adding test of SILGen for async actor prop accesses

Author: kavon

test/Concurrency/actor_inout_isolation.swift

@@ -29,6 +29,11 @@ actor TestActor {
   var value1: Int = 0
   var value2: Int = 1
   var points: [Point] = []
+
+  subscript(x : inout Int) -> Int { // expected-error {{'inout' must not be used on subscript parameters}}
+    x += 1
+    return x
+  }
 }
 
 func modifyAsynchronously(_ foo: inout Int) async { foo += 1 }

test/Concurrency/actor_isolation.swift

@@ -50,6 +50,14 @@ actor MyActor: MySuperActor {
 
   let point : Point = Point()
 
+  @MainActor
+  var name : String = "koala"
+
+  // FIXME: if you take the 'async' off of this, you get a very confusing error message.
+  func accessProp() async -> String {
+    return await self.name
+  }
+
   class func synchronousClass() { }
   static func synchronousStatic() { }
 
@@ -60,6 +68,12 @@ actor MyActor: MySuperActor {
   }
 }
 
+actor Camera {
+  func accessProp(act : MyActor) async -> String {
+    return await act.name
+  }
+}
+
 func checkAsyncPropertyAccess() async {
   let act = MyActor()
   let _ : Int = await act.mutable + act.mutable