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, 9 insertions, 8 deletions

diff --git a/sql/opt_subselect.cc b/sql/opt_subselect.cc
index 1c621c1c833..b5808ea9315 100644
--- a/sql/opt_subselect.cc
+++ b/sql/opt_subselect.cc
@@ -4019,12 +4019,13 @@ SJ_TMP_TABLE::create_sj_weedout_tmp_table(THD *thd)
 
   /* Create the field */
   {
+    LEX_CSTRING field_name= {STRING_WITH_LEN("rowids") };
     /*
       For the sake of uniformity, always use Field_varstring (altough we could
       use Field_string for shorter keys)
     */
-    field= new Field_varstring(uniq_tuple_length_arg, FALSE, "rowids", share,
-                               &my_charset_bin);
+    field= new Field_varstring(uniq_tuple_length_arg, FALSE, &field_name,
+                               share, &my_charset_bin);
     if (!field)
       DBUG_RETURN(0);
     field->table= table;
@@ -4894,7 +4895,7 @@ int rewrite_to_index_subquery_engine(JOIN *join)
     {
       Item *where= join->conds;
       if (join_tab[0].type == JT_EQ_REF &&
-	  join_tab[0].ref.items[0]->name == in_left_expr_name)
+	  join_tab[0].ref.items[0]->name.str == in_left_expr_name.str)
       {
         remove_subq_pushed_predicates(join, &where);
         save_index_subquery_explain_info(join_tab, where);
@@ -4908,7 +4909,7 @@ int rewrite_to_index_subquery_engine(JOIN *join)
                                                                   where)));
       }
       else if (join_tab[0].type == JT_REF &&
-	       join_tab[0].ref.items[0]->name == in_left_expr_name)
+	       join_tab[0].ref.items[0]->name.str == in_left_expr_name.str)
       {
 	remove_subq_pushed_predicates(join, &where);
         save_index_subquery_explain_info(join_tab, where);
@@ -4924,8 +4925,8 @@ int rewrite_to_index_subquery_engine(JOIN *join)
                                                                  0)));
       }
     } else if (join_tab[0].type == JT_REF_OR_NULL &&
-	       join_tab[0].ref.items[0]->name == in_left_expr_name &&
-               join->having->name == in_having_cond)
+	       join_tab[0].ref.items[0]->name.str == in_left_expr_name.str &&
+               join->having->name.str == in_having_cond.str)
     {
       join_tab[0].type= JT_INDEX_SUBQUERY;
       join->error= 0;
@@ -4956,7 +4957,7 @@ int rewrite_to_index_subquery_engine(JOIN *join)
 
 static Item *remove_additional_cond(Item* conds)
 {
-  if (conds->name == in_additional_cond)
+  if (conds->name.str == in_additional_cond.str)
     return 0;
   if (conds->type() == Item::COND_ITEM)
   {
@@ -4965,7 +4966,7 @@ static Item *remove_additional_cond(Item* conds)
     Item *item;
     while ((item= li++))
     {
-      if (item->name == in_additional_cond)
+      if (item->name.str == in_additional_cond.str)
       {
 	li.remove();
 	if (cnd->argument_list()->elements == 1)