Bug #46607: Assertion failed: (cond_type == Item::FUNC_ITEM)

            results in server crash 
 
check_group_min_max_predicates() assumed the input condition 
item to be one of COND_ITEM, SUBSELECT_ITEM, or FUNC_ITEM. 
Since a condition of the form "field" is also a valid condition 
equivalent to "field <> 0", using such a condition in a query 
where the loose index scan was chosen resulted in a debug 
assertion failure. 
 
Fixed by handling conditions of the FIELD_ITEM type in 
check_group_min_max_predicates(). 

mysql-test/r/group_min_max.result:
  Added a test case for bug #46607.
mysql-test/t/group_min_max.test:
  Added a test case for bug #46607.
sql/opt_range.cc:
  Handle conditions of the FUNC_ITEM type in 
  check_group_mix_max_predicates().

mysql-test/r/group_min_max.result

@@ -2502,3 +2502,15 @@ a	MAX(b)
 2	1
 DROP TABLE t;
 End of 5.0 tests
+#
+# Bug #46607: Assertion failed: (cond_type == Item::FUNC_ITEM) results in
+#              server crash
+#
+CREATE TABLE t (a INT, b INT, INDEX (a,b));
+INSERT INTO t VALUES (2,0), (2,0), (2,1), (2,1);
+INSERT INTO t SELECT * FROM t;
+SELECT a, MAX(b) FROM t WHERE b GROUP BY a;
+a	MAX(b)
+2	1
+DROP TABLE t;
+End of 5.1 tests

mysql-test/t/group_min_max.test

@@ -1018,3 +1018,18 @@ DROP TABLE t;
 
 
 --echo End of 5.0 tests
+
+--echo #
+--echo # Bug #46607: Assertion failed: (cond_type == Item::FUNC_ITEM) results in
+--echo #              server crash
+--echo #
+
+CREATE TABLE t (a INT, b INT, INDEX (a,b));
+INSERT INTO t VALUES (2,0), (2,0), (2,1), (2,1);
+INSERT INTO t SELECT * FROM t;
+
+SELECT a, MAX(b) FROM t WHERE b GROUP BY a;
+
+DROP TABLE t;
+
+--echo End of 5.1 tests

sql/opt_range.cc

@@ -9628,7 +9628,17 @@ check_group_min_max_predicates(COND *cond, Item_field *min_max_arg_item,
   */
   if (cond_type == Item::SUBSELECT_ITEM)
     DBUG_RETURN(FALSE);
-  
+
+  /*
+    Condition of the form 'field' is equivalent to 'field <> 0' and thus
+    satisfies the SA3 condition.
+  */
+  if (cond_type == Item::FIELD_ITEM)
+  {
+    DBUG_PRINT("info", ("Analyzing: %s", cond->full_name()));
+    DBUG_RETURN(TRUE);
+  }
+
   /* We presume that at this point there are no other Items than functions. */
   DBUG_ASSERT(cond_type == Item::FUNC_ITEM);