MDEV-5969 Crash in prepared statement with NO_ZERO_IN_DATE and ROLLUP

MDEV-5971 Asymmetry between CAST(DATE'2001-00-00') to INT and TO CHAR in prepared statements

Consistently set maybe_null flag, even not-NULL temporal literal may become NULL
in the restrictive sql_mode.

1 files changed, 23 insertions, 6 deletions

diff --git a/sql/item.cc b/sql/item.cc
index 7c04dc00880..9b27f730e80 100644
--- a/sql/item.cc
+++ b/sql/item.cc
@@ -341,12 +341,29 @@ String *Item::val_string_from_decimal(String *str)
 }
 
 
+/*
+ All val_xxx_from_date() must call this method, to expose consistent behaviour
+ regarding SQL_MODE when converting DATE/DATETIME to other data types.
+*/
+bool Item::get_temporal_with_sql_mode(MYSQL_TIME *ltime)
+{
+  return get_date(ltime, field_type() == MYSQL_TYPE_TIME
+                          ? TIME_TIME_ONLY
+                          : sql_mode_for_dates(current_thd));
+}
+
+
+bool Item::is_null_from_temporal()
+{
+  MYSQL_TIME ltime;
+  return get_temporal_with_sql_mode(&ltime);
+}
+
+
 String *Item::val_string_from_date(String *str)
 {
   MYSQL_TIME ltime;
-  if (get_date(&ltime, field_type() == MYSQL_TYPE_TIME
-                       ? TIME_TIME_ONLY
-                       : sql_mode_for_dates(current_thd)) ||
+  if (get_temporal_with_sql_mode(&ltime) ||
       str->alloc(MAX_DATE_STRING_REP_LENGTH))
   {
     null_value= 1;
@@ -403,7 +420,7 @@ my_decimal *Item::val_decimal_from_date(my_decimal *decimal_value)
 {
   DBUG_ASSERT(fixed == 1);
   MYSQL_TIME ltime;
-  if (get_date(&ltime, sql_mode_for_dates(current_thd)))
+  if (get_temporal_with_sql_mode(&ltime))
   {
     my_decimal_set_zero(decimal_value);
     null_value= 1;                               // set NULL, stop processing
@@ -430,7 +447,7 @@ longlong Item::val_int_from_date()
 {
   DBUG_ASSERT(fixed == 1);
   MYSQL_TIME ltime;
-  if (get_date(&ltime, 0))
+  if (get_temporal_with_sql_mode(&ltime))
     return 0;
   longlong v= TIME_to_ulonglong(&ltime);
   return ltime.neg ? -v : v;
@@ -441,7 +458,7 @@ double Item::val_real_from_date()
 {
   DBUG_ASSERT(fixed == 1);
   MYSQL_TIME ltime;
-  if (get_date(&ltime, 0))
+  if (get_temporal_with_sql_mode(&ltime))
     return 0;
   return TIME_to_double(&ltime);
 }