vm.c: initialize defined_module_hash early

* vm.c (Init_BareVM): initialize defined_module_hash here,
  Init_top_self() is too late to register core classes/modules.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43273 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,5 +1,8 @@
 2013-10-13  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
+	* vm.c (Init_BareVM): initialize defined_module_hash here,
+	  Init_top_self() is too late to register core classes/modules.
+
 	* compile.c (compile_array_): no hash to merge if it is empty.
 
 	* vm.c (m_core_hash_merge_kwd): just check keys if only one argument

bootstraptest/test_class.rb

@@ -11,6 +11,16 @@ assert_equal 'C',       %q( class C; end
                             C.new.class.name )
 assert_equal 'Class',   %q( class C; end
                             C.new.class.class )
+assert_equal 'true',    %q( Object.__send__(:remove_const, :TrueClass)
+                            GC.start
+                            true.inspect)
+assert_equal 'false',   %q( Object.__send__(:remove_const, :FalseClass)
+                            GC.start
+                            false.inspect)
+assert_equal 'nil',     %q( Object.__send__(:remove_const, :NilClass)
+                            GC.start
+                            nil.inspect)
+
 
 # inherited class
 assert_equal 'true',    %q( class A; end

vm.c

@@ -2617,6 +2617,7 @@ Init_BareVM(void)
     th->vm = vm;
     th_init(th, 0);
     ruby_thread_init_stack(th);
+    vm->defined_module_hash = rb_hash_new();
 }
 
 /* top self */
@@ -2644,7 +2645,6 @@ Init_top_self(void)
 
     /* initialize mark object array, hash */
     vm->mark_object_ary = rb_ary_tmp_new(1);
-    vm->defined_module_hash = rb_hash_new();
 }
 
 VALUE *