[SR-13064] Void closure crash with Swift 5.3

[keith]

Previous ID	SR-13064
Radar	None
Original Reporter	@keith
Type	Bug

Environment

Xcode 12 beta 1 Swift 5.3

Additional Detail from JIRA

Votes	0
Component/s	Compiler
Labels	Bug, CompilerCrash, TypeChecker
Assignee	None
Priority	Medium

md5: 601384b2b2e9ca949011a4a8a15a8dc0

Issue Description:

Compiling this code:

class A {
    init(completion: ((Void) -> Void)?) {}
}

class B: A {
    init(completion: (() -> Void)?) {
        super.init(completion: completion ?? {})
    }
}

With `swift foo.swift` causes this crash:

fromType->getCanonicalType() = (bound_generic_enum_type decl=Swift.(file).Optional
  (function_type escaping
    (input=function_params num_params=0)
    (output=tuple_type num_elements=0)))
toType->getCanonicalType() = (bound_generic_enum_type decl=Swift.(file).Optional
  (function_type escaping
    (input=function_params num_params=1
      (param
        (tuple_type num_elements=0)))
    (output=tuple_type num_elements=0)))
Stack dump:
0.      Program arguments: /Applications/Xcode-12.0.0-beta1.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift -frontend -interpret foo.swift -enable-objc-interop -stack-check -sdk /Applications/Xcode-12.0.0-beta1.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.16.sdk -color-diagnostics -target-sdk-version 10.16 -module-name foo
1.      Apple Swift version 5.3 (swiftlang-1200.0.16.9 clang-1200.0.22.5)
2.      While evaluating request TypeCheckSourceFileRequest(source_file "foo.swift")
3.      While evaluating request TypeCheckFunctionBodyUntilRequest(foo.(file).B.init(completion:)@foo.swift:6:5, )
4.      While type-checking statement at [foo.swift:6:37 - line:8:5] RangeText="{
        super.init(completion: completion ?? {})
    "
5.      While type-checking expression at [foo.swift:7:9 - line:7:48] RangeText="super.init(completion: completion ?? {}"
0  swift                    0x000000010478af65 llvm::sys::PrintStackTrace(llvm::raw_ostream&) + 37
1  swift                    0x0000000104789f65 llvm::sys::RunSignalHandlers() + 85
2  swift                    0x000000010478b51f SignalHandler(int) + 111
3  libsystem_platform.dylib 0x00007fff70dc25fd _sigtramp + 29
4  libsystem_malloc.dylib   0x00007fff70d852d6 tiny_free_no_lock + 1111
5  swift                    0x0000000100fea78f (anonymous namespace)::ExprRewriter::coerceCallArguments(swift::Expr*, swift::AnyFunctionType*, swift::ConcreteDeclRef, swift::ApplyExpr*, llvm::ArrayRef<swift::Identifier>, bool, swift::constraints::ConstraintLocatorBuilder) + 4191
6  swift                    0x0000000100fe8933 (anonymous namespace)::ExprRewriter::finishApply(swift::ApplyExpr*, swift::Type, swift::constraints::ConstraintLocatorBuilder, swift::constraints::ConstraintLocatorBuilder) + 12067
7  swift                    0x0000000100ff277d (anonymous namespace)::ExprRewriter::visitApplyExpr(swift::ApplyExpr*) + 477
8  swift                    0x0000000100fcafb2 (anonymous namespace)::ExprWalker::walkToExprPost(swift::Expr*) + 18
9  swift                    0x00000001014df7f4 swift::ASTVisitor<(anonymous namespace)::Traversal, swift::Expr*, swift::Stmt*, bool, swift::Pattern*, bool, void>::visit(swift::Expr*) + 164
10 swift                    0x0000000100fc1664 (anonymous namespace)::ExprWalker::rewriteTarget(swift::constraints::SolutionApplicationTarget) + 324
11 swift                    0x0000000100fc1380 swift::constraints::ConstraintSystem::applySolution(swift::constraints::Solution&, swift::constraints::SolutionApplicationTarget) + 6928
12 swift                    0x00000001011a81cb swift::TypeChecker::typeCheckExpression(swift::constraints::SolutionApplicationTarget&, bool&, swift::OptionSet<swift::TypeCheckExprFlags, unsigned int>) + 1307
13 swift                    0x00000001011a7bf8 swift::TypeChecker::typeCheckExpression(swift::Expr*&, swift::DeclContext*, swift::TypeLoc, swift::ContextualTypePurpose, swift::OptionSet<swift::TypeCheckExprFlags, unsigned int>) + 360
14 swift                    0x000000010128d4cb swift::ASTVisitor<(anonymous namespace)::StmtChecker, void, swift::Stmt*, void, void, void, void>::visit(swift::Stmt*) + 9115
15 swift                    0x0000000101288c7a bool (anonymous namespace)::StmtChecker::typeCheckStmt<swift::BraceStmt>(swift::BraceStmt*&) + 314
16 swift                    0x000000010128754e swift::TypeCheckFunctionBodyUntilRequest::evaluate(swift::Evaluator&, swift::AbstractFunctionDecl*, swift::SourceLoc) const + 2398
17 swift                    0x00000001012904fd llvm::Expected<swift::TypeCheckFunctionBodyUntilRequest::OutputType> swift::Evaluator::getResultCached<swift::TypeCheckFunctionBodyUntilRequest, (void*)0>(swift::TypeCheckFunctionBodyUntilRequest const&) + 925
18 swift                    0x00000001012886c8 swift::TypeCheckFunctionBodyUntilRequest::OutputType swift::evaluateOrDefault<swift::TypeCheckFunctionBodyUntilRequest>(swift::Evaluator&, swift::TypeCheckFunctionBodyUntilRequest, swift::TypeCheckFunctionBodyUntilRequest::OutputType) + 440
19 swift                    0x00000001012c5db4 swift::TypeCheckSourceFileRequest::evaluate(swift::Evaluator&, swift::SourceFile*) const + 1252
20 swift                    0x00000001012c89c9 llvm::Expected<swift::TypeCheckSourceFileRequest::OutputType> swift::Evaluator::getResultUncached<swift::TypeCheckSourceFileRequest>(swift::TypeCheckSourceFileRequest const&) + 953
21 swift                    0x00000001012c5744 swift::TypeCheckSourceFileRequest::OutputType swift::evaluateOrDefault<swift::TypeCheckSourceFileRequest>(swift::Evaluator&, swift::TypeCheckSourceFileRequest, swift::TypeCheckSourceFileRequest::OutputType) + 164
22 swift                    0x0000000100448c47 swift::CompilerInstance::performSemaUpTo(swift::SourceFile::ASTStage_t) + 6439
23 swift                    0x000000010030aee1 swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 6849
24 swift                    0x000000010028fa97 main + 1255
25 libdyld.dylib            0x00007fff70bc9cc9 start + 1
26 libdyld.dylib            0x000000000000000d start + 18446603338624754501
zsh: illegal hardware instruction  PATH="/usr/bin:/bin" swift foo.swift

[theblixguy]

Reproduced on master as well. I suppose you meant completion's type in A.init to be (() -> Void)? instead?

[keith]

In our actual case the hierarchy is more complicated and the `Void` there is actually a generic's associatedType which can be set to `Void`. But another workaround is to do:

let completion = completion ?? {}
super.init(completion: completion)

Which is what we've applied for now

[LucianoPAlmeida]

This seems to be fixed on main now