OpenURL action crash on macOS Sequoia

[beetee17]

Hi,

I've been using the default live implementation of openURL in a TCA production app, and have received multiple crash reports from users that point to an issue with openURL when calling it from an effect like so: .run { _ in await openURL(...) }.

It seems that the code is not running on the MainActor, even though the Task is marked @MainActor, causing a dispatch queue assertion failure. Weirdly, this assertion is not triggered on my machine that runs macOS Sonoma.

The crash reports are of the following format:

Thread 7 Crashed:
0   libdispatch.dylib             	0x0000000190c079c0 _dispatch_assert_queue_fail + 120 (queue.c:54)
1   libdispatch.dylib             	0x0000000190c07948 dispatch_assert_queue + 196 (queue.c:84)
2   libswift_Concurrency.dylib    	0x0000000271cd6e08 swift_task_isCurrentExecutorImpl(swift::SerialExecutorRef) + 284 (Actor.cpp:0)
3   RedactedApp                	0x00000001078f59b4 closure #1 in closure #1 in closure #1 in closure #1 in variable initialization expression of static OpenURLKey.liveValue + 92 (OpenURL.swift:0)
4   SwiftUI                       	0x00000001c06864e8 partial apply for closure #1 in closure #1 in SwiftUIGlue.defaultOpenSensitiveURLAction() + 36
5   SwiftUI                       	0x00000001c066ede0 thunk for @escaping @callee_guaranteed (@guaranteed NSRunningApplication?, @guaranteed Error?) -> () + 88 (<compiler-generated>:0)
6   AppKit                        	0x00000001955120ac _NSWorkspaceHandleLSOpenResult + 156 (NSWorkspace.m:1379)
7   LaunchServices                	0x000000019148d3ac _LSFireCompletionHandler(void (__LSASN const*, unsigned char, __CFError*) block_pointer, NSURL*, NSURL*, NSDictionary<NSString*, objc_object*>*, objc_object*, bool, NSError*) + 200 (LSOpenNewWorld.mm:1220)
8   LaunchServices                	0x00000001914915a4 _LSOpenAsyncCommonDispatched(objc_object*, NSArray<NSURL*>*, NSURL*, objc_object*, NSDictionary<NSString*, objc_object*>*, NSObject<OS_dispatch_semaphore>*, void (__LSASN const*, unsigned char, __C... + 2560 (LSOpenNewWorld.mm:1394)
9   LaunchServices                	0x0000000191491b58 invocation function for block in _LSOpenAsyncCommon(objc_object*, NSArray<NSURL*>*, NSURL*, objc_object*, NSDictionary<NSString*, objc_object*>*, void (__LSASN const*, unsigned char, __CFError*) bl... + 352 (LSOpenNewWorld.mm:1275)
10  libdispatch.dylib             	0x0000000190c03854 _dispatch_call_block_and_release + 32 (init.c:1549)
11  libdispatch.dylib             	0x0000000190c055b4 _dispatch_client_callout + 20 (object.m:576)
12  libdispatch.dylib             	0x0000000190c0cbd8 _dispatch_lane_serial_drain + 768 (queue.c:3934)
13  libdispatch.dylib             	0x0000000190c0d764 _dispatch_lane_invoke + 432 (queue.c:4025)
14  libdispatch.dylib             	0x0000000190c189a0 _dispatch_root_queue_drain_deferred_wlh + 288 (queue.c:7193)
15  libdispatch.dylib             	0x0000000190c181ec _dispatch_workloop_worker_thread + 540 (queue.c:6787)
16  libsystem_pthread.dylib       	0x0000000190db43d8 _pthread_wqthread + 288 (pthread.c:2696)
17  libsystem_pthread.dylib       	0x0000000190db30f0 start_wqthread + 8

I was able to create and test a fix for this crash by overriding the dependency with an implementation of openURL that marks the outermost closure as @MainActor:

OpenURLEffect { @MainActor url in
	let stream = AsyncStream<Bool> { continuation in
		let task = Task { @MainActor in
			#if os(watchOS)
			EnvironmentValues().openURL(url)
			continuation.yield(true)
			continuation.finish()
			#else
			EnvironmentValues().openURL(url) { canOpen in
				continuation.yield(canOpen)
				continuation.finish()
			}
			#endif
		}
		continuation.onTermination = { @Sendable _ in
			task.cancel()
		}
	}
	return await stream.first(where: { _ in true }) ?? false
}

Dependencies version information

1.4.1

Destination operating system

macOS Sequoia 15.0

Xcode version information

XCode 16.0

Swift Compiler version information

6.0

P.S. Did not want to open an issue as it is hard for me to test on macOS Sequoia, so I could not do many checks.

[stephencelis]

@beetee17 Thanks for the report! Are you able to open a PR with your fix and a test? I'd be happy to run it for you on Sequoia to check it.

[beetee17]

@stephencelis I have created a pull request with the changes that fixed the crash for my users (#305). Though this could be an integration bug, as the app calls openURL from a TCA reducer's .run effect.

FWIW, the exact fix I tested was to override the problematic reducer's dependency with .dependency(\.openURL, OpenURLEffect { @MainActor ... }), rather than modifying the liveValue implementation directly (which is what #305 is doing). Not sure if this makes any difference.

EDIT: I just got reports from users who were able to test an alternative fix that I tried, which was to write the reducer like so: .run { @MainActor _ in await openURL(...) }, with no modifications to the dependency. This does not work and the crash persists.