CA2216: Disposable types should declare finalizer
TypeName |
DisposableTypesShouldDeclareFinalizer |
CheckId |
CA2216 |
Category |
Microsoft.Usage |
Breaking Change |
Non Breaking |
Cause
A type that implements IDisposable, and has fields that suggest the use of unmanaged resources, does not implement a finalizer as described by Object.Finalize.
Rule Description
A violation of this rule is reported if the disposable type contains fields of the following types:
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.
Example
The following example shows a type that violates this rule.
using System;
using System.Runtime.InteropServices;
namespace UsageLibrary
{
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
CA2115: Call GC.KeepAlive when using native resources
CA1816: Call GC.SuppressFinalize correctly
CA1049: Types that own native resources should be disposable