Stop editing ARGV

Previously ARGV was edited by rake when it processed arguments.  This
made it difficult to re-exec rake within itself as the arguments were
gone when rake started.

Now rake duplicates ARGV and modifies only the duplicate.

Fixes #277

History.rdoc

@@ -7,6 +7,8 @@ Enhancements:
   Coulman.
 * Rake now ignores falsy dependencies which allows for easier programmatic
   creation of tasks.  Pull request #273 by Manav.
+* Rake no longer edits ARGV.  This allows you to re-exec rake from a rake
+  task.  Issue #277 by Matt Palmer.
 
 Bug fixes:
 

lib/rake/application.rb

@@ -20,6 +20,9 @@ class Application
     include TaskManager
     include TraceOutput
 
+    # The command-line arguments rake is using (defaults to ARGV)
+    attr_reader :argv # :nodoc:
+
     # The name of the application (typically 'rake')
     attr_reader :name
 
@@ -45,6 +48,7 @@ class Application
     # Initialize a Rake::Application object.
     def initialize
       super
+      @argv = ARGV.dup
       @name = 'rake'
       @rakefiles = DEFAULT_RAKEFILES.dup
       @rakefile = nil
@@ -73,6 +77,8 @@ def initialize
     # call +top_level+ to run your top level tasks.
     def run
       standard_exception_handling do
+        @argv = argv
+
         init
         load_rakefile
         top_level
@@ -633,7 +639,7 @@ def handle_options # :nodoc:
 
         standard_rake_options.each { |args| opts.on(*args) }
         opts.environment('RAKEOPT')
-      end.parse!
+      end.parse! @argv
     end
 
     # Similar to the regular Ruby +require+ command, but will check
@@ -729,7 +735,7 @@ def standard_system_dir #:nodoc:
     # Environmental assignments are processed at this time as well.
     def collect_command_line_tasks # :nodoc:
       @top_level_tasks = []
-      ARGV.each do |arg|
+      @argv.each do |arg|
         if arg =~ /^(\w+)=(.*)$/m
           ENV[$1] = $2
         else

test/test_rake_application.rb

@@ -10,9 +10,9 @@ def setup
   end
 
   def setup_command_line(*options)
-    ARGV.clear
+    @app.argv.clear
     options.each do |option|
-      ARGV << option
+      @app.argv << option
     end
   end
 
@@ -268,7 +268,7 @@ def test_load_rakefile_doesnt_print_rakefile_directory_from_subdir_if_silent
   end
 
   def test_load_rakefile_not_found
-    ARGV.clear
+    @app.argv.clear
     Dir.chdir @tempdir
     ENV['RAKE_SYSTEM'] = 'not_exist'
 
@@ -378,7 +378,7 @@ def test_handle_options_should_strip_options_from_argv
 
     @app.handle_options
 
-    assert !ARGV.include?(valid_option)
+    assert !@app.argv.include?(valid_option)
     assert @app.options.trace
   end
 
@@ -406,14 +406,14 @@ def test_handle_options_trace_does_not_eat_following_task_names
     setup_command_line("--trace", "sometask")
 
     @app.handle_options
-    assert ARGV.include?("sometask")
+    assert @app.argv.include?("sometask")
     assert @app.options.trace
   end
 
   def test_good_run
     ran = false
 
-    ARGV << '--rakelib=""'
+    @app.argv << '--rakelib=""'
 
     @app.options.silent = true
 
@@ -468,7 +468,7 @@ def test_bad_run
     }
     assert_match(/see full trace/i, err)
   ensure
-    ARGV.clear
+    @app.argv.clear
   end
 
   def test_bad_run_with_trace
@@ -479,7 +479,7 @@ def test_bad_run_with_trace
     }
     refute_match(/see full trace/i, err)
   ensure
-    ARGV.clear
+    @app.argv.clear
   end
 
   def test_bad_run_with_backtrace
@@ -492,7 +492,7 @@ def test_bad_run_with_backtrace
     }
     refute_match(/see full trace/, err)
   ensure
-    ARGV.clear
+    @app.argv.clear
   end
 
   CustomError = Class.new(RuntimeError)
@@ -549,7 +549,7 @@ def test_printing_original_exception_cause
     end
     assert_match(/Secondary Error/, err)
   ensure
-    ARGV.clear
+    @app.argv.clear
   end
 
   def test_run_with_bad_options
@@ -559,7 +559,7 @@ def test_run_with_bad_options
       capture_io { @app.run }
     }
   ensure
-    ARGV.clear
+    @app.argv.clear
   end
 
   def test_standard_exception_handling_invalid_option