[SR-10532] Assertion failed: (conforms != equivClass->conformsTo.end())

[SusanDoggie]

Previous ID	SR-10532
Radar	rdar://problem/50169558
Original Reporter	@SusanDoggie
Type	Bug
Status	Resolved
Resolution	Done

Environment

Swift 5

Additional Detail from JIRA

Votes	0
Component/s	Compiler
Labels	Bug, CompilerCrash, IRGen
Assignee	@slavapestov
Priority	Medium

md5: 5b1ae800fe04f78f4be7ad25bcc37128

Issue Description:

The following code shouldn't have any error but swift compiler get it wrong.

public protocol ScalarProtocol: ScalarMultiplicative where Self == Scalar {
    
}

public protocol ScalarMultiplicative {
    
    associatedtype Scalar : ScalarProtocol
    
}

public protocol MapReduceArithmetic : ScalarMultiplicative, Collection where Element : ScalarMultiplicative, Scalar == Element.Scalar {
    
}

public protocol Tensor : MapReduceArithmetic where Scalar : BinaryFloatingPoint, Element == Scalar {
    
    var magnitude: Scalar { get set }
}

extension Tensor {
    
    public var magnitude: Scalar {
        return self.reduce(0) { $0 + $1 * $1 }.squareRoot()
    }
}

[belkadan]

It actually crashes for me on master:

