Expanding a closure's type parameter pack into a tuple of metatypes can crash

[slice]

Description

Performing a pack expansion on a type parameter pack present within a closure's parameters in order to materialize a tuple of its metatypes sometimes crashes the compiler. Compilation can succeed and print (DiscordLib2CrashingSometimes.T, DiscordLib2CrashingSometimes.T), or crash and result in two distinct backtraces. (There can potentially be more, but I have personally only observed two.)

Also, I should note that I have no idea whether this code is actually "supposed" to compile or not—I ran into the crash while experimentally designing an API that uses parameter packs. Assuming that it'd be necessary to conditionalize code at runtime depending on the types in the pack, I instinctually reached for metatypes. I think what I'm aiming to achieve likely won't require this, though, but I haven't sorted all of the details just yet.

Reproduction

protocol Protocol {}
struct T: Protocol {}

struct Command<each A: Protocol> {
    let arguments: (repeat (each A).Type)
}

func command<each A: Protocol>(_ handler: (_ arg: repeat each A) -> Void) -> Command<repeat each A> {
    return Command(arguments: (repeat (each A).self))
}

let myCommand = command { (first: T, second: T) in () }
print(myCommand.arguments)

Stack dump

Warning

This is only one of the stack dumps I observed with this code; the other is linked below.

