// RUN: %target-run-simple-swift-swift3 | %FileCheck %s
// REQUIRES: executable_test
// REQUIRES: swift_test_mode_optimize_none

// REQUIRES: rdar44160503

class C: CustomStringConvertible {
  var value: Int
  init(_ v: Int) { value = v }

  var description: String { return String(value) }
}

var global = [C(1), C(2)]

print("Begin")
print("1. global[0] == \(global[0])")
// CHECK:      Begin
// CHECK-NEXT: 1. global[0] == 1

func doit(_ local: inout C) {
  print("2. local == \(local)")
  print("2. global[0] == \(global[0])")
  // CHECK-NEXT: 2. local == 1
  // CHECK-NEXT: 2. global[0] == 1

  // There's a connection between 'local' and 'global[0]'.
  local = C(4)
  print("3. local == \(local)")
  print("3. global[0] == \(global[0])")
  // CHECK-NEXT: 3. local == 4
  // CHECK-NEXT: 3. global[0] == 4

  // This assignment is to a different index and so is
  // not allowed to cause unspecified behavior.
  global[1] = C(5)
  print("4. local == \(local)")
  print("4. global[0] == \(global[0])")
  // CHECK-NEXT: 4. local == 4
  // CHECK-NEXT: 4. global[0] == 4

  // The connection is not yet broken.
  local = C(2)
  print("5. local == \(local)")
  print("5. global[0] == \(global[0])")
  // CHECK-NEXT: 5. local == 2
  // CHECK-NEXT: 5. global[0] == 4

  // This assignment structurally changes 'global' while a
  // simultaneous modification is occurring to it.  This is
  // allowed to have unspecified behavior but not to crash.
  global.append(C(3))
  print("6. local == \(local)")
  print("6. global[0] == \(global[0])")
  // CHECK-NEXT: 6. local == 2
  // CHECK-NEXT: 6. global[0] == 4

  // Note that here the connection is broken.
  local = C(7)
  print("7. local == \(local)")
  print("7. global[0] == \(global[0])")
  // CHECK-NEXT: 7. local == 7
  // CHECK-NEXT: 7. global[0] == 4
}
doit(&global[0])

print("8. global[0] == \(global[0])")
print("End")
// CHECK-NEXT: 8. global[0] == 4
// CHECK-NEXT: End