Assertion failed: (conforms != equivClass->conformsTo.end()), function buildConformanceAccessPath, file /Volumes/Data/swift-public/swift/lib/AST/GenericSignature.cpp, line 924.
Stack dump:
0.  Program arguments: /Volumes/Data/swift-public/build/ninja/swift-macosx-x86_64/bin/swift -frontend -c -primary-file - -target x86_64-apple-darwin18.6.0 -enable-objc-interop -sdk /Volumes/Data/Applications/Xcode10.2.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk -color-diagnostics -module-name main -o /var/folders/_d/dmrgv26d3bs6lkrks9z825_w0000gn/T/--f83a70.o 
1.  While emitting IR SIL function "@$s4main6TensorPAAE9magnitude7ElementQzvg".
 for getter for magnitude (at <stdin>:22:16)
0  swift                    0x000000010aa05425 llvm::sys::PrintStackTrace(llvm::raw_ostream&) + 37
1  swift                    0x000000010aa046e5 llvm::sys::RunSignalHandlers() + 85
2  swift                    0x000000010aa05a08 SignalHandler(int) + 264
3  libsystem_platform.dylib 0x00007fff60b19b5d _sigtramp + 29
4  libsystem_platform.dylib 0x00007fc9b18ff188 _sigtramp + 1356748360
5  libsystem_c.dylib        0x00007fff609d36a6 abort + 127
6  libsystem_c.dylib        0x00007fff6099c20d basename_r + 0
7  swift                    0x0000000107d3044b swift::GenericSignature::buildConformanceAccessPath(llvm::SmallVectorImpl<std::__1::pair<swift::Type, swift::ProtocolDecl*> >&, llvm::ArrayRef<swift::Requirement>, void const*, swift::ProtocolDecl*, swift::Type, swift::ProtocolDecl*) + 1691
8  swift                    0x0000000107d30345 swift::GenericSignature::buildConformanceAccessPath(llvm::SmallVectorImpl<std::__1::pair<swift::Type, swift::ProtocolDecl*> >&, llvm::ArrayRef<swift::Requirement>, void const*, swift::ProtocolDecl*, swift::Type, swift::ProtocolDecl*) + 1429
9  swift                    0x0000000107d2ffc4 swift::GenericSignature::buildConformanceAccessPath(llvm::SmallVectorImpl<std::__1::pair<swift::Type, swift::ProtocolDecl*> >&, llvm::ArrayRef<swift::Requirement>, void const*, swift::ProtocolDecl*, swift::Type, swift::ProtocolDecl*) + 532
10 swift                    0x0000000107d2ffc4 swift::GenericSignature::buildConformanceAccessPath(llvm::SmallVectorImpl<std::__1::pair<swift::Type, swift::ProtocolDecl*> >&, llvm::ArrayRef<swift::Requirement>, void const*, swift::ProtocolDecl*, swift::Type, swift::ProtocolDecl*) + 532
11 swift                    0x0000000107d2ffc4 swift::GenericSignature::buildConformanceAccessPath(llvm::SmallVectorImpl<std::__1::pair<swift::Type, swift::ProtocolDecl*> >&, llvm::ArrayRef<swift::Requirement>, void const*, swift::ProtocolDecl*, swift::Type, swift::ProtocolDecl*) + 532
12 swift                    0x0000000107d2ffc4 swift::GenericSignature::buildConformanceAccessPath(llvm::SmallVectorImpl<std::__1::pair<swift::Type, swift::ProtocolDecl*> >&, llvm::ArrayRef<swift::Requirement>, void const*, swift::ProtocolDecl*, swift::Type, swift::ProtocolDecl*) + 532
13 swift                    0x0000000107d30c75 swift::GenericSignature::getConformanceAccessPath(swift::Type, swift::ProtocolDecl*) + 725
14 swift                    0x0000000106feb1ce swift::irgen::emitArchetypeWitnessTableRef(swift::irgen::IRGenFunction&, swift::CanTypeWrapper<swift::ArchetypeType>, swift::ProtocolDecl*) + 126
15 swift                    0x0000000106feb05c swift::irgen::emitAssociatedTypeMetadataRef(swift::irgen::IRGenFunction&, swift::CanTypeWrapper<swift::ArchetypeType>, swift::AssociatedType, swift::irgen::DynamicMetadataRequest) + 108
16 swift                    0x0000000106feadb6 swift::irgen::emitArchetypeTypeMetadataRef(swift::irgen::IRGenFunction&, swift::CanTypeWrapper<swift::ArchetypeType>, swift::irgen::DynamicMetadataRequest) + 246
17 swift                    0x0000000107169217 swift::CanTypeVisitor<(anonymous namespace)::EmitTypeMetadataRef, swift::irgen::MetadataResponse, swift::irgen::DynamicMetadataRequest>::visit(swift::CanType, swift::irgen::DynamicMetadataRequest) + 215
18 swift                    0x0000000107167231 swift::irgen::IRGenFunction::emitTypeMetadataRef(swift::CanType, swift::irgen::DynamicMetadataRequest) + 145
19 swift                    0x0000000107167796 swift::CanTypeVisitor<(anonymous namespace)::EmitTypeMetadataRefForLayout, llvm::Value*, swift::irgen::DynamicMetadataRequest>::visit(swift::CanType, swift::irgen::DynamicMetadataRequest) + 150
20 swift                    0x00000001071676af swift::irgen::IRGenFunction::emitTypeMetadataRefForLayout(swift::SILType, swift::irgen::DynamicMetadataRequest) + 111
21 swift                    0x00000001070a82c9 swift::irgen::IRGenFunction::emitValueWitnessTableRef(swift::SILType, swift::irgen::DynamicMetadataRequest, llvm::Value**) + 201
22 swift                    0x00000001070a81f0 swift::irgen::IRGenFunction::emitValueWitnessTableRef(swift::SILType, llvm::Value**) + 48
23 swift                    0x00000001070ba19f swift::irgen::IRGenFunction::emitDynamicAlloca(swift::SILType, llvm::Twine const&) + 63
24 swift                    0x0000000106feec4a swift::irgen::WitnessSizedTypeInfo<(anonymous namespace)::OpaqueArchetypeTypeInfo>::allocateStack(swift::irgen::IRGenFunction&, swift::SILType, llvm::Twine const&) const + 42
25 swift                    0x000000010713235f swift::SILInstructionVisitor<(anonymous namespace)::IRGenSILFunction, void>::visit(swift::SILInstruction*) + 29311
26 swift                    0x0000000107127763 swift::irgen::IRGenModule::emitSILFunction(swift::SILFunction*) + 8131
27 swift                    0x00000001070312be swift::irgen::IRGenerator::emitGlobalTopLevel() + 734
28 swift                    0x0000000107101b9d 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**) + 1373
29 swift                    0x00000001071020e6 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
30 swift                    0x0000000106f96097 performCompile(swift::CompilerInstance&, swift::CompilerInvocation&, llvm::ArrayRef<char const*>, int&, swift::FrontendObserver*, swift::UnifiedStatsReporter*) + 14615
31 swift                    0x0000000106f91722 swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 2978
32 swift                    0x0000000106f384f8 main + 696
33 libdyld.dylib            0x00007fff6092e3d5 start + 1

@rjmccall, thoughts?

[rjmccall]

Usually this kind of crash is a problem with the generic signature checking code, in this case probably because of the knot-tying in `ScalarProtocol`. @slavapestov,@DougGregor?

[SusanDoggie]

As i known, the Swift 5.0 compiler assume Tensor.Self == Tensor.Scalar but it's not correct. This bugs has being long time ago.

If removing the constraint Scalar == Element.Scalar in protocol MapReduceArithmetic, it will work properly.

[slavapestov]

#42113