* gc.c (rb_objspace_markable_object_p): should check special_const_p
  first (by is_markable_object()).



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44242 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
test_io.rb: IO.write test

* test/ruby/test_io.rb (test_s_write): test for IO.write.  more
  conditions will be needed.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44243 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
class.c: fix option hash

* class.c (rb_scan_args): if no keywords is given return nil as
  the option hash.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44244 b2dd03c8-39d4-4d8f-98ff-823fe69b080e