[SR-13270] NSRegularExpression.numberOfMatches() with bad range doesn't fail

[swift-ci]

Previous ID	SR-13270
Radar	None
Original Reporter	NPAssoc (JIRA User)
Type	Bug

Environment

Raspian Linux Swift version 5.1.5-v0.1

Additional Detail from JIRA

| | | |------------------|-----------------| |Votes | 0 | |Component/s | Foundation | |Labels | Bug | |Assignee | None | |Priority | Medium | md5: 957478105529dab8d74d9fcb73634dae

Issue Description:

Given a regular expression like:

let testExp = try! NSRegularExpression(pattern: "(^| /) .", options: [])

The code:

let ss = "/Pairs Series/._Chair15.jpg"

let tRange = NSMakeRange(0, ss.count + 2)

let matches = testExp.numberOfMatches(in: ss, options: [], range: tRange)

fails on the Mac with: '...Range or index out of bounds'

but works under Raspian returning 0 matches.

Under Raspian, it should either fail or return 1 match.

[benrimmington]

When given an invalid range, the internal prepareRegularExpression function returns NULL, which results in a silent failure with zero matches. I'm not sure if this behavior is considered a bug.

Note that your ss.count example gives the number of characters (extended grapheme clusters), but NSRegularExpression needs an NSRange of UTF-16 code units.

let tRange = NSRange(location: 0, length: ss.utf16.count)

let tRange = NSRange(ss.startIndex..., in: ss)