VSTHRD113.md

VSTHRD113 Check for System.IAsyncDisposable

The Microsoft.VisualStudio.Threading.IAsyncDisposable interface is obsolete now that the System.IAsyncDisposable interface has been defined for .NET Standard 2.0 and .NET Framework 4.6.1 by the Microsoft.Bcl.AsyncInterfaces NuGet package.

Existing code that tests for the Microsoft.VisualStudio.Threading.IAsyncDisposable interface on some object should also check for System.IAsyncDisposable and behave similarly in either case. New code should consider only supporting the new System.IAsyncDisposable interface.

Examples of patterns that are flagged by this analyzer

The following code only checks for the obsolete interface and is flagged by this diagnostic:

using Microsoft.VisualStudio.Threading;

if (obj is IAsyncDisposable asyncDisposable)
{
    await asyncDisposable.DisposeAsync();
}

Solution

Fix this by adding a code branch for the new interface that behaves similarly within the same containing code block:

if (obj is Microsoft.VisualStudio.Threading.IAsyncDisposable vsThreadingAsyncDisposable)
{
    await vsThreadingAsyncDisposable.DisposeAsync();
}
else if (obj is System.IAsyncDisposable bclAsyncDisposable)
{
    await bclAsyncDisposable.DisposeAsync();
}