CharacterSet.inverted crashes on mutation

[WFT]

This code (see below) crashes with the message void CFCharacterSetRemoveCharactersInRange(CFMutableCharacterSetRef, CFRange): Immutable character set passed to mutable function.

If you comment out either the .inverted or the remove call, it does not crash.

The same code works fine on macOS Sequoia.

I reproduced this crash on these docker images:

• swiftlang/swift:nightly-6.2-jammy
• swift:6.1.2

And I originally found the issue on GitHub Actions ubuntu-latest while trying to run SwiftGrammar() from https://github.com/JohnSundell/Splash.

Sample code:

import Foundation

var cs = CharacterSet.alphanumerics.inverted
cs.remove("_")