Stack dump:
0.	Program arguments: /Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2024-02-11-a.xctoolchain/usr/bin/swift-frontend -frontend -interpret DiscordLib2CrashingSometimes.swift -enable-objc-interop -sdk /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk -empty-abi-descriptor -resource-dir /Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2024-02-11-a.xctoolchain/usr/lib/swift -module-name DiscordLib2CrashingSometimes -target-sdk-version 14.2 -target-sdk-name macosx14.2 -external-plugin-path /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/lib/swift/host/plugins#/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/bin/swift-plugin-server -external-plugin-path /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/local/lib/swift/host/plugins#/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/bin/swift-plugin-server -external-plugin-path /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/usr/lib/swift/host/plugins#/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/usr/bin/swift-plugin-server -external-plugin-path /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/usr/local/lib/swift/host/plugins#/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/usr/bin/swift-plugin-server -plugin-path /Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2024-02-11-a.xctoolchain/usr/lib/swift/host/plugins -plugin-path /Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2024-02-11-a.xctoolchain/usr/local/lib/swift/host/plugins
1.	Apple Swift version 5.11-dev (LLVM 1bcf1d71b715d0d, Swift 009a93a0f83dd5c)
2.	Compiling with the current language version
3.	While evaluating request ASTLoweringRequest(Lowering AST to SIL for module DiscordLib2CrashingSometimes)
 #0 0x00000001087867f8 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/llvm-project/llvm/lib/Support/Unix/Signals.inc:610:8
 #1 0x0000000108784ce5 llvm::sys::RunSignalHandlers() /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/llvm-project/llvm/lib/Support/Signals.cpp:105:18
 #2 0x0000000108786e4e SignalHandler(int) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/llvm-project/llvm/lib/Support/Unix/Signals.inc:413:1
 #3 0x00007ff80da6937d (/usr/lib/system/libsystem_platform.dylib+0x7ff80046937d)
 #4 0x0000000000000000 
 #5 0x00000001035e703a swift::Type::Type(swift::TypeBase*) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/include/swift/AST/Type.h:248:40
 #6 0x00000001035e703a swift::CanType::CanType(swift::TypeBase*) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/include/swift/AST/Type.h:447:39
 #7 0x00000001035e703a swift::CanType::CanType(swift::TypeBase*) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/include/swift/AST/Type.h:447:47
 #8 0x00000001035e703a swift::Lowering::AbstractionPattern::AbstractionPattern(swift::SubstitutionMap, swift::CanGenericSignature, swift::CanType) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/include/swift/SIL/AbstractionPattern.h:588:12
 #9 0x00000001035e703a swift::Lowering::AbstractionPattern::AbstractionPattern(swift::SubstitutionMap, swift::CanGenericSignature, swift::CanType) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/include/swift/SIL/AbstractionPattern.h:589:49
#10 0x00000001035e703a swift::Lowering::AbstractionPattern::getTupleElementType(unsigned int) const /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SIL/IR/AbstractionPattern.cpp:420:12
#11 0x0000000102dfa9de swift::TupleType::getElementType(unsigned int) const /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/include/swift/AST/Types.h:2539:12
#12 0x0000000102dfa9de swift::CanTypeWrapper<swift::TupleType>::getElementType(unsigned int) const /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/include/swift/AST/Types.h:2574:34
#13 0x0000000102dfa9de (anonymous namespace)::Transform::transform(swift::Lowering::RValue&&, swift::Lowering::AbstractionPattern, swift::CanType, swift::Lowering::AbstractionPattern, swift::CanType, swift::SILType, swift::Lowering::SGFContext) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenPoly.cpp:361:49
#14 0x0000000102df7782 swift::Lowering::SILGenFunction::emitOrigToSubstValue(swift::SILLocation, swift::Lowering::RValue&&, swift::Lowering::AbstractionPattern, swift::CanType, swift::Lowering::SGFContext) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenPoly.cpp:6424:3
#15 0x0000000102dcafba (anonymous namespace)::OrigToSubstComponent::translate(swift::Lowering::SILGenFunction&, swift::SILLocation, swift::Lowering::RValue&&, swift::Lowering::SGFContext) && /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenLValue.cpp:2619:7
#16 0x0000000102dba4a4 std::__1::vector<swift::Lowering::ManagedValue, std::__1::allocator<swift::Lowering::ManagedValue> >::__destroy_vector::operator()[abi:v160006]() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/vector:445:22
