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[SR-10600] Runtime fails to demangle superclass when superclass's generic constraints are satisified in a conditional conformance #53000

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swift-ci opened this issue May 2, 2019 · 3 comments
Open

[SR-10600] Runtime fails to demangle superclass when superclass's generic constraints are satisified in a conditional conformance #53000

swift-ci opened this issue May 2, 2019 · 3 comments
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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 run-time crash Bug → crash: Swift code crashed during execution

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@swift-ci
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swift-ci commented May 2, 2019

Previous ID SR-10600
Radar rdar://problem/50057445
Original Reporter benpious (JIRA User)
Type Bug

Attachment: Download

Environment

Xcode Version 10.2.1 (10E1001), running on the iOS simulator.

Additional Detail from JIRA
Votes 1
Component/s Compiler
Labels Bug, RunTimeCrash
Assignee None
Priority Medium

md5: e58a0fb9941799cfe7a5f7a11b213366

relates to:

  • SR-10721 Runtime fails to demangle superclass when a type used to satisfy the superclass's generic bound is used in a superficial way

Issue Description:

Firstly, to address the elephant in the room, I know that this is the exact same error message as a crash that's already a known issue according to the Xcode 10.2 release notes. But based on my conversation with @jckarter on Twitter it's not clear if it's the same crash, hence this ticket.

TL:DR is that if you have a class C<T: P>, class D<T2> conforms to P if T2 conforms to P2, and class C2: C<D>, then C2's superclass metadata will be corrupted somehow.

See the sample project's SwiftTest2.swift file for an implementation of this.
@jckarter
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jckarter commented May 2, 2019

Thanks for narrowing down the reproducer!

@jckarter
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Looks like @DougGregor fixed this in the Swift 5.1 runtime in #24759 To backward deploy the fix to Swift 5.0 runtimes in existing OSes, here's a PR that exercises our runtime compatibility hooks: #25030

@swift-ci
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swift-ci commented Jun 6, 2019

Comment by Helge Heß (JIRA)

public protocol Nice {
associatedtype Blub : Nice
var awesomeStuff : Self.Blub { get }
}

struct TestNice : Nice {
var awesomeStuff: some Nice { TestNice() }
}

func call<N: Nice>(for n: N) {
_ = n.awesomeStuff
}

call(for: TestNice())

got this one, which produces

2019-06-06 16:09:28.407874+0200 TestDemangle[62667:17535861] failed to demangle witness for associated type 'Blub' in conformance 'TestDemangle.TestNice: Nice' from mangled name '\^A%\^A'

And @jckarter says might be the same issue. Need to check.

@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 run-time crash Bug → crash: Swift code crashed during execution
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@jckarter @swift-ci @AnthonyLatsis