Adding "const" qualifier into a few methods and parameters in the LOAD code

Methods:
- Item_user_var_as_out_param::print_for_load()
- sql_exchange::escaped_given(void)

Parameters:
- sql_exchange in write_execute_load_query_log_event()
- sql_exchange in mysql_load()
- sql_exchange in Load_log_event::Load_log_event()

Also, removing cast to "char*" in a few places in
Load_log_event::Load_log_event()

sql/item_func.cc

@@ -5585,7 +5585,7 @@ bool Item_user_var_as_out_param::get_date(MYSQL_TIME *ltime, ulonglong fuzzy)
 }
 
 
-void Item_user_var_as_out_param::print_for_load(THD *thd, String *str)
+void Item_user_var_as_out_param::print_for_load(THD *thd, String *str) const
 {
   str->append('@');
   append_identifier(thd, str, &org_name);

sql/item_func.h

@@ -2507,7 +2507,7 @@ public:
   my_decimal *val_decimal(my_decimal *decimal_buffer);
   /* fix_fields() binds variable name with its entry structure */
   bool fix_fields(THD *thd, Item **ref);
-  void print_for_load(THD *thd, String *str);
+  void print_for_load(THD *thd, String *str) const;
   void set_null_value(CHARSET_INFO* cs);
   void set_value(const char *str, uint length, CHARSET_INFO* cs);
   const Type_handler *type_handler() const { return &type_handler_double; }

sql/log_event.cc

@@ -6832,7 +6832,7 @@ bool Load_log_event::write_data_body()
   Load_log_event::Load_log_event()
 */
 
-Load_log_event::Load_log_event(THD *thd_arg, sql_exchange *ex,
+Load_log_event::Load_log_event(THD *thd_arg, const sql_exchange *ex,
 			       const char *db_arg, const char *table_name_arg,
 			       List<Item> &fields_arg,
                                bool is_concurrent_arg,
@@ -6856,15 +6856,15 @@ Load_log_event::Load_log_event(THD *thd_arg, sql_exchange *ex,
   db_len = (uint32) strlen(db);
   table_name_len = (uint32) strlen(table_name);
   fname_len = (fname) ? (uint) strlen(fname) : 0;
-  sql_ex.field_term = (char*) ex->field_term->ptr();
+  sql_ex.field_term = ex->field_term->ptr();
   sql_ex.field_term_len = (uint8) ex->field_term->length();
-  sql_ex.enclosed = (char*) ex->enclosed->ptr();
+  sql_ex.enclosed = ex->enclosed->ptr();
   sql_ex.enclosed_len = (uint8) ex->enclosed->length();
-  sql_ex.line_term = (char*) ex->line_term->ptr();
+  sql_ex.line_term = ex->line_term->ptr();
   sql_ex.line_term_len = (uint8) ex->line_term->length();
-  sql_ex.line_start = (char*) ex->line_start->ptr();
+  sql_ex.line_start = ex->line_start->ptr();
   sql_ex.line_start_len = (uint8) ex->line_start->length();
-  sql_ex.escaped = (char*) ex->escaped->ptr();
+  sql_ex.escaped = ex->escaped->ptr();
   sql_ex.escaped_len = (uint8) ex->escaped->length();
   sql_ex.opt_flags = 0;
   sql_ex.cached_new_format = -1;

sql/log_event.h

@@ -2514,7 +2514,7 @@ public:
   String field_lens_buf;
   String fields_buf;
 
-  Load_log_event(THD* thd, sql_exchange* ex, const char* db_arg,
+  Load_log_event(THD* thd, const sql_exchange* ex, const char* db_arg,
 		 const char* table_name_arg,
 		 List<Item>& fields_arg,
                  bool is_concurrent_arg,

sql/sql_class.cc

@@ -2945,7 +2945,7 @@ sql_exchange::sql_exchange(const char *name, bool flag,
   cs= NULL;
 }
 
-bool sql_exchange::escaped_given(void)
+bool sql_exchange::escaped_given(void) const
 {
   return escaped != &default_escaped;
 }

sql/sql_class.h

@@ -4832,7 +4832,7 @@ public:
   CHARSET_INFO *cs;
   sql_exchange(const char *name, bool dumpfile_flag,
                enum_filetype filetype_arg= FILETYPE_CSV);
-  bool escaped_given(void);
+  bool escaped_given(void) const;
 };
 
 /*

sql/sql_load.cc

@@ -280,7 +280,7 @@ static int read_xml_field(THD *thd, COPY_INFO &info, TABLE_LIST *table_list,
                           bool ignore_check_option_errors);
 
 #ifndef EMBEDDED_LIBRARY
-static bool write_execute_load_query_log_event(THD *, sql_exchange*, const
+static bool write_execute_load_query_log_event(THD *, const sql_exchange*, const
            char*, const char*, bool, enum enum_duplicates, bool, bool, int);
 #endif /* EMBEDDED_LIBRARY */
 
@@ -305,7 +305,7 @@ static bool write_execute_load_query_log_event(THD *, sql_exchange*, const
     TRUE - error / FALSE - success
 */
 
-int mysql_load(THD *thd,sql_exchange *ex,TABLE_LIST *table_list,
+int mysql_load(THD *thd, const sql_exchange *ex, TABLE_LIST *table_list,
 	        List<Item> &fields_vars, List<Item> &set_fields,
                 List<Item> &set_values,
                 enum enum_duplicates handle_duplicates, bool ignore,
@@ -803,7 +803,7 @@ err:
 #ifndef EMBEDDED_LIBRARY
 
 /* Not a very useful function; just to avoid duplication of code */
-static bool write_execute_load_query_log_event(THD *thd, sql_exchange* ex,
+static bool write_execute_load_query_log_event(THD *thd, const sql_exchange* ex,
                                                const char* db_arg,  /* table's database */
                                                const char* table_name_arg,
                                                bool is_concurrent,

sql/sql_load.h

@@ -24,7 +24,7 @@ class Item;
 
 class sql_exchange;
 
-int mysql_load(THD *thd, sql_exchange *ex, TABLE_LIST *table_list,
+int mysql_load(THD *thd, const sql_exchange *ex, TABLE_LIST *table_list,
 	        List<Item> &fields_vars, List<Item> &set_fields,
                 List<Item> &set_values_list,
                 enum enum_duplicates handle_duplicates, bool ignore,