CSIsNull001

Property	Value
Title	Use is null for null checks
Category	Usage
Default severity	Info

This analyzer reports a diagnostic when C# code uses the built-in == operator to compare a reference or nullable value with null. Comparisons inside expression trees are excluded because expression trees may not support the equivalent pattern syntax.

Pattern syntax cannot invoke an overloaded equality operator. It also lets the compiler reject null checks against non-nullable value types.

Example

For example, this code produces a diagnostic:

if (value == null)
{
}

The code fix replaces the equality check with pattern syntax:

if (value is null)
{
}

The code fix replaces the comparison with is null and supports Fix All.

Configuration and suppression

The rule has no custom options. Configure its severity with the standard .editorconfig key dotnet_diagnostic.CSIsNull001.severity, or suppress a specific occurrence with standard pragma or SuppressMessage mechanisms.