Set proper class to subclass of Array

More compatibility to CRuby.

src/array.c

@@ -242,14 +242,19 @@ mrb_ary_resize(mrb_state *mrb, mrb_value ary, mrb_int new_len)
 }
 
 static mrb_value
-mrb_ary_s_create(mrb_state *mrb, mrb_value self)
+mrb_ary_s_create(mrb_state *mrb, mrb_value klass)
 {
+  mrb_value ary;
   mrb_value *vals;
   mrb_int len;
+  struct RArray *a;
 
   mrb_get_args(mrb, "*", &vals, &len);
+  ary = mrb_ary_new_from_values(mrb, len, vals);
+  a = mrb_ary_ptr(ary);
+  a->c = mrb_class_ptr(klass);
 
-  return mrb_ary_new_from_values(mrb, len, vals);
+  return ary;
 }
 
 static void

test/t/array.rb

@@ -13,6 +13,14 @@
   assert_equal([1, 2, 3], Array.[](1,2,3))
 end
 
+class SubArray < Array
+end
+
+assert('SubArray.[]') do
+  a = SubArray[1, 2, 3]
+  assert_equal(SubArray, a.class)
+end
+
 assert('Array#+', '15.2.12.5.1') do
   assert_equal([1, 1], [1].+([1]))
 end