shape.c: Add a hack to fix variation accounting of T_CLASS and T_MODULE.

This would be fixed by using proper T_IMEMO instead of T_OBJECT
to store class fields.

Author: byroot

shape.c

@@ -825,14 +825,11 @@ shape_get_next(rb_shape_t *shape, VALUE obj, ID id, bool emit_warnings)
 #endif
 
     VALUE klass;
-    switch (BUILTIN_TYPE(obj)) {
-      case T_CLASS:
-      case T_MODULE:
-        klass = rb_singleton_class(obj);
-        break;
-      default:
+    if (RB_TYPE_P(obj, T_OBJECT) && FL_TEST_RAW(obj, ROBJECT_HIDDEN)) { // HACK
+        klass = CLASS_OF(obj);
+    }
+    else {
         klass = rb_obj_class(obj);
-        break;
     }
 
     bool allow_new_shape = RCLASS_VARIATION_COUNT(klass) < SHAPE_MAX_VARIATIONS;