* gc.c (rb_gc): use rb_gc_mark_maybe() to mark registered C

addresses.  C variables may not hold valid reference to Ruby
  objects. [ruby-core:00975]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@3705 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/singleton.rb

@@ -156,7 +156,7 @@ module Singleton
                 @__instance__ = new
             ensure
                 if @__instance__
-                    def self.instance() @__instance__ end
+		    define_method(:instance) {@__instance__}
                 else
                     @__instance__ = nil
                 end