CA2264: Do not pass a non-nullable value to 'ArgumentNullException.ThrowIfNull'

#Cause

A value that's known to never be null is passed to ArgumentNullException.ThrowIfNull().

#Rule description

ArgumentNullException.ThrowIfNull throws when the passed argument is null. Certain constructs like non-nullable structs (except for System.Nullable), type parameters known to be non-nullable structs, 'nameof()' expressions, and 'new' expressions are known to never be null, so ArgumentNullException.ThrowIfNull will never throw. Thus, calling ArgumentNullException.ThrowIfNull is unnecessary.

In the case of a struct, since ArgumentNullException.ThrowIfNull accepts an object?, the struct is boxed, which causes an additional performance penalty.

#How to fix violations

Remove the ArgumentNullException.ThrowIfNull call.

#Example

The following code snippet shows a violation of CA2264:

static void Print(int value)
{
    ArgumentNullException.ThrowIfNull(value);
    Console.WriteLine(value);
}

The following code snippet fixes the violation:

static void Print(int value)
{
    Console.WriteLine(value.Value);
}

#When to suppress warnings

It's always safe to suppress this warning.

#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 CA2264
// The code that's violating the rule is on this line.
#pragma warning restore CA2264

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

[*.{cs,vb}]
dotnet_diagnostic.CA2264.severity = none

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

#See also

• CA1871: Do not pass a nullable struct to 'ArgumentNullException.ThrowIfNull