MDEV-16938 Move Item::get_time_with_conversion() to Time

The affected code is well covered by tests for MDEV-8766.
Adding only the missing part: the old mode OLD_MODE_ZERO_DATE_TIME_CAST
in combination with 0000-MM-00 and YYYY-00-00.

The old mode in combination with 0000-00-DD was already covered,
so was the new mode with all types of DATETIME values.

8 files changed, 77 insertions, 157 deletions

diff --git a/mysql-test/main/type_time.result b/mysql-test/main/type_time.result
index 51b2aecaa6b..8f50d49d4b9 100644
--- a/mysql-test/main/type_time.result
+++ b/mysql-test/main/type_time.result
@@ -841,6 +841,18 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	8	100.00	Using where
 Warnings:
 Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` = TIMESTAMP'0000-00-01 10:20:30' and octet_length(`test`.`t1`.`a`) = 30 + rand()
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE a=TIMESTAMP'0000-01-00 10:20:30' AND LENGTH(a)=8;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	8	100.00	Using where
+Warnings:
+Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` = TIMESTAMP'0000-01-00 10:20:30' and octet_length(`test`.`t1`.`a`) = 8
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE a=TIMESTAMP'0001-00-00 10:20:30' AND LENGTH(a)=8;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	8	100.00	Using where
+Warnings:
+Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` = TIMESTAMP'0001-00-00 10:20:30' and octet_length(`test`.`t1`.`a`) = 8
 # Old mode, TIMESTAMP-alike string literal, zero YYYYMMDD, Ok to propagate
 SELECT * FROM t1 WHERE a='0000-00-00 10:20:30';
 a
diff --git a/mysql-test/main/type_time.test b/mysql-test/main/type_time.test
index 17494cec04f..f4a1a474046 100644
--- a/mysql-test/main/type_time.test
+++ b/mysql-test/main/type_time.test
@@ -514,6 +514,11 @@ SELECT * FROM t1 WHERE a=TIMESTAMP'0000-00-01 10:20:30' AND LENGTH(a)=8;
 EXPLAIN EXTENDED
 SELECT * FROM t1 WHERE a=TIMESTAMP'0000-00-01 10:20:30' AND LENGTH(a)=30+RAND();
 
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE a=TIMESTAMP'0000-01-00 10:20:30' AND LENGTH(a)=8;
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE a=TIMESTAMP'0001-00-00 10:20:30' AND LENGTH(a)=8;
+
 --echo # Old mode, TIMESTAMP-alike string literal, zero YYYYMMDD, Ok to propagate
 SELECT * FROM t1 WHERE a='0000-00-00 10:20:30';
 SELECT * FROM t1 WHERE a='0000-00-00 10:20:30' AND LENGTH(a)=8;
diff --git a/sql/field.cc b/sql/field.cc
index 50644bf4f05..217fd2bb6e8 100644
--- a/sql/field.cc
+++ b/sql/field.cc
@@ -5952,14 +5952,28 @@ bool Field_time::can_be_substituted_to_equal_item(const Context &ctx,
 Item *Field_time::get_equal_const_item(THD *thd, const Context &ctx,
                                        Item *const_item)
 {
+  /*
+    Old mode conversion from DATETIME with non-zero YYYYMMDD part
+    to TIME works very inconsistently. Possible variants:
+    - truncate the YYYYMMDD part
+    - add (MM*33+DD)*24 to hours
+    - add (MM*31+DD)*24 to hours
+    Let's disallow propagation of DATETIME with non-zero YYYYMMDD
+    as an equal constant for a TIME field.
+  */
+  Time::datetime_to_time_mode_t mode=
+    (thd->variables.old_behavior & OLD_MODE_ZERO_DATE_TIME_CAST) ?
+    Time::DATETIME_TO_TIME_YYYYMMDD_00000000_ONLY :
+    Time::DATETIME_TO_TIME_MINUS_CURRENT_DATE;
+
   switch (ctx.subst_constraint()) {
   case ANY_SUBST:
     if (const_item->field_type() != MYSQL_TYPE_TIME)
     {
-      MYSQL_TIME ltime;
       // Get the value of const_item with conversion from DATETIME to TIME
-      ulonglong fuzzydate= Time::comparison_flags_for_get_date();
-      if (const_item->get_time_with_conversion(thd, &ltime, fuzzydate))
+      Time tm(const_item,
+              Time::Options(Time::comparison_flags_for_get_date(), mode));
+      if (!tm.is_valid_time())
         return NULL;
       /*
         Replace a DATE/DATETIME constant to a TIME constant:
@@ -5971,8 +5985,9 @@ Item *Field_time::get_equal_const_item(THD *thd, const Context &ctx,
 