#17 0x0000000102dba4a4 std::__1::vector<swift::Lowering::ManagedValue, std::__1::allocator<swift::Lowering::ManagedValue> >::~vector[abi:v160006]() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/vector:456:67
#18 0x0000000102dba4a4 std::__1::vector<swift::Lowering::ManagedValue, std::__1::allocator<swift::Lowering::ManagedValue> >::~vector[abi:v160006]() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/vector:456:65
#19 0x0000000102dba4a4 swift::Lowering::RValue::~RValue() /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/RValue.h:72:7
#20 0x0000000102dba4a4 swift::Lowering::RValue::~RValue() /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/RValue.h:72:7
#21 0x0000000102dba4a4 swift::Lowering::TranslationPathComponent::get(swift::Lowering::SILGenFunction&, swift::SILLocation, swift::Lowering::ManagedValue, swift::Lowering::SGFContext) && /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenLValue.cpp:2580:1
#22 0x0000000102dc01fa swift::Lowering::RValue::isComplete() const & /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/RValue.h:202:38
#23 0x0000000102dc01fa swift::Lowering::RValue::operator=(swift::Lowering::RValue&&) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/RValue.h:146:5
#24 0x0000000102dc01fa swift::Lowering::SILGenFunction::emitLoadOfLValue(swift::SILLocation, swift::Lowering::LValue&&, swift::Lowering::SGFContext, bool) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenLValue.cpp:5110:14
#25 0x0000000102d91095 std::__1::vector<std::__1::unique_ptr<swift::Lowering::PathComponent, std::__1::default_delete<swift::Lowering::PathComponent> >, std::__1::allocator<std::__1::unique_ptr<swift::Lowering::PathComponent, std::__1::default_delete<swift::Lowering::PathComponent> > > >::__destroy_vector::operator()[abi:v160006]() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/vector:445:22
#26 0x0000000102d91095 std::__1::vector<std::__1::unique_ptr<swift::Lowering::PathComponent, std::__1::default_delete<swift::Lowering::PathComponent> >, std::__1::allocator<std::__1::unique_ptr<swift::Lowering::PathComponent, std::__1::default_delete<swift::Lowering::PathComponent> > > >::~vector[abi:v160006]() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/vector:456:67
#27 0x0000000102d91095 std::__1::vector<std::__1::unique_ptr<swift::Lowering::PathComponent, std::__1::default_delete<swift::Lowering::PathComponent> >, std::__1::allocator<std::__1::unique_ptr<swift::Lowering::PathComponent, std::__1::default_delete<swift::Lowering::PathComponent> > > >::~vector[abi:v160006]() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/vector:456:65
#28 0x0000000102d91095 swift::Lowering::LValue::~LValue() /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/LValue.h:357:7
#29 0x0000000102d91095 swift::Lowering::LValue::~LValue() /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/LValue.h:357:7
#30 0x0000000102d91095 (anonymous namespace)::RValueEmitter::visitMemberRefExpr(swift::MemberRefExpr*, swift::Lowering::SGFContext) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenExpr.cpp:2573:1
#31 0x0000000102d8cd44 swift::ASTVisitor<(anonymous namespace)::RValueEmitter, swift::Lowering::RValue, void, void, void, void, void, swift::Lowering::SGFContext>::visit(swift::Expr*, swift::Lowering::SGFContext) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/include/swift/AST/ExprNodes.def:0:3
#32 0x0000000102d822ec swift::Lowering::SILGenFunction::emitRValue(swift::Expr*, swift::Lowering::SGFContext) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenExpr.cpp:0:31
#33 0x0000000102d822ec swift::Lowering::SILGenFunction::emitRValueAsSingleValue(swift::Expr*, swift::Lowering::SGFContext) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenExpr.cpp:6720:10
#34 0x0000000102df7cc7 swift::Lowering::SILGenFunction::emitRValueAsOrig(swift::Expr*, swift::Lowering::AbstractionPattern, swift::Lowering::TypeLowering const&, swift::Lowering::SGFContext) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenPoly.cpp:0:23
#35 0x0000000102da1bc7 swift::Lowering::ManagedValue llvm::function_ref<swift::Lowering::ManagedValue (swift::Lowering::SGFContext)>::callback_fn<(anonymous namespace)::RValueEmitter::visitErasureExpr(swift::ErasureExpr*, swift::Lowering::SGFContext)::$_11>(long, swift::Lowering::SGFContext) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/llvm-project/llvm/include/llvm/ADT/STLFunctionalExtras.h:45:5
#36 0x0000000102d67569 swift::Lowering::SILGenFunction::emitExistentialErasure(swift::SILLocation, swift::CanType, swift::Lowering::TypeLowering const&, swift::Lowering::TypeLowering const&, llvm::ArrayRef<swift::ProtocolConformanceRef>, swift::Lowering::SGFContext, llvm::function_ref<swift::Lowering::ManagedValue (swift::Lowering::SGFContext)>, bool)::$_6::operator()(swift::SILValue) const /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenConvert.cpp:870:29
