//-----------------------------------------------------------------------------
// This program demonstrates a compiler crash that happens ONLY
// for a release build AND using a recent snapshot.
//-----------------------------------------------------------------------------
// While playing around with the demo program for SR-7023, I noticed a compiler
// crash that turned out to only happen when using a recent dev snapshot AND
// only if doing a release build.
//
// This (unmodified) project is in the crashing state (provided that you use
// a recent dev snapshot of course).
//
// I've reduced the code as far as I could without loosing the compiler crash.
//
// I'm using Xcode 9.4 (9F1027a) and Swift Development Snapshot 2018-05-29 (a).
//-----------------------------------------------------------------------------

extension FixedWidthInteger {
    init<S>(foo: S) where S: FixedWidthInteger {
        if MemoryLayout<S>.size < MemoryLayout<Self>.size {
            self = 0
        } else {
            self = 1
        }
    }
}

func bar() {
    var arr = [Int16](repeating: 0, count: 123)
    var checksum = UInt64(0)
    let count = arr.count
    var i = 0 // There will be a warning for this, but ...
    while i < count {
        let dst = UInt64(foo: arr[i])
        checksum = checksum ^ dst
        // i = i &+ 1 // ... compiler crash goes away if uncommenting this.
    }
    print("  blabla: \(checksum))")
}

bar()

//-----------------------------------------------------------------------------
// Here's what the crash looks like (compiling with swiftc of above snapshot):
//
// $ /Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2018-05-29-a.xctoolchain/usr/bin/swiftc -O main.swift
// main.swift:32:9: warning: variable 'i' was never mutated; consider changing to 'let' constant
//     var i = 0 // There will be a warning for this, but ...
//     ~~~ ^
//     let
// 0  swift                    0x000000010eda3dc8 llvm::sys::PrintStackTrace(llvm::raw_ostream&) + 40
// 1  swift                    0x000000010eda3037 llvm::sys::RunSignalHandlers() + 39
// 2  swift                    0x000000010eda4442 SignalHandler(int) + 258
// 3  libsystem_platform.dylib 0x00007fff56393f5a _sigtramp + 26
// 4  libsystem_platform.dylib 0x000000011101a080 _sigtramp + 3133694272
// 5  swift                    0x000000010bf47213 swift::SILPassManager::runPassOnFunction(unsigned int, swift::SILFunction*) + 1475
// 6  swift                    0x000000010bf48163 swift::SILPassManager::runFunctionPasses(unsigned int, unsigned int) + 1315
// 7  swift                    0x000000010bf48e24 swift::SILPassManager::execute() + 660
// 8  swift                    0x000000010b75f32b swift::SILPassManager::executePassPipelinePlan(swift::SILPassPipelinePlan const&) + 187
// 9  swift                    0x000000010bf50c25 swift::runSILOptimizationPasses(swift::SILModule&) + 117
// 10 swift                    0x000000010b5fa2d0 performCompile(swift::CompilerInstance&, swift::CompilerInvocation&, llvm::ArrayRef<char const*>, int&, swift::FrontendObserver*, swift::UnifiedStatsReporter*) + 13520
// 11 swift                    0x000000010b5f5db1 swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 3297
// 12 swift                    0x000000010b5b1dad main + 2317
// 13 libdyld.dylib            0x00007fff56085015 start + 1
// 14 libdyld.dylib            0x000000000000000e start + 2851581946
// Stack dump:
// 0.  Program arguments: /Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2018-05-29-a.xctoolchain/usr/bin/swift -frontend -c -primary-file main.swift -target x86_64-apple-darwin17.5.0 -enable-objc-interop -O -color-diagnostics -module-name main -o /var/folders/50/br4kxvjd0t551h0fmtrzkwdw0000gn/T/main-a6eb9c.o
// 1.  While running pass #&#8203;3957 SILFunctionTransform "DCE" on SILFunction "@$S4main3baryyF".
//  for 'bar()' at main.swift:28:1
// <unknown>:0: error: unable to execute command: Segmentation fault: 11
// <unknown>:0: error: compile command failed due to signal 11 (use -v to see invocation)
//-----------------------------------------------------------------------------