[SR-5848] Infinite loop during compilation when using | operator multiple times and using the result

[swift-ci]

Previous ID	SR-5848
Radar	None
Original Reporter	cm0x4d (JIRA User)
Type	Bug

Attachment: Download

Environment

XCode 8.3.3

macOS 12.12.6

MacBook Pro (Retina, 13-inch, Mid 2014)

Additional Detail from JIRA

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

md5: b727b92fefc6c298fbb9238d25985e22

Issue Description:

The compiler enters an infinite loop when compiling the code attached.

[belkadan]

Not infinite, just very very slow.

[rudkx]

cm0x4d (JIRA User), your test case does not compile as-is, but with a few modifications I got it compiling. The bigger issue here is probably with ??, but | certainly doesn't help. A very small refactoring results in this compiling very quickly:

func encode(_ a: A) -> Int {
  return (settings[a] ?? .none).encode()
}

func encode() throws -> Int {
  return encode(.a) | encode(.b) | encode(.c) | encode(.d) | encode(.e) | encode(.f)
}

[swift-ci]

Comment by Michael Clausen (JIRA)

Thank you, I already refactored the code to get it working like this:

func encode() throws -> Int {
    var value = Int(0)
    value |= (settings[.a] ?? .none).encode()
    value |= (settings[.b] ?? .none).encode()
    value |= (settings[.c] ?? .none).encode()
    value |= (settings[.d] ?? .none).encode()
    value |= (settings[.e] ?? .none).encode()
    value |= (settings[.f] ?? .none).encode()
    return value
}

So it seems that effectively the combination of the ?? and the | operator makes the compiler struggle.

[slavapestov]

Still slow, I'll add a test case.

[slavapestov]

Actually, it's only slow if the return type is declared wrong. I'll add a fast test case for the correct form.