Fix for BUG#7885

mysql-test/r/subselect.result:
  Testcase for BUG#7885
mysql-test/t/subselect.test:
  Testcase for BUG#7885
sql/item_subselect.cc:
  Fix for BUG#7885: In Item_subselect::fix_fields, return error if engine->prepare fails.
  Also removed redundant code line.

mysql-test/r/subselect.result

@@ -2152,3 +2152,11 @@ WHERE f1 <> ALL ( SELECT SUM(f1) AS sf1 FROM t2 HAVING sf1 > 10000);
 f1
 NULL
 1
+drop table t1,t2;
+create table t1 (a1 int);
+create table t2 (b1 int);
+select * from t1 where a2 > any(select b1 from t2);
+ERROR 42S22: Unknown column 'a2' in 'scalar IN/ALL/ANY subquery'
+select * from t1 where a1 > any(select b1 from t2);
+a1
+drop table t1,t2;

mysql-test/t/subselect.test

@@ -1412,3 +1412,14 @@ SELECT f1 FROM t1
 
 SELECT f1 FROM t1
    WHERE f1 <> ALL ( SELECT SUM(f1) AS sf1 FROM t2 HAVING sf1 > 10000);
+
+drop table t1,t2;
+# Test for BUG#7885: Server crash when 'any' subselect compared to
+# non-existant field.
+create table t1 (a1 int);
+create table t2 (b1 int);
+--error 1054
+select * from t1 where a2 > any(select b1 from t2);
+select * from t1 where a1 > any(select b1 from t2);
+drop table t1,t2;
+

sql/item_subselect.cc

@@ -177,6 +177,8 @@ bool Item_subselect::fix_fields(THD *thd_param, TABLE_LIST *tables, Item **ref)
     }
     fix_length_and_dec();
   }
+  else
+    return 1;
   uint8 uncacheable= engine->uncacheable();
   if (uncacheable)
   {
@@ -264,7 +266,6 @@ Item_singlerow_subselect::Item_singlerow_subselect(st_select_lex *select_lex)
 {
   DBUG_ENTER("Item_singlerow_subselect::Item_singlerow_subselect");
   init(select_lex, new select_singlerow_subselect(this));
-  max_columns= 1;
   maybe_null= 1;
   max_columns= UINT_MAX;
   DBUG_VOID_RETURN;