[SR-3509] Foundation CharacterSet Crash

[swift-ci]

Previous ID	SR-3509
Radar	None
Original Reporter	bnut (JIRA User)
Type	Bug
Status	Resolved
Resolution	Done

Attachment: Download

Environment

xcodebuild -version Xcode 8.2 Build version 8C38

swift --version Apple Swift version 3.0.2 (swiftlang-800.0.63 clang-800.0.42.1) Target: x86_64-apple-macosx10.9

Additional Detail from JIRA

Votes	0
Component/s	Foundation
Labels	Bug, RunTimeCrash
Assignee	None
Priority	Medium

md5: b6a77aabb80a8d86278845247ab9a265

Issue Description:

The following code causes a crash in foundation at runtime:

var set = CharacterSet()
set.insert("\u{D7FF}") // no crash
set.insert("\u{D7FF}") // no crash
set.insert(charactersIn: "\u{D7FE}"..."\u{D7FF}") // crashes

According to the UnicodeScalar.init(_:UInt32) source, 0xD7FF is a valid character:

    //     * As a result of this definition, the set of Unicode scalar values
    //     consists of the ranges 0 to D7FF and E000 to 10FFFF, inclusive.

https://github.com/apple/swift/blob/2fe4254cb712fa101a220f95b6ade8f99f43dc74/stdlib/public/core/UnicodeScalar.swift#L97

I suspect there is an edge case where 0xD7FF is accidentally excluded.

[Dante-Broggi]

Interestingly, in the Xcode 9.4.1 toolchain on a Mac, the behavior is reversed:

var set = CharacterSet()
set.insert(charactersIn: "\u{D7FE}"..."\u{D7FF}") // no crash
set.insert("\u{D7FF}") // crashes

[spevans]

This now works without crashing, tested on swift 5.1 (Xcode 11.3.1) and swift-5.1.3 on Ubuntu18