SILGen crash with propertyWrapper on an implicitly initialized property

[ellishg]

Description
Swift hits an assert in some cases when using propertyWrappers. This is very similar to #58201 which I previously reported, but I found a different assert when @escaping is left out.

Steps to reproduce
Try to compile the following

@propertyWrapper
public class Bar<Value> {
  var value: Value
  // Add @escaping to fix
  public init(wrappedValue: @autoclosure () -> Value) {
    self.value = wrappedValue()
  }
  public var wrappedValue: Value { return value }
}

struct Foo {
  // Or manually initialize to nil to fix
  @Bar var blah: Bool?
}

0  swift-frontend           0x00000001076535b0 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) + 56
1  swift-frontend           0x00000001076525b4 llvm::sys::RunSignalHandlers() + 112
2  swift-frontend           0x0000000107653c34 SignalHandler(int) + 344
3  libsystem_platform.dylib 0x0000000188756a84 _sigtramp + 56
4  swift-frontend           0x00000001032e8de8 swift::Lowering::SILGenFunction::emitGeneratorFunction(swift::SILDeclRef, swift::Expr*, bool) + 1336
5  swift-frontend           0x00000001032e8de8 swift::Lowering::SILGenFunction::emitGeneratorFunction(swift::SILDeclRef, swift::Expr*, bool) + 1336
6  swift-frontend           0x0000000103257a54 swift::Lowering::SILGenModule::emitFunctionDefinition(swift::SILDeclRef, swift::SILFunction*) + 12920
7  swift-frontend           0x0000000103259740 emitOrDelayFunction(swift::Lowering::SILGenModule&, swift::SILDeclRef, bool) + 228
8  swift-frontend           0x000000010333672c (anonymous namespace)::SILGenType::emitType() + 876
9  swift-frontend           0x000000010325d6e0 swift::ASTVisitor<swift::Lowering::SILGenModule, void, void, void, void, void, void>::visit(swift::Decl*) + 104
10 swift-frontend           0x000000010325bee4 swift::ASTLoweringRequest::evaluate(swift::Evaluator&, swift::ASTLoweringDescriptor) const + 3356
11 swift-frontend           0x0000000103328f10 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&) + 216
12 swift-frontend           0x000000010325f6e4 llvm::Expected<swift::ASTLoweringRequest::OutputType> swift::Evaluator::getResultUncached<swift::ASTLoweringRequest>(swift::ASTLoweringRequest const&) + 628
13 swift-frontend           0x0000000102ca0758 swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 5860
14 swift-frontend           0x0000000102c41294 swift::mainEntry(int, char const**) + 3940
15 dyld                     0x00000001883cff28 start + 2236

Expected behavior
The compiler should not crash

Environment

• Swift compiler version info 1.62.15 Apple Swift version 5.7.2 (swiftlang-5.7.2.135.5 clang-1400.0.29.51)
• Xcode 14.2
• macosx 13.0

[ellishg]

@hank121314 since you fixed #58201, do you know what might be going on here?

[AnthonyLatsis]

The crash happens at a later compilation stage but essentially this is the same issue. All it takes to reproduce it via the #58201 snippet is to humor semantic analysis with an empty getter in var wrappedValue: Value { get {} }. We got rid of the type checker crash but forgot to verify the compiler behaves further down the line.

[ellishg]

Friendly ping. I'm seeing lots of workarounds in our codebase (usually by adding = nil) and I'd like to see this fixed. @AnthonyLatsis or @hank121314 do you have time to look into this?

[AnthonyLatsis]

For now, let’s make this a duplicate and reopen the older issue.

[AnthonyLatsis]

Duplicate of #58201