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[SR-7284] NSSet/NSDictionary instances aren't always bridgeable to Swift #3726

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lorentey opened this issue Mar 27, 2018 · 4 comments
Open

[SR-7284] NSSet/NSDictionary instances aren't always bridgeable to Swift #3726

lorentey opened this issue Mar 27, 2018 · 4 comments
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@lorentey
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bug Foundation Standard Library

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@lorentey
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Previous ID SR-7284
Radar rdar://problem/38922580
Original Reporter @lorentey
Type Bug
Environment

Apple Swift version 4.0 (swiftlang-900.0.65 clang-900.0.37)
Apple Swift version 4.1 (swiftlang-902.0.34 clang-902.0.30)
Swift version 4.2-dev (LLVM a481df9074, Clang 051a73f5bc, Swift 599b4bc952)

Additional Detail from JIRA
Votes 1
Component/s Foundation, Standard Library
Labels Bug
Assignee @lorentey
Priority Medium

md5: 3c6a82511a3c7c4552d6181c15f93ce9

Issue Description:

We currently assume that the elements of an NSSet (and the keys of an NSDictionary) are convertible to AnyHashable. Unfortunately, this is not necessarily the case – NSSets may contain elements of Swift types that aren't hashable:

import Foundation

struct NotHashable {
  let value: Int
}

let a = NotHashable(value: 42)
let set = NSSet(object: a as AnyObject)
let s1 = set as? Set<AnyHashable> // crashes
let s2 = set as AnyHashable       // crashes

4.2 stack trace for the Set<AnyHashable> crash:

0  swift                    0x000000010728a418 llvm::sys::PrintStackTrace(llvm::raw_ostream&) + 40
1  swift                    0x000000010728ab26 SignalHandler(int) + 694
2  libsystem_platform.dylib 0x00007fff797e1d9a _sigtramp + 26
3  libsystem_platform.dylib 0x000000000000ffff _sigtramp + 2256724607
4  libswiftObjectiveC.dylib 0x000000010eb0bfab $SSo8NSObjectCs8Hashable10ObjectiveCsACP5_hash4intoys7_HasherVz_tFTW + 43
5  libswiftCore.dylib       0x000000010f3e2462 $Ss20_ConcreteHashableBoxV5_hash5_intoys7_HasherVz_tF + 18
6  libswiftCore.dylib       0x000000010f3e2629 $Ss20_ConcreteHashableBoxVyxGs04_AnybC0ssADP5_hash5_intoys7_HasherVz_tFTW + 9
7  libswiftCore.dylib       0x000000010f3e2f87 $Ss11AnyHashableVs0B0ssACP5_hash4intoys7_HasherVz_tFTW + 71
8  libswiftCore.dylib       0x000000010f3c5fcd $Ss17_VariantSetBufferO12nativeInsert_6forKeySb8inserted_x011memberAfterE0tx_xtF + 221
9  libswiftFoundation.dylib 0x000000010fdc09bf $Ss35_setBridgeFromObjectiveCConditionalys3SetVyq_GSgACyxGs8HashableRzsAGR_r0_lFACySo8NSObjectCGAeIRszsAGR_r0_lIetgo_Tp5 + 623
10 libswiftFoundation.dylib 0x000000010fdc02c1 $Ss3SetV10FoundationE34_conditionallyBridgeFromObjectiveC_6resultSbSo5NSSetC_AByxGSgztFZ + 113
11 libswiftFoundation.dylib 0x000000010fdc0e14 $Ss3SetVyxGs21_ObjectiveCBridgeable10FoundationsADP024_conditionallyBridgeFromB1C_6resultSb01_B5CTypeQz_xSgztFZTW + 20
12 libswiftCore.dylib       0x000000010f2b3a01 $Ss45_conditionallyBridgeFromObjectiveC_bridgeableyxSg01_D5CTypeQz_xmts01_D11CBridgeableRzlF + 65
13 libswiftCore.dylib       0x000000010c7c2110 $Ss45_conditionallyBridgeFromObjectiveC_bridgeableyxSg01_D5CTypeQz_xmts01_D11CBridgeableRzlF + 4249937744
14 swift                    0x00000001045ed00d llvm::MCJIT::runFunction(llvm::Function*, llvm::ArrayRef<llvm::GenericValue>) + 461
15 swift                    0x00000001045f0b31 llvm::ExecutionEngine::runFunctionAsMain(llvm::Function*, std::__1::vector<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::allocator<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > > const&, char const* const*) + 1313
16 swift                    0x0000000103b35367 swift::RunImmediately(swift::CompilerInstance&, std::__1::vector<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::allocator<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > > const&, swift::IRGenOptions&, swift::SILOptions const&) + 3639
17 swift                    0x0000000103af1a8b performCompile(swift::CompilerInstance&, swift::CompilerInvocation&, llvm::ArrayRef<char const*>, int&, swift::FrontendObserver*, swift::UnifiedStatsReporter*) + 15179
18 swift                    0x0000000103aecf2e swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 3310
19 swift                    0x0000000103aa3a83 main + 2051
20 libdyld.dylib            0x00007fff795f0c91 start + 1

Trace for AnyHashable conversion:

0  swift                    0x000000010bbab418 llvm::sys::PrintStackTrace(llvm::raw_ostream&) + 40
1  swift                    0x000000010bbabb26 SignalHandler(int) + 694
2  libsystem_platform.dylib 0x00007fff797e1d9a _sigtramp + 26
3  libsystem_platform.dylib 0x000000000000ffff _sigtramp + 2256724607
4  libswiftObjectiveC.dylib 0x000000011342cfab $SSo8NSObjectCs8Hashable10ObjectiveCsACP5_hash4intoys7_HasherVz_tFTW + 43
5  libswiftCore.dylib       0x0000000113d03462 $Ss20_ConcreteHashableBoxV5_hash5_intoys7_HasherVz_tF + 18
6  libswiftCore.dylib       0x0000000113d03629 $Ss20_ConcreteHashableBoxVyxGs04_AnybC0ssADP5_hash5_intoys7_HasherVz_tFTW + 9
7  libswiftCore.dylib       0x0000000113ed73b7 $Ss15_AnyHashableBoxP5_hash5_intoys7_HasherVz_tFTj + 7
8  libswiftFoundation.dylib 0x00000001147b2e05 $Ss3SetV10FoundationE26_forceBridgeFromObjectiveC_6resultySo5NSSetC_AByxGSgztFZyyp_Spy0F1C8ObjCBoolVGtXEfU0_s11AnyHashableV_Tg5TA + 309
9  libswiftFoundation.dylib 0x00000001146e1152 $SypSpy10ObjectiveC8ObjCBoolVGIgny_yXlADIyByy_TR + 66
10 CoreFoundation           0x00007fff4cc704a3 -[__NSSingleObjectSetI enumerateObjectsWithOptions:usingBlock:] + 99
11 libswiftFoundation.dylib 0x000000011474efc8 $Ss3SetV10FoundationE26_forceBridgeFromObjectiveC_6resultySo5NSSetC_AByxGSgztFZs11AnyHashableV_Tg5Tf4nnd_n + 424
12 libswiftFoundation.dylib 0x00000001146e1e8a $SSo5NSSetC10FoundationE20_toCustomAnyHashables0eF0VSgyF + 58
13 libswiftFoundation.dylib 0x00000001146e20c0 $SSo5NSSetCs35_HasCustomAnyHashableRepresentation10FoundationsACP03_tocdE0s0dE0VSgyFTW + 16
14 libswiftCore.dylib       0x0000000113d03977 $Ss11AnyHashableVyABxcs0B0RzlufC + 231
15 libswiftCore.dylib       0x0000000113d0470e $Ss21_convertToAnyHashableys0cD0Vxs0D0RzlF + 78
16 libswiftCore.dylib       0x00000001110e30fc $Ss21_convertToAnyHashableys0cD0Vxs0D0RzlF + 4248693308
17 swift                    0x0000000108f0e00d llvm::MCJIT::runFunction(llvm::Function*, llvm::ArrayRef<llvm::GenericValue>) + 461
18 swift                    0x0000000108f11b31 llvm::ExecutionEngine::runFunctionAsMain(llvm::Function*, std::__1::vector<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::allocator<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > > const&, char const* const*) + 1313
19 swift                    0x0000000108456367 swift::RunImmediately(swift::CompilerInstance&, std::__1::vector<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::allocator<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > > const&, swift::IRGenOptions&, swift::SILOptions const&) + 3639
20 swift                    0x0000000108412a8b performCompile(swift::CompilerInstance&, swift::CompilerInvocation&, llvm::ArrayRef<char const*>, int&, swift::FrontendObserver*, swift::UnifiedStatsReporter*) + 15179
21 swift                    0x000000010840df2e swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 3310
22 swift                    0x00000001083c4a83 main + 2051
23 libdyld.dylib            0x00007fff795f0c91 start + 1
@lorentey
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With the conditional Hashable conformances introduced in SE-0143, this issue also applies to NSArray and the values of an NSDictionary.

apple/swift#15382

@lorentey
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What if we made all _SwiftValues convertible to AnyHashable? (They already are in a way, although only when Foundation is imported, and the resulting AnyHashable is broken.) If the original Swift value isn't Hashable, its AnyHashable representation could still use _SwiftValue identity for hashing – this wouldn't be very useful, but at least it wouldn't crash.

$ swift
Welcome to Apple Swift version 4.1 (swiftlang-902.0.34 clang-902.0.30). Type :help for assistance.
  1> struct NotHashable { let value: Int }
  2> let a = NotHashable(value: 42)
a: NotHashable = {
  value = 42
}
  3> let o = a as AnyObject
o: Swift.AnyObject = {
  instance_type = 0x0000000101700130
}
  4> o as? AnyHashable
$R0: AnyHashable? = nil
  5> import Foundation
  6> o as? AnyHashable
$R1: AnyHashable? = some {
  _box = {
    _baseHashable = {
      value = 42
    }
  }
  _usedCustomRepresentation = false
}
  7> (o as? AnyHashable)?.hashValue
Execution interrupted. Enter code to recover and continue.
Enter LLDB commands to investigate (type :help for assistance.)
Process 31806 stopped
* thread #&#8203;1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x2a)
    frame #&#8203;0: 0x00007fff78635e57 libobjc.A.dylib`objc_msgSend + 23
libobjc.A.dylib`objc_msgSend:
->  0x7fff78635e57 <+23>: andq   (%rdi), %r10
    0x7fff78635e5a <+26>: movq   %rsi, %r11
    0x7fff78635e5d <+29>: andl   0x18(%r10), %r11d
    0x7fff78635e61 <+33>: shlq   $0x4, %r11
Target 0: (repl_swift) stopped.
  8>

@jckarter
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Yeah, that's what we should do. If the value isn't the box isn't hashable, we should make a best effort by hashing the boxes.

@lorentey
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@swift-ci create

@swift-ci swift-ci transferred this issue from apple/swift-issues Apr 25, 2022
@shahmishal shahmishal transferred this issue from apple/swift May 5, 2022
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