[SR-8682] Sort doesn't work correctly in recent master

[palimondo]

Previous ID	SR-8682
Radar	rdar://problem/44099288
Original Reporter	@palimondo
Type	Bug

Attachment: Download

Environment

Swift `master` September 1st.

Additional Detail from JIRA

Votes	0
Component/s	Compiler, Standard Library
Labels	Bug, 5.0Regression
Assignee	None
Priority	Medium

md5: 95127a31654eb1c96497beda220fecf6

Issue Description:

The attached reduced test case shows that sorting [Int] doesn't work in recent master.

How wasn't this caught by validation tests?! It looks like the array has to have a certain size for this to manifest itself?

Issue wan't reproducible on Xcode Beta 6 from 13th of August. Binary search for the onset of the problem with swift-DEVELOPMENT snapshots points to introduction of the issue between 16th of 18th of August.

[palimondo]

I'd suspect some of these PRs.

[palimondo]

cc overlazy (JIRA User), @airspeedswift

[hamishknight]

Another example:

let a = [3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4]
print(a.sorted())
// [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 3, 4]
//                               ~~~

[belkadan]

@swift-ci create

[moiseev]

Fixed in #19107

[xwu]

@palimondo Should this bug be closed?