[cxx-interop] add a test to cover accessing non-copyable field

Author: hyp

test/Interop/Cxx/class/move-only/Inputs/move-only-cxx-value-type.h

@@ -37,7 +37,7 @@ struct NonCopyableHolder {
     inline NonCopyable &returnMutNonCopyableRef() { return x; }
 
     inline const NonCopyable &returnNonCopyableRef() const { return x; }
-private:
+
     NonCopyable x;
 };
 

test/Interop/Cxx/class/move-only/move-only-cxx-value-type.swift

@@ -33,4 +33,21 @@ MoveOnlyCxxValueType.test("Test derived move only type member access") {
   expectEqual(k, -13)
 }
 
+func borrowNC(_ x: borrowing NonCopyable) -> CInt {
+  return x.method(3)
+}
+
+func inoutNC(_ x: inout NonCopyable, _ y: CInt) -> CInt {
+  return x.mutMethod(y)
+}
+
+MoveOnlyCxxValueType.test("Test move only field access in holder") {
+  var c = NonCopyableHolder(11)
+  var k = borrowNC(c.x)
+  expectEqual(k, 33)
+  k = inoutNC(&c.x, 7)
+  expectEqual(k, 7)
+  expectEqual(c.x.x, 7)
+}
+
 runAllTests()