Crash While Type Checking

[ed-irl]

Description

This code compiled under the previous 5.x compiler release (not sure which one - perhaps 5.10?). Xcode upgraded itself today, and now with the swift 6 compiler I get a crash.

Reproduction

import Foundation
import SwiftUI

protocol Workout: AnyObject, Observable, Hashable, Identifiable {
  associatedtype WorkoutExerciseSet: ExerciseSet & Observable

  var workoutId: UUID { get set }
  var name: String { get set }
  var createdAt: Date { get set }
  var updatedAt: Date { get set }
  var sets: [WorkoutExerciseSet] { get set }
}

@Observable class EphemeralExerciseSet: ExerciseSet {
  var order: Int
  var name: String
  var reps: Int
  var resistance: Double
  var resistanceUnit: String
  var markedCompleteAt: Date?

  init(order: Int, name: String, reps: Int, resistance: Double, resistanceUnit: String, markedCompleteAt: Date?) {
    self.order = order
    self.name = name
    self.reps = reps
    self.resistance = resistance
    self.resistanceUnit = resistanceUnit
    self.markedCompleteAt = markedCompleteAt
  }

  func hash(into hasher: inout Hasher) {
    hasher.combine(order)
    hasher.combine(name)
    hasher.combine(reps)
    hasher.combine(resistance)
    hasher.combine(resistanceUnit)
    hasher.combine(markedCompleteAt)
  }

  static func == (lhs: EphemeralExerciseSet, rhs: EphemeralExerciseSet) -> Bool {
    return lhs.order == rhs.order &&
      lhs.name == rhs.name &&
      lhs.reps == rhs.reps &&
      lhs.resistance == rhs.resistance &&
      lhs.resistanceUnit == rhs.resistanceUnit &&
      lhs.markedCompleteAt == rhs.markedCompleteAt
  }
}

@Observable class EphemeralWorkout: Workout {
  var workoutId: UUID

  var name: String
  var createdAt: Date
  var updatedAt: Date
  var sets: [EphemeralExerciseSet]

  init(workoutId: UUID = UUID(), name: String = "", createdAt: Date = Date(), updatedAt: Date = Date(), sets: [EphemeralExerciseSet] = []) {
    self.workoutId = workoutId
    self.name = name
    self.createdAt = createdAt
    self.updatedAt = updatedAt
    self.sets = sets
  }

  func hash(into hasher: inout Hasher) {
    hasher.combine(workoutId)
    hasher.combine(name)
    hasher.combine(createdAt)
    hasher.combine(updatedAt)
    hasher.combine(sets)
  }

  static func == (lhs: EphemeralWorkout, rhs: EphemeralWorkout) -> Bool {
    return lhs.workoutId == rhs.workoutId &&
      lhs.name == rhs.name &&
      lhs.createdAt == rhs.createdAt &&
      lhs.updatedAt == rhs.updatedAt &&
      lhs.sets == rhs.sets
  }
}

protocol ExerciseSet: Observable, Hashable, Identifiable {
  var name: String { get set }
  var reps: Int { get set }
  var resistance: Double { get set }
  var resistanceUnit: String { get set }
  var markedCompleteAt: Date? { get set }
  var order: Int { get set }
}

@MainActor
protocol WorkoutPersistence<WorkoutType> {
  associatedtype WorkoutType: Workout
  func insert(_ workout: WorkoutType)
  func copy(_ workout: any Workout) -> WorkoutType
  func delete(_ workout: WorkoutType)
  func copy(_ exerciseSet: any ExerciseSet) -> WorkoutType.WorkoutExerciseSet
  func newSet(name: String, reps: Int, resistance: Double, resistanceUnit: String, order: Int) -> WorkoutType.WorkoutExerciseSet
}

class EphemeralWorkoutPersistence: WorkoutPersistence {
  func insert(_ workout: EphemeralWorkout) {}

  func copy(_ workout: any Workout) -> EphemeralWorkout {
    let originalSets: [any ExerciseSet] = workout.sets
    let setsCopy: [EphemeralExerciseSet] = originalSets.map(copy)
    return EphemeralWorkout(name: workout.name, sets: setsCopy)
  }

  func delete(_ workout: EphemeralWorkout) {}

  func copy(_ exerciseSet: any ExerciseSet) -> EphemeralExerciseSet {
    return EphemeralExerciseSet(
      order: exerciseSet.order,
      name: exerciseSet.name,
      reps: exerciseSet.reps,
      resistance: exerciseSet.resistance,
      resistanceUnit: exerciseSet.resistanceUnit,
      markedCompleteAt: Date()
    )
  }

  func newSet(name: String, reps: Int, resistance: Double, resistanceUnit: String, order: Int) -> EphemeralExerciseSet {
    return EphemeralExerciseSet(order: order, name: name, reps: reps, resistance: resistance, resistanceUnit: resistanceUnit, markedCompleteAt: Date())
  }

