CA2259: Ensure `ThreadStatic` is only used with static fields

#Cause

The System.ThreadStaticAttribute attribute is applied to an instance field.

#Rule description

System.ThreadStaticAttribute, which indicates that the value of a field is unique for each thread, only affects static (Shared in Visual Basic) fields. When applied to instance fields, the attribute has no impact on behavior.

#How to fix a violation

To fix a violation, remove the System.ThreadStaticAttribute attribute from the field.

#Example

The following code snippet shows a violation of CA2259:

class C
{
    [ThreadStatic]
    public int number = 404;
}

Class C
    <ThreadStatic>
    Public number As Integer = 404
End Class

#When to suppress warnings

It's safe to suppress a warning from this rule. However, the [ThreadStatic] attribute is a nop and isn't doing what you intended it to do.

#See also

• Usage warnings