#37 0x0000000102d67569 void llvm::function_ref<void (swift::SILValue)>::callback_fn<swift::Lowering::SILGenFunction::emitExistentialErasure(swift::SILLocation, swift::CanType, swift::Lowering::TypeLowering const&, swift::Lowering::TypeLowering const&, llvm::ArrayRef<swift::ProtocolConformanceRef>, swift::Lowering::SGFContext, llvm::function_ref<swift::Lowering::ManagedValue (swift::Lowering::SGFContext)>, bool)::$_6>(long, swift::SILValue) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/llvm-project/llvm/include/llvm/ADT/STLFunctionalExtras.h:45:12
#38 0x0000000102d493f2 swift::Lowering::SGFContext::getAddressForInPlaceInitialization(swift::Lowering::SILGenFunction&, swift::SILLocation) const /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SGFContext.h:95:15
#39 0x0000000102d493f2 swift::Lowering::SILGenBuilder::bufferForExpr(swift::SILLocation, swift::SILType, swift::Lowering::TypeLowering const&, swift::Lowering::SGFContext, llvm::function_ref<void (swift::SILValue)>) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenBuilder.cpp:387:30
#40 0x0000000102d62d2e swift::Lowering::SILGenFunction::emitExistentialErasure(swift::SILLocation, swift::CanType, swift::Lowering::TypeLowering const&, swift::Lowering::TypeLowering const&, llvm::ArrayRef<swift::ProtocolConformanceRef>, swift::Lowering::SGFContext, llvm::function_ref<swift::Lowering::ManagedValue (swift::Lowering::SGFContext)>, bool) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenConvert.cpp:0:14
#41 0x0000000102d9875c (anonymous namespace)::RValueEmitter::visitErasureExpr(swift::ErasureExpr*, swift::Lowering::SGFContext) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenExpr.cpp:2149:25
#42 0x0000000102d8cf2b swift::ASTVisitor<(anonymous namespace)::RValueEmitter, swift::Lowering::RValue, void, void, void, void, void, swift::Lowering::SGFContext>::visit(swift::Expr*, swift::Lowering::SGFContext) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/include/swift/AST/ExprNodes.def:0:3
#43 0x0000000102d7f2fc swift::Lowering::RValue::isInContext() const & /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/RValue.h:211:57
#44 0x0000000102d7f2fc swift::Lowering::SILGenFunction::emitExprInto(swift::Expr*, swift::Lowering::Initialization*, std::__1::optional<swift::SILLocation>) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenExpr.cpp:413:14
#45 0x0000000102ce7f8b swift::Lowering::ArgumentSource::forwardInto(swift::Lowering::SILGenFunction&, swift::Lowering::Initialization*) && /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/ArgumentSource.cpp:125:1
#46 0x0000000102ce853b swift::Lowering::ArgumentSource::forwardInto(swift::Lowering::SILGenFunction&, swift::Lowering::AbstractionPattern, swift::Lowering::Initialization*, swift::Lowering::TypeLowering const&) && /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/ArgumentSource.cpp:0:22
#47 0x0000000102d9efd8 swift::Lowering::ArgumentSource::~ArgumentSource() /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/ArgumentSource.h:115:22
#48 0x0000000102d9efd8 swift::Lowering::ArgumentSource::~ArgumentSource() /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/ArgumentSource.h:114:21
#49 0x0000000102d9efd8 (anonymous namespace)::RValueEmitter::visitCollectionExpr(swift::CollectionExpr*, swift::Lowering::SGFContext) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenExpr.cpp:4445:5
#50 0x0000000102d8cc7c swift::ASTVisitor<(anonymous namespace)::RValueEmitter, swift::Lowering::RValue, void, void, void, void, void, swift::Lowering::SGFContext>::visit(swift::Expr*, swift::Lowering::SGFContext) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/include/swift/AST/ExprNodes.def:0:0
#51 0x0000000102d822ec swift::Lowering::SILGenFunction::emitRValue(swift::Expr*, swift::Lowering::SGFContext) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenExpr.cpp:0:31
#52 0x0000000102d822ec swift::Lowering::SILGenFunction::emitRValueAsSingleValue(swift::Expr*, swift::Lowering::SGFContext) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenExpr.cpp:6720:10
#53 0x0000000102d2a8a0 swift::isConsumedParameter(swift::ParameterConvention) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/include/swift/AST/Types.h:4096:3
#54 0x0000000102d2a8a0 swift::SILParameterInfo::isConsumed() const /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/include/swift/AST/Types.h:4243:12
#55 0x0000000102d2a8a0 (anonymous namespace)::ArgEmitter::emitDirect(swift::Lowering::ArgumentSource&&, swift::SILType, swift::Lowering::AbstractionPattern, swift::SILParameterInfo, std::__1::optional<swift::AnyFunctionType::Param>) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenApply.cpp:3855:18
#56 0x0000000102d2a8a0 (anonymous namespace)::ArgEmitter::emit(swift::Lowering::ArgumentSource&&, swift::Lowering::AbstractionPattern, std::__1::optional<swift::AnyFunctionType::Param>) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenApply.cpp:3546:5
