MDEV-25462: Assertion `m_status == DA_ERROR || m_status == DA_OK ||

m_status == DA_OK_BULK' failed in Diagnostics_area::message from
get_schema_tables_record

Analysis: SET NAMES changes character set for character_set_client,
character_set_connection, character_set_results to 'filename'. The .frm file of view
has @xx sequences in the SELECT query, which give parsing error because 'filename'
character set is not parser friendly. When we get parsing error (ER_PARSE_ERROR), we
directly return true without setting error status. This is caught later in assertion.
Fix: Disallow 'filename' character set in SET NAMES because it is not parser
friendly.

mysql-test/r/ctype_filename.result

@@ -21,3 +21,32 @@ SET NAMES utf8;
 SELECT @a:=CONVERT('aя' USING filename) AS `@a`, BINARY @a, REVERSE(@a), HEX(@a), HEX(REVERSE(@a));
 @a	BINARY @a	REVERSE(@a)	HEX(@a)	HEX(REVERSE(@a))
 aя	a@r1	яa	61407231	40723161
+#
+# Beginning of 10.2 test.
+#
+# MDEV-25462: Assertion `m_status == DA_ERROR || m_status == DA_OK ||
+# m_status == DA_OK_BULK' failed in Diagnostics_area::message from
+# get_schema_tables_record
+#
+SELECT @@character_set_client, @@character_set_connection, @@character_set_results;
+@@character_set_client	@@character_set_connection	@@character_set_results
+utf8	utf8	utf8
+SET @old_character_set_client= @@character_set_client;
+SET @old_character_set_connection= @@character_set_connection;
+SET @old_character_set_results= @@character_set_results;
+SET NAMES 'filename';
+ERROR 42000: Variable 'character_set_client' can't be set to the value of 'filename'
+SELECT @@character_set_client, @@character_set_connection, @@character_set_results;
+@@character_set_client	@@character_set_connection	@@character_set_results
+utf8	utf8	utf8
+CREATE VIEW v2 AS SELECT 1;
+SHOW TABLE STATUS;
+Name	Engine	Version	Row_format	Rows	Avg_row_length	Data_length	Max_data_length	Index_length	Data_free	Auto_increment	Create_time	Update_time	Check_time	Collation	Checksum	Create_options	Comment
+v2	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	VIEW
+DROP VIEW v2;
+SET @@character_set_client= @old_character_set_client;
+SET @@character_set_connection= @old_character_set_connection;
+SET @@character_set_results= @old_character_set_results;
+#
+# End of 10.2 test
+#

mysql-test/t/ctype_filename.test

@@ -27,3 +27,29 @@ select convert(convert(',' using filename) using binary);
 --echo #
 SET NAMES utf8;
 SELECT @a:=CONVERT('aя' USING filename) AS `@a`, BINARY @a, REVERSE(@a), HEX(@a), HEX(REVERSE(@a));
+
+--echo #
+--echo # Beginning of 10.2 test.
+--echo #
+--echo # MDEV-25462: Assertion `m_status == DA_ERROR || m_status == DA_OK ||
+--echo # m_status == DA_OK_BULK' failed in Diagnostics_area::message from
+--echo # get_schema_tables_record
+--echo #
+
+SELECT @@character_set_client, @@character_set_connection, @@character_set_results;
+SET @old_character_set_client= @@character_set_client;
+SET @old_character_set_connection= @@character_set_connection;
+SET @old_character_set_results= @@character_set_results;
+--error ER_WRONG_VALUE_FOR_VAR
+SET NAMES 'filename';
+SELECT @@character_set_client, @@character_set_connection, @@character_set_results;
+CREATE VIEW v2 AS SELECT 1;
+SHOW TABLE STATUS;
+DROP VIEW v2;
+SET @@character_set_client= @old_character_set_client;
+SET @@character_set_connection= @old_character_set_connection;
+SET @@character_set_results= @old_character_set_results;
+
+--echo #
+--echo # End of 10.2 test
+--echo #

sql/sql_class.h

@@ -921,7 +921,7 @@ mysqld_collation_get_by_name(const char *name,
 
 static inline bool is_supported_parser_charset(CHARSET_INFO *cs)
 {
-  return MY_TEST(cs->mbminlen == 1);
+  return MY_TEST(cs->mbminlen == 1 && cs->number != 17 /* filename */);
 }
 
 #ifdef MYSQL_SERVER

sql/sql_view.cc

@@ -878,6 +878,13 @@ static int mysql_register_view(THD *thd, TABLE_LIST *view,
 {
   LEX *lex= thd->lex;
 
+  /*
+    Ensure character set number != 17 (character set = filename) and mbminlen=1
+    because these character sets are not parser friendly, which can give weird
+    sequence in .frm file of view and later give parsing error.
+  */
+  DBUG_ASSERT(thd->charset()->mbminlen == 1 && thd->charset()->number != 17);
+
   /*
     View definition query -- a SELECT statement that fully defines view. It
     is generated from the Item-tree built from the original (specified by