Compiler crash when setting strict concurrency complete and default UIView param

[bartcone]

Description

While prepping for Swift 6, I set Strict Concurrency Checking to Complete and encountered a compiler crash because of a default UIView param.

Reproduction

• Xcode 15.4
• Create a new app project
• Set strict concurrency checking to complete
• Create new file and paste the code below and try compiling

class CustomView: UIView {

    // default param of UIView() causes compiler crash
    // changing to nil compiles
    // lowering strict concurrency checking compiles
    init(foo: UIView? = UIView()) {
        super.init(frame: .zero)
    }

    required init?(coder: NSCoder) {
        nil
    }
}

class TestViewController: UIViewController {

    private let customView = CustomView()

    override func viewDidLoad() {
        super.viewDidLoad()
        self.view.addSubview(self.customView)
    }
}

Stack dump

Stack dump:
0.	Program arguments: /Applications/Xcode-15.4.0.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift-frontend -frontend -c -primary-file /Users/bartcone/Documents/dev/StrictConcurrencyBug/StrictConcurrencyBug/TestViewController.swift /Users/bartcone/Library/Developer/Xcode/DerivedData/StrictConcurrencyBug-dibbntunibjwjtfewlxsuacsrdmj/Build/Intermediates.noindex/StrictConcurrencyBug.build/Debug-iphonesimulator/StrictConcurrencyBug.build/DerivedSources/GeneratedAssetSymbols.swift -emit-dependencies-path /Users/bartcone/Library/Developer/Xcode/DerivedData/StrictConcurrencyBug-dibbntunibjwjtfewlxsuacsrdmj/Build/Intermediates.noindex/StrictConcurrencyBug.build/Debug-iphonesimulator/StrictConcurrencyBug.build/Objects-normal/arm64/TestViewController.d -emit-const-values-path /Users/bartcone/Library/Developer/Xcode/DerivedData/StrictConcurrencyBug-dibbntunibjwjtfewlxsuacsrdmj/Build/Intermediates.noindex/StrictConcurrencyBug.build/Debug-iphonesimulator/StrictConcurrencyBug.build/Objects-normal/arm64/TestViewController.swiftconstvalues -emit-reference-dependencies-path /Users/bartcone/Library/Developer/Xcode/DerivedData/StrictConcurrencyBug-dibbntunibjwjtfewlxsuacsrdmj/Build/Intermediates.noindex/StrictConcurrencyBug.build/Debug-iphonesimulator/StrictConcurrencyBug.build/Objects-normal/arm64/TestViewController.swiftdeps -serialize-diagnostics-path /Users/bartcone/Library/Developer/Xcode/DerivedData/StrictConcurrencyBug-dibbntunibjwjtfewlxsuacsrdmj/Build/Intermediates.noindex/StrictConcurrencyBug.build/Debug-iphonesimulator/StrictConcurrencyBug.build/Objects-normal/arm64/TestViewController.dia -emit-localized-strings -emit-localized-strings-path /Users/bartcone/Library/Developer/Xcode/DerivedData/StrictConcurrencyBug-dibbntunibjwjtfewlxsuacsrdmj/Build/Intermediates.noindex/StrictConcurrencyBug.build/Debug-iphonesimulator/StrictConcurrencyBug.build/Objects-normal/arm64 -target arm64-apple-ios17.4-simulator -Xllvm -aarch64-use-tbi -enable-objc-interop -sdk /Applications/Xcode-15.4.0.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator17.5.sdk -I /Users/bartcone/Library/Developer/Xcode/DerivedData/StrictConcurrencyBug-dibbntunibjwjtfewlxsuacsrdmj/Build/Products/Debug-iphonesimulator -F /Users/bartcone/Library/Developer/Xcode/DerivedData/StrictConcurrencyBug-dibbntunibjwjtfewlxsuacsrdmj/Build/Products/Debug-iphonesimulator -no-color-diagnostics -enable-testing -g -module-cache-path /Users/bartcone/Library/Developer/Xcode/DerivedData/ModuleCache.noindex -swift-version 5 -enforce-exclusivity=checked -Onone -D DEBUG -serialize-debugging-options -const-gather-protocols-file /Users/bartcone/Library/Developer/Xcode/DerivedData/StrictConcurrencyBug-dibbntunibjwjtfewlxsuacsrdmj/Build/Intermediates.noindex/StrictConcurrencyBug.build/Debug-iphonesimulator/StrictConcurrencyBug.build/Objects-normal/arm64/StrictConcurrencyBug_const_extract_protocols.json -enable-bare-slash-regex -strict-concurrency=complete -empty-abi-descriptor -validate-clang-modules-once -clang-build-session-file /Users/bartcone/Library/Developer/Xcode/DerivedData/ModuleCache.noindex/Session.modulevalidation -Xcc -working-directory -Xcc /Users/bartcone/Documents/dev/StrictConcurrencyBug -resource-dir /Applications/Xcode-15.4.0.