Bug#31384 DATE_ADD() and DATE_SUB() return binary data

Problem: DATE_ADD() is a hybrid function and can return
DATE, DATETIME or VARCHAR data type depending on arguments.

In case of VARCHAR data type, DATE_ADD() reported "binary" character set,
which was wrong.

Fix: make DATE_ADD() return @character_set_connection in VARCHAR context.
 @ mysql-test/include/ctype_numconv.inc
   Adding tests
 @ mysql-test/r/ctype_binary.result
   Adding tests
 @ mysql-test/r/ctype_cp1251.result
   Adding tests
 @ mysql-test/r/ctype_latin1.result
   Adding tests
 @ mysql-test/r/ctype_ucs.result
   Adding tests
 @ mysql-test/r/ctype_utf8.result
   Adding tests
 @ sql/item_strfunc.cc
  - Moving code from Item_str_ascii_func::val_str() to
  Item_str_func::val_str_from_val_str_ascii(), as
  this code needs to be shared by Item_date_add_interval.
  - Adding str2 parameter to be used as a buffer, instead of
   using private ascii_buf member.
 @ sql/item_strfunc.h
  - Moving code from Item_str_ascii_func::val_str() to
  Item_str_func::val_str_from_val_str_ascii()
  - Removing "String *val_str_convert_from_ascii(String *str, String *ascii_buf)"
    prototype as it was neither used nor declared.
 @ sql/item_timefunc.h
  - Overwriting parent's charset_for_protocol() method,
    becase we need to behave differenlty in VARCHAR and DATE/DATETYPE context.
  - Adding ascii_buf for conversion.
  - Adding val_str_ascii() prototype.
  - Adding val_str() which uses newly added
    Item_str_func::val_str_from_val_str_ascii(),
    passing ascii_buf as a conversion buffer.

1 files changed, 5 insertions, 2 deletions

diff --git a/sql/item_strfunc.h b/sql/item_strfunc.h
index e26f9b4467a..fef4f9f975d 100644
--- a/sql/item_strfunc.h
+++ b/sql/item_strfunc.h
@@ -51,6 +51,7 @@ public:
   enum Item_result result_type () const { return STRING_RESULT; }
   void left_right_max_length();
   bool fix_fields(THD *thd, Item **ref);
+  String *val_str_from_val_str_ascii(String *str, String *str2);
 };
 
 
@@ -66,8 +67,10 @@ public:
   Item_str_ascii_func(Item *a) :Item_str_func(a) {}
   Item_str_ascii_func(Item *a,Item *b) :Item_str_func(a,b) {}
   Item_str_ascii_func(Item *a,Item *b,Item *c) :Item_str_func(a,b,c) {}
-  String *val_str_convert_from_ascii(String *str, String *ascii_buf);
-  String *val_str(String *str);
+  String *val_str(String *str)
+  {
+    return val_str_from_val_str_ascii(str, &ascii_buf);
+  }
   virtual String *val_str_ascii(String *)= 0;
 };