bugfix: Item_func_get_system_var::print()

mysql-test/r/variables.result

@@ -1801,3 +1801,23 @@ select * from information_schema.session_variables where variable_name='sql_mode
 VARIABLE_NAME	VARIABLE_VALUE
 SQL_MODE	ANSI_QUOTES
 End of 5.5 tests
+explain extended select @@VERsion from dual where rand() > @@verSION;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
+Warnings:
+Note	1003	select @@VERsion AS "@@VERsion" from DUAL  where (rand() > @@version)
+explain extended select @@SESsion.SQL_mode from dual where rand() > @@sesSION.sql_MODE;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
+Warnings:
+Note	1003	select @@SESsion.SQL_mode AS "@@SESsion.SQL_mode" from DUAL  where (rand() > @@sql_mode)
+explain extended select @@GLObal.COLLATION_connection from dual where rand() > @@gloBAL.collation_CONNECTION;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
+Warnings:
+Note	1003	select @@GLObal.COLLATION_connection AS "@@GLObal.COLLATION_connection" from DUAL  where (rand() > @@global.collation_connection)
+explain extended select @@FOObar.KEY_BUFfer_size from dual where rand() > @@fooBAR.key_bufFER_SIZE;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
+Warnings:
+Note	1003	select @@FOObar.KEY_BUFfer_size AS "@@FOObar.KEY_BUFfer_size" from DUAL  where (rand() > @@fooBAR.key_buffer_size)

mysql-test/t/variables.test

@@ -1532,3 +1532,11 @@ show global status like 'foobar';
 select * from information_schema.session_variables where variable_name='sql_mode';
 
 --echo End of 5.5 tests
+
+#
+# test Item_func_get_system_var::print()
+#
+explain extended select @@VERsion from dual where rand() > @@verSION;
+explain extended select @@SESsion.SQL_mode from dual where rand() > @@sesSION.sql_MODE;
+explain extended select @@GLObal.COLLATION_connection from dual where rand() > @@gloBAL.collation_CONNECTION;
+explain extended select @@FOObar.KEY_BUFfer_size from dual where rand() > @@fooBAR.key_bufFER_SIZE;

sql/item_func.cc

@@ -5841,7 +5841,22 @@ void Item_func_get_system_var::fix_length_and_dec()
 
 void Item_func_get_system_var::print(String *str, enum_query_type query_type)
 {
-  str->append(name, name_length);
+  if (name_length)
+    str->append(name, name_length);
+  else
+  {
+    str->append(STRING_WITH_LEN("@@"));
+    if (component.length)
+    {
+      str->append(&component);
+      str->append('.');
+    }
+    else if (var_type == SHOW_OPT_GLOBAL && var->scope() != sys_var::GLOBAL)
+    {
+      str->append(STRING_WITH_LEN("global."));
+    }
+    str->append(&var->name);
+  }
 }
 
 bool Item_func_get_system_var::check_vcol_func_processor(void *arg)

sql/sql_string.h

@@ -466,10 +466,8 @@ class String
   }
   bool append(const String &s);
   bool append(const char *s);
-  bool append(const LEX_STRING *ls)
-  {
-    return append(ls->str, ls->length);
-  }
+  bool append(const LEX_STRING *ls) { return append(ls->str, ls->length); }
+  bool append(const LEX_CSTRING *ls) { return append(ls->str, ls->length); }
   bool append(const char *s, uint32 arg_length);
   bool append(const char *s, uint32 arg_length, CHARSET_INFO *cs);
   bool append_ulonglong(ulonglong val);