Compiler crash on incorrect (non-existent) distributed actor declaration

[mr-swifter]

Describe the bug
I use snapshot of trunk development for 4th of May 2022. When I compile simple code with distributed actors I've got a crash

Stacktrace:

1.	Apple Swift version 5.7-dev (LLVM cd62c186b914a47, Swift c58d4dba34ef37a)
2.	Compiling with the current language version
3.	While evaluating request TypeCheckSourceFileRequest(source_file "/Users/ordo/Dev/Server/DistributedActorsCrash/Sources/DistributedActorsPlayground/DataActors.swift")
4.	While evaluating request TypeCheckFunctionBodyRequest(DistributedActorsPlayground.(file).Server.send())
5.	While evaluating request ParseAbstractFunctionBodyRequest(DistributedActorsPlayground.(file).Server.send())
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           0x0000000109281be8 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) + 56
1  swift-frontend           0x0000000109280e48 llvm::sys::RunSignalHandlers() + 128
2  swift-frontend           0x000000010928224c SignalHandler(int) + 304
3  libsystem_platform.dylib 0x00000001aed854c4 _sigtramp + 56
4  libsystem_pthread.dylib  0x00000001aed6dee0 pthread_kill + 288
5  libsystem_c.dylib        0x00000001aeca8340 abort + 168
6  libsystem_c.dylib        0x00000001aeca7754 err + 0
7  swift-frontend           0x00000001095a3f94 deriveBodyDistributed_thunk(swift::AbstractFunctionDecl*, void*) (.cold.6) + 0
8  swift-frontend           0x00000001058e6c54 deriveBodyDistributed_thunk(swift::AbstractFunctionDecl*, void*) + 7936
9  swift-frontend           0x000000010607bf34 swift::ParseAbstractFunctionBodyRequest::evaluate(swift::Evaluator&, swift::AbstractFunctionDecl*) const + 320
10 swift-frontend           0x0000000105e48038 llvm::Expected<swift::ParseAbstractFunctionBodyRequest::OutputType> swift::Evaluator::getResultUncached<swift::ParseAbstractFunctionBodyRequest>(swift::ParseAbstractFunctionBodyRequest const&) + 404
11 swift-frontend           0x0000000105e47d38 llvm::Expected<swift::ParseAbstractFunctionBodyRequest::OutputType> swift::Evaluator::getResultCached<swift::ParseAbstractFunctionBodyRequest, (void*)0>(swift::ParseAbstractFunctionBodyRequest const&) + 116
12 swift-frontend           0x0000000105da8e98 swift::ParseAbstractFunctionBodyRequest::OutputType swift::evaluateOrDefault<swift::ParseAbstractFunctionBodyRequest>(swift::Evaluator&, swift::ParseAbstractFunctionBodyRequest, swift::ParseAbstractFunctionBodyRequest::OutputType) + 56
13 swift-frontend           0x0000000105d8b4a4 swift::AbstractFunctionDecl::getBody(bool) const + 212
14 swift-frontend           0x0000000105a78640 swift::TypeCheckFunctionBodyRequest::evaluate(swift::Evaluator&, swift::AbstractFunctionDecl*) const + 208
15 swift-frontend           0x0000000105e49da0 llvm::Expected<swift::TypeCheckFunctionBodyRequest::OutputType> swift::Evaluator::getResultUncached<swift::TypeCheckFunctionBodyRequest>(swift::TypeCheckFunctionBodyRequest const&) + 404
16 swift-frontend           0x0000000105e49b24 llvm::Expected<swift::TypeCheckFunctionBodyRequest::OutputType> swift::Evaluator::getResultCached<swift::TypeCheckFunctionBodyRequest, (void*)0>(swift::TypeCheckFunctionBodyRequest const&) + 140
17 swift-frontend           0x0000000105da9048 swift::TypeCheckFunctionBodyRequest::OutputType swift::evaluateOrDefault<swift::TypeCheckFunctionBodyRequest>(swift::Evaluator&, swift::TypeCheckFunctionBodyRequest, swift::TypeCheckFunctionBodyRequest::OutputType) + 52
18 swift-frontend           0x0000000105aa5aec swift::TypeCheckSourceFileRequest::evaluate(swift::Evaluator&, swift::SourceFile*) const + 308
19 swift-frontend           0x0000000105aa7900 llvm::Expected<swift::TypeCheckSourceFileRequest::OutputType> swift::Evaluator::getResultUncached<swift::TypeCheckSourceFileRequest>(swift::TypeCheckSourceFileRequest const&) + 400
20 swift-frontend           0x0000000105aa76a0 llvm::Expected<swift::TypeCheckSourceFileRequest::OutputType> swift::Evaluator::getResultCached<swift::TypeCheckSourceFileRequest, (void*)0>(swift::TypeCheckSourceFileRequest const&) + 124
21 swift-frontend           0x0000000105aa58ac swift::TypeCheckSourceFileRequest::OutputType swift::evaluateOrDefault<swift::TypeCheckSourceFileRequest>(swift::Evaluator&, swift::TypeCheckSourceFileRequest, swift::TypeCheckSourceFileRequest::OutputType) + 44
22 swift-frontend           0x0000000104dfdedc bool llvm::function_ref<bool (swift::SourceFile&)>::callback_fn<swift::CompilerInstance::performSema()::$_7>(long, swift::SourceFile&) + 16
23 swift-frontend           0x0000000104dfa39c swift::CompilerInstance::forEachFileToTypeCheck(llvm::function_ref<bool (swift::SourceFile&)>) + 76
24 swift-frontend           0x0000000104dfa324 swift::CompilerInstance::performSema() + 76
25 swift-frontend           0x0000000104dabea8 withSemanticAnalysis(swift::CompilerInstance&, swift::FrontendObserver*, llvm::function_ref<bool (swift::CompilerInstance&)>, bool) + 60
26 swift-frontend           0x0000000104da0b50 swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 3388
27 swift-frontend           0x0000000104c98cfc swift::mainEntry(int, char const**) + 3748
28 dyld                     0x0000000111ae5088 start + 516
error: Abort trap: 6 (in target 'DistributedActorsPlayground' from project 'DistributedActorsPlayground')

