xcodecompiler-errorsduplicatessymbols

Duplicate symbol error in Xcode


I am encountering 'duplicate symbol' errors in Xcode 4.5.1 when I try to build a project after adding my own framework. I verified the framework files for duplicates and there are none. But when I add the framework to a project, it complains with these error. Please suggest..

duplicate symbol _NXArgc in:
    /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.0.sdk/usr/lib/crt1.3.1.o
/Users/idcc/Test/MyFW/Products/MyTestFW.framework/MyTestFW

duplicate symbol _NXArgv in:
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.0.sdk/usr/lib/crt1.3.1.o
/Users/idcc/Test/MyFW/Products/MyTestFW.framework/MyTestFW

duplicate symbol ___progname in:
  /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.0.sdk/usr/lib/crt1.3.1.o
/Users/idcc/Test/MyFW/Products/MyTestFW.framework/MyTestFW

duplicate symbol _environ in:
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.0.sdk/usr/lib/crt1.3.1.o
/Users/idcc/Test/MyFW/Products/MyTestFW.framework/MyTestFW

duplicate symbol start in:
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.0.sdk/usr/lib/crt1.3.1.o
/Users/idcc/Test/MyFW/Products/MyTestFW.framework/MyTestFW
ld: 8 duplicate symbols for architecture armv7
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Thanks in advance..


Solution

  • Those symbols are in crt.o, the startup code of standard C library. Normally it should be the entry point of executable file to initialize global variables and objects. It will also call your main function.

    But for a framework, you should not include it in your binary because framework should not have main. I believe you have "Link with Standard Library" option as "YES" in your framework's target build setting. This will link crt.o into your framework. And when you link the framework into a project, there will be duplicated symbols.

    Please set the option "Link with Standard Library" to NO in your build setting.