Swift compiler segmentation fault after Swift 3 / Xcode 8 port - ios

Question

I have checked multiple answers here in SO, but no solution seems to work for me. When compiling my iOS (≥9.3) app, the following compiler error appears since I converted my project to Swift 3 / Xcode 8.
I tried to clean, delete DerivedData, rebuild Carthage frameworks, etc. - but nothing worked - yet.
Maybe somebody who has experienced this before can immediately spot the problem.
Console output / Stacktrace :
0 swift 0x000000010bc8cb6d PrintStackTraceSignalHandler(void*) + 45
1 swift 0x000000010bc8c5b6 SignalHandler(int) + 470
2 libsystem_platform.dylib 0x00007fffd300dbba _sigtramp + 26
3 libsystem_platform.dylib 000000000000000000 _sigtramp + 754918496
4 swift 0x00000001090c98d2 llvm::Value* llvm::function_ref<llvm::Value* (unsigned int)>::callback_fn<swift::irgen::emitArchetypeWitnessTableRef(swift::irgen::IRGenFunction&, swift::CanTypeWrapper<swift::ArchetypeType>, swift::ProtocolDecl*)::$_0>(long, unsigned int) + 530
5 swift 0x00000001091a7600 swift::irgen::emitImpliedWitnessTableRef(swift::irgen::IRGenFunction&, llvm::ArrayRef<swift::irgen::ProtocolEntry>, swift::ProtocolDecl*, llvm::function_ref<llvm::Value* (unsigned int)> const&) + 240
6 swift 0x00000001090c96a7 swift::irgen::emitArchetypeWitnessTableRef(swift::irgen::IRGenFunction&, swift::CanTypeWrapper<swift::ArchetypeType>, swift::ProtocolDecl*) + 247
7 swift 0x00000001091a39cd swift::SILWitnessVisitor<(anonymous namespace)::WitnessTableBuilder>::visitProtocolDecl(swift::ProtocolDecl*) + 5997
8 swift 0x00000001091a14d7 swift::irgen::IRGenModule::emitSILWitnessTable(swift::SILWitnessTable*) + 503
9 swift 0x00000001091138ed swift::irgen::IRGenerator::emitGlobalTopLevel() + 2077
10 swift 0x00000001091d4fcb performIRGeneration(swift::IRGenOptions&, swift::ModuleDecl*, swift::SILModule*, llvm::StringRef, llvm::LLVMContext&, swift::SourceFile*, unsigned int) + 1259
11 swift 0x00000001090a31c7 performCompile(swift::CompilerInstance&, swift::CompilerInvocation&, llvm::ArrayRef<char const*>, int&, swift::FrontendObserver*) + 23687
12 swift 0x000000010909b265 swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 17029
13 swift 0x000000010905882d main + 8685
14 libdyld.dylib 0x00007fffd2e01255 start + 1
15 libdyld.dylib 0x0000000000000067 start + 757067283
And the problematic file / class is the following:
class JSONDataProvider<Input, Output, APIInformation>: DataProvider
where APIInformation: APIAccessInformation, APIInformation.Input == Input,
Output: JSONDataType, Input: Equatable, Input: SignificanceComparable
{
static var updateCallbacksWithoutInputChange: Bool { return false }
// MARK: - Protocol Variables
var callbackId: Int = 0
var callbacks: [Int : (Result<(Output, Input)>) -> ()]
var inputCache: Input?
var outputCache: Result<(Output, Input)>?
// MARK: - Private Properties
fileprivate let apiInformation: APIInformation
fileprivate let requestHandler: URLRequestHandler
// MARK: - Init
init(apiInformation: APIInformation, requestHandler: URLRequestHandler)
{
self.apiInformation = apiInformation
self.requestHandler = requestHandler
self.callbacks = [:]
}
}
For context: (leaving out extensions)
protocol DataProvider
{
associatedtype Input: Equatable, SignificanceComparable
associatedtype Output
static var updateCallbacksWithoutInputChange: Bool { get }
var inputCache: Input? { get set }
var outputCache: Result<(Output, Input)>? { get set }
var callbackId: Int { get set }
var callbacks: [Int : (Result<(Output, Input)>) -> Void] { get set }
func fetchData(from input: Input)
mutating func registerCallback(_ callback: #escaping (Result<(Output, Input)>) -> Void) -> Int
mutating func unregisterCallback(with id: Int)
}
And:
protocol APIAccessInformation
{
associatedtype Input: Equatable, SignificanceComparable
var requestMethod: Alamofire.HTTPMethod { get }
var baseURL: String { get }
func apiParameters(for input: Input) -> [String : Any]
}
Any ideas? Thank you!

Answer 1

Turns out the generic type was the problem. As nobody seems to know exactly why, I have adapted my architecture so I don't need this generic type.
I'm leaving this question here in case others run into a similar issue or someone who knows the exact reason and fix finds this thread.