Fixed bug #32556: assert in "using index for group-by" :

                  is_last_prefix <= 0, file .\opt_range.cc.

SELECT ... GROUP BY bit field failed with an assertion if the
bit length of that field was not divisible by 8.

mysql-test/r/type_bit.result

@@ -672,4 +672,14 @@ COUNT(DISTINCT b,c)
 2
 2
 DROP TABLE t2;
+CREATE TABLE t1(a BIT(13), KEY(a));
+INSERT INTO t1(a) VALUES
+(65535),(65525),(65535),(65535),(65535),(65535),(65535),(65535),(65535),(65535);
+EXPLAIN SELECT 1 FROM t1 GROUP BY a;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	range	NULL	a	3	NULL	6	Using index for group-by
+SELECT 1 FROM t1 GROUP BY a;
+1
+1
+DROP TABLE t1;
 End of 5.0 tests

mysql-test/t/type_bit.test

@@ -318,4 +318,19 @@ INSERT INTO t2 VALUES (3, 2, 'two'), (2, 3, 'three'), (2, 0, 'zero'),
 SELECT COUNT(DISTINCT b,c) FROM t2 GROUP BY a;
 DROP TABLE t2;
 
+#
+# BUG#32556 assert in "using index for group-by" : is_last_prefix <= 0,
+#           file .\opt_range.cc
+
+CREATE TABLE t1(a BIT(13), KEY(a));
+--disable_warnings
+INSERT INTO t1(a) VALUES
+(65535),(65525),(65535),(65535),(65535),(65535),(65535),(65535),(65535),(65535);
+--enable_warnings
+
+EXPLAIN SELECT 1 FROM t1 GROUP BY a;
+SELECT 1 FROM t1 GROUP BY a;
+
+DROP TABLE t1;
+
 --echo End of 5.0 tests

sql/key.cc

@@ -106,19 +106,6 @@ void key_copy(byte *to_key, byte *from_record, KEY *key_info, uint key_length)
 		   key_part->null_bit);
       key_length--;
     }
-    if (key_part->type == HA_KEYTYPE_BIT)
-    {
-      Field_bit *field= (Field_bit *) (key_part->field);
-      if (field->bit_len)
-      {
-        uchar bits= get_rec_bits((uchar*) from_record +
-                                 key_part->null_offset +
-                                 (key_part->null_bit == 128),
-                                 field->bit_ofs, field->bit_len);
-        *to_key++= bits;
-        key_length--;
-      }
-    }
     if (key_part->key_part_flag & HA_BLOB_PART ||
         key_part->key_part_flag & HA_VAR_LENGTH_PART)
     {