Copies of BuildOptions should not share underlying collections

Library/Homebrew/build_options.rb

@@ -6,11 +6,20 @@ class BuildOptions
   attr_accessor :args
   include Enumerable
 
+  attr_reader :options
+  protected :options
+
   def initialize args
     @args = Options.coerce(args)
     @options = Options.new
   end
 
+  def initialize_copy(other)
+    super
+    @options = other.options.dup
+    @args = other.args.dup
+  end
+
   def add name, description=nil
     description ||= case name.to_s
       when "universal" then "Build a universal binary"

Library/Homebrew/test/test_build_options.rb

@@ -71,4 +71,20 @@ class BuildOptionsTests < Test::Unit::TestCase
   def test_actually_recognizes_implicit_options
     assert @build.has_opposite_of?("--with-baz")
   end
+
+  def test_copies_do_not_share_underlying_options
+    orig = BuildOptions.new []
+    copy = orig.dup
+    copy.add 'foo'
+    assert_empty orig
+    assert_equal 1, copy.count
+  end
+
+  def test_copies_do_not_share_underlying_args
+    orig = BuildOptions.new []
+    copy = orig.dup
+    copy.args << Option.new('foo')
+    assert_empty orig.args
+    assert_equal 1, copy.args.count
+  end
 end