swift-async-algorithms 1.0.1 can no longer be built in Swift Playgrounds on iPadOS

[kkebo]

#311 has broken apps depending on swift-async-algorithms on Swift Playgrounds on iPadOS.

• iPadOS 18 Developer Beta 1
• Swift Playgrounds 4.5.1

The reproducible example is here. Or, you can reproduce the issue by the following steps.

1. Create a new app on Swift Playgrounds (iPadOS)
2. Add a swift package
3. Input https://github.com/apple/swift-async-algorithms to the "Package URL" field
4. Press the return key

Then, the following error will be shown.

error message

Could not resolve package graph. Cannot continue.

unknownError(PlaygroundExecution.ConsoleReadingExecutionOperation.OperationError.failed(PlaygroundExecution.ExecutionError.remoteProcessWasInterrupted, Optional(["ThreadInfoDictionaries": <__NSFrozenArrayM 0x307900540>(
{
    DispatchQueueName = "com.apple.main-thread";
    StackFrameDictionaries =     (
                {
            CrashAnnotationMessage = "PackageDescription/Context.swift:19: Fatal error: 'try!' expression unexpectedly raised an error: Could not decode ContextModel parameter.\n";
            StackFrameModule = "libswiftCore.dylib";
            StackFramePC = 6842454440;
            StackFrameSymbolName = "_$ss17_assertionFailure__4file4line5flagss5NeverOs12StaticStringV_SSAHSus6UInt32VtF";
        },
                {
            CrashAnnotationMessage = "PackageDescription/Context.swift:19: Fatal error: 'try!' expression unexpectedly raised an error: Could not decode ContextModel parameter.\n";
            StackFrameModule = "libswiftCore.dylib";
            StackFramePC = 6842925296;
            StackFrameSymbolName = "_swift_unexpectedError";
        },
                {
            StackFrameModule = "libPackageDescription.dylib";
            StackFramePC = 4465283188;
            StackFrameSymbolName = "_$s18PackageDescription7ContextV5model33_16EFAD36DA072BCD1C8EFF86E7A18833LL_WZ";
        },
                {
            StackFrameModule = "libdispatch.dylib";
            StackFramePC = 7002132832;
            StackFrameSymbolName = "__dispatch_client_callout";
        },
                {
            StackFrameModule = "libdispatch.dylib";
            StackFramePC = 7002139048;
            StackFrameSymbolName = "__dispatch_once_callout";
        },
                {
            StackFrameModule = "libPackageDescription.dylib";
            StackFramePC = 4465283448;
            StackFrameSymbolName = "_$s18PackageDescription7ContextV11environmentSDyS2SGvgZ";
        },
                {
            StackFrameModule = "manifest_bjwdoqlmuklnzyeenvxrrponpzzy";
            StackFramePC = 4377719596;
            StackFrameSymbolName = "_main";
        },
                {
            StackFrameModule = ExecutionExtension;
            StackFramePC = 4374972024;
        },
                {
            StackFrameModule = CoreFoundation;
            StackFramePC = 6869403044;
            StackFrameSymbolName = "___CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK__";
        },
                {
            StackFrameModule = CoreFoundation;
            StackFramePC = 6869330004;
            StackFrameSymbolName = "___CFRunLoopDoBlocks";
        },
                {
            StackFrameModule = CoreFoundation;
            StackFramePC = 6869327644;
            StackFrameSymbolName = "___CFRunLoopRun";
        },
                {
            StackFrameModule = CoreFoundation;
            StackFramePC = 6869325588;
            StackFrameSymbolName = "_CFRunLoopRunSpecific";
        },
                {
            StackFrameModule = GraphicsServices;
            StackFramePC = 8138953156;
            StackFrameSymbolName = "_GSEventRunModal";
        },
                {
            StackFrameModule = UIKitCore;
            StackFramePC = 6914872676;
            StackFrameSymbolName = "-[UIApplication _run]";
        },
                {
            StackFrameModule = UIKitCore;
            StackFramePC = 6915585328;
            StackFrameSymbolName = "_UIApplicationMain";
        },
                {
            StackFrameModule = "libxpc.dylib";
            StackFramePC = 9129525396;
            StackFrameSymbolName = "__xpc_objc_uimain";
        },
                {
            StackFrameModule = "libxpc.dylib";
            StackFramePC = 9129524880;
            StackFrameSymbolName = "__xpc_objc_main";
        },
                {
            StackFrameModule = "libxpc.dylib";
            StackFramePC = 9129534688;
            StackFrameSymbolName = "__xpc_main";
        },
                {
            StackFrameModule = "libxpc.dylib";
            StackFramePC = 9129535168;
            StackFrameSymbolName = "_xpc_main";
        },
                {
            StackFrameModule = Foundation;
            StackFramePC = 6849683752;
            StackFrameSymbolName = "-[NSXPCListener resume]";
        },
                {
            StackFrameModule = PlugInKit;
            StackFramePC = 7673820444;
        },
                {
            StackFrameModule = PlugInKit;
            StackFramePC = 7673820072;
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                {
            StackFrameModule = PlugInKit;
            StackFramePC = 7673819236;
        },
                {
            StackFrameModule = PlugInKit;
            StackFramePC = 7673821304;
        },
                {
            StackFrameModule = ExtensionFoundation;
            StackFramePC = 7123324860;
            StackFrameSymbolName = "_EXExtensionMain";
        },
                {
            StackFrameModule = Foundation;
            StackFramePC = 6850132160;
            StackFrameSymbolName = "_NSExtensionMain";
        },
                {
            StackFrameModule = dyld;
            StackFramePC = 7502216400;
            StackFrameSymbolName = start;
        }
    );
    ThreadCrashed = 1;
    ThreadID = 461139;
    ThreadIsMain = 1;
},
{
    StackFrameDictionaries =     (
                {