  typealias WorkoutType = EphemeralWorkout
}

Stack dump

error: compile command failed due to signal 6 (use -v to see invocation)
Unhandled coercion:
(array_slice_type
  (opened_archetype_type address=0x1202908b8 conforms_to="Contents.(file)[email protected]:83:10" opened_existential_id="F29E82FE-750E-11EF-92AF-DE0800FD984B"
    (interface_type=dependent_member_type assoc_type="Contents.(file)[email protected]:5:18"
      (base=generic_type_param_type depth=0 index=0))
    (opened_existential=existential_type
      (protocol_type decl="Contents.(file)[email protected]:4:10"))))
(lvalue_type
  (array_slice_type
    (existential_type
      (protocol_type decl="Contents.(file)[email protected]:83:10"))))
Please submit a bug report (https://swift.org/contributing/#reporting-bugs) and include the crash backtrace.
Stack dump:
0.	Program arguments: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift-frontend -frontend -c -primary-file Contents.swift -target arm64-apple-macosx15.0 -Xllvm -aarch64-use-tbi -enable-objc-interop -stack-check -sdk /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX15.0.sdk -color-diagnostics -new-driver-path /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift-driver -empty-abi-descriptor -resource-dir /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift -module-name Contents -disable-clang-spi -target-sdk-version 15.0 -target-sdk-name macosx15.0 -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 /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/host/plugins -plugin-path /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/local/lib/swift/host/plugins -o /var/folders/fp/3l06jfz175s6w114bdhcsc1h0000gn/T/TemporaryDirectory.5wpURp/Contents-1.o
1.	Apple Swift version 6.0 (swiftlang-6.0.0.9.10 clang-1600.0.26.2)
2.	Compiling with effective version 5.10
3.	While evaluating request TypeCheckSourceFileRequest(source_file "Contents.swift")
4.	While evaluating request TypeCheckFunctionBodyRequest(Contents.(file)[email protected]:105:8)
5.	While type-checking statement at [Contents.swift:105:57 - line:109:3] RangeText="{
    let originalSets: [any ExerciseSet] = workout.sets
    let setsCopy: [EphemeralExerciseSet] = originalSets.map(copy)
    return EphemeralWorkout(name: workout.name, sets: setsCopy)
  "
6.	While type-checking declaration 0x1501e1770 (at Contents.swift:106:5)
7.	While type-checking expression at [Contents.swift:106:43 - line:106:51] RangeText="workout."
8.	While type-checking-target starting at Contents.swift:106:51
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           0x00000001088770fc llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) + 56
1  swift-frontend           0x0000000108875350 llvm::sys::RunSignalHandlers() + 112
2  swift-frontend           0x00000001088776c8 SignalHandler(int) + 292
3  libsystem_platform.dylib 0x0000000188b00184 _sigtramp + 56
4  libsystem_pthread.dylib  0x0000000188acaf70 pthread_kill + 288
5  libsystem_c.dylib        0x00000001889d7908 abort + 128
6  swift-frontend           0x00000001042e310c (anonymous namespace)::ExprRewriter::coerceToType(swift::Expr*, swift::Type, swift::constraints::ConstraintLocatorBuilder) + 10492
7  swift-frontend           0x00000001042e21ac (anonymous namespace)::ExprRewriter::coerceToType(swift::Expr*, swift::Type, swift::constraints::ConstraintLocatorBuilder) + 6556
8  swift-frontend           0x00000001043024d4 (anonymous namespace)::ExprRewriter::closeExistential(swift::Expr*&, swift::constraints::ConstraintLocatorBuilder, bool) + 596
9  swift-frontend           0x00000001042fb118 (anonymous namespace)::ExprRewriter::buildMemberRef(swift::Expr*, swift::SourceLoc, swift::constraints::SelectedOverload, swift::DeclNameLoc, swift::constraints::ConstraintLocatorBuilder, swift::constraints::ConstraintLocatorBuilder, bool, swift::AccessSemantics) + 9320
10 swift-frontend           0x00000001042eceb8 (anonymous namespace)::ExprRewriter::walkToExprPost(swift::Expr*) + 21120
11 swift-frontend           0x00000001042e4664 (anonymous namespace)::ExprWalker::walkToExprPost(swift::Expr*) + 24
12 swift-frontend           0x00000001042dee40 (anonymous namespace)::ExprWalker::rewriteTarget(swift::constraints::SyntacticElementTarget) + 2748
