Looks like the -fobj-arc flag we added to OTHER_LD_FLAGS in ea918cd9 was

an unsupported feature as it has now been removed from Xcode 4.3.2, 
causing lib tool to complain about an unrecognised flag.

I considered removing this entirely but have decided to keep it around 
as an option for the time being. You can get the previous behaviour by
adding set_arc_compatibility_flag! to your Podfile.

I'd like to get rid of this entirely eventually. Re-closes #142 unless
anybody has any objections.

lib/cocoapods/installer/target_installer.rb

@@ -13,10 +13,8 @@ module Pod
       def xcconfig
         @xcconfig ||= Xcodeproj::Config.new({
           # In a workspace this is where the static library headers should be found.
-          'PODS_ROOT' => '$(SRCROOT)/Pods',
+          'PODS_ROOT'                => '$(SRCROOT)/Pods',
           'ALWAYS_SEARCH_USER_PATHS' => 'YES', # needed to make EmbedReader build
-          # This makes categories from static libraries work, which many libraries
-          # require, so we add these by default.
           'OTHER_LDFLAGS'            => default_ld_flags,
         })
       end
@@ -118,7 +116,7 @@ module Pod
       
       def default_ld_flags
         flags = %w{-ObjC -all_load}
-        flags << '-fobjc-arc' if self.requires_arc
+        flags << '-fobjc-arc' if @podfile.set_arc_compatibility_flag? && self.requires_arc
         flags.join(" ")
       end
     end

lib/cocoapods/podfile.rb

@@ -215,6 +215,19 @@ module Pod
       @post_install_callback = block
     end
 
+    # Specifies that the -fobjc-arc flag should be added to the OTHER_LD_FLAGS.
+    #
+    # This is used as a workaround for a compiler bug with non-ARC projects.
+    # (see https://github.com/CocoaPods/CocoaPods/issues/142)
+    #
+    # This was originally done automatically but libtool as of Xcode 4.3.2 no 
+    # longer seems to support the -fobjc-arc flag. Therefore it now has to be
+    # enabled explicitly using this method.
+    #
+    # This may be removed in a future release.
+    def set_arc_compatibility_flag!
+      @set_arc_compatibility_flag = true
+    end
 
     # Not attributes
 
@@ -236,6 +249,10 @@ module Pod
     def generate_bridge_support?
       @generate_bridge_support
     end
+    
+    def set_arc_compatibility_flag?
+      @set_arc_compatibility_flag
+    end
 
     def post_install!(installer)
       @post_install_callback.call(installer) if @post_install_callback

spec/unit/podfile_spec.rb

@@ -48,6 +48,10 @@ describe "Pod::Podfile" do
     Pod::Podfile.new {}.should.not.generate_bridge_support
     Pod::Podfile.new { generate_bridge_support! }.should.generate_bridge_support
   end
+  
+  it 'specifies that ARC compatibility flag should be generated' do
+    Pod::Podfile.new { set_arc_compatibility_flag! }.should.set_arc_compatibility_flag
+  end
 
   it "stores a block that will be called with the Installer instance once installation is finished (but the project is not written to disk yet)" do
     yielded = nil

spec/unit/target_installer_spec.rb

@@ -8,7 +8,9 @@ describe Pod::Installer::TargetInstaller do
     @target_definition = stub('target', :lib_name => "FooLib")
 
     platform = Pod::Platform.new(:ios)
-    @podfile = stub('podfile', :platform => platform, :generate_bridge_support? => false)
+    @podfile = stub('podfile', :platform => platform, 
+                  :generate_bridge_support? => false, 
+                  :set_arc_compatibility_flag? => false)
 
     @project = Pod::Project.for_platform(platform)
     @project.main_group.groups.new('name' => 'Targets Support Files')
@@ -45,9 +47,20 @@ describe Pod::Installer::TargetInstaller do
     @installer.xcconfig.to_hash['HEADER_SEARCH_PATHS'].should.include("\"#{@sandbox.header_search_paths.join(" ")}\"")
   end
   
-  it 'adds the -fobjc-arc to OTHER_LDFLAGS if any pods require arc (to support non-ARC projects on iOS 4.0)' do
-    @specification.stubs(:requires_arc).returns(true)
+  it 'does not add the -fobjc-arc to OTHER_LDFLAGS by default as Xcode 4.3.2 does not support it' do
     do_install!
-    @installer.xcconfig.to_hash['OTHER_LDFLAGS'].split(" ").should.include("-fobjc-arc")
+    @installer.xcconfig.to_hash['OTHER_LDFLAGS'].split(" ").should.not.include("-fobjc-arc")
+  end
+  
+  describe "when ARC compatibility flag is set" do
+    before do
+      @podfile.stubs(:set_arc_compatibility_flag? => true)
+    end
+    
+    it 'adds the -fobjc-arc to OTHER_LDFLAGS if any pods require arc (to support non-ARC projects on iOS 4.0)' do
+      @specification.stubs(:requires_arc).returns(true)
+      @installer.install!(@pods, @sandbox)
+      @installer.xcconfig.to_hash['OTHER_LDFLAGS'].split(" ").should.include("-fobjc-arc")
+    end
   end
 end