This might be a Swift issue or just me not understanding how generics work in Swift but I am getting a compiler error / crash with the following code example and I don't understand why
import Foundation
import ReactiveCocoa
protocol MyErrorType {
}
enum MyCustomError: MyErrorType {
case AnError
}
enum MyCustomReactiveError: ReactiveCocoa.ErrorType {
case Foo
case Bar
var nsError: NSError {
switch self {
case .Foo:
return NSError(domain: "", code: 0, userInfo: nil)
case .Bar:
return NSError(domain: "", code: 1, userInfo: nil)
}
}
}
class Container1<T> {
let value: T
init(value: T) {
self.value = value
}
}
class Container2<E: MyErrorType> {
let error: E
init(error: E) {
self.error = error
}
}
class TestClass1<T> {
let defaultValue: T
init(defaultValue: T) {
self.defaultValue = defaultValue
}
func foo() -> Container1<T> {
return Container1(value: defaultValue)
}
}
class TestClass2<E: MyErrorType> {
let defaultValue: E
init(defaultValue: E) {
self.defaultValue = defaultValue
}
func foo() -> Container2<E> {
return Container2(error: defaultValue)
}
}
class TestClass3: TestClass1<Int> {
override func foo() -> Container1<Int> {
return Container1(value: 20)
}
}
class TestClass4: TestClass2<MyCustomError> {
override func foo() -> Container2<MyCustomError> {
return Container2(error: MyCustomError.AnError)
}
}
class TestClass5<E: ReactiveCocoa.ErrorType> {
func foo() -> SignalProducer<(), E> {
return SignalProducer.empty
}
}
class TestClass6: TestClass5<MyCustomReactiveError> {
override func foo() -> SignalProducer<(), MyCustomReactiveError> {
return SignalProducer(error: MyCustomReactiveError.Foo)
}
}
I am getting the following error
SIL verification failed: vtable entry for #TestClass5.foo!1 must be ABI-compatible
ABI-incompatible return values
@convention(method) <τ_0_0 where τ_0_0 : ErrorType> (@guaranteed TestClass5<τ_0_0>) -> @owned SignalProducer<(), τ_0_0>
@convention(method) (@guaranteed TestClass6) -> @owned SignalProducer<(), MyCustomReactiveError>
In function:
// WLXViewModel.TestClass6.foo (WLXViewModel.TestClass6)() -> ReactiveCocoa.SignalProducer<(), WLXViewModel.MyCustomReactiveError>
sil @_TFC12WLXViewModel10TestClass63foofS0_FT_GV13ReactiveCocoa14SignalProducerT_OS_21MyCustomReactiveError_ : $@convention(method) (@guaranteed TestClass6) -> @owned SignalProducer<(), MyCustomReactiveError> {
bb0(%0 : $TestClass6):
debug_value %0 : $TestClass6 // let self // id: %1
// function_ref ReactiveCocoa.SignalProducer.init <A, B where B: ReactiveCocoa.ErrorType> (ReactiveCocoa.SignalProducer<A, B>.Type)(error : B) -> ReactiveCocoa.SignalProducer<A, B>
%2 = function_ref @_TFV13ReactiveCocoa14SignalProducerCu0_Rq0_S_9ErrorType_fMGS0_q_q0__FT5errorq0__GS0_q_q0__ : $@convention(thin) <τ_0_0, τ_0_1 where τ_0_1 : ErrorType> (@in τ_0_1, @thin SignalProducer<τ_0_0, τ_0_1>.Type) -> @owned SignalProducer<τ_0_0, τ_0_1> // user: %9
%3 = metatype $@thin SignalProducer<(), MyCustomReactiveError>.Type // user: %9
// function_ref WLXViewModel.MyCustomReactiveError.Foo (WLXViewModel.MyCustomReactiveError.Type) -> WLXViewModel.MyCustomReactiveError
%4 = function_ref @_TFO12WLXViewModel21MyCustomReactiveError3FooFMS0_S0_ : $@convention(thin) (@thin MyCustomReactiveError.Type) -> MyCustomReactiveError // user: %6
%5 = metatype $@thin MyCustomReactiveError.Type // user: %6
%6 = apply %4(%5) : $@convention(thin) (@thin MyCustomReactiveError.Type) -> MyCustomReactiveError // user: %8
%7 = alloc_stack $MyCustomReactiveError // users: %8, %9, %10
store %6 to %7#1 : $*MyCustomReactiveError // id: %8
%9 = apply %2<(), MyCustomReactiveError>(%7#1, %3) : $@convention(thin) <τ_0_0, τ_0_1 where τ_0_1 : ErrorType> (@in τ_0_1, @thin SignalProducer<τ_0_0, τ_0_1>.Type) -> @owned SignalProducer<τ_0_0, τ_0_1> // user: %11
dealloc_stack %7#0 : $*@local_storage MyCustomReactiveError // id: %10
return %9 : $SignalProducer<(), MyCustomReactiveError> // id: %11
}
0 swift 0x000000010cba1e0b llvm::sys::PrintStackTrace(__sFILE*) + 43
1 swift 0x000000010cba254b SignalHandler(int) + 379
2 libsystem_platform.dylib 0x00007fff9117ef1a _sigtramp + 26
3 swift 0x000000010d19ba2e FirstTarget + 60550
4 swift 0x000000010cba2346 abort + 22
5 swift 0x000000010ad72c49 (anonymous namespace)::SILVerifier::_require(bool, llvm::Twine const&, std::__1::function<void ()> const&) + 425
6 swift 0x000000010ad7182b (anonymous namespace)::SILVerifier::requireABICompatibleFunctionTypes(swift::CanTypeWrapper<swift::SILFunctionType>, swift::CanTypeWrapper<swift::SILFunctionType>, llvm::Twine const&) + 651
7 swift 0x000000010ad713eb swift::SILVTable::verify(swift::SILModule const&) const + 795
8 swift 0x000000010ad7223f swift::SILModule::verify() const + 447
9 swift 0x000000010adac730 swift::Lowering::SILGenModule::~SILGenModule() + 32
10 swift 0x000000010adb214b swift::SILModule::constructSIL(swift::ModuleDecl*, swift::SILOptions&, swift::FileUnit*, llvm::Optional<unsigned int>, bool, bool) + 923
11 swift 0x000000010adb228b swift::performSILGeneration(swift::FileUnit&, swift::SILOptions&, llvm::Optional<unsigned int>, bool) + 123
12 swift 0x000000010abbb691 performCompile(swift::CompilerInstance&, swift::CompilerInvocation&, llvm::ArrayRef<char const*>, int&) + 9153
13 swift 0x000000010abb90b3 frontend_main(llvm::ArrayRef<char const*>, char const*, void*) + 2515
14 swift 0x000000010abb528f main + 1983
15 libdyld.dylib 0x00007fff9b1685c9 start + 1
Stack dump:
I don't see what is the difference between TestClass6 and TestClass4. Why one compiles and the other doesn't when they are virtually the same?
By the way I am using XCode 7.0 beta (7A120f) and ReactiveCocoa branch swift2 commit 1b7e41328d22902e5357d10c38c04606be4cd478
Apple replaced NSError with ErrorType in Swift 2.
Continuing explicitly using NSError in your own code works in some cases but causes some weird errors in other cases.
Replace all explicit usages of NSError in your own code with ErrorType.