#57 0x0000000102d17be4 (anonymous namespace)::ArgEmitter::emitSingleArg(swift::Lowering::ArgumentSource&&, swift::Lowering::AbstractionPattern, std::__1::optional<swift::AnyFunctionType::Param>) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenApply.cpp:3409:5
#58 0x0000000102d28b15 (anonymous namespace)::ArgEmitter::emitPreparedArgs(swift::Lowering::PreparedArguments&&, swift::Lowering::AbstractionPattern) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenApply.cpp:0:9
#59 0x0000000102d36643 (anonymous namespace)::CallSite::emit(swift::Lowering::SILGenFunction&, swift::Lowering::AbstractionPattern, swift::CanTypeWrapper<swift::SILFunctionType>, (anonymous namespace)::ParamLowering&, llvm::SmallVectorImpl<swift::Lowering::ManagedValue>&, llvm::SmallVectorImpl<(anonymous namespace)::DelayedArgument>&, swift::ForeignInfo const&) && /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenApply.cpp:0:13
#60 0x0000000102d35d5e llvm::ArrayRef<swift::SILParameterInfo>::empty() const /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/llvm-project/llvm/include/llvm/ADT/ArrayRef.h:160:40
#61 0x0000000102d35d5e (anonymous namespace)::ParamLowering::~ParamLowering() /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenApply.cpp:4691:5
#62 0x0000000102d35d5e (anonymous namespace)::ParamLowering::~ParamLowering() /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenApply.cpp:4690:20
#63 0x0000000102d35d5e (anonymous namespace)::CallEmission::emitArgumentsForNormalApply(swift::Lowering::AbstractionPattern, swift::CanTypeWrapper<swift::SILFunctionType>, swift::ForeignInfo const&, llvm::SmallVectorImpl<swift::Lowering::ManagedValue>&, std::__1::optional<swift::SILLocation>&) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenApply.cpp:5371:3
#64 0x0000000102d1bd25 (anonymous namespace)::CallEmission::applyNormalCall(swift::Lowering::SGFContext) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenApply.cpp:5097:26
#65 0x0000000102d1bd25 (anonymous namespace)::CallEmission::applyFirstLevelCallee(swift::Lowering::SGFContext) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenApply.cpp:5044:10
#66 0x0000000102d1bd25 (anonymous namespace)::CallEmission::apply(swift::Lowering::SGFContext) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenApply.cpp:4845:18
#67 0x0000000102d197f2 swift::Lowering::SILGenFunction::emitApplyExpr(swift::ApplyExpr*, swift::Lowering::SGFContext) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenApply.cpp:6144:1
#68 0x0000000102d8cc59 swift::ASTVisitor<(anonymous namespace)::RValueEmitter, swift::Lowering::RValue, void, void, void, void, void, swift::Lowering::SGFContext>::visit(swift::Expr*, swift::Lowering::SGFContext) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/include/swift/AST/ExprNodes.def:0:0
#69 0x0000000102d82a0f std::__1::vector<swift::Lowering::ManagedValue, std::__1::allocator<swift::Lowering::ManagedValue> >::__destroy_vector::operator()[abi:v160006]() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/vector:445:22
#70 0x0000000102d82a0f std::__1::vector<swift::Lowering::ManagedValue, std::__1::allocator<swift::Lowering::ManagedValue> >::~vector[abi:v160006]() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/vector:456:67
#71 0x0000000102d82a0f std::__1::vector<swift::Lowering::ManagedValue, std::__1::allocator<swift::Lowering::ManagedValue> >::~vector[abi:v160006]() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/vector:456:65
#72 0x0000000102d82a0f swift::Lowering::RValue::~RValue() /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/RValue.h:72:7
#73 0x0000000102d82a0f swift::Lowering::RValue::~RValue() /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/RValue.h:72:7
#74 0x0000000102d82a0f swift::Lowering::SILGenFunction::emitIgnoredExpr(swift::Expr*) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenExpr.cpp:6714:3
#75 0x0000000102e32ff3 swift::Lowering::SILGenTopLevel::visitTopLevelCodeDecl(swift::TopLevelCodeDecl*) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenTopLevel.cpp:0:11
#76 0x0000000102e3101b swift::Lowering::SILGenTopLevel::visitSourceFile(swift::SourceFile*) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenTopLevel.cpp:380:16
#77 0x0000000102e3053d swift::DiverseStackBase::stable_iterator::isValid() const /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/include/swift/Basic/DiverseStack.h:119:20
#78 0x0000000102e3053d swift::Lowering::Scope::~Scope() /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/Scope.h:78:15
#79 0x0000000102e3053d swift::Lowering::Scope::~Scope() /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/Scope.h:77:12
#80 0x0000000102e3053d swift::Lowering::SILGenModule::emitEntryPoint(swift::SourceFile*, swift::SILFunction*) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenTopLevel.cpp:88:3
