Fix GCC 11.2.0 -Wmaybe-uninitialized

TABLE_LIST::calc_md5(): Remove an untruthful const qualifier.

thd_get_query_start_data(): Pass empty_clex_str instead of
an uninitialized LEX_CSTRING.

sql/sql_class.cc

@@ -5156,8 +5156,8 @@ extern "C" bool thd_is_strict_mode(const MYSQL_THD thd)
 */
 void thd_get_query_start_data(THD *thd, char *buf)
 {
-  LEX_CSTRING field_name;
-  Field_timestampf f((uchar *)buf, NULL, 0, Field::NONE, &field_name, NULL, 6);
+  Field_timestampf f((uchar *)buf, NULL, 0, Field::NONE, &empty_clex_str,
+                     NULL, 6);
   f.store_TIME(thd->query_start(), thd->query_start_sec_part());
 }
 

sql/sql_view.cc

 /* Copyright (c) 2004, 2013, Oracle and/or its affiliates.
-   Copyright (c) 2011, 2016, MariaDB Corporation
+   Copyright (c) 2011, 2021, MariaDB Corporation.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -836,7 +836,7 @@ int mariadb_fix_view(THD *thd, TABLE_LIST *view, bool wrong_checksum,
        if ((view->md5.str= (char *)thd->alloc(32 + 1)) == NULL)
          DBUG_RETURN(HA_ADMIN_FAILED);
     }
-    view->calc_md5(view->md5.str);
+    view->calc_md5(const_cast<char*>(view->md5.str));
     view->md5.length= 32;
   }
   view->mariadb_version= MYSQL_VERSION_ID;

sql/table.cc

 /* Copyright (c) 2000, 2017, Oracle and/or its affiliates.
-   Copyright (c) 2008, 2020, MariaDB
+   Copyright (c) 2008, 2021, MariaDB
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -4879,12 +4879,12 @@ void TABLE::reset_item_list(List<Item> *item_list, uint skip) const
     buffer	buffer for md5 writing
 */
 
-void  TABLE_LIST::calc_md5(const char *buffer)
+void  TABLE_LIST::calc_md5(char *buffer)
 {
   uchar digest[16];
   compute_md5_hash(digest, select_stmt.str,
                    select_stmt.length);
-  sprintf((char *) buffer,
+  sprintf(buffer,
 	    "%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x",
 	    digest[0], digest[1], digest[2], digest[3],
 	    digest[4], digest[5], digest[6], digest[7],

sql/table.h

 #ifndef TABLE_INCLUDED
 #define TABLE_INCLUDED
 /* Copyright (c) 2000, 2017, Oracle and/or its affiliates.
-   Copyright (c) 2009, 2020, MariaDB
+   Copyright (c) 2009, 2021, MariaDB
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -2562,7 +2562,7 @@ struct TABLE_LIST
   List<String> *partition_names;
 #endif /* WITH_PARTITION_STORAGE_ENGINE */
 
-  void calc_md5(const char *buffer);
+  void calc_md5(char *buffer);
   int view_check_option(THD *thd, bool ignore_failure);
   bool create_field_translation(THD *thd);
   bool setup_underlying(THD *thd);