[SR-4439] Compiler crashes when chaining case statements that capture values with weak references

[swift-ci]

Previous ID	SR-4439
Radar	None
Original Reporter	ibsh (JIRA User)
Type	Bug
Status	Resolved
Resolution	Done

Attachment: Download

Additional Detail from JIRA

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

md5: 42ecce32954c17632e7caea2dde28d5f

is duplicated by:

• SR-4487 Crash when pattern matching two cases with associated values of protocol type

relates to:

• SR-4417 Compiler crashes when get value from enum specific case.

Issue Description:

If a value type has a weak property, a switch statement that chains multiple case statements together, where those case statements each capture an instance of that type, will crash the Swift compiler with a segfault when attempting to emit SIL.

See the attached Playground and compare the two implementations of equality for TroubledEnum, but in short:

switch self {
    case .a(let x): return x
    case .b(let x): return x
}

works fine but

switch self {
    case .a(let x), .b(let x): return x
}

does not.

[belkadan]

Possibly related to SR-4417?

[DougGregor]

Seems to work in Swift 5.3