To Reproduce
Steps to reproduce the behavior:

1. Create empty package
2. Add settings to enable distributed actors functionality

            swiftSettings: [
                .unsafeFlags(["-Xfrontend", "-enable-experimental-distributed"])
            ]

3. Declare distributed actor with non-existing DistributedActorSystem

@available(macOS 9999, *)
distributed actor Server {
    
    typealias ActorSystem = DataSystem
    
    typealias SerializationRequirement = Codable
    
    distributed func send() {
        
    }
    
}

4. Compile...

Expected behavior
Compilation error highlights that declared DistributedActorSystem doesn't exist

Screenshots
If applicable, add screenshots to help explain your problem.

Environment (please complete the following information):

• OS: [macOS 12.3]
• Swift version:

~/Dev/Server/ /Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2022-05-04-a.xctoolchain/usr/bin/swift --version
Apple Swift version 5.7-dev (LLVM cd62c186b914a47, Swift c58d4dba34ef37a)
Target: arm64-apple-macosx12.0

[ktoso]

While I agree it should not crash, the issue here lies with the DataSystem that is wrongly declared -- as mentioned in https://forums.swift.org/t/help-some-issues-with-compiling-distributed-actors-project-with-latest-trunk/57134/3 and related fix in #58672

Please include actor system declarations when reporting distributed actor issues as they are often very related to the AS declarations themselfes.

This crash should not happen even with an illegal DA declaration though, I'll look into it.

[ktoso]

Oh I see, you mean the system not existing and it crashes... got it, thanks for reporting!

Radar: rdar://92757561