[SR-7330] Crash in String.enumerateLinguisticTags

[swift-ci]

Previous ID	SR-7330
Radar	rdar://problem/39142691
Original Reporter	Ringo_D (JIRA User)
Type	Bug

Additional Detail from JIRA

Votes	0
Component/s	Compiler, Foundation
Labels	Bug, 4.1Regression
Assignee	None
Priority	Medium

md5: e547299bbe6c43ea5d9eb8aa616a255e

Issue Description:

When I upgrade from Swift 4.0 to 4.1, the enumerateLinguisticTags method crash.

var string = "1"
let orthography = NSOrthography(dominantScript: "Latin", languageMap: [ "Latn": ["en"]])
string.enumerateLinguisticTags(in: string.startIndex..<string.endIndex,
                               scheme: NSLinguisticTagScheme.lemma.rawValue,
                               options: NSLinguisticTagger.Options.omitWhitespace,
                               orthography: orthography,
                               invoking: { (tag, _, _, stop) in
                                stop = true
})

It works fine in Swift 4.0. But now it's crash with `EXC_BAD_ADDRESS(code=1, address=0x0)`.

[belkadan]

Crashing in CFStringCreateCopy, which to me suggests a nil string. @milseman, did something change here? It doesn't appear to be the same as SR-7240.

[belkadan]

@swift-ci create

[milseman]

I don't know. There may be a latent bug in Foundation exposed by some change to String, but otherwise I have no idea what this would be about.

CC @parkera

[parkera]

I moved the bug around to the right component internally.