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[SR-6850] Conditional conformance crasher: condition on inner type #49399

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airspeedswift opened this issue Jan 26, 2018 · 4 comments
Closed

[SR-6850] Conditional conformance crasher: condition on inner type #49399

airspeedswift opened this issue Jan 26, 2018 · 4 comments
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@DougGregor
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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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@airspeedswift
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Previous ID SR-6850
Radar rdar://problem/36906751
Original Reporter @airspeedswift
Type Bug
Status Resolved
Resolution Done
Additional Detail from JIRA
Votes 0
Component/s Compiler
Labels Bug, CompilerCrash
Assignee @DougGregor
Priority Medium

md5: e8456335d92edf60e1adcc1da963def0

Issue Description:

The following currently crashes on compilation.

The cause appears to be that the Inner type is defined conditionally (when Bound: Strideable) but the conditional conformance leaves this out.

To fix the crasher, add the necessary conditions for Inner to exist. Instead this should be implied, or generate a compiler warning. (my preference is implied, and I think that's more in keeping with other similar situations)

This is a reduction of the implementation for CountableRange.Index: Hashable where Bound: Hashable

struct S<T: Comparable> { }

// Inner only exists where T: Strideable
extension S where T: Strideable {
struct Inner { }

var inner: Inner { return Inner() }
}

extension S.Inner: Equatable {
static func == (lhs: S<T>.Inner, rhs: S<T>.Inner) -> Bool { return true }
}

// T: Strideable should be inferred, or maybe required,
// but currently it just crashes on compilation
extension S.Inner: Hashable 
where T: Hashable 
// uncomment to make it compile...
// , T: Strideable
{
var hashValue: Int { return 0 }
}

let s = S<Int>()
let i = s.inner.hashValue

print(i)
@airspeedswift
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@swift-ci create

@huonw
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huonw mannequin commented Jan 30, 2018

Reduced slightly:

protocol P {}
protocol Q { func foo() }

struct S<T> {}

extension S where T: P {
    struct Inner {}
}

extension S.Inner: Q where T: Q {
    func foo() {}
}

Backtrace:

9  swift                    0x000000010e8af6cb swift::irgen::GenericTypeRequirements::enumerateFulfillments(swift::irgen::IRGenModule&, swift::SubstitutionMap const&, llvm::function_ref<void (unsigned int, swift::CanType, llvm::Optional<swift::ProtocolConformanceRef>)>) + 507
10 swift                    0x000000010e6df0e9 swift::irgen::FulfillmentMap::searchNominalTypeMetadata(swift::irgen::IRGenModule&, swift::CanType, unsigned int, swift::irgen::MetadataPath&&, swift::irgen::FulfillmentMap::InterestingKeysCallback const&) + 521
11 swift                    0x000000010e6dea7b swift::irgen::FulfillmentMap::searchTypeMetadata(swift::irgen::IRGenModule&, swift::CanType, swift::irgen::IsExact_t, unsigned int, swift::irgen::MetadataPath&&, swift::irgen::FulfillmentMap::InterestingKeysCallback const&) + 843
12 swift                    0x000000010e6de842 swift::irgen::FulfillmentMap::searchTypeMetadata(swift::irgen::IRGenModule&, swift::CanType, swift::irgen::IsExact_t, unsigned int, swift::irgen::MetadataPath&&, swift::irgen::FulfillmentMap::InterestingKeysCallback const&) + 274
13 swift                    0x000000010ea1a38b swift::irgen::LocalTypeDataCache::addAbstractForTypeMetadata(swift::irgen::IRGenFunction&, swift::CanType, swift::irgen::IsExact_t, llvm::Value*) + 187
14 swift                    0x000000010ea1a2bf swift::irgen::IRGenFunction::bindLocalTypeDataFromTypeMetadata(swift::CanType, swift::irgen::IsExact_t, llvm::Value*) + 207
15 swift                    0x000000010e8bfd2c (anonymous namespace)::EmitPolymorphicParameters::bindExtraSource(swift::irgen::MetadataSource const&, swift::irgen::Explosion&, swift::irgen::WitnessMetadata*) + 620
16 swift                    0x000000010e8ad319 (anonymous namespace)::EmitPolymorphicParameters::emit(swift::irgen::Explosion&, swift::irgen::WitnessMetadata*, llvm::function_ref<llvm::Value* (unsigned int)> const&) + 137
17 swift                    0x000000010e8ad23e swift::irgen::emitPolymorphicParameters(swift::irgen::IRGenFunction&, swift::SILFunction&, swift::irgen::Explosion&, swift::irgen::WitnessMetadata*, llvm::function_ref<llvm::Value* (unsigned int)> const&) + 78
18 swift                    0x000000010e9a4ce5 emitEntryPointArgumentsNativeCC((anonymous namespace)::IRGenSILFunction&, swift::SILBasicBlock*, swift::irgen::Explosion&) + 1157
19 swift                    0x000000010e99f7a5 (anonymous namespace)::IRGenSILFunction::emitSILFunction() + 1605

@huonw
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Mannequin

huonw mannequin commented Jan 31, 2018

Possibly fixed in #14293

@huonw
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huonw mannequin commented Apr 5, 2018

Yeah, that PR fixed it.

@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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@DougGregor DougGregor

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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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