RNUL_MemberIsMissingNullabilityAnnotation.md

RNUL: Member is missing nullability annotation

Cause

A member or parameter technically can contain null, but it is not indicated whether callers should account for a null value.

Rule description

Resharper performs nullability analysis and issues warnings, such as missing or redundant null checks. Annotating members and parameters with nullability attributes improves the results of that analysis engine.

How to fix violations

Annotate the target member or parameter with JetBrains.Annotations.CanBeNullAttribute or JetBrains.Annotations.NotNullAttribute.

When to suppress warnings

There is no technical reason to suppress this warning.

Example of a violation

Description

The type C defines members and parameters that can contain null, which are not annotated.

Code

namespace N
{
    public class C
    {
        private string _f;

        public string P => _f;

        public string M(string p)
        {
            _f = p;
            return p;
        }
    }
}

Example of how to fix

Description

All members of the type C that can contain null are now annotated.

Code

using JetBrains.Annotations;

namespace N
{
    public class C
    {
        [CanBeNull] private string _f;

        [CanBeNull] public string P => _f;

        [NotNull] public string M([NotNull] string p)
        {
            _f = p;
            return p;
        }
    }
}

Related rules

RINUL: Member is missing item nullability annotation

XNUL: Suggest to disable reporting on nullable value types