13 swift-frontend           0x00000001042ddec0 swift::constraints::ConstraintSystem::applySolution(swift::constraints::Solution&, swift::constraints::SyntacticElementTarget) + 7120
14 swift-frontend           0x000000010459d6a8 swift::TypeChecker::typeCheckTarget(swift::constraints::SyntacticElementTarget&, swift::optionset::OptionSet<swift::TypeCheckExprFlags, unsigned int>) + 680
15 swift-frontend           0x000000010459d2dc swift::TypeChecker::typeCheckExpression(swift::constraints::SyntacticElementTarget&, swift::optionset::OptionSet<swift::TypeCheckExprFlags, unsigned int>) + 416
16 swift-frontend           0x000000010459e918 swift::TypeChecker::typeCheckBinding(swift::Pattern*&, swift::Expr*&, swift::DeclContext*, swift::Type, swift::PatternBindingDecl*, unsigned int, swift::optionset::OptionSet<swift::TypeCheckExprFlags, unsigned int>) + 172
17 swift-frontend           0x000000010459eba8 swift::TypeChecker::typeCheckPatternBinding(swift::PatternBindingDecl*, unsigned int, swift::Type, swift::optionset::OptionSet<swift::TypeCheckExprFlags, unsigned int>) + 356
18 swift-frontend           0x00000001045f26c8 (anonymous namespace)::DeclChecker::visit(swift::Decl*) + 6940
19 swift-frontend           0x00000001045f0b9c swift::TypeChecker::typeCheckDecl(swift::Decl*) + 152
20 swift-frontend           0x000000010468d97c swift::ASTVisitor<(anonymous namespace)::StmtChecker, void, swift::Stmt*, void, void, void, void>::visit(swift::Stmt*) + 288
21 swift-frontend           0x000000010468b2bc bool (anonymous namespace)::StmtChecker::typeCheckStmt<swift::BraceStmt>(swift::BraceStmt*&) + 316
22 swift-frontend           0x0000000104689e58 swift::TypeCheckFunctionBodyRequest::evaluate(swift::Evaluator&, swift::AbstractFunctionDecl*) const + 1512
23 swift-frontend           0x0000000104a9a798 swift::TypeCheckFunctionBodyRequest::OutputType swift::Evaluator::getResultUncached<swift::TypeCheckFunctionBodyRequest, swift::TypeCheckFunctionBodyRequest::OutputType swift::evaluateOrDefault<swift::TypeCheckFunctionBodyRequest>(swift::Evaluator&, swift::TypeCheckFunctionBodyRequest, swift::TypeCheckFunctionBodyRequest::OutputType)::'lambda'()>(swift::TypeCheckFunctionBodyRequest const&, swift::TypeCheckFunctionBodyRequest::OutputType swift::evaluateOrDefault<swift::TypeCheckFunctionBodyRequest>(swift::Evaluator&, swift::TypeCheckFunctionBodyRequest, swift::TypeCheckFunctionBodyRequest::OutputType)::'lambda'()) + 636
24 swift-frontend           0x0000000104a09308 swift::AbstractFunctionDecl::getTypecheckedBody() const + 160
25 swift-frontend           0x00000001046d7e2c swift::TypeCheckSourceFileRequest::evaluate(swift::Evaluator&, swift::SourceFile*) const + 868
26 swift-frontend           0x00000001046df3c0 swift::TypeCheckSourceFileRequest::OutputType swift::Evaluator::getResultUncached<swift::TypeCheckSourceFileRequest, swift::TypeCheckSourceFileRequest::OutputType swift::evaluateOrDefault<swift::TypeCheckSourceFileRequest>(swift::Evaluator&, swift::TypeCheckSourceFileRequest, swift::TypeCheckSourceFileRequest::OutputType)::'lambda'()>(swift::TypeCheckSourceFileRequest const&, swift::TypeCheckSourceFileRequest::OutputType swift::evaluateOrDefault<swift::TypeCheckSourceFileRequest>(swift::Evaluator&, swift::TypeCheckSourceFileRequest, swift::TypeCheckSourceFileRequest::OutputType)::'lambda'()) + 620
27 swift-frontend           0x00000001046d7aac swift::performTypeChecking(swift::SourceFile&) + 328
28 swift-frontend           0x00000001035f6ce0 swift::CompilerInstance::performSema() + 260
29 swift-frontend           0x0000000103224190 performCompile(swift::CompilerInstance&, int&, swift::FrontendObserver*) + 1528
30 swift-frontend           0x0000000103222f58 swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 3572
31 swift-frontend           0x00000001031aa01c swift::mainEntry(int, char const**) + 3680
32 dyld                     0x0000000188748274 start + 2840

Expected behavior

The code should compile, or if the language standard has changed in an incompatible way it should produce an error message.

Environment

$ swiftc -version
swift-driver version: 1.115 Apple Swift version 6.0 (swiftlang-6.0.0.9.10 clang-1600.0.26.2)
Target: arm64-apple-macosx15.0

Additional information

No response