Bump debug version to 0.2.1

lib/debug.gemspec

@@ -1,6 +1,6 @@
 Gem::Specification.new do |spec|
   spec.name          = "debug"
-  spec.version       = "0.2.0"
+  spec.version       = "0.2.1"
   spec.authors       = ["Yukihiro Matsumoto"]
   spec.email         = ["matz@ruby-lang.org"]
 

lib/debug.rb

@@ -3,7 +3,10 @@
 # Copyright (C) 2000  Information-technology Promotion Agency, Japan
 # Copyright (C) 2000-2003  NAKAMURA, Hiroshi  <nahi@ruby-lang.org>
 
-require 'continuation'
+if $SAFE > 0
+  STDERR.print "-r debug.rb is not available in safe mode\n"
+  exit 1
+end
 
 require 'tracer'
 require 'pp'
@@ -178,6 +181,9 @@ SCRIPT_LINES__ = {} unless defined? SCRIPT_LINES__ # :nodoc:
 
 class DEBUGGER__
   MUTEX = Thread::Mutex.new # :nodoc:
+  CONTINUATIONS_SUPPORTED = RUBY_ENGINE == 'ruby'
+
+  require 'continuation' if CONTINUATIONS_SUPPORTED
 
   class Context # :nodoc:
     DEBUG_LAST_CMD = []
@@ -375,8 +381,10 @@ class DEBUGGER__
 
     def debug_command(file, line, id, binding)
       MUTEX.lock
-      unless defined?($debugger_restart) and $debugger_restart
-        callcc{|c| $debugger_restart = c}
+      if CONTINUATIONS_SUPPORTED
+        unless defined?($debugger_restart) and $debugger_restart
+          callcc{|c| $debugger_restart = c}
+        end
       end
       set_last_thread(Thread.current)
       frame_pos = 0
@@ -648,7 +656,11 @@ class DEBUGGER__
             stdout.printf "%s\n", debug_eval($', binding).inspect
 
           when /^\s*r(?:estart)?$/
-            $debugger_restart.call
+            if CONTINUATIONS_SUPPORTED
+              $debugger_restart.call
+            else
+              stdout.print "Restart requires continuations.\n"
+            end
 
           when /^\s*h(?:elp)?$/
             debug_print_help()
@@ -1097,9 +1109,11 @@ EOHELP
 
   stdout.printf "Debug.rb\n"
   stdout.printf "Emacs support available.\n\n"
-  RubyVM::InstructionSequence.compile_option = {
-    trace_instruction: true
-  }
+  if defined?(RubyVM::InstructionSequence)
+    RubyVM::InstructionSequence.compile_option = {
+      trace_instruction: true
+    }
+  end
   set_trace_func proc { |event, file, line, id, binding, klass, *rest|
     DEBUGGER__.context.trace_func event, file, line, id, binding, klass
   }