My project compiles, but the unit test target crashes only on Linux. The same unit tests run fine on OS X.

With MySQLSwift.tar.gz :

coleman@ubuntu:~/Swift/MySQLSwift$ .build/debug/UnitTests
Test Case 'MySQLTests.testNewDB' started.
UnitTests: /home/buildslave/jenkins/workspace/oss-swift-linux-packages-ubuntu_14_04-one-off-build/swift/include/swift/Runtime/../../../stdlib/public/SwiftShims/RefCount.h:207: bool StrongRefCount::doDecrementShouldDeallocate() [ClearPinnedFlag = false]: Assertion `newval + quantum >= RC_ONE && "releasing reference with a refcount of zero"' failed.
Aborted (core dumped)

Was able to fix the crash. It seems that my Error enum with a associated string will crash on Linux. Here's the fix:

in Connection.swift

Comment by Dan Appel (JIRA)

I'm getting the same error, but in my case its a struct (which conforms to ErrorType). The error I'm getting is:

fatal error: _StringCore elementWidth doesn't match its buffer's: file /home/buildslave/jenkins/workspace/oss-swift-linux-packages-ubuntu_15_10-one-off-build/swift/stdlib/public/core/StringCore.swift, line 68

My workaround is to set the description to be empty as shown in this file.

We are using the following work-around in SwiftPM:

func safeStringify(error: ErrorType) -> String {
    // work around for a miscompile when converting error type to string

    struct TempStream: OutputStreamType {
        var result: String = ""
        mutating func write(string: String) {
            result += string
        }
    }

    var stream = TempStream()
    print(error, toStream: &stream)
    return stream.result
}

Also, I've found that this crash happens on OS X intermittently too. Though I don't get a reliable backtrace it often seems to involve refcounting named functions.