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[SR-8279] Array - Fatal error: Index out of range #50810

swift-ci opened this issue Jul 17, 2018 · 2 comments

[SR-8279] Array - Fatal error: Index out of range #50810

swift-ci opened this issue Jul 17, 2018 · 2 comments


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@swift-ci swift-ci commented Jul 17, 2018

Previous ID SR-8279
Radar None
Original Reporter Em (JIRA User)
Type Bug
Status Resolved
Resolution Invalid

Attachment: Download

Additional Detail from JIRA
Votes 1
Labels Bug, Runtime
Assignee None
Priority Medium

md5: 026c4d8e4dfba6db92c712ef6b41a38e

Issue Description:

Is receiving a fatal error in variable sized array when setting an object at an index desired behaviour?

typealias Coordinate2D = Double
typealias Point2D = [Coordinate2D]

extension Array where Element == Coordinate2D {
  init(x: Coordinate2D, y: Coordinate2D) {

  var x: Coordinate2D { get { return self[0] } set { self[0] = newValue } }
  var y: Coordinate2D { get { return self[1] } set { self[1] = newValue } }

var array = [Point2D]()

let point = Point2D.init(x: 0, y: 0)
array[0] = point // fatal error: index out of range

Above code reproduces the issue in the playground resulting in indefinite execution time.

The project reproducing the above mentioned error is in the attachments.

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@belkadan belkadan commented Jul 17, 2018

Yes, this is expected behavior. Array out-of-bounds errors are a sign that the program is incorrect and that the developer needs to investigate the issue. This is consistent with the behavior of Objective-C's NSArray, as well as array types in many other languages.

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@Azoy Azoy commented Jul 17, 2018

You can solve this issue by simply appending point:


@swift-ci swift-ci transferred this issue from apple/swift-issues Apr 25, 2022
This issue was closed.
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