Bug#54422 query with = 'variables'

During creation of the table list of
processed tables hidden I_S table 'VARIABLES'
is erroneously added into the table list.
it leads to ER_UNKNOWN_TABLE error in
TABLE_LIST::add_table_to_list() function.
The fix is to skip addition of hidden I_S
tables into the table list.


mysql-test/r/information_schema.result:
  test case
mysql-test/t/information_schema.test:
  test case
sql/sql_show.cc:
  The fix is to skip addition of hidden I_S
  tables into the table list.

mysql-test/r/information_schema.result

@@ -1747,4 +1747,14 @@ COUNT(*)
 DROP USER nonpriv;
 DROP TABLE db1.t1;
 DROP DATABASE db1;
+
+Bug#54422 query with = 'variables'
+
+CREATE TABLE variables(f1 INT);
+SELECT COLUMN_DEFAULT, TABLE_NAME
+FROM INFORMATION_SCHEMA.COLUMNS
+WHERE INFORMATION_SCHEMA.COLUMNS.TABLE_NAME = 'variables';
+COLUMN_DEFAULT	TABLE_NAME
+NULL	variables
+DROP TABLE variables;
 End of 5.1 tests.

mysql-test/t/information_schema.test

@@ -1445,6 +1445,15 @@ DROP USER nonpriv;
 DROP TABLE db1.t1;
 DROP DATABASE db1;
 
+--echo
+--echo Bug#54422 query with = 'variables'
+--echo
+
+CREATE TABLE variables(f1 INT);
+SELECT COLUMN_DEFAULT, TABLE_NAME
+FROM INFORMATION_SCHEMA.COLUMNS
+WHERE INFORMATION_SCHEMA.COLUMNS.TABLE_NAME = 'variables';
+DROP TABLE variables;
 
 --echo End of 5.1 tests.
 

sql/sql_show.cc

@@ -2921,7 +2921,9 @@ make_table_name_list(THD *thd, List<LEX_STRING> *table_names, LEX *lex,
   {
     if (with_i_schema)
     {
-      if (find_schema_table(thd, lookup_field_vals->table_value.str))
+      ST_SCHEMA_TABLE *schema_table=
+        find_schema_table(thd, lookup_field_vals->table_value.str);
+      if (schema_table && !schema_table->hidden)
       {
         if (table_names->push_back(&lookup_field_vals->table_value))
           return 1;