group_by.result, group_by.test:

  Added a test case for bug #11414.
sql_select.cc:
  Fixed bug #11414: crash on Windows with some simple
  GROUP BY queries.
  It happened to an allocation of an array containing
  0 Copy_field elements in setup_copy_fields.
  The bug had been already fixed in 5.0.

mysql-test/r/group_by.result

@@ -751,3 +751,9 @@ COUNT(DISTINCT(t1.id))	err_comment
 1	NULL
 1	a problem
 DROP TABLE t1, t2;
+CREATE TABLE t1 (n int);
+INSERT INTO t1 VALUES (1);
+SELECT n+1 AS n FROM t1 GROUP BY n;
+n
+2
+DROP TABLE t1;

mysql-test/t/group_by.test

@@ -580,3 +580,15 @@ SELECT COUNT(DISTINCT(t1.id)), LEFT(err_comment, 256) AS err_comment
   FROM t1 LEFT JOIN t2 ON t1.id=t2.id GROUP BY err_comment;
 
 DROP TABLE t1, t2;
+
+#
+# Test for bug #11414: crash on Windows for a simple GROUP BY query 
+#  
+                    
+CREATE TABLE t1 (n int);
+INSERT INTO t1 VALUES (1);
+
+SELECT n+1 AS n FROM t1 GROUP BY n;
+
+DROP TABLE t1;
+

sql/sql_select.cc

@@ -8727,7 +8727,7 @@ setup_copy_fields(THD *thd, TMP_TABLE_PARAM *param,
 {
   Item *pos;
   List_iterator_fast<Item> li(all_fields);
-  Copy_field *copy;
+  Copy_field *copy= NULL;
   res_selected_fields.empty();
   res_all_fields.empty();
   List_iterator_fast<Item> itr(res_all_fields);
@@ -8735,7 +8735,8 @@ setup_copy_fields(THD *thd, TMP_TABLE_PARAM *param,
   uint i, border= all_fields.elements - elements;
   DBUG_ENTER("setup_copy_fields");
 
-  if (!(copy=param->copy_field= new Copy_field[param->field_count]))
+  if (param->field_count && 
+      !(copy=param->copy_field= new Copy_field[param->field_count]))
     goto err2;
 
   param->copy_funcs.empty();