MDEV-11129 CREATE OR REPLACE TABLE t1 AS SELECT spfunc() crashes if spfunc() references t1

Fixed by extending unique_table() with a flag to not allow usage of
the replaced table.

I also cleaned up find_dup_table() to not use goto next.
I also added more comments to the code in find_dup_table()

1 files changed, 5 insertions, 1 deletions

diff --git a/sql/sql_base.h b/sql/sql_base.h
index 04f132ac936..af42a15ab29 100644
--- a/sql/sql_base.h
+++ b/sql/sql_base.h
@@ -61,6 +61,10 @@ enum find_item_error_report_type {REPORT_ALL_ERRORS, REPORT_EXCEPT_NOT_FOUND,
 				  IGNORE_ERRORS, REPORT_EXCEPT_NON_UNIQUE,
                                   IGNORE_EXCEPT_NON_UNIQUE};
 
+/* Flag bits for unique_table() */
+#define CHECK_DUP_ALLOW_DIFFERENT_ALIAS 1
+#define CHECK_DUP_FOR_CREATE 2
+
 uint create_tmp_table_def_key(THD *thd, char *key, const char *db,
                               const char *table_name);
 uint get_table_def_key(const TABLE_LIST *table_list, const char **key);
@@ -254,7 +258,7 @@ void kill_delayed_threads_for_table(TABLE_SHARE *share);
 void close_thread_table(THD *thd, TABLE **table_ptr);
 bool close_temporary_tables(THD *thd);
 TABLE_LIST *unique_table(THD *thd, TABLE_LIST *table, TABLE_LIST *table_list,
-                         bool check_alias);
+                         uint check_flag);
 int drop_temporary_table(THD *thd, TABLE *table, bool *is_trans);
 void close_temporary_table(THD *thd, TABLE *table, bool free_share,
                            bool delete_table);