CA2000 reported on every using statement with IAsyncDisposable

[cytoph]

Analyzer

Diagnostic ID: CA2000: Dispose objects before losing scope

Analyzer source

NuGet Package: Microsoft.CodeAnalysis.NetAnalyzers

Version: 7.0.0 (Latest Stable)

(The bug also exists in all versions of the analyzer built-in into the SDK in 5.0, 6.0 and 7.0)

Describe the bug

Whenever one uses a using statement with an IAsyncDisposable the analyzer falsely reports CA2000.

Steps To Reproduce

OPTIONAL: If you want, create a custom implementation of IAsyncDisposable. For this example I'll use FileStream to show that the bug affects even the most common built-in types.

1. Create an async method that contains a async using statement (like shown belown)
2. See error

public async Task DoSomethingAsync()
{
    await using var stream = new FileStream("C:\somefile.txt", FileMode.OpenOrCreate).ConfigureAwait(false); // this already shows the false issue
}

Expected behavior

await using var stream = new FileStream("C:\somefile.txt", FileMode.OpenOrCreate).ConfigureAwait(false); will not report CA2000. Maybe if not used with a using it should report an issue, but that should be a newly created one, not CA2000, because CA2000 explicitly states one should call System.IDisposable.Dispose which is not correct for IAsyncDisposable.

Actual behavior

await using var stream = new FileStream("C:\somefile.txt", FileMode.OpenOrCreate).ConfigureAwait(false); reports CA2000. IAsyncDisposable in general reports this, no matter if used in a using or not. The only way to suppress the issue is to initialize a variable and after that start a try-finally-block where the variable is disposed in the finally part, which is exactly what the using is for in C#.

Additional context

This bug was already reported in issue #3042 but no one bothered to re-open it even though it was not fixed - so what other way to call attention to this bug than creating a new issue? 🤷‍♂️

[alexrp]

I'm also regularly running into this in a project using .NET 8 Preview 3.