            StackFrameModule = "libsystem_kernel.dylib";
            StackFramePC = 8209470608;
            StackFrameSymbolName = "___workq_kernreturn";
        },
                {
            StackFrameModule = "libsystem_pthread.dylib";
            StackFramePC = 9129123016;
            StackFrameSymbolName = "__pthread_wqthread";
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                {
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            StackFramePC = 9129108616;
            StackFrameSymbolName = "_start_wqthread";
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    );
    ThreadID = 461141;
},
{
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    StackFrameDictionaries =     (
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            StackFramePC = 8209470748;
            StackFrameSymbolName = "___ulock_wait2";
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            StackFramePC = 9128407640;
            StackFrameSymbolName = "__os_unfair_lock_lock_slow";
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                {
            StackFrameModule = PencilKit;
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            StackFrameSymbolName = "-[PKInkManager inkBehaviorForIdentifier:version:variant:]";
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                {
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            StackFrameModule = "libdispatch.dylib";
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            StackFrameSymbolName = "__dispatch_client_callout";
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            StackFramePC = 7002206152;
            StackFrameSymbolName = "__dispatch_root_queue_drain";
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            StackFrameSymbolName = "__dispatch_worker_thread2";
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                {
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            StackFrameSymbolName = "_start_wqthread";
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    );
    ThreadID = 461142;
},
{
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            StackFrameSymbolName = "_start_wqthread";
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    );
    ThreadID = 461143;
},
{
    StackFrameDictionaries =     (
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    );
    ThreadID = 461144;
},
{
    StackFrameDictionaries =     (
                {
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            StackFrameSymbolName = "___workq_kernreturn";
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                {
            StackFrameModule = "libsystem_pthread.dylib";
            StackFramePC = 9129123016;
            StackFrameSymbolName = "__pthread_wqthread";
        },
                {
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            StackFramePC = 9129108616;
            StackFrameSymbolName = "_start_wqthread";
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    );
    ThreadID = 461145;
},
{
    StackFrameDictionaries =     (
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            StackFrameSymbolName = "_mach_msg2_internal";
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            StackFrameSymbolName = "_mach_msg_overwrite";
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                {
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            StackFrameSymbolName = "-[NSRunLoop(NSRunLoop) runUntilDate:]";
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            StackFrameSymbolName = "-[UIEventFetcher threadMain]";
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    ThreadID = 461146;
    ThreadName = "com.apple.uikit.eventfetch-thread";
},
{
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{
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            StackFrameSymbolName = "__pthread_wqthread";
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    ThreadID = 461148;
},
{
    DispatchQueueName = "com.apple.root.user-initiated-qos";
    StackFrameDictionaries =     (
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},
{
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                {
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    ThreadID = 461150;
},
{
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},
{
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                {
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            StackFrameSymbolName = "__pthread_wqthread";
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                {
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            StackFrameSymbolName = "_start_wqthread";
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    );
    ThreadID = 461152;
},
{
    StackFrameDictionaries =     (
    );
    ThreadID = 461153;
}
)
, "ExceptionType": 6, "ExceptionData": <01000000 00000000 a891d797 01000000>, "CrashCatcherPID": 1333, "SignalNumber": 5]))) in https://github.com/apple/swift-async-algorithms

It seems that Context is not safe on Swift Playgrounds. If Context.environment is used in Package.swift, Swift Playgrounds's SwiftPM will crash.

• https://github.com/apple/swift-package-manager/blob/swift-5.10-RELEASE/Sources/PackageDescription/Context.swift#L19
• https://github.com/apple/swift-package-manager/blob/swift-5.10-RELEASE/Sources/PackageLoading/ContextModel.swift#L47

[kkebo]

I also sent a feedback to Swift Playgrounds. FB13946579

[kkebo]

Enclosing Context.environment with something like #if !os(iOS) would solve the problem. However, it may become a debt when the new Swift runtime other than Swift Playgrounds appears in the future on iOS or iPadOS.

[FranzBusch]

Thanks for reporting this. This isn't an async-algorithms problem but rather a Swift Playgrounds/Swift PM problem. I am going to close this issue since this is now being tracked in the feedback you filed.

[kkebo]

OK, thank you.