CA2216: Disposable types should declare finalizer

Cause

A type that implements System.IDisposable, and has fields that suggest the use of unmanaged resources, does not implement a finalizer as described by System.Object.Finalize.

Rule description

A violation of this rule is reported if the disposable type contains fields of the following types:

• System.IntPtr

• System.UIntPtr

• System.Runtime.InteropServices.HandleRef

How to fix violations

To fix a violation of this rule, implement a finalizer that calls your Dispose method.

When to suppress warnings

It is safe to suppress a warning from this rule if the type does not implement IDisposable for the purpose of releasing unmanaged resources.

Suppress a warning

If you just want to suppress a single violation, add preprocessor directives to your source file to disable and then re-enable the rule.

#pragma warning disable CA2216 // The code that's violating the rule is on this line. #pragma warning restore CA2216 

To disable the rule for a file, folder, or project, set its severity to none in the configuration file.

[*.{cs,vb}] dotnet_diagnostic.CA2216.severity = none 

For more information, see How to suppress code analysis warnings.

Example

The following example shows a type that violates this rule.

public class DisposeMissingFinalize : IDisposable { private bool disposed = false; private IntPtr unmanagedResource; [DllImport("native.dll")] private static extern IntPtr AllocateUnmanagedResource(); [DllImport("native.dll")] private static extern void FreeUnmanagedResource(IntPtr p); DisposeMissingFinalize() { unmanagedResource = AllocateUnmanagedResource(); } protected virtual void Dispose(bool disposing) { if (!disposed) { // Dispose of resources held by this instance. FreeUnmanagedResource(unmanagedResource); disposed = true; // Suppress finalization of this disposed instance. if (disposing) { GC.SuppressFinalize(this); } } } public void Dispose() { Dispose(true); } // Disposable types with unmanaged resources implement a finalizer. // Uncomment the following code to satisfy rule: // DisposableTypesShouldDeclareFinalizer // ~TypeA() // { // Dispose(false); // } } 

Related rules

CA1816: Call GC.SuppressFinalize correctly

See also

• System.IDisposable
• System.IntPtr
• System.Runtime.InteropServices.HandleRef
• System.UIntPtr
• System.Object.Finalize
• Dispose Pattern