MDEV-10524 Assertion `arg1_int >= 0' failed in Item_func_additive_op::result_precision()

This change is a backport from 10.0 to 5.5 for:
1. The full patch for:
     MDEV-4841 Wrong character set of ADDTIME() and DATE_ADD()
     9adb6e991ec87b65d04929f115d9d0c899e4ab19

2. A small fragment of:
     MDEV-5298 Illegal mix of collations on timestamp
     03f6778d61a74bdd7d09103a16473a2a5624cf66
   which overrides Item_temporal_hybrid_func::cmp_type(),
   and adds a new line into cache_temporal_4265.result.

1 files changed, 17 insertions, 0 deletions

diff --git a/sql/sql_time.cc b/sql/sql_time.cc
index c5c65391758..d912a7b78d6 100644
--- a/sql/sql_time.cc
+++ b/sql/sql_time.cc
@@ -838,6 +838,23 @@ const char *get_date_time_format_str(KNOWN_DATE_TIME_FORMAT *format,
   }
 }
 
+
+/**
+  Convert TIME/DATE/DATETIME value to String.
+  @param l_time   DATE value
+  @param OUT str  String to convert to
+  @param dec      Number of fractional digits.
+*/
+bool my_TIME_to_str(const MYSQL_TIME *ltime, String *str, uint dec)
+{
+  if (str->alloc(MAX_DATE_STRING_REP_LENGTH))
+    return true;
+  str->set_charset(&my_charset_numeric);
+  str->length(my_TIME_to_str(ltime, const_cast<char*>(str->ptr()), dec));
+  return false;
+}
+
+
 void make_truncated_value_warning(THD *thd,
                                   MYSQL_ERROR::enum_warning_level level,
                                   const ErrConv *sval,