bug(priproc) make last_day type a bit more accurate

This fixes discrepance with the server, which assigns DATE type to
last_day()'s result.

Now we also assigns DATE result type and, also, use proper
dataconvert::Day data structure to return date.

Tests agree with InnoDB.

Also, this patch includes test for MCOL-5669, to show we fixed it.

dbcon/mysql/ha_mcs_execplan.cpp

@@ -4388,6 +4388,13 @@ ReturnedColumn* buildFunctionColumn(Item_func* ifp, gp_walk_info& gwi, bool& non
       ct.colWidth = 8;
       fc->resultType(ct);
     }
+    if (funcName == "last_day")
+    {
+        CalpontSystemCatalog::ColType ct;
+        ct.colDataType = CalpontSystemCatalog::DATE;
+        ct.colWidth = 4;
+        fc->resultType(ct);
+    }
 
 #if 0
 

mysql-test/columnstore/bugfixes/mcol-5670.result

@@ -0,0 +1,18 @@
+DROP DATABASE IF EXISTS mcol_5670;
+CREATE DATABASE mcol_5670;
+USE mcol_5670;
+create table my_colstore_tab(`yyyymmdd` date DEFAULT NULL) engine=COLUMNSTORE;
+insert into my_colstore_tab values(date('2024-03-18'));
+insert into my_colstore_tab values(date(date('2024-03-18')-interval 1 year));
+select day(s.yyyymmdd) as OK_1, last_day(s.yyyymmdd) as OK_2, day(last_day(s.yyyymmdd)) as OK_3 from my_colstore_tab s;
+OK_1	OK_2	OK_3
+18	2024-03-31	31
+18	2023-03-31	31
+create table my_colstore_tab2(`yyyymmdd` datetime DEFAULT NULL) engine=COLUMNSTORE;
+insert into my_colstore_tab2 values('2024-03-18 13:40:31');
+insert into my_colstore_tab2 values('2024-03-18 13:40:31'-interval 1 year);
+select day(s.yyyymmdd) as OK_1, last_day(s.yyyymmdd) as OK_2, day(last_day(s.yyyymmdd)) as OK_3 from my_colstore_tab2 s;
+OK_1	OK_2	OK_3
+18	2024-03-31	31
+18	2023-03-31	31
+DROP DATABASE mcol_5670;

mysql-test/columnstore/bugfixes/mcol-5670.test

@@ -0,0 +1,21 @@
+--source ../include/have_columnstore.inc
+--disable_warnings
+DROP DATABASE IF EXISTS mcol_5670;
+--enable_warnings
+CREATE DATABASE mcol_5670;
+USE mcol_5670;
+
+
+# using lastday with DATE type
+create table my_colstore_tab(`yyyymmdd` date DEFAULT NULL) engine=COLUMNSTORE;
+insert into my_colstore_tab values(date('2024-03-18'));
+insert into my_colstore_tab values(date(date('2024-03-18')-interval 1 year));
+select day(s.yyyymmdd) as OK_1, last_day(s.yyyymmdd) as OK_2, day(last_day(s.yyyymmdd)) as OK_3 from my_colstore_tab s;
+
+# using lastday with DATETIME type
+create table my_colstore_tab2(`yyyymmdd` datetime DEFAULT NULL) engine=COLUMNSTORE;
+insert into my_colstore_tab2 values('2024-03-18 13:40:31');
+insert into my_colstore_tab2 values('2024-03-18 13:40:31'-interval 1 year);
+select day(s.yyyymmdd) as OK_1, last_day(s.yyyymmdd) as OK_2, day(last_day(s.yyyymmdd)) as OK_3 from my_colstore_tab2 s;
+
+DROP DATABASE mcol_5670;

utils/funcexp/func_last_day.cpp

@@ -163,6 +163,12 @@ int64_t Func_last_day::getIntVal(rowgroup::Row& row, FunctionParm& parm, bool& i
 
   uint32_t lastday = day;
 
+  if (month < 1 || month > 12)
+  {
+    isNull = true;
+    return -1;
+  }
+
   if (isLeapYear(year) && (month == 2))
   {
     lastday = 29;
@@ -182,16 +188,13 @@ int64_t Func_last_day::getIntVal(rowgroup::Row& row, FunctionParm& parm, bool& i
     return -1;
   }
 
-  dataconvert::DateTime aDay;
+  dataconvert::Date aDay;
   aDay.year = year;
   aDay.month = month;
   aDay.day = lastday;
-  aDay.hour = 0;
+  val = *(reinterpret_cast<uint32_t*>(&aDay));
-  aDay.minute = 0;
-  aDay.second = 0;
-  aDay.msecond = 0;
-  val = *(reinterpret_cast<uint64_t*>(&aDay));
   return val;
+
 }
 
 }  // namespace funcexp