Allow build_args to be directly specified

Eventually, I'd like to get rid of Gem::Command.build_args all together.
For now, this is a good compromise.

lib/rubygems/commands/pristine_command.rb

@@ -97,13 +97,12 @@ def execute
       install_defaults = Gem::ConfigFile::PLATFORM_DEFAULTS['install']
       installer_env_shebang = install_defaults.to_s['--env-shebang']
 
-      Gem::Command.build_args = spec.build_args
-
       installer = Gem::Installer.new(gem,
                                      :wrappers => true,
                                      :force => true,
                                      :install_dir => spec.base_dir,
-                                     :env_shebang => installer_env_shebang)
+                                     :env_shebang => installer_env_shebang,
+                                     :build_args => spec.build_args)
       installer.install
 
       say "Restored #{spec.full_name}"

lib/rubygems/ext/configure_builder.rb

@@ -8,10 +8,10 @@
 
 class Gem::Ext::ConfigureBuilder < Gem::Ext::Builder
 
-  def self.build(extension, directory, dest_path, results)
+  def self.build(extension, directory, dest_path, results, args=[])
     unless File.exist?('Makefile') then
       cmd = "sh ./configure --prefix=#{dest_path}"
-      cmd << " #{Gem::Command.build_args.join ' '}" unless Gem::Command.build_args.empty?
+      cmd << " #{args.join ' '}" unless args.empty?
 
       run cmd, results
     end

lib/rubygems/ext/ext_conf_builder.rb

@@ -9,9 +9,9 @@
 
 class Gem::Ext::ExtConfBuilder < Gem::Ext::Builder
 
-  def self.build(extension, directory, dest_path, results)
+  def self.build(extension, directory, dest_path, results, args=[])
     cmd = "#{Gem.ruby} #{File.basename extension}"
-    cmd << " #{Gem::Command.build_args.join ' '}" unless Gem::Command.build_args.empty?
+    cmd << " #{args.join ' '}" unless args.empty?
 
     run cmd, results
 

lib/rubygems/ext/rake_builder.rb

@@ -9,10 +9,10 @@
 
 class Gem::Ext::RakeBuilder < Gem::Ext::Builder
 
-  def self.build(extension, directory, dest_path, results)
+  def self.build(extension, directory, dest_path, results, args=[])
     if File.basename(extension) =~ /mkrf_conf/i then
       cmd = "#{Gem.ruby} #{File.basename extension}"
-      cmd << " #{Gem::Command.build_args.join " "}" unless Gem::Command.build_args.empty?
+      cmd << " #{args.join " "}" unless args.empty?
       run cmd, results
     end
 

lib/rubygems/installer.rb

@@ -94,6 +94,8 @@ def exec_format
   # :only_install_dir:: Only validate dependencies against what is in the
   #                     install_dir
   # :wrappers:: Install wrappers if true, symlinks if false.
+  # :build_args:: An Array of arguments to pass to the extension builder
+  #               process. If not set, then Gem::Command.build_args is used
 
   def initialize(gem, options={})
     require 'fileutils'
@@ -230,10 +232,9 @@ def install
     generate_bin
     write_spec
 
-    args = Gem::Command.build_args
-    unless args.empty?
+    unless @build_args.empty?
       File.open spec.build_info_file, "w" do |f|
-        args.each { |a| f.puts a }
+        @build_args.each { |a| f.puts a }
       end
     end
 
@@ -560,6 +561,8 @@ def process_options
     # (or use) a new bin dir under the gem_home.
     @bin_dir             = options[:bin_dir] || Gem.bindir(gem_home)
     @development         = options[:development]
+
+    @build_args          = options[:build_args] || Gem::Command.build_args
   end
 
   # DOC: Missing docs or :nodoc:.
@@ -631,12 +634,10 @@ def windows_stub_script(bindir, bin_file_name)
   def build_extensions
     return if spec.extensions.empty?
 
-    args = Gem::Command.build_args
-
-    if args.empty?
+    if @build_args.empty?
       say "Building native extensions.  This could take a while..."
     else
-      say "Building native extensions with: '#{args.join(' ')}'"
+      say "Building native extensions with: '#{@build_args.join(' ')}'"
       say "This could take a while..."
     end
 
@@ -665,7 +666,8 @@ def build_extensions
 
       begin
         Dir.chdir extension_dir do
-          results = builder.build(extension, gem_dir, dest_path, results)
+          results = builder.build(extension, gem_dir, dest_path,
+                                  results, @build_args)
 
           say results.join("\n") if Gem.configuration.really_verbose
         end

lib/rubygems/installer_test_case.rb

@@ -11,6 +11,11 @@ class Gem::Installer
   ##
   # Available through requiring rubygems/installer_test_case
 
+  attr_writer :build_args
+
+  ##
+  # Available through requiring rubygems/installer_test_case
+
   attr_writer :gem_dir
 
   ##

test/rubygems/test_gem_commands_pristine_command.rb

@@ -6,12 +6,6 @@ class TestGemCommandsPristineCommand < Gem::TestCase
   def setup
     super
     @cmd = Gem::Commands::PristineCommand.new
-    @orig_args = Gem::Command.build_args
-  end
-
-  def teardown
-    super
-    Gem::Command.build_args = @orig_args
   end
 
   def test_execute
@@ -97,8 +91,6 @@ def test_execute_no_extension
   end
 
   def test_execute_with_extension_with_build_args
-    Gem::Command.build_args = %w!--with-awesome=true --sweet!
-
     a = quick_spec 'a' do |s| s.extensions << 'ext/a/extconf.rb' end
 
     ext_path = File.join @tempdir, 'ext', 'a', 'extconf.rb'
@@ -111,11 +103,11 @@ def test_execute_with_extension_with_build_args
       RUBY
     end
 
-    install_gem a
+    build_args = %w!--with-awesome=true --sweet!
 
-    @cmd.options[:args] = %w[a]
+    install_gem a, :build_args => build_args
 
-    Gem::Command.build_args = @orig_args
+    @cmd.options[:args] = %w[a]
 
     use_ui @ui do
       @cmd.execute

test/rubygems/test_gem_installer.rb

@@ -106,6 +106,35 @@ def test_build_extensions_unsupported
     FileUtils.rm_f gem_make_out
   end
 
+  def test_build_extensions_with_build_args
+    args = ["--aa", "--bb"]
+    @installer.build_args = args
+    @installer.spec = @spec
+    @spec.extensions << 'extconf.rb'
+
+    File.open File.join(@spec.gem_dir, "extconf.rb"), "w" do |f|
+      f.write <<-'RUBY'
+        puts "IN EXTCONF"
+        File.open 'extconf_args', 'w' do |f|
+          f.puts ARGV.inspect
+        end
+
+        File.open 'Makefile', 'w' do |f|
+          f.puts "default:\n\techo built"
+          f.puts "install:\n\techo installed"
+        end
+      RUBY
+    end
+
+    use_ui @ui do
+      @installer.build_extensions
+    end
+
+    path = File.join @spec.gem_dir, "extconf_args"
+
+    assert_equal args.inspect, File.read(path).strip
+  end
+
   def test_check_executable_overwrite
     @installer.generate_bin