Disposing an object twice, either with the using keyword or by calling Dispose directly, in the same method is at best confusing and at worst error-prone. The next developer might see only one of the Dispose/using and try to use an already-disposed object.

In addition, even if the documentation of Disposable explicitly states that calling the Dispose method multiple times should not throw an exception, some implementation still do it. Thus it is safer to not dispose an object twice when possible.

This rule raises an issue when, in the same method, the Dispose method is explicitly called twice on the same object, or when using is used with a direct call to Dispose().

Noncompliant Code Example

using (var d = new Disposable()) // Noncompliant
{
    d.Dispose();
}

using var d = new Disposable();
d.Dispose(); // Noncompliant {{Refactor this code to make sure 'd' is disposed only once.}}

Compliant Solution

using var d = new Disposable();