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[SR-4375] Using Generic with Protocols causes Segmentation Fault #46954

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swift-ci opened this issue Mar 27, 2017 · 5 comments
Closed

[SR-4375] Using Generic with Protocols causes Segmentation Fault #46954

swift-ci opened this issue Mar 27, 2017 · 5 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

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@swift-ci
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Previous ID SR-4375
Radar None
Original Reporter arup193 (JIRA User)
Type Bug
Status Resolved
Resolution Duplicate
Environment

MacBook Pro
Operating System: OS X El Capitan (10.11.6)
RAM: 16GB
Xcode: 8.2.1
Swift Version: 3.0.2

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

md5: 6420fbb80f768d47f694f48e2932126c

duplicates:

  • SR-75 Referencing a protocol function crashes the compiler

Issue Description:

I will explain the issue with a sample example, that you can run on a playground project.

import Foundation
class IProtocol {
     func meth1(arg: Int){}
}
class IObserver: IProtocol {
    private var className: String
    init(name: String) {
        className = name
    }
    override func meth1(arg: Int) {
        print(className, ":", arg)
    }
}
class Notifier<T> {
    private var listOfObservers = NSMutableArray()
    func addObserver(observer: T) {
        listOfObservers.add(observer)
    }
    func callObservers<ARG, RET>(function: (T)->(ARG)->RET, arg: ARG) {
        for obj in listOfObservers {
            let observer = obj as! T
            _ = function(observer)(arg)
        }
    }
}
let a = IObserver(name: "First I Observer")
let b = IObserver(name: "Second I Observer")
let n = Notifier<IProtocol>()
n.addObserver(observer: a)
n.addObserver(observer: b)
n.callObservers(function: IProtocol.meth1, arg: Int(1))

OUTPUT:
First I Observer: 1
Second I Observer: 1

Explanation:
The above example fails and does not build giving Command failed due to signal: Segmentation Fault: 11, when I change IProtocol to protocol from class. I have different protocols and different observer classes confirming those protocols. I am trying to implement a Notifier class that notifies the observers by taking the method from the protocol and arguments to be passed for that method.

Note:
I remove the {} from meth1(arg: ) and also remove the override keyword from IObserver class, when I change IProtocol to a protocol
@belkadan
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Reproduced on master:

not existential
UNREACHABLE executed at /Volumes/Data/swift-public/swift/lib/SILGen/SILGenConvert.cpp:857!
0  swift                    0x000000010e70a1b8 llvm::sys::PrintStackTrace(llvm::raw_ostream&) + 40
1  swift                    0x000000010e7093d6 llvm::sys::RunSignalHandlers() + 86
2  swift                    0x000000010e70a809 SignalHandler(int) + 361
3  libsystem_platform.dylib 0x00007fffd6ec1fba _sigtramp + 26
4  libsystem_platform.dylib 0x0000000112cba75c _sigtramp + 1004505020
5  libsystem_c.dylib        0x00007fffd6d20f83 abort + 127
6  swift                    0x000000010e6a9ca7 llvm::llvm_unreachable_internal(char const*, char const*, unsigned int) + 471
7  swift                    0x000000010bd03a82 swift::Lowering::SILGenFunction::emitOpenExistential(swift::SILLocation, swift::Lowering::ManagedValue, swift::ArchetypeType*, swift::SILType, swift::AccessKind) + 1330
8  swift                    0x000000010bd1f4fa swift::Lowering::SILGenFunction::emitOpenExistentialExprImpl(swift::OpenExistentialExpr*, llvm::function_ref<void (swift::Expr*)>) + 554
9  swift                    0x000000010bd2c531 swift::Lowering::RValue swift::Lowering::SILGenFunction::emitOpenExistentialExpr<swift::Lowering::RValue, (anonymous namespace)::RValueEmitter::visitOpenExistentialExpr(swift::OpenExistentialExpr*, swift::Lowering::SGFContext)::$_4>(swift::OpenExistentialExpr*, (anonymous namespace)::RValueEmitter::visitOpenExistentialExpr(swift::OpenExistentialExpr*, swift::Lowering::SGFContext)::$_4) + 65
10 swift                    0x000000010bd2214c swift::ASTVisitor<(anonymous namespace)::RValueEmitter, swift::Lowering::RValue, void, void, void, void, void, swift::Lowering::SGFContext>::visit(swift::Expr*, swift::Lowering::SGFContext) + 7452
11 swift                    0x000000010bd1eb89 swift::Lowering::SILGenFunction::emitRValueAsSingleValue(swift::Expr*, swift::Lowering::SGFContext) + 57
12 swift                    0x000000010bd26a70 swift::ASTVisitor<(anonymous namespace)::RValueEmitter, swift::Lowering::RValue, void, void, void, void, void, swift::Lowering::SGFContext>::visit(swift::Expr*, swift::Lowering::SGFContext) + 26176
13 swift                    0x000000010bd19f93 swift::Lowering::SILGenFunction::emitRValue(swift::Expr*, swift::Lowering::SGFContext) + 35
14 swift                    0x000000010bce44f0 (anonymous namespace)::ArgEmitter::emitArgumentFromSource(swift::Lowering::ArgumentSource&&, swift::SILType, swift::Lowering::AbstractionPattern, swift::SILParameterInfo) + 288
15 swift                    0x000000010bce0217 (anonymous namespace)::ArgEmitter::emit(swift::Lowering::ArgumentSource&&, swift::Lowering::AbstractionPattern) + 3735
16 swift                    0x000000010bce13fa (anonymous namespace)::ArgEmitter::emitExpanded(swift::Lowering::ArgumentSource&&, swift::Lowering::AbstractionPattern) + 234
17 swift                    0x000000010bcdf4b0 (anonymous namespace)::ArgEmitter::emit(swift::Lowering::ArgumentSource&&, swift::Lowering::AbstractionPattern) + 304
18 swift                    0x000000010bcdeb04 (anonymous namespace)::CallSite::emit(swift::Lowering::SILGenFunction&, swift::Lowering::AbstractionPattern, (anonymous namespace)::ParamLowering&, llvm::SmallVectorImpl<swift::Lowering::ManagedValue>&, llvm::SmallVectorImpl<std::__1::pair<swift::Lowering::LValue, swift::SILLocation> >&, llvm::Optional<swift::ForeignErrorConvention> const&, swift::ImportAsMemberStatus const&) && + 452
19 swift                    0x000000010bcde2e8 (anonymous namespace)::CallEmission::emitArgumentsForNormalApply(swift::CanTypeWrapper<swift::FunctionType>&, swift::Lowering::AbstractionPattern&, swift::CanTypeWrapper<swift::SILFunctionType>&, llvm::Optional<swift::ForeignErrorConvention>&, swift::ImportAsMemberStatus&, swift::Lowering::ApplyOptions&, llvm::SmallVectorImpl<swift::Lowering::ManagedValue>&, llvm::Optional<swift::SILLocation>&, swift::CanTypeWrapper<swift::FunctionType>&) + 2232
20 swift                    0x000000010bccc1af (anonymous namespace)::CallEmission::apply(swift::Lowering::SGFContext) + 3311
21 swift                    0x000000010bccaf73 swift::Lowering::SILGenFunction::emitApplyExpr(swift::Expr*, swift::Lowering::SGFContext) + 51
22 swift                    0x000000010bd20484 swift::ASTVisitor<(anonymous namespace)::RValueEmitter, swift::Lowering::RValue, void, void, void, void, void, swift::Lowering::SGFContext>::visit(swift::Expr*, swift::Lowering::SGFContext) + 84
23 swift                    0x000000010bd1ee53 swift::Lowering::SILGenFunction::emitIgnoredExpr(swift::Expr*) + 467
24 swift                    0x000000010bcc1ad7 swift::Lowering::SILGenModule::visitTopLevelCodeDecl(swift::TopLevelCodeDecl*) + 375

@belkadan
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Looks like we still don't handle direct references to protocol methods. Reduced:

protocol IProtocol {
  func meth1()
}
struct IObserver: IProtocol {
  func meth1() { print("success") }
}
let x = IProtocol.meth1
x(IObserver())()

@jckarter, what's the bug for this?

arup193 (JIRA User), your workaround is to pass an explicit closure instead, something like

n.callObservers(function: { obj in { arg in obj.meth1(arg: arg) } }, arg: 1)

@jckarter
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I think @slavapestov has that one.

@slavapestov
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https://bugs.swift.org/browse/SR-75

@swift-ci
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Comment by Arup Dandapat (JIRA)

Jordan Rose, thanks for the work around.

@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
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@slavapestov @jckarter @belkadan @swift-ci @AnthonyLatsis