Changing field::field_name and Item::name to LEX_CSTRING

Benefits of this patch:
- Removed a lot of calls to strlen(), especially for field_string
- Strings generated by parser are now const strings, less chance of
  accidently changing a string
- Removed a lot of calls with LEX_STRING as parameter (changed to pointer)
- More uniform code
- Item::name_length was not kept up to date. Now fixed
- Several bugs found and fixed (Access to null pointers,
  access of freed memory, wrong arguments to printf like functions)
- Removed a lot of casts from (const char*) to (char*)

Changes:
- This caused some ABI changes
  - lex_string_set now uses LEX_CSTRING
  - Some fucntions are now taking const char* instead of char*
- Create_field::change and after changed to LEX_CSTRING
- handler::connect_string, comment and engine_name() changed to LEX_CSTRING
- Checked printf() related calls to find bugs. Found and fixed several
  errors in old code.
- A lot of changes from LEX_STRING to LEX_CSTRING, especially related to
  parsing and events.
- Some changes from LEX_STRING and LEX_STRING & to LEX_CSTRING*
- Some changes for char* to const char*
- Added printf argument checking for my_snprintf()
- Introduced null_clex_str, star_clex_string, temp_lex_str to simplify
  code
- Added item_empty_name and item_used_name to be able to distingush between
  items that was given an empty name and items that was not given a name
  This is used in sql_yacc.yy to know when to give an item a name.
- select table_name."*' is not anymore same as table_name.*
- removed not used function Item::rename()
- Added comparision of item->name_length before some calls to
  my_strcasecmp() to speed up comparison
- Moved Item_sp_variable::make_field() from item.h to item.cc
- Some minimal code changes to avoid copying to const char *
- Fixed wrong error message in wsrep_mysql_parse()
- Fixed wrong code in find_field_in_natural_join() where real_item() was
  set when it shouldn't
- ER_ERROR_ON_RENAME was used with extra arguments.
- Removed some (wrong) ER_OUTOFMEMORY, as alloc_root will already
  give the error.

TODO:
- Check possible unsafe casts in plugin/auth_examples/qa_auth_interface.c
- Change code to not modify LEX_CSTRING for database name
  (as part of lower_case_table_names)

1 files changed, 4 insertions, 3 deletions

diff --git a/sql/sql_test.cc b/sql/sql_test.cc
index 804a6b5c493..33a82883f8f 100644
--- a/sql/sql_test.cc
+++ b/sql/sql_test.cc
@@ -135,7 +135,8 @@ void TEST_filesort(SORT_FIELD *sortorder,uint s_length)
 	out.append(*sortorder->field->table_name);
 	out.append('.');
       }
-      out.append(sortorder->field->field_name ? sortorder->field->field_name:
+      out.append(sortorder->field->field_name.str ?
+                 sortorder->field->field_name.str :
 		 "tmp_table_column");
     }
     else
@@ -236,11 +237,11 @@ static void print_keyuse(KEYUSE *keyuse)
   keyuse->val->print(&str, QT_ORDINARY);
   str.append('\0');
   if (keyuse->is_for_hash_join())
-    fieldname= keyuse->table->field[keyuse->keypart]->field_name;
+    fieldname= keyuse->table->field[keyuse->keypart]->field_name.str;
   else if (keyuse->keypart == FT_KEYPART)
     fieldname= "FT_KEYPART";
   else
-    fieldname= key_info->key_part[keyuse->keypart].field->field_name;
+    fieldname= key_info->key_part[keyuse->keypart].field->field_name.str;
   ll2str(keyuse->used_tables, buf2, 16, 0); 
   fprintf(DBUG_FILE, "KEYUSE: %s.%s=%s  optimize: %u  used_tables: %s "
           "ref_table_rows: %lu  keypart_map: %0lx\n",