Fix for bug #31154: field.h:1649: virtual int Field_bit::cmp(const uchar*, const uchar*): Assertion

Problem: GROUP_CONCAT(DISTINCT BIT_FIELD...) uses a tree to store keys;
which are constructed using a temporary table fields,
see Item_func_group_concat::setup().
As a) we don't store null bits in the tree where the bit fields store parts 
of their data and b) there's no method to properly compare two table records
we've got problem.

Fix: convert BIT fields to INT in the temporary table used.

mysql-test/r/func_gconcat.result

@@ -819,4 +819,46 @@ id	group_concat(b.name)
 1	ra,ra
 2	ra,ra
 drop table t1;
+create table t1(a bit not null);
+insert into t1 values (), (), ();
+Warnings:
+Warning	1364	Field 'a' doesn't have a default value
+select group_concat(distinct a) from t1;
+group_concat(distinct a)
+0
+select group_concat(distinct a order by a) from t1;
+group_concat(distinct a order by a)
+0
+drop table t1;
+create table t1(a bit(2) not null);
+insert into t1 values (1), (0), (0), (3), (1);
+select group_concat(distinct a) from t1;
+group_concat(distinct a)
+1,0,3
+select group_concat(distinct a order by a) from t1;
+group_concat(distinct a order by a)
+0,1,3
+select group_concat(distinct a order by a desc) from t1;
+group_concat(distinct a order by a desc)
+3,1,0
+drop table t1;
+create table t1(a bit(2), b varchar(10), c bit);
+insert into t1 values (1, 'a', 0), (0, 'b', 1), (0, 'c', 0), (3, 'd', 1),
+(1, 'e', 1), (3, 'f', 1), (0, 'g', 1);
+select group_concat(distinct a, c) from t1;
+group_concat(distinct a, c)
+10,01,00,31,11
+select group_concat(distinct a, c order by a) from t1;
+group_concat(distinct a, c order by a)
+00,01,11,10,31
+select group_concat(distinct a, c) from t1;
+group_concat(distinct a, c)
+10,01,00,31,11
+select group_concat(distinct a, c order by a, c) from t1;
+group_concat(distinct a, c order by a, c)
+00,01,10,11,31
+select group_concat(distinct a, c order by a desc, c desc) from t1;
+group_concat(distinct a, c order by a desc, c desc)
+31,11,10,01,00
+drop table t1;
 End of 5.0 tests

mysql-test/t/func_gconcat.test

@@ -562,4 +562,32 @@ insert into t1 (id, name) values (2, "
 select b.id, group_concat(b.name) from t1 a, t1 b group by b.id;
 drop table t1;
 
+#
+# Bug #31154: group_concat() and bit fields;
+#
+create table t1(a bit not null);
+insert into t1 values (), (), ();
+select group_concat(distinct a) from t1;
+select group_concat(distinct a order by a) from t1;
+drop table t1;
+
+create table t1(a bit(2) not null);
+insert into t1 values (1), (0), (0), (3), (1);
+select group_concat(distinct a) from t1;
+select group_concat(distinct a order by a) from t1;
+select group_concat(distinct a order by a desc) from t1;
+drop table t1;
+
+create table t1(a bit(2), b varchar(10), c bit);
+insert into t1 values (1, 'a', 0), (0, 'b', 1), (0, 'c', 0), (3, 'd', 1),
+(1, 'e', 1), (3, 'f', 1), (0, 'g', 1);
+select group_concat(distinct a, c) from t1;
+select group_concat(distinct a, c order by a) from t1;
+select group_concat(distinct a, c) from t1;
+select group_concat(distinct a, c order by a, c) from t1;
+select group_concat(distinct a, c order by a desc, c desc) from t1;
+
+drop table t1;
+
+
 --echo End of 5.0 tests

sql/item_sum.cc

@@ -3307,15 +3307,34 @@ bool Item_func_group_concat::setup(THD *thd)
   count_field_types(select_lex, tmp_table_param, all_fields, 0);
   tmp_table_param->force_copy_fields= force_copy_fields;
   DBUG_ASSERT(table == 0);
-  /*
-    Currently we have to force conversion of BLOB values to VARCHAR's
-    if we are to store them in TREE objects used for ORDER BY and
-    DISTINCT. This leads to truncation if the BLOB's size exceeds
-    Field_varstring::MAX_SIZE.
-  */
   if (arg_count_order > 0 || distinct)
+  {
+    /*
+      Currently we have to force conversion of BLOB values to VARCHAR's
+      if we are to store them in TREE objects used for ORDER BY and
+      DISTINCT. This leads to truncation if the BLOB's size exceeds
+      Field_varstring::MAX_SIZE.
+    */
     set_if_smaller(tmp_table_param->convert_blob_length, 
                    Field_varstring::MAX_SIZE);
+
+    /*
+      Force the create_tmp_table() to convert BIT columns to INT
+      as we cannot compare two table records containg BIT fields
+      stored in the the tree used for distinct/order by.
+      Moreover we don't even save in the tree record null bits 
+      where BIT fields store parts of their data.
+    */
+    List_iterator_fast<Item> li(all_fields);
+    Item *item;
+    while ((item= li++))
+    {
+      if (item->type() == Item::FIELD_ITEM && 
+          ((Item_field*) item)->field->type() == FIELD_TYPE_BIT)
+        item->marker= 4;
+    }
+  }
+
   /*
     We have to create a temporary table to get descriptions of fields
     (types, sizes and so on).