         (assuming CURRENT_DATE is '2015-08-30'
       */
-      return new (thd->mem_root) Item_time_literal(thd, &ltime,
-                                                   ltime.second_part ?
+      return new (thd->mem_root) Item_time_literal(thd, tm.get_mysql_time(),
+                                                   tm.get_mysql_time()->
+                                                   second_part ?
                                                    TIME_SECOND_PART_DIGITS :
                                                    0);
     }
@@ -5981,8 +5996,8 @@ Item *Field_time::get_equal_const_item(THD *thd, const Context &ctx,
     if (const_item->field_type() != MYSQL_TYPE_TIME ||
         const_item->decimals != decimals())
     {
-      MYSQL_TIME ltime;
-      if (const_item->get_time_with_conversion(thd, &ltime, TIME_TIME_ONLY))
+      Time tm(const_item, Time::Options(TIME_TIME_ONLY, mode));
+      if (!tm.is_valid_time())
         return NULL;
       /*
         Note, the value returned in "ltime" can have more fractional
@@ -5998,7 +6013,8 @@ Item *Field_time::get_equal_const_item(THD *thd, const Context &ctx,
         The optimized WHERE will return with "Impossible WHERE", without
         having to do the full table scan.
       */
-      return new (thd->mem_root) Item_time_literal(thd, &ltime, decimals());
+      return new (thd->mem_root) Item_time_literal(thd, tm.get_mysql_time(),
+                                                   decimals());
     }
     break;
   }
diff --git a/sql/item.cc b/sql/item.cc
index 8b962d1706d..4422d73787b 100644
--- a/sql/item.cc
+++ b/sql/item.cc
@@ -128,50 +128,6 @@ longlong Item::val_datetime_packed_result()
 }
 
 
-/**
-  Get date/time/datetime.
-  If DATETIME or DATE result is returned, it's converted to TIME.
-*/
-bool Item::get_time_with_conversion(THD *thd, MYSQL_TIME *ltime,
-                                    ulonglong fuzzydate)
-{
-  if (get_date(ltime, fuzzydate))
-    return true;
-  if (ltime->time_type != MYSQL_TIMESTAMP_TIME)
-  {
-    MYSQL_TIME ltime2;
-    if ((thd->variables.old_behavior & OLD_MODE_ZERO_DATE_TIME_CAST) &&
-        (ltime->year || ltime->day || ltime->month))
-    {
-      /*
-        Old mode conversion from DATETIME with non-zero YYYYMMDD part
-        to TIME works very inconsistently. Possible variants:
-        - truncate the YYYYMMDD part
-        - add (MM*33+DD)*24 to hours
-        - add (MM*31+DD)*24 to hours
-        Let's return TRUE here, to disallow equal field propagation.
-        Note, If we start to use this method in more pieces of the code other
-        than equal field propagation, we should probably return
-        TRUE only if some flag in fuzzydate is set.
-      */
-      return true;
-    }
-    if (datetime_to_time_with_warn(thd, ltime, &ltime2, TIME_SECOND_PART_DIGITS))
-    {
-      /*
-        If the time difference between CURRENT_DATE and ltime
-        did not fit into the supported TIME range, then we set the
-        difference to the maximum possible value in the supported TIME range
-      */
-      DBUG_ASSERT(0);
-      return (null_value= true);
-    }
-    *ltime= ltime2;
-  }
-  return false;
-}
-
-
 /*
   For the items which don't have its own fast val_str_ascii()
   implementation we provide a generic slower version,
diff --git a/sql/item.h b/sql/item.h
index a96406fa0cd..73584fd3293 100644
--- a/sql/item.h
+++ b/sql/item.h
@@ -1611,40 +1611,6 @@ public:
   bool get_date_from_string(MYSQL_TIME *ltime, ulonglong fuzzydate);
   bool get_time(MYSQL_TIME *ltime)
   { return get_date(ltime, Time::flags_for_get_date()); }
-  /*
-    Get time with automatic DATE/DATETIME to TIME conversion,
-    by subtracting CURRENT_DATE.
-
-    Performce a reverse operation to CAST(time AS DATETIME)
-    Suppose:
-    - we have a set of items (typically with the native MYSQL_TYPE_TIME type)
-      whose item->get_date() return TIME1 value, and
-    - CAST(AS DATETIME) for the same Items return DATETIME1,
-      after applying time-to-datetime conversion to TIME1.
-
-    then all items (typically of the native MYSQL_TYPE_{DATE|DATETIME} types)
-    whose get_date() return DATETIME1 must also return TIME1 from
-    get_time_with_conversion()
-
-    @param thd        - the thread, its variables.old_mode is checked
-                        to decide if use simple YYYYMMDD truncation (old mode),
-                        or perform full DATETIME-to-TIME conversion with
-                        CURRENT_DATE subtraction.
-    @param[out] ltime - store the result here
-    @param fuzzydate  - flags to be used for the get_date() call.
-                        Normally, should include TIME_TIME_ONLY, to let
-                        the called low-level routines, e.g. str_to_date(),
-                        know that we prefer TIME rather that DATE/DATETIME
-                        and do less conversion outside of the low-level
-                        routines.
-
-    @returns true     - on error, e.g. get_date() returned NULL value,
-                        or get_date() returned DATETIME/DATE with non-zero
-                        YYYYMMDD part.
-    @returns false    - on success
-  */
-  bool get_time_with_conversion(THD *thd, MYSQL_TIME *ltime,
-                                ulonglong fuzzydate);
   // Get a DATE or DATETIME value in numeric packed format for comparison
   virtual longlong val_datetime_packed()
   {
diff --git a/sql/sql_time.cc b/sql/sql_time.cc
index c75b8b19e1a..430eb192052 100644
--- a/sql/sql_time.cc
+++ b/sql/sql_time.cc
@@ -1365,26 +1365,6 @@ time_to_datetime_with_warn(THD *thd,
 }
 
