[SR-4059] Compiler Crash on Subclasses Further Constraining Generics Initializer

[swift-ci]

Previous ID	SR-4059
Radar	None
Original Reporter	Logan (JIRA User)
Type	Bug
Status	Resolved
Resolution	Done

Additional Detail from JIRA

Votes	0
Component/s	Compiler
Labels	Bug, 3.1Regression, CompilerCrash
Assignee	None
Priority	Medium

md5: 918fe3645f29300276cb0a409197574f

Issue Description:

Not sure if that title is the ticket, but here's repro. Runs and builds fine on 3.0.2, crash seg fault on 3.1:

    class Base {
        init<S: Sequence>(_ s: S) where S.Iterator.Element == UInt8 {

        }
    }

    class Sub: Base {
        init(_ b: [UInt8]) {
            super.init(b)
        }
    }

[belkadan]

Looks like this is fixed on master but still fails on the 3.1 branch. @huonw, any insights? Is there something small enough to pull in?

[huonw]

I don't think anything I've done would've touched this. I recall @DougGregor doing something with where-clauses on methods a while ago, but I also recall that the situation there was possibly a little different. In summary, no insights.

[DougGregor]

Swift 3.1 is apparently considering this initializer to be an override, then crashes later in SILGen. Master correctly doesn't consider it to be an override.

[DougGregor]

GitHub master: #7788

Porting this to Swift 3.1 fixes the crasher there, which I'll do as soon as that PR merges.

[DougGregor]

3.1 PR: #7792

[DougGregor]

691c11f