Swift-frontend crash switching over (any Error)?

Using Swift
, , ,
1

Here's the code:

var error: Error?
// ... something which may or may not set error ...

switch error {
case AFError.explicitlyCancelled:
    // Task was cancelled, don't continue
    return
case let e?:
    debugPrint(e)
    self.error = e
default:
    break
}

For some reason, this switch statement causes swift-frontend to blow up:

swift-frontend: /home/build-user/llvm-project/llvm/include/llvm/Support/Casting.h:578: decltype(auto) llvm::cast(From *) [To = swift::ExistentialArchetypeType, From = swift::TypeBase]: Assertion `isa(Val) && "cast() argument of incompatible type!"' failed.

Restructuring this so the switch is not over an optional works fine, i.e:

if let error {
    switch error {
    case AFError.explicitlyCancelled:
        // Task was cancelled, don't continue
        return
    default:
        debugPrint(error)
        self.error = error
    }
}

Is this a known issue, or should I file one?

2

i've made some assumptions about the rest of your code, but it doesn't seem to compile for me. i get an error like:

error: pattern of type 'AFError' cannot match '(any Error)?'
3

The project is public here: GitHub - bbrk24/weather-app Replace the if let on line 105 of Sources/WeatherApp/ViewModels/ForecastViewModel.swift with the switch from the offending code to reproduce the crash. It’s possible there’s more relevant context I’m missing.

4

Also in case it's relevant, I'm on Ubuntu 24.04 with this Swift version:

Swift version 6.3-dev (LLVM 2bc32d2793f525d, Swift f1a704763ffd2c8)
Target: x86_64-unknown-linux-gnu
Build config: +assertions
5

Could you provide a reproducer in Godbolt?