I am seeing a weird crash from Xcode 27 Beta 3 when building a variadic type DynamicProperty that also needs SwiftUI.State. This does not crash from Xcode 26.
Here is a repro:
import SwiftUI
struct Repeater<each Input>: DynamicProperty {
@State private var storage = Storage()
private var input: (repeat each Input)
init(_ input: repeat each Input) {
self.input = (repeat each input)
}
}
extension Repeater {
final class Storage {
}
}
@main
struct CrashDemoApp: App {
private var repeater = Repeater(1)
var body: some Scene {
WindowGroup {
EmptyView()
}
}
}
Here is the crash:
Thread 1 Queue : com.apple.main-thread (serial)
#0 0x000000019a93aec0 in swift::TargetMetadata<swift::InProcess>::isCanonicalStaticallySpecializedGenericMetadata ()
#1 0x000000019a946b38 in performOnMetadataCache<swift::MetadataResponse, swift_checkMetadataState::CheckStateCallbacks> ()
#2 0x000000019a8c85f0 in swift_checkMetadataState ()
#3 0x00000001004a2c78 in type metadata completion function for Repeater ()
#4 0x000000019a94cfe4 in swift::GenericCacheEntry::tryInitialize ()
#5 0x000000019a94c870 in swift::MetadataCacheEntryBase<swift::GenericCacheEntry, void const*>::doInitialization ()
#6 0x000000019a94f820 in swift::LockingConcurrentMap<swift::GenericCacheEntry, swift::LockingConcurrentMapStorage<swift::GenericCacheEntry, (unsigned short)14>>::getOrInsert<swift::MetadataCacheKey, swift::MetadataRequest&, swift::TargetTypeContextDescriptor<swift::InProcess> const*&, void const* const*&> ()
#7 0x000000019a93c714 in _swift_getGenericMetadata ()
#8 0x00000001004a4190 in __swift_instantiateGenericMetadata ()
#9 0x00000001004a2a5c in type metadata accessor for Repeater ()
#10 0x00000001004a5094 in type metadata accessor for Repeater<Pack{Int}> ()
#11 0x00000001004a4fcc in type metadata completion function for CrashDemoApp ()
#12 0x000000019a9543bc in swift::MetadataCacheEntryBase<(anonymous namespace)::SingletonMetadataCacheEntry, int>::doInitialization ()
#13 0x000000019a8d2ae0 in swift_getSingletonMetadata ()
#14 0x00000001004a479c in type metadata accessor for CrashDemoApp ()
#15 0x00000001004a473c in static CrashDemoApp.$main() ()
#16 0x00000001004a4a34 in main ()
#17 0x0000000186e47e00 in start ()
Here is a repo to demo:
https://github.com/vanvoorden/2026-07-17
Please let me know if you have any ideas about that. Thanks!