[Tests] InitAccessors/NFC: Add a test-case for rdar://112417250

(cherry picked from commit ff19286)

Author: xedin

test/SILOptimizer/init_accessors.swift

@@ -4,6 +4,8 @@
 
 // REQUIRES: asserts
 
+class NSObject {}
+
 struct TestInit {
   var x: Int
   var y: Int
@@ -479,3 +481,31 @@ func test_assignments() {
     }
   }
 }
+
+// rdar://112417250 (Crash with macro expansion on generic NSObject subclass)
+// self is already borrowed within the initializer.
+//
+// CHECK-LABEL: sil private [ossa] @$s14init_accessors8testObjCyyF07GenericD9CSubclassL_CyADyxGxcfc : $@convention(method) <T> (@in T, @owned GenericObjCSubclass<T>) -> @owned GenericObjCSubclass<T> {
+// CHECK: [[BORROW:%.*]] = load_borrow %{{.*}} : $*GenericObjCSubclass<T>
+// CHECK: ref_element_addr [[BORROW]] : $GenericObjCSubclass<T>, #<abstract function>GenericObjCSubclass._value
+// CHECK: apply
+// CHECK: end_borrow [[BORROW]] : $GenericObjCSubclass<T>
+// CHECK-NOT: end_borrow [[BORROW]] : $GenericObjCSubclass<T>
+func testObjC() {
+  class GenericObjCSubclass<T>: NSObject {
+    var _value: T
+
+    var value: T {
+      @storageRestrictions(initializes: _value)
+      init {
+        self._value = newValue
+      }
+      get { _value }
+      set { _value = newValue }
+    }
+
+    init(_ value: T) {
+      self.value = value
+    }
+  }
+}