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[SR-9225] Compiler Crash with protocol conformance, associated types and multiple files #51714

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nsalmoria opened this issue Nov 12, 2018 · 4 comments
Closed

[SR-9225] Compiler Crash with protocol conformance, associated types and multiple files #51714

nsalmoria opened this issue Nov 12, 2018 · 4 comments
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@slavapestov
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bug A deviation from expected or documented behavior. Also: expected but undesirable behavior. compiler The Swift compiler in itself conformances Feature → protocol: protocol conformances crash Bug: A crash, i.e., an abnormal termination of software multiple files Flag: An issue whose reproduction requires multiple files

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@nsalmoria
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Previous ID SR-9225
Radar rdar://problem/46031080
Original Reporter @nsalmoria
Type Bug
Status Resolved
Resolution Done
Environment

macOS 10.14.1, Xcode 10.1 both with default toolchain and with development snapshot 2018-11-01.

Additional Detail from JIRA
Votes 0
Component/s Compiler
Labels Bug, CompilerCrash, MultiFile, ProtocolConformance
Assignee @slavapestov
Priority Medium

md5: f49501a729183a52337fbf6a11e4f898

Issue Description:

This crash happens only when the source is split over two files.

I cannot reduce it more than this.

In main.swift:

protocol P1 {
    associatedtype P1_T1
    associatedtype P1_T2: Collection where P1_T2.Element == P1_T1
}

protocol P2 {
    associatedtype P2_T
}

protocol P3: P1, P2 {
    associatedtype P3_T: P1 where P3_T.P1_T2 == Range<P2_T>
}

in a separate file:

struct S1: P1 {
    typealias P1_T1 = Int
    typealias P1_T2 = Range<Int>
}

struct S2<P1_T1>: P1, P3 {
    typealias P1_T2 = [P1_T1]
    typealias P2_T = Int
    typealias P3_T = S1
}

The crash only happens when compiling the Debug build. Release compiles fine.

With the default toolchain, this is the crash dump:

0  swift                    0x00000001059e659a PrintStackTraceSignalHandler(void*) + 42
1  swift                    0x00000001059e5d4e SignalHandler(int) + 302
2  libsystem_platform.dylib 0x00007fff5ab79b3d _sigtramp + 29
3  libsystem_platform.dylib 0x00007fbab2e07460 _sigtramp + 1479072064
4  swift                    0x0000000101df0b6e swift::irgen::IRGenModule::emitSILWitnessTable(swift::SILWitnessTable*) + 1310
5  swift                    0x0000000101d38e2b swift::irgen::IRGenerator::emitGlobalTopLevel(bool) + 2491
6  swift                    0x0000000101e37386 performIRGeneration(swift::IRGenOptions&, swift::ModuleDecl*, std::__1::unique_ptr<swift::SILModule, std::__1::default_delete<swift::SILModule> >, llvm::StringRef, swift::PrimarySpecificPaths const&, llvm::LLVMContext&, swift::SourceFile*, llvm::GlobalVariable**, unsigned int) + 1382
7  swift                    0x0000000101c77980 performCompile(swift::CompilerInstance&, swift::CompilerInvocation&, llvm::ArrayRef<char const*>, int&, swift::FrontendObserver*, swift::UnifiedStatsReporter*) + 46928
8  swift                    0x0000000101c68d35 swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 7717
9  swift                    0x0000000101c0e965 main + 1349
10 libdyld.dylib            0x00007fff5a99008d start + 1

error: Segmentation fault: 11

and with development snapshot 2018-11-01:

Assertion failed: (hasConformanceInSignature(reqs, rootType, conformingProto) && "missing explicit conformance in signature"), function buildConformanceAccessPath, file /Users/buildnode/jenkins/workspace/oss-swift-package-osx/swift/lib/AST/GenericSignature.cpp, line 964.

...

