is already in use
 };
 
 static inline const char *vcol_type_name(enum_vcol_info_type type)
@@ -578,6 +581,8 @@ static inline const char *vcol_type_name(enum_vcol_info_type type)
   case VCOL_CHECK_FIELD:
   case VCOL_CHECK_TABLE:
     return "CHECK";
+  case VCOL_TYPE_NONE:
+    return "UNTYPED";
   }
   return 0;
 }
@@ -591,7 +596,8 @@ static inline const char *vcol_type_name(enum_vcol_info_type type)
 #define VCOL_NON_DETERMINISTIC 2
 #define VCOL_SESSION_FUNC      4  /* uses session data, e.g. USER or DAYNAME */
 #define VCOL_TIME_FUNC         8
-#define VCOL_IMPOSSIBLE       16
+#define VCOL_AUTO_INC         16
+#define VCOL_IMPOSSIBLE       32
 
 #define VCOL_NOT_STRICTLY_DETERMINISTIC                       \
   (VCOL_NON_DETERMINISTIC | VCOL_TIME_FUNC | VCOL_SESSION_FUNC)
@@ -609,6 +615,7 @@ static inline const char *vcol_type_name(enum_vcol_info_type type)
 class Virtual_column_info: public Sql_alloc
 {
 private:
+  enum_vcol_info_type vcol_type; /* Virtual column expression type */
   /*
     The following data is only updated by the parser and read
     when a Create_field object is created/initialized.
@@ -626,7 +633,8 @@ class Virtual_column_info: public Sql_alloc
   uint flags;
 
   Virtual_column_info()
-  : field_type((enum enum_field_types)MYSQL_TYPE_VIRTUAL),
+  : vcol_type((enum_vcol_info_type)VCOL_TYPE_NONE),
+    field_type((enum enum_field_types)MYSQL_TYPE_VIRTUAL),
     in_partitioning_expr(FALSE), stored_in_db(FALSE),
     utf8(TRUE), expr(NULL), flags(0)
   {
@@ -634,6 +642,19 @@ class Virtual_column_info: public Sql_alloc
     name.length= 0;
   };
   ~Virtual_column_info() {}
+  enum_vcol_info_type get_vcol_type() const
+  {
+    return vcol_type;
+  }
+  void set_vcol_type(enum_vcol_info_type v_type)
+  {
+    vcol_type= v_type;
+  }
+  const char *get_vcol_type_name() const
+  {
+    DBUG_ASSERT(vcol_type != VCOL_TYPE_NONE);
+    return vcol_type_name(vcol_type);
+  }
   enum_field_types get_real_type() const
   {
     return field_type;

sql/item.cc

@@ -979,7 +979,7 @@ bool Item_field::register_field_in_write_map(void *arg)
   This means:
   - For default fields we can't access the same field or a field after
     itself that doesn't have a non-constant default value.
-  - A virtual fields can't access itself or a virtual field after itself.
+  - A virtual field can't access itself or a virtual field after itself.
   - user-specified values will not see virtual fields or default expressions,
     as in INSERT t1 (a) VALUES (b);
   - no virtual fields can access auto-increment values
@@ -995,13 +995,6 @@ bool Item_field::check_field_expression_processor(void *arg)
   Field *org_field= (Field*) arg;
   if (field->flags & NO_DEFAULT_VALUE_FLAG)
     return 0;
-  if (field->flags & AUTO_INCREMENT_FLAG)
-  {
-      my_error(ER_EXPRESSION_REFERS_TO_UNINIT_FIELD,
-               MYF(0),
-               org_field->field_name, field->field_name);
-      return 1;
-  }
   if ((field->default_value && field->default_value->flags) || field->vcol_info)
   {
     if (field == org_field ||

sql/item.h

@@ -2611,6 +2611,11 @@ class Item_field :public Item_ident
   bool check_vcol_func_processor(void *arg)
   {
     context= 0;
+    if (field && (field->unireg_check == Field::NEXT_NUMBER))
+    {
+      // Auto increment fields are unsupported
+      return mark_unsupported_function(field_name, arg, VCOL_FIELD_REF | VCOL_AUTO_INC);
+    }
     return mark_unsupported_function(field_name, arg, VCOL_FIELD_REF);
   }
   void cleanup();

sql/table.cc

@@ -1962,6 +1962,7 @@ int TABLE_SHARE::init_from_binary_frm_image(THD *thd, bool write,
         unireg_check == Field::TIMESTAMP_DN_FIELD)
     {
       reg_field->default_value= new (&share->mem_root) Virtual_column_info();
+      reg_field->default_value->set_vcol_type(VCOL_DEFAULT);
       reg_field->default_value->stored_in_db= 1;
       share->default_expressions++;
     }
@@ -2361,6 +2362,7 @@ int TABLE_SHARE::init_from_binary_frm_image(THD *thd, bool write,
 
       if (!(vcol_info=   new (&share->mem_root) Virtual_column_info()))
         goto err;
+
       /* The following can only be true for check_constraints */
 
       if (field_nr != UINT_MAX16)
@@ -2370,6 +2372,7 @@ int TABLE_SHARE::init_from_binary_frm_image(THD *thd, bool write,
       }
 
       vcol_screen_pos+= FRM_VCOL_NEW_HEADER_SIZE;
+      vcol_info->set_vcol_type((enum_vcol_info_type) type);
       vcol_info->name.length= name_length;
       if (name_length)
         vcol_info->name.str= strmake_root(&share->mem_root,
@@ -2811,6 +2814,20 @@ static bool fix_and_check_vcol_expr(THD *thd, TABLE *table,
              "???", "?????");
     DBUG_RETURN(1);
   }
+  else if (res.errors & VCOL_AUTO_INC)
+  {
+    /*
+      An auto_increment field may not be used in an expression for
+      a check constraint, a default value or a generated column
+
+      Note that this error condition is not detected during parsing
+      of the statement because the field item does not have a field
+      pointer at that time
+    */
+    my_error(ER_VIRTUAL_COLUMN_FUNCTION_IS_NOT_ALLOWED, MYF(0),
+             "AUTO_INCREMENT", vcol->get_vcol_type_name(), res.name);
+    DBUG_RETURN(1);
+  }
   vcol->flags= res.errors;
 
   if (vcol->flags & VCOL_SESSION_FUNC)
@@ -2879,6 +2896,7 @@ unpack_vcol_info_from_frm(THD *thd, MEM_ROOT *mem_root, TABLE *table,
   if (error)
     goto end;
 
+  vcol_storage.vcol_info->set_vcol_type(vcol->get_vcol_type());
   vcol_storage.vcol_info->stored_in_db=      vcol->stored_in_db;
   vcol_storage.vcol_info->name=              vcol->name;
   vcol_storage.vcol_info->utf8=              vcol->utf8;