Issue Description:

When using the generic argument of a function as a parameter of another generic class that is used in the signature, the compiler crashes with Illegal instruction: 4

Example

class GenericClass<T> { }

protocol MyProtocol { }

class MyClass {
  func myFunction<T, O: GenericClass<T> where T: MyProtocol>(myArg: O) -> T {
    fatalError()
  }
}

Interesting crash facts

• This used to work with Swift 2.1

• This works with the version of Swift that is shipped with Xcode 7.3 beta 2 (7D129n)

• It crashes the Swift 2.2 and Swift 3 compiler since the snapshot of 01/11/2016 (that’s the oldest snapshot I have installed)

• The code compiles fine with the current master (as of 02/10/2016, commit 073df63) iff myFunction is a global function and not a method in a class