ObjectSpace.count_objects was incorrectly checking if an object was already freed. Amended the count_objects test to ensure the correct distinction

src/gc.c

@@ -1168,6 +1168,7 @@ mrb_value os_count_objects(mrb_state *mrb, mrb_value self)
     size_t total = 0;
     size_t i;
     mrb_value hash;
+    RVALUE *free;
     struct heap_page* page = mrb->heaps;
 
     if (mrb_get_args(mrb, "|H", &hash) == 0) {
@@ -1188,13 +1189,15 @@ mrb_value os_count_objects(mrb_state *mrb, mrb_value self)
         p = page->objects;
         pend = p + MRB_HEAP_PAGE_SIZE;
         for (;p < pend; p++) {
-            if (p->as.basic.flags) {
-                counts[mrb_type(p->as.basic)]++;
-            }
-            else {
-                freed++;
-            }
+            counts[mrb_type(p->as.basic)]++;
         }
+
+        free = (RVALUE*)page->freelist;
+        while (free) {
+            freed++;
+            free = (RVALUE*)free->as.free.next;
+        }
+
         total += MRB_HEAP_PAGE_SIZE;
         page = page->next;
     }

test/t/objectspace.rb

@@ -16,4 +16,20 @@ assert('ObjectSpace.count_objects') do
     h0 = {:MRB_TT_FOO=>1000}
     h = ObjectSpace.count_objects(h0)
     assert_false(h0.has_key?(:MRB_TT_FOO))
+
+    GC.start
+    h_after = {}
+    h_before = ObjectSpace.count_objects
+
+    objs = []
+    1000.times do
+        objs << {}
+    end
+    objs = nil
+    ObjectSpace.count_objects(h)
+    GC.start
+    ObjectSpace.count_objects(h_after)
+
+    assert_equal(h_before[:MRB_TT_HASH] + 1000, h[:MRB_TT_HASH])
+    assert_equal(h_before[:MRB_TT_HASH], h_after[:MRB_TT_HASH])
   end