How do I implement an operator for a class nested in a generic struct?

问题

When I nest a class inside a generic struct and try to implement the equality operator, like this:

struct Outer<T> {
    class Inner : Equatable {}
}

@infix func == <T>(lhs: Outer<T>.Inner, rhs: Outer<T>.Inner) -> Bool {
    return lhs === rhs
}

I get the following error when I try to run the project:

While emitting IR SIL function @_TFCC4Test5Outer5InnerCU__fMS1_FT_S1_ for 'init' at .../Testing.swift:20:11
<unknown>:0: error: unable to execute command: Segmentation fault: 11
<unknown>:0: error: swift frontend command failed due to signal (use -v to see invocation)
Command /Applications/Xcode6-Beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift failed with exit code 254

However, it works fine when I do the same thing without nesting the class:

class MyClass : Equatable {}

@infix func == (lhs: MyClass, rhs: MyClass) -> Bool {
    return lhs === rhs
}

Is this a bug with the compiler, or am I doing something wrong?

回答1:

Nesting a class or struct in a generic type struct is now flagged as invalid by XCode6 Beta6

回答2:

You could define the Inner class in a separate file or space, defining its operator then make a var of that type in your inner class:

class Inner: Equatable {}
func == (left: Inner, right: Inner) -> Bool {
    return true
}
struct Outer {
    var myVar: Inner
}

As of beta 6

来源：https://stackoverflow.com/questions/24127250/how-do-i-implement-an-operator-for-a-class-nested-in-a-generic-struct