#81 0x0000000102e327e1 swift::Lowering::SILGenModule::emitEntryPoint(swift::SourceFile*) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGenTopLevel.cpp:0:3
#82 0x0000000102d090ce (anonymous namespace)::SILGenModuleRAII::emitSourceFile(swift::SourceFile*) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGen.cpp:1991:11
#83 0x0000000102d090ce swift::ASTLoweringRequest::evaluate(swift::Evaluator&, swift::ASTLoweringDescriptor) const /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGen.cpp:2142:13
#84 0x0000000102e1fe41 std::__1::__optional_destruct_base<llvm::SmallVector<swift::SymbolSource, 1u>, false>::~__optional_destruct_base[abi:v160006]() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/optional:247:13
#85 0x0000000102e1fe41 std::__1::__optional_storage_base<llvm::SmallVector<swift::SymbolSource, 1u>, false>::~__optional_storage_base() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/optional:322:8
#86 0x0000000102e1fe41 std::__1::__optional_copy_base<llvm::SmallVector<swift::SymbolSource, 1u>, false>::~__optional_copy_base() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/optional:495:8
#87 0x0000000102e1fe41 std::__1::__optional_move_base<llvm::SmallVector<swift::SymbolSource, 1u>, false>::~__optional_move_base() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/optional:523:8
#88 0x0000000102e1fe41 std::__1::__optional_copy_assign_base<llvm::SmallVector<swift::SymbolSource, 1u>, false>::~__optional_copy_assign_base() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/optional:556:8
#89 0x0000000102e1fe41 std::__1::__optional_move_assign_base<llvm::SmallVector<swift::SymbolSource, 1u>, false>::~__optional_move_assign_base() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/optional:588:8
#90 0x0000000102e1fe41 std::__1::optional<llvm::SmallVector<swift::SymbolSource, 1u> >::~optional() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/optional:631:7
#91 0x0000000102e1fe41 std::__1::optional<llvm::SmallVector<swift::SymbolSource, 1u> >::~optional() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/optional:631:7
#92 0x0000000102e1fe41 swift::ASTLoweringDescriptor::~ASTLoweringDescriptor() /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/include/swift/AST/SILGenRequests.h:50:8
#93 0x0000000102e1fe41 swift::ASTLoweringDescriptor::~ASTLoweringDescriptor() /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/include/swift/AST/SILGenRequests.h:50:8
#94 0x0000000102e1fe41 std::__1::unique_ptr<swift::SILModule, std::__1::default_delete<swift::SILModule> > swift::SimpleRequest<swift::ASTLoweringRequest, std::__1::unique_ptr<swift::SILModule, std::__1::default_delete<swift::SILModule> > (swift::ASTLoweringDescriptor), (swift::RequestFlags)9>::callDerived<0ul>(swift::Evaluator&, std::__1::integer_sequence<unsigned long, 0ul>) const /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/include/swift/AST/SimpleRequest.h:267:5
#95 0x0000000102e1fe41 swift::SimpleRequest<swift::ASTLoweringRequest, std::__1::unique_ptr<swift::SILModule, std::__1::default_delete<swift::SILModule> > (swift::ASTLoweringDescriptor), (swift::RequestFlags)9>::evaluateRequest(swift::ASTLoweringRequest const&, swift::Evaluator&) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/include/swift/AST/SimpleRequest.h:290:20
#96 0x0000000102d0eda9 swift::ASTLoweringRequest::OutputType swift::Evaluator::getResultUncached<swift::ASTLoweringRequest, swift::ASTLoweringRequest::OutputType swift::evaluateOrFatal<swift::ASTLoweringRequest>(swift::Evaluator&, swift::ASTLoweringRequest)::'lambda'()>(swift::ASTLoweringRequest const&, swift::ASTLoweringRequest::OutputType swift::evaluateOrFatal<swift::ASTLoweringRequest>(swift::Evaluator&, swift::ASTLoweringRequest)::'lambda'()) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/include/swift/AST/Evaluator.h:324:14
#97 0x0000000102d09a79 std::__1::__optional_destruct_base<llvm::SmallVector<swift::SymbolSource, 1u>, false>::~__optional_destruct_base[abi:v160006]() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/optional:247:13
#98 0x0000000102d09a79 std::__1::__optional_storage_base<llvm::SmallVector<swift::SymbolSource, 1u>, false>::~__optional_storage_base() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/optional:322:8
#99 0x0000000102d09a79 std::__1::__optional_copy_base<llvm::SmallVector<swift::SymbolSource, 1u>, false>::~__optional_copy_base() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/optional:495:8
#100 0x0000000102d09a79 std::__1::__optional_move_base<llvm::SmallVector<swift::SymbolSource, 1u>, false>::~__optional_move_base() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/optional:523:8
#101 0x0000000102d09a79 std::__1::__optional_copy_assign_base<llvm::SmallVector<swift::SymbolSource, 1u>, false>::~__optional_copy_assign_base() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/optional:556:8
