Open Radar

 
Summary:
The code can not be linked. Please check the attached code sample Readme.md file or this github project for specific details

https://github.com/Karumi/ExtensionProtocolforStruct

Steps to Reproduce:
When compiling the ExtensionProtocolforStruct project the linker crash with the following error message:

Undefined symbols for architecture x86_64:
  "__TFV9submodule10testStructg3fooSS", referenced from:
      __TTWV9submodule10testStruct26ExtensionProtocolforStruct12testProtocolS1_FS2_g3fooSS in ProtocolExtension.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
The setup is:

1 - Declare a public struct in a framework


public struct TestStruct {
    public let foo: String = ""
}

2 - Declare a protocol that matches the property names of the struct in your project

protocol TestProtocol {

    var foo: String { get }

}

3 - Declare an extension for the struct that implements the protocol

extension TestStruct : TestProtocol { }


Expected Results:
Expected: The code compiles and runs

Actual Results:
Actual: The linking breaks with the error described at the beginning.

Note: If the struct in the framework is replaced with a public class, the code works as expected 

Version:
OSX 10.3, Xcode 6.3.1 (it happened also in 6.3)

Notes:


Configuration:
rMBP 13 inches mid 2015

See: https://github.com/Karumi/ExtensionProtocolforStruct