BUG#21811 Odd casting with date + INTERVAL arithmetic

- Type casting was not consequent, thus when adding a DATE type with
  a WEEK interval the result tpe was DATETIME and not DATE as is the
  norm.
- By changing the order of the date type enumerations the type casting
  bug is resolved. To comply with the new order the array 
  interval_type_to_name needed to change accordingly.


include/my_time.h:
  Changed enumeration order to make week interval appear in a more
  logical order. This affects type casting when a date is added to an
  interval.
sql/time.cc:
  Moved string WEEK to match enumeration in interval_type

1 files changed, 12 insertions, 1 deletions

diff --git a/sql/time.cc b/sql/time.cc
index 0461f7723c6..467dbc684a5 100644
--- a/sql/time.cc
+++ b/sql/time.cc
@@ -25,14 +25,25 @@
 
 #ifndef TESTTIME
 
+/*
+  Name description of interval names used in statements.
+
+  'interval_type_to_name' is ordered and sorted on interval size and
+  interval complexity.
+  Order of elements in 'interval_type_to_name' should correspond to 
+  the order of elements in 'interval_type' enum
+  
+  See also interval_type, interval_names
+*/
+
 LEX_STRING interval_type_to_name[INTERVAL_LAST] = {
   { C_STRING_WITH_LEN("YEAR")},
   { C_STRING_WITH_LEN("QUARTER")},
   { C_STRING_WITH_LEN("MONTH")},
+  { C_STRING_WITH_LEN("WEEK")},
   { C_STRING_WITH_LEN("DAY")},
   { C_STRING_WITH_LEN("HOUR")},
   { C_STRING_WITH_LEN("MINUTE")},
-  { C_STRING_WITH_LEN("WEEK")},
   { C_STRING_WITH_LEN("SECOND")},
   { C_STRING_WITH_LEN("MICROSECOND")},
   { C_STRING_WITH_LEN("YEAR_MONTH")},