import Foundation

let INPUT_NOTIFICATION = "InputNotification"
let nc = NSNotificationCenter.defaultCenter()

nc.addObserverForName(INPUT_NOTIFICATION, object:nil, queue:nil) {
  (notification) in
  let userInfo = notification.userInfo as! [NSString:NSString]
}

swiftc swift_crash.swift   
0  swift           0x0000000002f3a348 llvm::sys::PrintStackTrace(llvm::raw_ostream&) + 40
1  swift           0x0000000002f38b16 llvm::sys::RunSignalHandlers() + 54
2  swift           0x0000000002f3ae7a
3  libpthread.so.0 0x00007f9dfe2a8340
4  swift           0x0000000000988d9b
5  swift           0x000000000098870b swift::Lowering::emitUnconditionalCheckedCast(swift::Lowering::SILGenFunction&, swift::SILLocation, swift::Expr*, swift::Type, swift::CheckedCastKind, swift::Lowering::SGFContext) + 139
6  swift           0x00000000009944c9
7  swift           0x000000000098c949
8  swift           0x000000000097d320
9  swift           0x000000000097d40d
10 swift           0x00000000009d1b17
11 swift           0x00000000009d193e
12 swift           0x00000000009a598e
13 swift           0x00000000009407f5
14 swift           0x000000000099f1fa
15 swift           0x0000000000991b6e
16 swift           0x000000000098ca84
17 swift           0x0000000000959b9b
18 swift           0x000000000095ac15
19 swift           0x000000000095984b
20 swift           0x0000000000958fa4
21 swift           0x000000000094c79b
22 swift           0x000000000094b1b3
23 swift           0x0000000000991b2e
24 swift           0x000000000099083c
25 swift           0x0000000000943bb9
26 swift           0x000000000094444b
27 swift           0x0000000000945162 swift::SILModule::constructSIL(swift::ModuleDecl*, swift::SILOptions&, swift::FileUnit*, llvm::Optional<unsigned int>, bool, bool) + 498
28 swift           0x00000000009456d6 swift::performSILGeneration(swift::FileUnit&, swift::SILOptions&, llvm::Optional<unsigned int>, bool) + 118
29 swift           0x0000000000766690
30 swift           0x0000000000761e62 frontend_main(llvm::ArrayRef<char const*>, char const*, void*) + 2482
31 swift           0x000000000075ca41 main + 2705
32 libc.so.6       0x00007f9dfd4a9ec5 __libc_start_main + 245
33 swift           0x000000000075bebd
Stack dump:
0.  Program arguments: /usr/bin/swift -frontend -c -primary-file swift_crash.swift -target x86_64-unknown-linux-gnu -disable-objc-interop -color-diagnostics -module-name swift_crash -o /tmp/swift_crash-dea395.o 
1.  While silgen closureexpr SIL function @_TF11swift_crashU_FC10Foundation14NSNotificationT_ for expression at [swift_crash.swift:6:66 - line:9:1] RangeText="{
  (notification) in
  let userInfo = notification.userInfo as! [NSString:NSString]
}"
<unknown>:0: error: unable to execute command: Segmentation fault
<unknown>:0: error: compile command failed due to signal (use -v to see invocation)