#102 0x0000000102d09a79 std::__1::__optional_move_assign_base<llvm::SmallVector<swift::SymbolSource, 1u>, false>::~__optional_move_assign_base() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/optional:588:8
#103 0x0000000102d09a79 std::__1::optional<llvm::SmallVector<swift::SymbolSource, 1u> >::~optional() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/optional:631:7
#104 0x0000000102d09a79 std::__1::optional<llvm::SmallVector<swift::SymbolSource, 1u> >::~optional() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/optional:631:7
#105 0x0000000102d09a79 swift::ASTLoweringDescriptor::~ASTLoweringDescriptor() /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/include/swift/AST/SILGenRequests.h:50:8
#106 0x0000000102d09a79 swift::ASTLoweringDescriptor::~ASTLoweringDescriptor() /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/include/swift/AST/SILGenRequests.h:50:8
#107 0x0000000102d09a79 std::__1::__tuple_leaf<0ul, swift::ASTLoweringDescriptor, false>::~__tuple_leaf() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/tuple:293:7
#108 0x0000000102d09a79 std::__1::__tuple_impl<std::__1::__tuple_indices<0ul>, swift::ASTLoweringDescriptor>::~__tuple_impl() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/tuple:479:37
#109 0x0000000102d09a79 std::__1::__tuple_impl<std::__1::__tuple_indices<0ul>, swift::ASTLoweringDescriptor>::~__tuple_impl() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/tuple:479:37
#110 0x0000000102d09a79 std::__1::tuple<swift::ASTLoweringDescriptor>::~tuple() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/tuple:566:28
#111 0x0000000102d09a79 std::__1::tuple<swift::ASTLoweringDescriptor>::~tuple() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/tuple:566:28
#112 0x0000000102d09a79 swift::SimpleRequest<swift::ASTLoweringRequest, std::__1::unique_ptr<swift::SILModule, std::__1::default_delete<swift::SILModule> > (swift::ASTLoweringDescriptor), (swift::RequestFlags)9>::~SimpleRequest() /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/include/swift/AST/SimpleRequest.h:252:7
#113 0x0000000102d09a79 swift::ASTLoweringRequest::~ASTLoweringRequest() /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/include/swift/AST/SILGenRequests.h:111:7
#114 0x0000000102d09a79 swift::ASTLoweringRequest::~ASTLoweringRequest() /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/include/swift/AST/SILGenRequests.h:111:7
#115 0x0000000102d09a79 swift::performASTLowering(swift::ModuleDecl*, swift::Lowering::TypeConverter&, swift::SILOptions const&, swift::IRGenOptions const*) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/SILGen/SILGen.cpp:2165:3
#116 0x000000010262a317 std::__1::unique_ptr<swift::SILModule, std::__1::default_delete<swift::SILModule> >::release[abi:v160006]() /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/__memory/unique_ptr.h:288:26
#117 0x000000010262a317 std::__1::unique_ptr<swift::SILModule, std::__1::default_delete<swift::SILModule> >::unique_ptr[abi:v160006](std::__1::unique_ptr<swift::SILModule, std::__1::default_delete<swift::SILModule> >&&) /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/__memory/unique_ptr.h:211:20
#118 0x000000010262a317 std::__1::unique_ptr<swift::SILModule, std::__1::default_delete<swift::SILModule> >::unique_ptr[abi:v160006](std::__1::unique_ptr<swift::SILModule, std::__1::default_delete<swift::SILModule> >&&) /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/__memory/unique_ptr.h:211:80
#119 0x000000010262a317 swift::performCompileStepsPostSema(swift::CompilerInstance&, int&, swift::FrontendObserver*) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/FrontendTool/FrontendTool.cpp:882:52
#120 0x000000010263d7cf withSemanticAnalysis(swift::CompilerInstance&, swift::FrontendObserver*, llvm::function_ref<bool (swift::CompilerInstance&)>, bool) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/FrontendTool/FrontendTool.cpp:1304:25
#121 0x000000010262cc47 performAction(swift::CompilerInstance&, int&, swift::FrontendObserver*) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/FrontendTool/FrontendTool.cpp:0:12
#122 0x000000010262cc47 performCompile(swift::CompilerInstance&, int&, swift::FrontendObserver*) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/FrontendTool/FrontendTool.cpp:1515:19
#123 0x000000010262b96e swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/FrontendTool/FrontendTool.cpp:2470:19
#124 0x000000010244aecb run_driver(llvm::StringRef, llvm::ArrayRef<char const*>, llvm::ArrayRef<char const*>) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/DriverTool/driver.cpp:0:0
#125 0x000000010244aecb swift::mainEntry(int, char const**) /Users/ec2-user/jenkins/workspace/oss-swift-package-macos/swift/lib/DriverTool/driver.cpp:531:10
#126 0x0000000215fb2386