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift -enable-anonymous-context-mangled-names -Xcc -ivfsstatcache -Xcc /Users/bartcone/Library/Developer/Xcode/DerivedData/SDKStatCaches.noindex/iphonesimulator17.5-21F77-89c9b7af80e5612d0557fcca3b72165f.sdkstatcache -Xcc -I/Users/bartcone/Library/Developer/Xcode/DerivedData/StrictConcurrencyBug-dibbntunibjwjtfewlxsuacsrdmj/Build/Intermediates.noindex/StrictConcurrencyBug.build/Debug-iphonesimulator/StrictConcurrencyBug.build/swift-overrides.hmap -Xcc -iquote -Xcc /Users/bartcone/Library/Developer/Xcode/DerivedData/StrictConcurrencyBug-dibbntunibjwjtfewlxsuacsrdmj/Build/Intermediates.noindex/StrictConcurrencyBug.build/Debug-iphonesimulator/StrictConcurrencyBug.build/StrictConcurrencyBug-generated-files.hmap -Xcc -I/Users/bartcone/Library/Developer/Xcode/DerivedData/StrictConcurrencyBug-dibbntunibjwjtfewlxsuacsrdmj/Build/Intermediates.noindex/StrictConcurrencyBug.build/Debug-iphonesimulator/StrictConcurrencyBug.build/StrictConcurrencyBug-own-target-headers.hmap -Xcc -I/Users/bartcone/Library/Developer/Xcode/DerivedData/StrictConcurrencyBug-dibbntunibjwjtfewlxsuacsrdmj/Build/Intermediates.noindex/StrictConcurrencyBug.build/Debug-iphonesimulator/StrictConcurrencyBug.build/StrictConcurrencyBug-all-target-headers.hmap -Xcc -iquote -Xcc /Users/bartcone/Library/Developer/Xcode/DerivedData/StrictConcurrencyBug-dibbntunibjwjtfewlxsuacsrdmj/Build/Intermediates.noindex/StrictConcurrencyBug.build/Debug-iphonesimulator/StrictConcurrencyBug.build/StrictConcurrencyBug-project-headers.hmap -Xcc -I/Users/bartcone/Library/Developer/Xcode/DerivedData/StrictConcurrencyBug-dibbntunibjwjtfewlxsuacsrdmj/Build/Products/Debug-iphonesimulator/include -Xcc -I/Users/bartcone/Library/Developer/Xcode/DerivedData/StrictConcurrencyBug-dibbntunibjwjtfewlxsuacsrdmj/Build/Intermediates.noindex/StrictConcurrencyBug.build/Debug-iphonesimulator/StrictConcurrencyBug.build/DerivedSources-normal/arm64 -Xcc -I/Users/bartcone/Library/Developer/Xcode/DerivedData/StrictConcurrencyBug-dibbntunibjwjtfewlxsuacsrdmj/Build/Intermediates.noindex/StrictConcurrencyBug.build/Debug-iphonesimulator/StrictConcurrencyBug.build/DerivedSources/arm64 -Xcc -I/Users/bartcone/Library/Developer/Xcode/DerivedData/StrictConcurrencyBug-dibbntunibjwjtfewlxsuacsrdmj/Build/Intermediates.noindex/StrictConcurrencyBug.build/Debug-iphonesimulator/StrictConcurrencyBug.build/DerivedSources -Xcc -DDEBUG=1 -module-name StrictConcurrencyBug -frontend-parseable-output -disable-clang-spi -target-sdk-version 17.5 -target-sdk-name iphonesimulator17.5 -external-plugin-path /Applications/Xcode-15.4.0.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator17.5.sdk/usr/lib/swift/host/plugins#/Applications/Xcode-15.4.0.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator17.5.sdk/usr/bin/swift-plugin-server -external-plugin-path /Applications/Xcode-15.4.0.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator17.5.sdk/usr/local/lib/swift/host/plugins#/Applications/Xcode-15.4.0.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator17.5.sdk/usr/bin/swift-plugin-server -external-plugin-path /Applications/Xcode-15.4.0.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/lib/swift/host/plugins#/Applications/Xcode-15.4.0.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/swift-plugin-server -external-plugin-path /Applications/Xcode-15.4.0.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/local/lib/swift/host/plugins#/Applications/Xcode-15.4.0.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/swift-plugin-server -plugin-path /Applications/Xcode-15.4.0.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/host/plugins -plugin-path /Applications/Xcode-15.4.0.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/local/lib/swift/host/plugins -o /Users/bartcone/Library/Developer/Xcode/DerivedData/StrictConcurrencyBug-dibbntunibjwjtfewlxsuacsrdmj/Build/Intermediates.noindex/StrictConcurrencyBug.build/Debug-iphonesimulator/StrictConcurrencyBug.build/Objects-normal/arm64/TestViewController.o -index-unit-output-path /StrictConcurrencyBug.build/Debug-iphonesimulator/StrictConcurrencyBug.build/Objects-normal/arm64/TestViewController.o -index-store-path /Users/bartcone/Library/Developer/Xcode/DerivedData/StrictConcurrencyBug-dibbntunibjwjtfewlxsuacsrdmj/Index.noindex/DataStore -index-system-modules
1.	Apple Swift version 5.10 (swiftlang-5.10.0.13 clang-1500.3.9.4)
2.	Compiling with the current language version
