[SR-13887] Crash (Segmentation fault: 11)

[swift-ci]

Previous ID	SR-13887
Radar	rdar://problem/71677775
Original Reporter	ken (JIRA User)
Type	Bug

Environment

Xcode "Version 12.0.1 (12A7300)".
Above the stack trace, it says: "Apple Swift version 5.3 (swiftlang-1200.0.29.2 clang-1200.0.30.1)"

Additional Detail from JIRA

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

md5: 654d4c44de8b60abe51e70a344291715

Issue Description:

I was writing a Swift program in Xcode 12 (Swift 5.3), and I started consistently crashing the compiler. I made a copy of the project and started removing pieces until I found what I believe is a fairly minimal example.

I'll prefix this by saying: I know this isn't a valid Swift program. I was adding conformance to a protocol, and I couldn't remember the protocol definition, so I was going to declare conformance and have Xcode show the error with the "Add stubs?" fixer. But it just kept segfaulting.

In file A.swift:

class E {
    func n(_ num: N) { }
}

func test() {
    let e = E()
    e.n(5)
}

In file B.swift:

struct N {
    let str: String

    init(_ int: Int) {
        self.str = String(int)
    }
}

extension N: ExpressibleByIntegerLiteral {

}

Curiously, Xcode reports "Command CompileSwift failed with a nonzero exit code", but changing almost any remaining aspect of this program (for example, commenting out the "self.str = String(int)" line, or the "e.n(5)" line, or even putting all the code in one file) changes the error to "Type 'N' does not conform to protocol 'ExpressibleByIntegerLiteral'" – which is what I expected in the first place.

[typesanitizer]

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