MDEV-31684 Add timezone information to DATE_FORMAT

Before starting to go over the format string, prepare the current time
zone information incase '%z' or '%Z' is encountered.
This information can be obtained as given below:

A) If timezone is not set ( meaning we are working with system timezone):
Get the MYSQL_TIME representation for current time and GMT time using
current thread variable for timezone and timezone variable for UTC
respectively. This MYSQL_TIME variable will be used to calculate time
difference. Also convert current time in second to tm structure to
get system timezone information.

B) If timezone is set as offset:
Get timezone information using current timezone information and store
in appropriate variable.

C) If timezone is set as some place (example: Europe/Berlin)
Get timezone information by searching the timezone. During internal
timezone search, information like timeoffset from UTC and abbrevation
is stored in another relevant structure. Hence use the same information.

mysql-test/main/date_formats.result

@@ -555,3 +555,49 @@ time_format('01 02:02:02', '%T')
 select time_format('2001-01-01 02:02:02', '%T');
 time_format('2001-01-01 02:02:02', '%T')
 02:02:02
+#
+# Beginning of 11.3 test
+#
+# MDEV-31684: Add timezone information to DATE_FORMAT
+#
+SET @old_timezone= @@time_zone;
+# Using named timezones
+SET TIME_ZONE='Japan';
+SELECT DATE_FORMAT('2009-10-04 22:23:00', '%z %Z') AS current_timezone;
+current_timezone
++0900 JST
+SET @@time_zone='Europe/Moscow';
+SELECT DATE_FORMAT('1965-02-17 22:23:00', '%z %Z') AS current_timezone;
+current_timezone
++0300 MSK
+SELECT DATE_FORMAT('1965-12-31 22:23:00', '%z %Z') AS current_timezone;
+current_timezone
++0300 MSK
+SELECT DATE_FORMAT('1985-06-01', '%z %Z');
+DATE_FORMAT('1985-06-01', '%z %Z')
++0400 MSD
+# Using positive and negative offset
+SET TIME_ZONE= '-05:30';
+SELECT DATE_FORMAT('2009-10-04 22:23:00', '%z %Z') AS current_timezone;
+current_timezone
+-0530 -05:30
+SET TIME_ZONE= '+04:30';
+SELECT DATE_FORMAT('2009-10-04 22:23:00', '%z %Z') AS current_timezone;
+current_timezone
++0430 +04:30
+# Using UTC
+SET TIME_ZONE='UTC';
+SELECT DATE_FORMAT('2009-10-04 22:23:00', '%z %Z') AS current_timezone;
+current_timezone
++0000 UTC
+# using system time
+#
+# output depends on system time information. Hence replacing
+# to avoid result diff test failures.
+#
+SET @@time_zone= default;
+SELECT DATE_FORMAT('2009-10+|-HH:MM ABC22:23:00', '%z %Z') AS current_timezone;
+current_timezone
++|-HH:MM ABC
+SET @@time_zone= @old_timezone;
+# End of 11.3 test

mysql-test/main/date_formats.test

@@ -256,3 +256,51 @@ select time_format('2001-01-01 02:02:02', '%d %T');
 select time_format('01 02:02:02', '%d %T');
 select time_format('01 02:02:02', '%T');
 select time_format('2001-01-01 02:02:02', '%T');
+
+--echo #
+--echo # Beginning of 11.3 test
+--echo #
+--echo # MDEV-31684: Add timezone information to DATE_FORMAT
+--echo #
+
+SET @old_timezone= @@time_zone;
+
+
+--echo # Using named timezones
+
+SET TIME_ZONE='Japan';
+SELECT DATE_FORMAT('2009-10-04 22:23:00', '%z %Z') AS current_timezone;
+
+SET @@time_zone='Europe/Moscow';
+SELECT DATE_FORMAT('1965-02-17 22:23:00', '%z %Z') AS current_timezone;
+SELECT DATE_FORMAT('1965-12-31 22:23:00', '%z %Z') AS current_timezone;
+SELECT DATE_FORMAT('1985-06-01', '%z %Z');
+
+--echo # Using positive and negative offset
+
+SET TIME_ZONE= '-05:30';
+SELECT DATE_FORMAT('2009-10-04 22:23:00', '%z %Z') AS current_timezone;
+
+SET TIME_ZONE= '+04:30';
+SELECT DATE_FORMAT('2009-10-04 22:23:00', '%z %Z') AS current_timezone;
+
+
+--echo # Using UTC
+
+SET TIME_ZONE='UTC';
+SELECT DATE_FORMAT('2009-10-04 22:23:00', '%z %Z') AS current_timezone;
+
+--echo # using system time
+--echo #
+--echo # output depends on system time information. Hence replacing
+--echo # to avoid result diff test failures.
+--echo #
+
+SET @@time_zone= default;
+
+--replace_regex /[+-][0-9]* [A-Z]*/+|-HH:MM ABC/
+SELECT DATE_FORMAT('2009-10-04 22:23:00', '%z %Z') AS current_timezone;
+
+SET @@time_zone= @old_timezone;
+
+--echo # End of 11.3 test

mysql-test/main/mysqldump-system,win.rdiff

@@ -3,24 +3,24 @@
 @@ -449,9 +449,9 @@
  Table	Checksum
  mysql.roles_mapping	2510045525
- mysql.time_zone_transition	3895294076
+ mysql.time_zone_transition	3719776009
 -mysql.plugin	1587119305
 +mysql.plugin	2184891911
  mysql.servers	2079085450
 -mysql.func	3241572444
 +mysql.func	310494789
- mysql.innodb_table_stats	347867921
- mysql.table_stats	664320059
+ mysql.innodb_table_stats	1285726777
+ mysql.table_stats	2836905944
  # Opps....
 @@ -484,9 +484,9 @@
  Table	Checksum
  mysql.roles_mapping	2510045525
- mysql.time_zone_transition	3895294076
+ mysql.time_zone_transition	3719776009
 -mysql.plugin	1587119305
 +mysql.plugin	2184891911
  mysql.servers	2079085450
 -mysql.func	3241572444
 +mysql.func	310494789
- mysql.innodb_table_stats	347867921
- mysql.table_stats	664320059
+ mysql.innodb_table_stats	1285726777
+ mysql.table_stats	2836905944
  DROP FUNCTION IF EXISTS metaphon;