a fix (bug #7405: group_concat with distinct and rollup => ignores distinct in some rows).

sql/item_sum.cc:
  a fix (bug #7405: group_concat with distinct and rollup => ignores distinct in some rows).
  Code changed in order to work with rollup extension.

mysql-test/r/func_gconcat.result

@@ -469,3 +469,26 @@ x	(select group_concat(x) from r2)
 1	1,1
 2	2,2
 drop table r2;
+create table t1 (d int, a int, b int, c int);
+insert into t1(a,b) values (1,3), (1,4), (1,2), (2,7), (1,1), (1,2), (2,3), (2,3);
+select a, group_concat(b) from t1 group by a with rollup;
+a	group_concat(b)
+1	3,4,2,1,2
+2	7,3,3
+NULL	3,4,2,1,2,7,3,3
+select a, group_concat(distinct b) from t1 group by a with rollup;
+a	group_concat(distinct b)
+1	3,4,2,1
+2	7,3
+NULL	3,4,2,1,7
+select a, group_concat(b order by b) from t1 group by a with rollup;
+a	group_concat(b order by b)
+1	1,2,2,3,4
+2	3,3,7
+NULL	1,2,2,3,3,3,4,7
+select a, group_concat(distinct b order by b) from t1 group by a with rollup;
+a	group_concat(distinct b order by b)
+1	1,2,3,4
+2	3,7
+NULL	1,2,3,4,7
+drop table t1;

mysql-test/t/func_gconcat.test

@@ -292,3 +292,15 @@ create table r2 (a int, b int);
 insert into r2 values (1,1), (2,2);
 select  b x, (select group_concat(x) from r2) from  r2;
 drop table r2;
+
+#
+# Bug #7405: problems with rollup
+#
+
+create table t1 (d int, a int, b int, c int);
+insert into t1(a,b) values (1,3), (1,4), (1,2), (2,7), (1,1), (1,2), (2,3), (2,3);
+select a, group_concat(b) from t1 group by a with rollup;
+select a, group_concat(distinct b) from t1 group by a with rollup;
+select a, group_concat(b order by b) from t1 group by a with rollup;
+select a, group_concat(distinct b order by b) from t1 group by a with rollup;
+drop table t1;

sql/item_sum.cc

@@ -1566,7 +1566,6 @@ int group_concat_key_cmp_with_distinct(void* arg, byte* key1,
 {
   Item_func_group_concat* grp_item= (Item_func_group_concat*)arg;
   Item **field_item, **end;
-  char *record= (char*) grp_item->table->record[0];
 
   for (field_item= grp_item->args, end= field_item + grp_item->arg_count_field;
        field_item < end;
@@ -1581,7 +1580,7 @@ int group_concat_key_cmp_with_distinct(void* arg, byte* key1,
     if (field)
     {
       int res;
-      uint offset= (uint) (field->ptr - record);
+      uint offset= field->offset();
       if ((res= field->key_cmp(key1 + offset, key2 + offset)))
 	return res;
     }
@@ -1599,7 +1598,6 @@ int group_concat_key_cmp_with_order(void* arg, byte* key1, byte* key2)
 {
   Item_func_group_concat* grp_item= (Item_func_group_concat*) arg;
   ORDER **order_item, **end;
-  char *record= (char*) grp_item->table->record[0];
 
   for (order_item= grp_item->order, end=order_item+ grp_item->arg_count_order;
        order_item < end;
@@ -1615,7 +1613,7 @@ int group_concat_key_cmp_with_order(void* arg, byte* key1, byte* key2)
     if (field)
     {
       int res;
-      uint offset= (uint) (field->ptr - record);
+      uint offset= field->offset();
       if ((res= field->key_cmp(key1 + offset, key2 + offset)))
         return (*order_item)->asc ? res : -res;
     }
@@ -1657,7 +1655,6 @@ int dump_leaf_key(byte* key, uint32 count __attribute__((unused)),
 {
   char buff[MAX_FIELD_WIDTH];
   String tmp((char *)&buff,sizeof(buff),default_charset_info), tmp2;
-  char *record= (char*) item->table->record[0];
 
   if (item->result.length())
     item->result.append(*item->separator);
@@ -1677,9 +1674,8 @@ int dump_leaf_key(byte* key, uint32 count __attribute__((unused)),
       Field *field= show_item->get_tmp_table_field();
       String *res;
       char *save_ptr= field->ptr;
-      uint offset= (uint) (save_ptr - record);
-      DBUG_ASSERT(offset < item->table->reclength);
-      field->ptr= (char *) key + offset;
+      DBUG_ASSERT(field->offset() < item->table->reclength);
+      field->ptr= (char *) key + field->offset();
       res= field->val_str(&tmp,&tmp2);
       item->result.append(*res);
       field->ptr= save_ptr;
@@ -1852,12 +1848,6 @@ void Item_func_group_concat::clear()
   result.copy();
   null_value= TRUE;
   warning_for_row= FALSE;
-  if (table)
-  {
-    table->file->extra(HA_EXTRA_NO_CACHE);
-    table->file->delete_all_rows();
-    table->file->extra(HA_EXTRA_WRITE_CACHE);
-  }
   if (tree_mode)
     reset_tree(tree);
 }
@@ -1870,19 +1860,13 @@ bool Item_func_group_concat::add()
   copy_fields(tmp_table_param);
   copy_funcs(tmp_table_param->items_to_copy);
 
-  for (uint i= 0; i < arg_count_field; i++)
+  for (Item **arg= args, **arg_end= args + arg_count_field;
+       arg < arg_end; arg++)
   {
-    Item *show_item= args[i];
-    if (!show_item->const_item())
-    {
-      /*
-	Here we use real_item as we want the original field data that should
-	be written to table->record[0]
-      */
-      Field *f= show_item->real_item()->get_tmp_table_field();
-      if (f->is_null())
+    if (!(*arg)->const_item() &&
+        (*arg)->get_tmp_table_field()->is_null_in_record(
+          (const uchar*) table->record[0]))
 	return 0;				// Skip row if it contains null
-    }
   }
 
   null_value= FALSE;
@@ -1945,10 +1929,6 @@ Item_func_group_concat::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
   null_value= 1;
   max_length= group_concat_max_len;
   thd->allow_sum_func= 1;			
-  if (!(tmp_table_param= new TMP_TABLE_PARAM))
-    return 1;
-  /* We'll convert all blobs to varchar fields in the temporary table */
-  tmp_table_param->convert_blob_length= group_concat_max_len;
   tables_list= tables;
   fixed= 1;
   return 0;
@@ -1967,6 +1947,11 @@ bool Item_func_group_concat::setup(THD *thd)
   if (select_lex->linkage == GLOBAL_OPTIONS_TYPE)
     DBUG_RETURN(1);
 
+  if (!(tmp_table_param= new TMP_TABLE_PARAM))
+    return 1;
+  /* We'll convert all blobs to varchar fields in the temporary table */
+  tmp_table_param->convert_blob_length= group_concat_max_len;
+
   /*
     push all not constant fields to list and create temp table
   */