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[SR-1930] Passing an invalid value to UnicodeScalar initializer crashes the app #44539

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swift-ci opened this issue Jun 29, 2016 · 4 comments
Closed

[SR-1930] Passing an invalid value to UnicodeScalar initializer crashes the app #44539

swift-ci opened this issue Jun 29, 2016 · 4 comments
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bug A deviation from expected or documented behavior. Also: expected but undesirable behavior. standard library Area: Standard library umbrella swift evolution proposal needed Flag → feature: A feature that warrants a Swift evolution proposal

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@swift-ci
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Previous ID SR-1930
Radar rdar://problem/24110013
Original Reporter dunkelstern (JIRA User)
Type Bug
Status Closed
Resolution Done
Environment

Tested on Xcode Version 7.3.1 (7D1014), but happens in newer versions too.

Additional Detail from JIRA
Votes 0
Component/s Standard Library
Labels Bug, swift-evolution-proposal-needed
Assignee 酷酷的哀殿 (JIRA)
Priority Medium

md5: 55ec1ebb5dd1238e7abbe723f7df69c9

Issue Description:

What happens:

When you pass an invalid value to the UnicodeScalar initializer the swift stdlib crashes the program by calling _precondition this is bad if you construct a unicode scalar from user input (e.g. JSON parser)

Example:

var string = ""
let codepoint: UInt32 = 55357 // this is invalid
string.append(UnicodeScalar(codepoint))

What do I expect:

Either the initializer is non-failable or it should be marked as failable and throw an error, but crashing the whole app seems like a bad idea. The documentation states:

Requires: v is a valid Unicode scalar value.

But it does in no way mention that the app will crash otherwise.

NOTE: Requires a swift-evolution proposal.
@belkadan
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In all cases violating a "Requires" precondition means the app may crash. Should this initializer be failable, though, @gribozavr? It's hard to validate whether something is a good UnicodeScalar without having access to a Unicode table.

@gribozavr
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Yes, this initializer should be failable.

@Dante-Broggi
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I think this bug should be closed as `Unicode.Scalar(UInt32)` is now failable.

@swift-ci
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Comment by bohong sun (JIRA)

`Unicode.Scalar(UInt32)` is now failable.

This is a sample.

```

var string = ""

let codepoint: UInt32 = 55357 // this is invalid

string.append(String(UnicodeScalar(codepoint) ?? "\u{61}"))

```

@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. standard library Area: Standard library umbrella swift evolution proposal needed Flag → feature: A feature that warrants a Swift evolution proposal
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@belkadan @gribozavr @swift-ci @Dante-Broggi