3.	While evaluating request IRGenRequest(IR Generation for file "/Users/bartcone/Documents/dev/StrictConcurrencyBug/StrictConcurrencyBug/TestViewController.swift")
4.	While emitting IR SIL function "@$s20StrictConcurrencyBug18TestViewControllerC06customE033_03C22878A9D7B47F4D9332263C356D40LLAA06CustomE0Cvpfi".
 for expression at [/Users/bartcone/Documents/dev/StrictConcurrencyBug/StrictConcurrencyBug/TestViewController.swift:36:30 - line:36:41] RangeText="CustomView("
Stack dump without symbol names (ensure you have llvm-symbolizer in your PATH or set the environment var `LLVM_SYMBOLIZER_PATH` to point to it):
0  swift-frontend           0x0000000109febf3c llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) + 56
1  swift-frontend           0x0000000109feb0f8 llvm::sys::RunSignalHandlers() + 112
2  swift-frontend           0x0000000109fec544 SignalHandler(int) + 360
3  libsystem_platform.dylib 0x000000019137b584 _sigtramp + 56
4  swift-frontend           0x000000010497c79c llvm::IRBuilderBase::CreateAlignedLoad(llvm::Type*, llvm::Value*, llvm::MaybeAlign, bool, llvm::Twine const&) + 88
5  swift-frontend           0x000000010497c79c llvm::IRBuilderBase::CreateAlignedLoad(llvm::Type*, llvm::Value*, llvm::MaybeAlign, bool, llvm::Twine const&) + 88
6  swift-frontend           0x0000000104cd5704 swift::irgen::IRGenFunction::emitSuspensionPoint(swift::irgen::Explosion&, llvm::Value*) + 984
7  swift-frontend           0x0000000104e1e9a8 (anonymous namespace)::IRGenSILFunction::visitSILBasicBlock(swift::SILBasicBlock*) + 68520
8  swift-frontend           0x0000000104e0c4fc swift::irgen::IRGenModule::emitSILFunction(swift::SILFunction*) + 11556
9  swift-frontend           0x0000000104c60430 swift::irgen::IRGenerator::emitGlobalTopLevel(std::__1::vector<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>, std::__1::allocator<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>>> const&) + 2472
10 swift-frontend           0x0000000104dbf940 swift::IRGenRequest::evaluate(swift::Evaluator&, swift::IRGenDescriptor) const + 4016
11 swift-frontend           0x0000000104e0954c swift::SimpleRequest<swift::IRGenRequest, swift::GeneratedModule (swift::IRGenDescriptor), (swift::RequestFlags)9>::evaluateRequest(swift::IRGenRequest const&, swift::Evaluator&) + 176
12 swift-frontend           0x0000000104dcc264 llvm::Expected<swift::IRGenRequest::OutputType> swift::Evaluator::getResultUncached<swift::IRGenRequest>(swift::IRGenRequest const&) + 836
13 swift-frontend           0x0000000104dc2438 swift::performIRGeneration(swift::FileUnit*, swift::IRGenOptions const&, swift::TBDGenOptions const&, std::__1::unique_ptr<swift::SILModule, std::__1::default_delete<swift::SILModule>>, llvm::StringRef, swift::PrimarySpecificPaths const&, llvm::StringRef, llvm::GlobalVariable**) + 264
14 swift-frontend           0x00000001048f00b8 generateIR(swift::IRGenOptions const&, swift::TBDGenOptions const&, std::__1::unique_ptr<swift::SILModule, std::__1::default_delete<swift::SILModule>>, swift::PrimarySpecificPaths const&, llvm::StringRef, llvm::PointerUnion<swift::ModuleDecl*, swift::SourceFile*>, llvm::GlobalVariable*&, llvm::ArrayRef<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>>) + 156
15 swift-frontend           0x00000001048ea294 performCompileStepsPostSILGen(swift::CompilerInstance&, std::__1::unique_ptr<swift::SILModule, std::__1::default_delete<swift::SILModule>>, llvm::PointerUnion<swift::ModuleDecl*, swift::SourceFile*>, swift::PrimarySpecificPaths const&, int&, swift::FrontendObserver*) + 1892
16 swift-frontend           0x00000001048e9444 swift::performCompileStepsPostSema(swift::CompilerInstance&, int&, swift::FrontendObserver*) + 608
17 swift-frontend           0x00000001048ed694 performCompile(swift::CompilerInstance&, int&, swift::FrontendObserver*) + 1448
18 swift-frontend           0x00000001048eb6d0 swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 4968
19 swift-frontend           0x000000010487ae8c swift::mainEntry(int, char const**) + 2612
20 dyld                     0x0000000190fc20e0 start + 2360

Expected behavior

Expected an error or warning with descriptive reasoning.

Environment

swift-driver version: 1.90.11.1 Apple Swift version 5.10 (swiftlang-5.10.0.13 clang-1500.3.9.4)

Additional information

No response

[hborla]

I can't reproduce this in Swift 6.0. I believe this was fixed by #72332