Expected behavior

I expect the code to print (DiscordLib2CrashingSometimes.T, DiscordLib2CrashingSometimes.T) all the time.

Environment

Apple Swift version 5.11-dev (LLVM 1bcf1d71b715d0d, Swift 009a93a)
Target: x86_64-apple-macosx14.0

Additional information

The stack dump provided is only one of the observed stack traces. Here is the other one: run_other.txt

Also, I noticed that by removing the second parameter in the code like this:

-let myCommand = command { (first: T, second: T) in () }
+let myCommand = command { (first: T) in () }

You get a different (albeit consistent, phew) compilation error. This might be a separate issue, but I figured I'd note it.

[slice]

Target: x86_64-apple-macosx14.0

I installed a trunk toolchain (with symbols) in an effort to build with the latest version of the compiler, but it's going through Rosetta (?) for some reason; I am on an Mac with Apple silicon.

The code still intermittently crashes (or suceeds) on the latest stable Xcode at the time of writing, but with (yet) another different stack dump. Luckily, there only seems to be one failure path here:

swift-driver version: 1.87.3 Apple Swift version 5.9.2 (swiftlang-5.9.2.2.56 clang-1500.1.0.2.5)
Target: arm64-apple-macosx14.0
Stack dump: run_swift592.txt

Again, it could be an unrelated or since-solved issue, but I figured I'd note it anyways.