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[SR-10032] Crash using a class and protocol constraint on a collection passed to the Set initializer #52435

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tjw opened this issue Mar 2, 2019 · 7 comments
Open

[SR-10032] Crash using a class and protocol constraint on a collection passed to the Set initializer #52435

tjw opened this issue Mar 2, 2019 · 7 comments
Labels
bug A deviation from expected or documented behavior. Also: expected but undesirable behavior. compiler The Swift compiler in itself crash Bug: A crash, i.e., an abnormal termination of software optimized only Flag: An issue whose reproduction requires optimized compilation

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@tjw
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tjw commented Mar 2, 2019

Previous ID SR-10032
Radar rdar://problem/48566320
Original Reporter @tjw
Type Bug

Attachment: Download

Environment

Xcode 10.1 or Xcode 10.2b3

macOS 10.14.3

Additional Detail from JIRA
Votes 0
Component/s Compiler
Labels Bug, CompilerCrash, OptimizedOnly
Assignee None
Priority Medium

md5: 13545070b8de89da21dab248cbe72e95

Issue Description:

The following code crashes the compiler when built in Release mode:

@objc public protocol P : NSObjectProtocol {}

private func _makeCopies<C: Collection>(objects: C) where C.Element : NSObject & P {
    _ = Set(objects)
}
public func duplicateSections() {
    let objects = [NSObject & P]()
    _makeCopies(objects: objects)
}

with the backtrace:

1.  While running pass #&#8203;1117 SILFunctionTransform "EarlyInliner" on SILFunction "@$ss10_NativeSetV6resize8capacityySi_tF9CrashTest1P_So8NSObjectCXc_Tg5".
 for <<debugloc at "<compiler-generated>":0:0>>0  swift                    0x000000010504befa PrintStackTraceSignalHandler(void*) + 42
1  swift                    0x000000010504b6dc SignalHandler(int) + 348
2  libsystem_platform.dylib 0x00007fff7d0f1b3d _sigtramp + 29
3  libsystem_platform.dylib 0x00007f851fa9d068 _sigtramp + 2728047944
4  swift                    0x0000000101e3b5be swift::SILInstructionVisitor<swift::SILInlineCloner, void>::visit(swift::SILInstruction*) + 13886
5  swift                    0x0000000101e36ac3 swift::SILInliner::inlineFunction(swift::SILFunction*, swift::FullApplySite, llvm::ArrayRef<swift::SILValue>) + 6003
6  swift                    0x0000000101d2124e (anonymous namespace)::SILPerformanceInlinerPass::run() + 1438
7  swift                    0x0000000101c909bb swift::SILPassManager::execute() + 4587
8  swift                    0x0000000100ebb7b5 performCompile(swift::CompilerInstance&, swift::CompilerInvocation&, llvm::ArrayRef<char const*>, int&, swift::FrontendObserver*, swift::UnifiedStatsReporter*) + 46789
9  swift                    0x0000000100eacac7 swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 6823
10 swift                    0x0000000100e4c90d main + 1261
11 libdyld.dylib            0x00007fff7cf06ed9 start + 1

  • Open the attached project

  • Ensure the build configuration is set to Release

  • Build

  • Crash
@tjw
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tjw commented Mar 2, 2019

Inlining the private function into the caller results in an error instead of a crash, `'NSObject & P' cannot be used as a type conforming to protocol 'Hashable' because 'Hashable' has static requirements`

@tjw
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tjw commented Mar 2, 2019

In this case, a workaround was to convert the incoming Collection<NSObject & P> to [NSObject] before passing it off to the Set initializer with Set(objects.map { $0 as NSObject}). This avoided the compiler getting confused about how to deal with Hashable for the given type. It seems like it shouldn't have been a problem since both NSObject and P get -hash from NSObjectProtocol.

@belkadan
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belkadan commented Mar 4, 2019

With assertions:

Assertion failed: (optConformance && "existential type didn't self-conform"), function subst, file /Volumes/Data/swift-public/swift/lib/AST/ProtocolConformance.cpp, line 121.
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-darwin18.5.0 -enable-objc-interop -sdk /Volumes/Data/Applications/Xcode10.2.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk -O -color-diagnostics -module-name main -o /var/folders/_d/dmrgv26d3bs6lkrks9z825_w0000gn/T/--bcbf87.o 
1.  While running pass #&#8203;1174 SILFunctionTransform "GenericSpecializer" on SILFunction "@$s4main11_makeCopies33_1A61A3E7348A44FC8FF8726B26BEB4EDLL7objectsyx_tSlRzSo8NSObjectC7ElementRczAA1PAHRQlFSayAaI_AFXcG_Tg5".
 for '_makeCopies(objects:)' (at <stdin>:5:9)

NSObjectProtocol isn't actually Hashable, because protocols can't conform to other protocols today, but throwing away the `& P` part would have worked. @eeckstein, who handles inlining these days?

@eeckstein
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@belkadan The crash is already in the GenericSpecializer. Anyway, this looks like a type-system/frontend issue.

@belkadan
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belkadan commented Mar 4, 2019

Ah, good point. SR-10031 shows that this should have been rejected.

@belkadan
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belkadan commented Mar 4, 2019

Er, wait, no, it's an @objc protocol. That means we do accept this, but maybe we don't SILGen it correctly.

@tjw
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tjw commented Oct 8, 2019

This is still an issue in Xcode 11.2b1

@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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bug A deviation from expected or documented behavior. Also: expected but undesirable behavior. compiler The Swift compiler in itself crash Bug: A crash, i.e., an abnormal termination of software optimized only Flag: An issue whose reproduction requires optimized compilation
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@tjw @belkadan @eeckstein @AnthonyLatsis