Iphone 更新到xcode 4.2和ios5后的编译错误

我有一个项目在xcode 4上运行得很好，我更新到4.2和ios5，现在它不会编译了！ 我得到：

命令/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/clang++失败，退出代码为1

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其他人以前有过此类问题吗？

请尝试删除派生数据：

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转到“组织者”并选择顶部的项目。“派生数据”项右侧有一个删除按钮

您需要发布实际的错误消息，这就是我的控制台中显示的全部内容。我怎样才能获得更多信息？当它失败时，它正在尝试链接。您已经在xcode中尝试过

clean

了吗？是的，尝试了好几次。我怎么知道哪个链接失败了？我没有这样的运气。。。在升级到5.0 SDK后，我修复了项目中的所有警告，用最新版本替换了所有链接库，等等。我尝试过清理、删除派生数据等等。但我仍然遇到这个神秘的链接器错误。

Ld "build/Debug-iphoneos/Send Video.app/Send Video" normal armv7
cd "/Volumes/Untitled 1/iOS/projects/SharedMomentsApp"
setenv IPHONEOS_DEPLOYMENT_TARGET 4.0
setenv PATH "/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin:/Developer/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin"
/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/clang++ -arch armv7 -isysroot /Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS5.0.sdk "-L/Volumes/Untitled 1/iOS/projects/SharedMomentsApp/build/Debug-iphoneos" "-L/Volumes/Untitled 1/iOS/projects/SharedMomentsApp/SharedMomentsApp" "-L/Volumes/Untitled 1/iOS/projects/SharedMomentsApp" "-L/Developer/Platforms/iPhoneOS.platform/DeviceSupport/4.3.5 (8L1)/Symbols/usr/lib" "-F/Volumes/Untitled 1/iOS/projects/SharedMomentsApp/build/Debug-iphoneos" -filelist "/Volumes/Untitled 1/iOS/projects/SharedMomentsApp/build/SharedMomentsApp.build/Debug-iphoneos/SharedMomentsApp.build/Objects-normal/armv7/Send Video.LinkFileList" -dead_strip /Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS4.3.sdk/usr/lib/libxml2.2.dylib -miphoneos-version-min=4.0 -lz -lxml2.2 -framework AssetsLibrary -framework CoreMedia -framework AVFoundation -framework CoreLocation -framework MapKit -framework QuartzCore -framework AddressBookUI -framework AddressBook -framework SystemConfiguration -framework MediaPlayer -framework MobileCoreServices -lsqlite3.0 -framework UIKit -framework Foundation -framework CoreGraphics -framework CoreData -o "/Volumes/Untitled 1/iOS/projects/SharedMomentsApp/build/Debug-iphoneos/Send Video.app/Send Video"