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[SR-10546] Runtime crash while iterating through collection of Decodable structs w/ URL fields #52946

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swift-ci opened this issue Apr 25, 2019 · 2 comments
Closed

[SR-10546] Runtime crash while iterating through collection of Decodable structs w/ URL fields #52946

swift-ci opened this issue Apr 25, 2019 · 2 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 regression run-time crash Bug → crash: Swift code crashed during execution swift 5.0

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Previous ID SR-10546
Radar rdar://problem/50207580
Original Reporter djs-code (JIRA User)
Type Bug
Status Resolved
Resolution Done

Attachment: Download

Environment

macOS 10.14.4 (18E226)

Xcode 10.2.1 (10E1001)

Swift 4.2 / 5.0

iOS Simulator 12.2

iPhone XS w/ iOS 12.0 (16A366)

Additional Detail from JIRA
Votes 0
Component/s Compiler
Labels Bug, 5.0Regression, RunTimeCrash
Assignee None
Priority Medium

md5: 646ddc117720b95cfdf9b2a4aebb06cb

Issue Description:

When synchronizing our Core Data state with the server, we employ an O(n+m) algorithm leveraging iterators to perform the necessary insert/update/delete operations. However, as-of updating to Xcode 10.2.1, we're now seeing a consistent crash during one of these upsert operations:

* thread #5, queue = 'NSManagedObjectContext 0x10ac2d900', stop reason = EXC_BAD_ACCESS (code=1, address=0x54c0000b0)
frame #0: 0x000000019d54b6f0 libobjc.A.dylib`objc_retain + 16
frame #1: 0x00000001055112d4 libswiftCore.dylib`swift::metadataimpl::ValueWitnesses<swift::metadataimpl::ObjCRetainableBox>::initializeWithCopy(swift::OpaqueValue*, swift::OpaqueValue*, swift::TargetMetadata<swift::InProcess> const*) + 28
frame #2: 0x00000001040bebb4 StructIterationCrasher`outlined init with copy of (offset: Int, element: AppDelegate.NotificationStreamPayload.Item)? at <compiler-generated>:0

From experimenting with this, it seems that the given payload's URL field is what's triggering this, as omitting it seemingly resolves the issue.

A sample project has been attached.
@aschwaighofer
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This does not reproduce with a recent Xcode.

@swift-ci
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Comment by August S. Freytag (JIRA)

For any future investigators, I triggered this issue when adding a computed property `var ids: Set<UUID>` to a store-like class; if you'd try to iterate over the contents of the store with that property in place, you'd get a `swift::metadataimpl::ValueWitnesses` execution fault inside the `Array` iteration. Renaming the property without making any other changes resolved this, so I'm suspecting a collision of sorts under the hood.

@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 regression run-time crash Bug → crash: Swift code crashed during execution swift 5.0
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@aschwaighofer @swift-ci @AnthonyLatsis