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, 50 insertions, 12 deletions

diff --git a/sql/item_timefunc.h b/sql/item_timefunc.h
index 3a03ee4b27a..0062d500835 100644
--- a/sql/item_timefunc.h
+++ b/sql/item_timefunc.h
@@ -506,6 +506,50 @@ public:
 };
 
 
+/**
+  Abstract class for functions returning TIME, DATE, DATETIME or string values,
+  whose data type depends on parameters and is set at fix_fields time.
+*/
+class Item_temporal_hybrid_func: public Item_temporal_func
+{
+protected:
+  enum_field_types cached_field_type; // TIME, DATE, DATETIME or STRING
+  String ascii_buf; // Conversion buffer
+public:
+  Item_temporal_hybrid_func(Item *a,Item *b)
+    :Item_temporal_func(a,b) {}
+  enum_field_types field_type() const { return cached_field_type; }
+  Item_result cmp_type() const
+  {
+    return cached_field_type == MYSQL_TYPE_STRING ?
+           STRING_RESULT : TIME_RESULT;
+  }
+  const CHARSET_INFO *charset_for_protocol() const
+  {
+    /*
+      Can return TIME, DATE, DATETIME or VARCHAR depending on arguments.
+      Send using "binary" when TIME, DATE or DATETIME,
+      or using collation.collation when VARCHAR
+      (which is fixed from @@collation_connection in fix_length_and_dec).
+    */
+    DBUG_ASSERT(fixed == 1);
+    return cached_field_type == MYSQL_TYPE_STRING ?
+           collation.collation : &my_charset_bin;
+  }
+  /**
+    Return string value in ASCII character set.
+  */
+  String *val_str_ascii(String *str);
+  /**
+    Return string value in @@character_set_connection.
+  */
+  String *val_str(String *str)
+  {
+    return val_str_from_val_str_ascii(str, &ascii_buf);
+  }
+};
+
+
 class Item_datefunc :public Item_temporal_func
 {
 public:
@@ -763,17 +807,15 @@ public:
 };
 
 
-class Item_date_add_interval :public Item_temporal_func
+class Item_date_add_interval :public Item_temporal_hybrid_func
 {
-  enum_field_types cached_field_type;
 public:
   const interval_type int_type; // keep it public
   const bool date_sub_interval; // keep it public
   Item_date_add_interval(Item *a,Item *b,interval_type type_arg,bool neg_arg)
-    :Item_temporal_func(a,b),int_type(type_arg), date_sub_interval(neg_arg) {}
+    :Item_temporal_hybrid_func(a,b),int_type(type_arg), date_sub_interval(neg_arg) {}
   const char *func_name() const { return "date_add_interval"; }
   void fix_length_and_dec();
-  enum_field_types field_type() const { return cached_field_type; }
   bool get_date(MYSQL_TIME *res, ulonglong fuzzy_date);
   bool eq(const Item *item, bool binary_cmp) const;
   void print(String *str, enum_query_type query_type);
@@ -911,16 +953,14 @@ public:
 };
 
 
-class Item_func_add_time :public Item_temporal_func
+class Item_func_add_time :public Item_temporal_hybrid_func
 {
   const bool is_date;
   int sign;
-  enum_field_types cached_field_type;
 
 public:
   Item_func_add_time(Item *a, Item *b, bool type_arg, bool neg_arg)
-    :Item_temporal_func(a, b), is_date(type_arg) { sign= neg_arg ? -1 : 1; }
-  enum_field_types field_type() const { return cached_field_type; }
+    :Item_temporal_hybrid_func(a, b), is_date(type_arg) { sign= neg_arg ? -1 : 1; }
   void fix_length_and_dec();
   bool get_date(MYSQL_TIME *ltime, ulonglong fuzzy_date);
   void print(String *str, enum_query_type query_type);
@@ -1019,9 +1059,8 @@ public:
 };
 
 
-class Item_func_str_to_date :public Item_temporal_func
+class Item_func_str_to_date :public Item_temporal_hybrid_func
 {
-  enum_field_types cached_field_type;
   timestamp_type cached_timestamp_type;
   bool const_item;
   String subject_converter;
@@ -1029,12 +1068,11 @@ class Item_func_str_to_date :public Item_temporal_func
   CHARSET_INFO *internal_charset;
 public:
   Item_func_str_to_date(Item *a, Item *b)
-    :Item_temporal_func(a, b), const_item(false),
+    :Item_temporal_hybrid_func(a, b), const_item(false),
     internal_charset(NULL)
   {}
   bool get_date(MYSQL_TIME *ltime, ulonglong fuzzy_date);
   const char *func_name() const { return "str_to_date"; }
-  enum_field_types field_type() const { return cached_field_type; }
   void fix_length_and_dec();
 };