[SR-4978] Crasher - UNREACHABLE executed at ReferenceDependencies.cpp

[hartbit]

Previous ID	SR-4978
Radar	None
Original Reporter	@hartbit
Type	Bug
Status	Resolved
Resolution	Done

Environment

2017-05-21 master snapshot

Additional Detail from JIRA

Votes	0
Component/s	Compiler
Labels	Bug, CompilerCrash, StarterBug
Assignee	contraultra (JIRA)
Priority	Medium

md5: 1b1d922f3b1681ed275a144c5ee1c591

Issue Description:

I found the following crasher on the 2017-05-21 master snapshot:

class A init

cannot appear at the top level of a file
UNREACHABLE executed at /Users/buildnode/jenkins/workspace/oss-swift-package-osx/swift/lib/FrontendTool/ReferenceDependencies.cpp:258!
0  swift                    0x000000010c8f8908 llvm::sys::PrintStackTrace(llvm::raw_ostream&) + 40
1  swift                    0x000000010c8f78d6 llvm::sys::RunSignalHandlers() + 86
2  swift                    0x000000010c8f8ec9 SignalHandler(int) + 361
3  libsystem_platform.dylib 0x00007fffbb951b3a _sigtramp + 26
4  swift                    0x000000010c924acf char const* parse_builtin_type<(anonymous namespace)::Db>(char const*, char const*, (anonymous namespace)::Db&) + 39727
5  libsystem_c.dylib        0x00007fffbb7d6420 abort + 129
6  swift                    0x000000010c898097 llvm::llvm_unreachable_internal(char const*, char const*, unsigned int) + 471
7  swift                    0x00000001096f62b4 swift::emitReferenceDependencies(swift::DiagnosticEngine&, swift::SourceFile*, swift::DependencyTracker&, swift::FrontendOptions const&) + 12020
8  swift                    0x00000001096ed772 performCompile(swift::CompilerInstance&, swift::CompilerInvocation&, llvm::ArrayRef<char const*>, int&, swift::FrontendObserver*, swift::UnifiedStatsReporter*) + 5266
9  swift                    0x00000001096eb20a swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 2650
10 swift                    0x00000001096a7860 main + 3312
11 libdyld.dylib            0x00007fffbb742235 start + 1
Stack dump:
0.  Program arguments: /Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2017-05-21-a.xctoolchain/usr/bin/swift -frontend -c /Users/david/Desktop/Testing/Testing/ViewController.swift /Users/david/Desktop/Testing/Testing/AppDelegate.swift -primary-file /Users/david/Desktop/Testing/Testing/GitRepository.swift -target x86_64-apple-ios10.3 -enable-objc-interop -sdk /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator10.3.sdk -I /Users/david/Library/Developer/Xcode/DerivedData/Testing-eedmljfslgrtvohadygdohywmczi/Build/Products/Debug-iphonesimulator -F /Users/david/Library/Developer/Xcode/DerivedData/Testing-eedmljfslgrtvohadygdohywmczi/Build/Products/Debug-iphonesimulator -enable-testing -g -module-cache-path /Users/david/Library/Developer/Xcode/DerivedData/ModuleCache -D DEBUG -serialize-debugging-options -Xcc -I/Users/david/Library/Developer/Xcode/DerivedData/Testing-eedmljfslgrtvohadygdohywmczi/Build/Intermediates/Testing.build/Debug-iphonesimulator/Testing.build/swift-overrides.hmap -Xcc -iquote -Xcc /Users/david/Library/Developer/Xcode/DerivedData/Testing-eedmljfslgrtvohadygdohywmczi/Build/Intermediates/Testing.build/Debug-iphonesimulator/Testing.build/Testing-generated-files.hmap -Xcc -I/Users/david/Library/Developer/Xcode/DerivedData/Testing-eedmljfslgrtvohadygdohywmczi/Build/Intermediates/Testing.build/Debug-iphonesimulator/Testing.build/Testing-own-target-headers.hmap -Xcc -I/Users/david/Library/Developer/Xcode/DerivedData/Testing-eedmljfslgrtvohadygdohywmczi/Build/Intermediates/Testing.build/Debug-iphonesimulator/Testing.build/Testing-all-target-headers.hmap -Xcc -iquote -Xcc /Users/david/Library/Developer/Xcode/DerivedData/Testing-eedmljfslgrtvohadygdohywmczi/Build/Intermediates/Testing.build/Debug-iphonesimulator/Testing.build/Testing-project-headers.hmap -Xcc -I/Users/david/Library/Developer/Xcode/DerivedData/Testing-eedmljfslgrtvohadygdohywmczi/Build/Products/Debug-iphonesimulator/include -Xcc -I/Users/david/Library/Developer/Xcode/DerivedData/Testing-eedmljfslgrtvohadygdohywmczi/Build/Intermediates/Testing.build/Debug-iphonesimulator/Testing.build/DerivedSources/x86_64 -Xcc -I/Users/david/Library/Developer/Xcode/DerivedData/Testing-eedmljfslgrtvohadygdohywmczi/Build/Intermediates/Testing.build/Debug-iphonesimulator/Testing.build/DerivedSources -Xcc -DDEBUG=1 -Xcc -working-directory/Users/david/Desktop/Testing -emit-module-doc-path /Users/david/Library/Developer/Xcode/DerivedData/Testing-eedmljfslgrtvohadygdohywmczi/Build/Intermediates/Testing.build/Debug-iphonesimulator/Testing.build/Objects-normal/x86_64/GitRepository~partial.swiftdoc -serialize-diagnostics-path /Users/david/Library/Developer/Xcode/DerivedData/Testing-eedmljfslgrtvohadygdohywmczi/Build/Intermediates/Testing.build/Debug-iphonesimulator/Testing.build/Objects-normal/x86_64/GitRepository.dia -Onone -module-name Testing -emit-module-path /Users/david/Library/Developer/Xcode/DerivedData/Testing-eedmljfslgrtvohadygdohywmczi/Build/Intermediates/Testing.build/Debug-iphonesimulator/Testing.build/Objects-normal/x86_64/GitRepository~partial.swiftmodule -emit-dependencies-path /Users/david/Library/Developer/Xcode/DerivedData/Testing-eedmljfslgrtvohadygdohywmczi/Build/Intermediates/Testing.build/Debug-iphonesimulator/Testing.build/Objects-normal/x86_64/GitRepository.d -emit-reference-dependencies-path /Users/david/Library/Developer/Xcode/DerivedData/Testing-eedmljfslgrtvohadygdohywmczi/Build/Intermediates/Testing.build/Debug-iphonesimulator/Testing.build/Objects-normal/x86_64/GitRepository.swiftdeps -o /Users/david/Library/Developer/Xcode/DerivedData/Testing-eedmljfslgrtvohadygdohywmczi/Build/Intermediates/Testing.build/Debug-iphonesimulator/Testing.build/Objects-normal/x86_64/GitRepository.o 

[belkadan]

Wow, that's awful. Thanks.

[belkadan]

The fix here is to go through swift::emitReferenceDependencies in ReferenceDependencies.cpp and change the llvm_unreachable to a simple break, with a comment that these can occur in malformed ASTs.

[swift-ci]

Comment by nate (JIRA)

Fix merged.