1.  While emitting witness table for type 'S2<P1_T1>' (declared at [/Users/nicolasalmoria/Documents/bugReportCompilerCrash/CompilerCrash/file.swift:6:1 - line:10:1] RangeText="struct S2<P1_T1>: P1, P3 {
    typealias P1_T2 = [P1_T1]
    typealias P2_T = Int
    typealias P3_T = S1
")
2.  While ...conforming to 'P3' at /Users/nicolasalmoria/Documents/bugReportCompilerCrash/CompilerCrash/main.swift:10:1
0  swift                    0x0000000112dbbef8 llvm::sys::PrintStackTrace(llvm::raw_ostream&) + 40
1  swift                    0x0000000112dbb175 llvm::sys::RunSignalHandlers() + 85
2  swift                    0x0000000112dbc502 SignalHandler(int) + 258
3  libsystem_platform.dylib 0x00007fff5ab79b3d _sigtramp + 29
4  swift                    0x00000001105c1f19 substType(swift::Type, llvm::function_ref<swift::Type (swift::SubstitutableType*)>, llvm::function_ref<llvm::Optional<swift::ProtocolConformanceRef> (swift::CanType, swift::Type, swift::ProtocolDecl*)>, swift::SubstOptions) + 281
5  libsystem_c.dylib        0x00007fff5aa381c9 abort + 127
6  libsystem_c.dylib        0x00007fff5aa00868 basename_r + 0
7  swift                    0x000000011053899a swift::GenericSignature::buildConformanceAccessPath(llvm::SmallVectorImpl<std::__1::pair<swift::Type, swift::ProtocolDecl*> >&, llvm::ArrayRef<swift::Requirement>, void const*, swift::ProtocolDecl*, swift::Type, swift::ProtocolDecl*) + 1978
8  swift                    0x0000000110539075 swift::GenericSignature::getConformanceAccessPath(swift::Type, swift::ProtocolDecl*) + 725
9  swift                    0x00000001105b355e swift::SubstitutionMap::lookupConformance(swift::CanType, swift::ProtocolDecl*) const + 494
10 swift                    0x00000001105c1bfd getMemberForBaseType(llvm::function_ref<llvm::Optional<swift::ProtocolConformanceRef> (swift::CanType, swift::Type, swift::ProtocolDecl*)>, swift::Type, swift::Type, swift::AssociatedTypeDecl*, swift::Identifier, swift::SubstOptions) + 1069
11 swift                    0x00000001105c763f llvm::Optional<swift::Type> llvm::function_ref<llvm::Optional<swift::Type> (swift::TypeBase*)>::callback_fn<substType(swift::Type, llvm::function_ref<swift::Type (swift::SubstitutableType*)>, llvm::function_ref<llvm::Optional<swift::ProtocolConformanceRef> (swift::CanType, swift::Type, swift::ProtocolDecl*)>, swift::SubstOptions)::$_15>(long, swift::TypeBase*) + 943
12 swift                    0x00000001105c3ba8 swift::Type::transformRec(llvm::function_ref<llvm::Optional<swift::Type> (swift::TypeBase*)>) const + 216
13 swift                    0x00000001105c1f19 substType(swift::Type, llvm::function_ref<swift::Type (swift::SubstitutableType*)>, llvm::function_ref<llvm::Optional<swift::ProtocolConformanceRef> (swift::CanType, swift::Type, swift::ProtocolDecl*)>, swift::SubstOptions) + 281
14 swift                    0x00000001105bc066 swift::Type::subst(swift::SubstitutionMap, swift::SubstOptions) const + 118
15 swift                    0x00000001105a9391 swift::ProtocolConformanceRef::getAssociatedType(swift::Type, swift::Type, swift::LazyResolver*) const + 481
16 swift                    0x00000001105aa557 swift::ProtocolConformance::getAssociatedType(swift::Type, swift::LazyResolver*) const + 279
17 swift                    0x000000010f35caa0 swift::SILWitnessVisitor<(anonymous namespace)::WitnessTableBuilder>::visitProtocolDecl(swift::ProtocolDecl*) + 656
18 swift                    0x000000010f355076 swift::irgen::IRGenModule::emitSILWitnessTable(swift::SILWitnessTable*) + 1190
19 swift                    0x000000010f2cc7cd swift::irgen::IRGenerator::emitGlobalTopLevel(bool) + 1053
20 swift                    0x000000010f397a0b performIRGeneration(swift::IRGenOptions&, swift::ModuleDecl*, std::__1::unique_ptr<swift::SILModule, std::__1::default_delete<swift::SILModule> >, llvm::StringRef, swift::PrimarySpecificPaths const&, llvm::LLVMContext&, swift::SourceFile*, llvm::GlobalVariable**) + 1067
21 swift                    0x000000010f397f46 swift::performIRGeneration(swift::IRGenOptions&, swift::SourceFile&, std::__1::unique_ptr<swift::SILModule, std::__1::default_delete<swift::SILModule> >, llvm::StringRef, swift::PrimarySpecificPaths const&, llvm::LLVMContext&, llvm::GlobalVariable**) + 86
22 swift                    0x000000010f2274a1 performCompile(swift::CompilerInstance&, swift::CompilerInvocation&, llvm::ArrayRef<char const*>, int&, swift::FrontendObserver*, swift::UnifiedStatsReporter*) + 13697
23 swift                    0x000000010f222e8d swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 3021
24 swift                    0x000000010f1d4e5e main + 686
25 libdyld.dylib            0x00007fff5a99008d start + 1
error: Abort trap: 6
@slavapestov
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The problem is the missing constraint that P2_T is Strideable. This should not crash, however, so there's something for us to fix.

@nsalmoria
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But is it technically true that the Strideable conformance should be explicitly requested? In other contexts, such conformances are implicitly inferred. Also, note that if you put everything into a single file the code compiles fine.

@slavapestov
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You're right that the behavior is inconsistent. However in the multi-file case it's not inferring the constraint at all.

@slavapestov
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This was fixed at some point so I'm just adding a regression test - #29714

@swift-ci swift-ci transferred this issue from apple/swift-issues Apr 25, 2022
@AnthonyLatsis AnthonyLatsis added the crash Bug: A crash, i.e., an abnormal termination of software label Dec 12, 2022
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@slavapestov slavapestov

Labels
bug A deviation from expected or documented behavior. Also: expected but undesirable behavior. compiler The Swift compiler in itself conformances Feature → protocol: protocol conformances crash Bug: A crash, i.e., an abnormal termination of software multiple files Flag: An issue whose reproduction requires multiple files
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@slavapestov @AnthonyLatsis @nsalmoria