 
-bool datetime_to_time_with_warn(THD *thd, const MYSQL_TIME *dt,
-                                MYSQL_TIME *tm, uint dec)
-{
-  if (thd->variables.old_behavior & OLD_MODE_ZERO_DATE_TIME_CAST)
-  {
-    *tm= *dt;
-    datetime_to_time(tm);
-    return false;
-  }
-  else /* new mode */
-  {
-    MYSQL_TIME current_date;
-    set_current_date(thd, &current_date);
-    calc_time_diff(dt, &current_date, 1, tm, 0);
-  }
-  int warnings= 0;
-  return check_time_range(tm, dec, &warnings);
-}
-
-
 longlong pack_time(const MYSQL_TIME *my_time)
 {
   return  ((((((my_time->year     * 13ULL +
diff --git a/sql/sql_time.h b/sql/sql_time.h
index cfa1468841b..8c6e58856e6 100644
--- a/sql/sql_time.h
+++ b/sql/sql_time.h
@@ -54,50 +54,6 @@ bool time_to_datetime(THD *thd, const MYSQL_TIME *tm, MYSQL_TIME *dt);
 bool time_to_datetime_with_warn(THD *thd,
                                 const MYSQL_TIME *tm, MYSQL_TIME *dt,
                                 ulonglong fuzzydate);
-/*
-  Simply truncate the YYYY-MM-DD part to 0000-00-00
-  and change time_type to MYSQL_TIMESTAMP_TIME
-*/
-inline void datetime_to_time(MYSQL_TIME *ltime)
-{
-  DBUG_ASSERT(ltime->time_type == MYSQL_TIMESTAMP_DATE ||
-              ltime->time_type == MYSQL_TIMESTAMP_DATETIME);
-  DBUG_ASSERT(ltime->neg == 0);
-  ltime->year= ltime->month= ltime->day= 0;
-  ltime->time_type= MYSQL_TIMESTAMP_TIME;
-}
-
-
-/**
-  Convert DATE/DATETIME to TIME(dec)
-  using CURRENT_DATE in a non-old mode,
-  or using simple truncation in old mode (OLD_MODE_ZERO_DATE_TIME_CAST).
-
-  @param      thd - the thread to get the variables.old_behaviour value from
-  @param      dt  - the DATE of DATETIME value to convert
-  @param[out] tm  - store result here
-  @param      dec - the desired scale. The fractional part of the result
-                    is checked according to this parameter before returning
-                    the conversion result. "dec" is important in the corner
-                    cases near the max/min limits.
-                    If the result is '838:59:59.999999' and the desired scale
-                    is less than 6, an error is returned.
-                    Note, dec is not important in the
-                    OLD_MODE_ZERO_DATE_TIME_CAST old mode.
-
-  - in case of OLD_MODE_ZERO_DATE_TIME_CAST
-    the TIME part is simply truncated and "false" is returned.
-  - otherwise, the result is calculated effectively similar to:
-    TIMEDIFF(dt, CAST(CURRENT_DATE AS DATETIME))
-    If the difference fits into the supported TIME range, "false" is returned,
-    otherwise a warning is issued and "true" is returned.
-
-  @return false - on success
-  @return true  - on error
-*/
-bool datetime_to_time_with_warn(THD *, const MYSQL_TIME *dt,
-                                MYSQL_TIME *tm, uint dec);
-
 
