Bug#19844: time_format in Union truncates values

time_format() claimed %H and %k would return at most two digits
(hours 0-23), but this coincided neither with actual behaviour
nor with docs.  this is not visible in simple queries; forcing
a temp-table is probably the easiest way to see this.  adjusted
the return-length appropriately; the alternative would be to
adjust the docs to say that behaviour for > 99 hours is undefined.
---
Bug#19844: time_format in Union truncates values

time_format() claimed %H and %k would return at most two digits
(hours 0-23), but this coincided neither with actual behaviour
nor with docs.  this is not visible in simple queries; forcing
a temp-table is probably the easiest way to see this.  adjusted
the return-length appropriately; the alternative would be to
adjust the docs to say that behaviour for > 99 hours is undefined.


mysql-test/r/func_time.result:
  Bug#19844: time_format in Union truncates values
  
  show time_format() handles %H and %k correctly four > 99 hours
mysql-test/t/func_time.test:
  Bug#19844: time_format in Union truncates values
  
  show time_format() handles %H and %k correctly four > 99 hours
sql/item_timefunc.cc:
  Bug#19844: time_format in Union truncates values
  
  unbreak promises we make about field-length of %H and %k in
  time_format() so they coincide with the actual range rather
  than just 0..23. the docs say we must operate outside that
  range, so we'd better do it right.
  ---
  Bug#19844: time_format in Union truncates values
  
  unbreak promises we make about field-length of %H and %k in
  time_format() so they coincide with the actual range rather
  than just 0..23. the docs say we must operate outside that
  range, so we'd better do it right.
  One digit values are padded to two digits with %H, "longer"
  values are handled correctly up to seven digits including
  any sign.
  (clarified comments as per jimw's suggestion.)

mysql-test/r/func_time.result

@@ -695,3 +695,24 @@ t1	CREATE TABLE `t1` (
   `from_unixtime(1) + 0` double(23,6) default NULL
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 drop table t1;
+(select time_format(timediff(now(), DATE_SUB(now(),INTERVAL 5 DAY)),'%H') As H)
+union
+(select time_format(timediff(now(), DATE_SUB(now(),INTERVAL 5 DAY)),'%H') As H);
+H
+120
+(select time_format(timediff(now(), DATE_SUB(now(),INTERVAL 5 DAY)),'%k') As H)
+union
+(select time_format(timediff(now(), DATE_SUB(now(),INTERVAL 5 DAY)),'%k') As H);
+H
+120
+(select time_format(timediff(now(), DATE_SUB(now(),INTERVAL 5 HOUR)),'%H') As H)
+union
+(select time_format(timediff(now(), DATE_SUB(now(),INTERVAL 5 HOUR)),'%H') As H);
+H
+05
+(select time_format(timediff(now(), DATE_SUB(now(),INTERVAL 5 HOUR)),'%k') As H)
+union
+(select time_format(timediff(now(), DATE_SUB(now(),INTERVAL 5 HOUR)),'%k') As H);
+H
+5
+End of 4.1 tests

mysql-test/t/func_time.test

@@ -368,4 +368,22 @@ create table t1 select now() - now(), curtime() - curtime(),
 show create table t1;
 drop table t1;
 
-# End of 4.1 tests
+#
+# Bug #19844 time_format in Union truncates values
+#
+
+(select time_format(timediff(now(), DATE_SUB(now(),INTERVAL 5 DAY)),'%H') As H)
+union
+(select time_format(timediff(now(), DATE_SUB(now(),INTERVAL 5 DAY)),'%H') As H);
+(select time_format(timediff(now(), DATE_SUB(now(),INTERVAL 5 DAY)),'%k') As H)
+union
+(select time_format(timediff(now(), DATE_SUB(now(),INTERVAL 5 DAY)),'%k') As H);
+(select time_format(timediff(now(), DATE_SUB(now(),INTERVAL 5 HOUR)),'%H') As H)
+union
+(select time_format(timediff(now(), DATE_SUB(now(),INTERVAL 5 HOUR)),'%H') As H);
+
+(select time_format(timediff(now(), DATE_SUB(now(),INTERVAL 5 HOUR)),'%k') As H)
+union
+(select time_format(timediff(now(), DATE_SUB(now(),INTERVAL 5 HOUR)),'%k') As H);
+
+--echo End of 4.1 tests

sql/item_timefunc.cc

@@ -1600,14 +1600,12 @@ uint Item_func_date_format::format_length(const String *format)
       case 'u': /* week (00..52), where week starts with Monday */
       case 'V': /* week 1..53 used with 'x' */
       case 'v': /* week 1..53 used with 'x', where week starts with Monday */
-      case 'H': /* hour (00..23) */
       case 'y': /* year, numeric, 2 digits */
       case 'm': /* month, numeric */
       case 'd': /* day (of the month), numeric */
       case 'h': /* hour (01..12) */
       case 'I': /* --||-- */
       case 'i': /* minutes, numeric */
-      case 'k': /* hour ( 0..23) */
       case 'l': /* hour ( 1..12) */
       case 'p': /* locale's AM or PM */
       case 'S': /* second (00..61) */
@@ -1616,6 +1614,10 @@ uint Item_func_date_format::format_length(const String *format)
       case 'e': /* day (0..31) */
 	size += 2;
 	break;
+      case 'k': /* hour ( 0..23) */
+      case 'H': /* hour (00..23; value > 23 OK, padding always 2-digit) */
+	size += 7; /* docs allow > 23, range depends on sizeof(unsigned int) */
+	break;
       case 'r': /* time, 12-hour (hh:mm:ss [AP]M) */
 	size += 11;
 	break;