Code inspection: Return value of a property must be disposed by the callee

If you are using the [MustDisposeResourceAttribute] from JetBrains.Annotations to enforce resource disposal in the calling code, JetBrains Rider reports properties that directly return a resource from an annotated source. This means that users of the API must handle a disposable resource that is created each time they use the property. Here is an example:

        
    [MustDisposeResource]
    public class HasNativeResources : IDisposable
    {
        private IDisposable _resource;

        public void DoTaskOne() {/*do something with _resource*/}
        public void DoTaskTwo() {/*do something with _resource*/}
        public void Dispose() => _resource.Dispose();

    }

    public class Item
    {
        // The potential problem is reported here
        public HasNativeResources Resource => new HasNativeResources();
    }

    public class Test
    {
        public Test()
        {
            var item = new Item();
            // Resource leak can happen here if the resource is not properly handled
            item.Resource.DoTaskOne();
            item.Resource.DoTaskTwo();
        }
    }
        
    

There are two general ways to fix this problem:

Communicate to the API users that the property is not a part of the object. This can be done, for example, by converting the property to a method.
Make the property a part of the object and handle the resource internally. This can be done, for example, by adding a backing field for the property and disposing it in the object's Dispose() method.

Last modified: 11 February 2024