 inline void datetime_to_date(MYSQL_TIME *ltime)
 {
diff --git a/sql/sql_type.h b/sql/sql_type.h
index 3465708f768..40433fdaabd 100644
--- a/sql/sql_type.h
+++ b/sql/sql_type.h
@@ -534,7 +534,9 @@ public:
   enum datetime_to_time_mode_t
   {
     DATETIME_TO_TIME_YYYYMMDD_000000DD_MIX_TO_HOURS,
-    DATETIME_TO_TIME_YYYYMMDD_TRUNCATE
+    DATETIME_TO_TIME_YYYYMMDD_TRUNCATE,
+    DATETIME_TO_TIME_YYYYMMDD_00000000_ONLY,
+    DATETIME_TO_TIME_MINUS_CURRENT_DATE
   };
   class Options
   {
@@ -601,6 +603,21 @@ private:
       hour+= from_day * 24;
   }
   /*
+    The result is calculated effectively similar to:
+    TIMEDIFF(dt, CAST(CURRENT_DATE AS DATETIME))
+    If the difference does not fit to the supported TIME range, it's truncated.
+  */
+  void datetime_to_time_minus_current_date(THD *thd)
+  {
+    MYSQL_TIME current_date, tmp;
+    set_current_date(thd, &current_date);
+    calc_time_diff(this, &current_date, 1, &tmp, 0);
+    static_cast<MYSQL_TIME*>(this)[0]= tmp;
+    int warnings= 0;
+    (void) check_time_range(this, TIME_SECOND_PART_DIGITS, &warnings);
+    DBUG_ASSERT(is_valid_time());
+  }
+  /*
     Convert a valid DATE or DATETIME to TIME.
     Before this call, "this" must be a valid DATE or DATETIME value,
     e.g. returned from Item::get_date(), str_to_time(), number_to_time().
@@ -621,11 +638,18 @@ private:
     */
     DBUG_ASSERT(day < 32);
     DBUG_ASSERT(hour < 24);
-    if (opt.datetime_to_time_mode() ==
-        DATETIME_TO_TIME_YYYYMMDD_000000DD_MIX_TO_HOURS)
-      datetime_to_time_YYYYMMDD_000000DD_mix_to_hours(warn, year, month, day);
-    year= month= day= 0;
-    time_type= MYSQL_TIMESTAMP_TIME;
+    if (opt.datetime_to_time_mode() == DATETIME_TO_TIME_MINUS_CURRENT_DATE)
+    {
+      datetime_to_time_minus_current_date(current_thd);
+    }
+    else
+    {
+      if (opt.datetime_to_time_mode() ==
+          DATETIME_TO_TIME_YYYYMMDD_000000DD_MIX_TO_HOURS)
+        datetime_to_time_YYYYMMDD_000000DD_mix_to_hours(warn, year, month, day);
+      year= month= day= 0;
+      time_type= MYSQL_TIMESTAMP_TIME;
+    }
     DBUG_ASSERT(is_valid_time_slow());
   }
   /**
@@ -646,7 +670,12 @@ private:
     switch (time_type) {
     case MYSQL_TIMESTAMP_DATE:
     case MYSQL_TIMESTAMP_DATETIME:
-      valid_datetime_to_valid_time(warn, opt);
+      if (opt.datetime_to_time_mode() ==
+          DATETIME_TO_TIME_YYYYMMDD_00000000_ONLY &&
+          (year || month || day))
+        make_from_out_of_range(warn);
+      else
+        valid_datetime_to_valid_time(warn, opt);
       break;
     case MYSQL_TIMESTAMP_NONE:
       break;