MDEV-32002 Remove my_casedn_str() in append_identifier() context

- Adding a helper function append_identifier_opt_casedn()

- Reusing it in:

    Item_ident::print()
    Item_func_nextval::print()
    Item_func_setval::print()

This change remove six my_casedn_str() calls and reduces the code size.

sql/item.cc

@@ -3261,9 +3261,6 @@ LEX_CSTRING Item_ident::full_name_cstring() const
 void Item_ident::print(String *str, enum_query_type query_type)
 {
   THD *thd= current_thd;
-  char d_name_buff[MAX_ALIAS_NAME], t_name_buff[MAX_ALIAS_NAME];
-  LEX_CSTRING d_name= db_name;
-  LEX_CSTRING t_name= table_name;
   bool use_table_name= table_name.str && table_name.str[0];
   bool use_db_name= use_table_name && db_name.str && db_name.str[0] &&
                     !alias_name_used;
@@ -3304,32 +3301,18 @@ void Item_ident::print(String *str, enum_query_type query_type)
     return;
   }
 
-  if (lower_case_table_names== 1 ||
-      (lower_case_table_names == 2 && !alias_name_used))
-  {
-    if (use_table_name)
-    {
-      strmov(t_name_buff, table_name.str);
-      my_casedn_str(files_charset_info, t_name_buff);
-      t_name= Lex_cstring_strlen(t_name_buff);
-    }
-    if (use_db_name)
-    {
-      strmov(d_name_buff, db_name.str);
-      my_casedn_str(files_charset_info, d_name_buff);
-      d_name= Lex_cstring_strlen(d_name_buff);
-    }
-  }
+  bool casedn= lower_case_table_names== 1 ||
+               (lower_case_table_names == 2 && !alias_name_used);
 
   if (use_db_name)
   {
-    append_identifier(thd, str, d_name.str, (uint) d_name.length);
+    append_identifier_opt_casedn(thd, str, db_name, casedn);
     str->append('.');
     DBUG_ASSERT(use_table_name);
   }
   if (use_table_name)
   {
-    append_identifier(thd, str, t_name.str, (uint) t_name.length);
+    append_identifier_opt_casedn(thd, str, table_name, casedn);
     str->append('.');
   }
   append_identifier(thd, str, &field_name);

sql/item_func.cc

@@ -7097,14 +7097,24 @@ longlong Item_func_nextval::val_int()
 }
 
 
+bool Item_func_nextval::print_table_list_identifier(THD *thd, String *to) const
+{
+  if (table_list->db.str && table_list->db.str[0])
+  {
+    if (append_identifier_opt_casedn(thd, to, table_list->db,
+                                     lower_case_table_names) ||
+        to->append('.'))
+      return true;
+  }
+  return append_identifier_opt_casedn(thd, to, table_list->table_name,
+                                      lower_case_table_names);
+}
+
+
 /* Print for nextval and lastval */
 
 void Item_func_nextval::print(String *str, enum_query_type query_type)
 {
-  char d_name_buff[MAX_ALIAS_NAME], t_name_buff[MAX_ALIAS_NAME];
-  LEX_CSTRING d_name= table_list->db;
-  LEX_CSTRING t_name= table_list->table_name;
-  bool use_db_name= d_name.str && d_name.str[0];
   THD *thd= current_thd;                        // Don't trust 'table'
 
   str->append(func_name_cstring());
@@ -7114,26 +7124,8 @@ void Item_func_nextval::print(String *str, enum_query_type query_type)
     for next_val we assume that table_list has been updated to contain
     the current db.
   */
+  print_table_list_identifier(thd, str);
 
-  if (lower_case_table_names > 0)
-  {
-    strmake(t_name_buff, t_name.str, MAX_ALIAS_NAME-1);
-    t_name.length= my_casedn_str(files_charset_info, t_name_buff);
-    t_name.str= t_name_buff;
-    if (use_db_name)
-    {
-      strmake(d_name_buff, d_name.str, MAX_ALIAS_NAME-1);
-      d_name.length= my_casedn_str(files_charset_info, d_name_buff);
-      d_name.str= d_name_buff;
-    }
-  }
-
-  if (use_db_name)
-  {
-    append_identifier(thd, str, &d_name);
-    str->append('.');
-  }
-  append_identifier(thd, str, &t_name);
   str->append(')');
 }
 
@@ -7225,10 +7217,6 @@ longlong Item_func_setval::val_int()
 
 void Item_func_setval::print(String *str, enum_query_type query_type)
 {
-  char d_name_buff[MAX_ALIAS_NAME], t_name_buff[MAX_ALIAS_NAME];
-  LEX_CSTRING d_name= table_list->db;
-  LEX_CSTRING t_name= table_list->table_name;
-  bool use_db_name= d_name.str && d_name.str[0];
   THD *thd= current_thd;                        // Don't trust 'table'
 
   str->append(func_name_cstring());
@@ -7238,26 +7226,8 @@ void Item_func_setval::print(String *str, enum_query_type query_type)
     for next_val we assume that table_list has been updated to contain
     the current db.
   */
+  print_table_list_identifier(thd, str);
 
-  if (lower_case_table_names > 0)
-  {
-    strmake(t_name_buff, t_name.str, MAX_ALIAS_NAME-1);
-    t_name.length= my_casedn_str(files_charset_info, t_name_buff);
-    t_name.str= t_name_buff;
-    if (use_db_name)
-    {
-      strmake(d_name_buff, d_name.str, MAX_ALIAS_NAME-1);
-      d_name.length= my_casedn_str(files_charset_info, d_name_buff);
-      d_name.str= d_name_buff;
-    }
-  }
-
-  if (use_db_name)
-  {
-    append_identifier(thd, str, &d_name);
-    str->append('.');
-  }
-  append_identifier(thd, str, &t_name);
   str->append(',');
   str->append_longlong(nextval);
   str->append(',');

sql/item_func.h

@@ -4139,6 +4139,7 @@ class Item_func_nextval :public Item_longlong_func
 protected:
   TABLE_LIST *table_list;
   TABLE *table;
+  bool print_table_list_identifier(THD *thd, String *to) const;
 public:
   Item_func_nextval(THD *thd, TABLE_LIST *table_list_arg):
   Item_longlong_func(thd), table_list(table_list_arg) {}

sql/sql_show.cc

@@ -1630,6 +1630,20 @@ append_identifier(THD *thd, String *packet, const char *name, size_t length)
 }
 
 
+/**
+  Similar to append_identifier(), but with optional casedn conversion.
+*/
+bool append_identifier_opt_casedn(THD *thd, String *to,
+                                  const LEX_CSTRING &ident, bool casedn)
+{
+  if (!casedn)
+    return append_identifier(thd, to, &ident);
+  CharBuffer<MAX_ALIAS_NAME> buff;
+  LEX_CSTRING ls= buff.copy_casedn(system_charset_info, ident).to_lex_cstring();
+  return append_identifier(thd, to, &ls);
+}
+
+
 /*
   Get the quote character for displaying an identifier.
 

sql/sql_show.h

@@ -96,6 +96,10 @@ static inline bool append_identifier(THD *thd, String *packet, const LEX_CSTRING
 {
   return append_identifier(thd, packet, name->str, name->length);
 }
+
+bool append_identifier_opt_casedn(THD *thd, String *to,
+                                  const LEX_CSTRING &ident, bool casedn);
+
 void mysqld_list_fields(THD *thd,TABLE_LIST *table, const char *wild);
 int mysqld_dump_create_info(THD *thd, TABLE_LIST *table_list, int fd);
 bool mysqld_show_create_get_fields(THD *thd, TABLE_LIST *table_list,