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[SR-9934] Conditional binding (if let) does not work with try? expressions #52340

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swift-ci opened this issue Feb 15, 2019 · 1 comment
Closed

[SR-9934] Conditional binding (if let) does not work with try? expressions #52340

swift-ci opened this issue Feb 15, 2019 · 1 comment
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bug A deviation from expected or documented behavior. Also: expected but undesirable behavior. compiler The Swift compiler in itself

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@swift-ci
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Previous ID SR-9934
Radar None
Original Reporter yasin.turkdogan (JIRA User)
Type Bug
Status Resolved
Resolution Done
Environment

iOS 12.1.2, Swift 4.2

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

md5: 186af1cebd0fa81ac5b79ad8fd491033

Issue Description:

Optional binding ends up with nil value unexpectedly when the given function marked as throws and wrapped with try?

Sample code block :

func test() throws -> String?  {
    return nil
}

if let A = try? test() {
    print("Case 1. Value of A: \(String(describing: A))")
} else {
    print("Case 2")
}

//Output: Case 1. Value of A: nil
@belkadan
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This is behaving as designed in Swift 4.2: the original return type is String?, i.e. Optional<String>, and so try? produces Optional<Optional<String>>. In Swift 5 mode this will change to have the flattening behavior you were expecting, per SE-0230.

Note that that change is limited to Swift 5 mode, for source compatibility reasons. That means updating your build settings if you want the new behavior.

@swift-ci swift-ci transferred this issue from apple/swift-issues Apr 25, 2022
This issue was closed.
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bug A deviation from expected or documented behavior. Also: expected but undesirable behavior. compiler The Swift compiler in itself
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@belkadan @swift-ci