C# Error CS8334 – Members of {0} ‘{1}’ cannot be returned by writable reference because it is a readonly variable

C# Error

CS8334 – Members of {0} ‘{1}’ cannot be returned by writable reference because it is a readonly variable

Reason for the Error & Solution

Members of cannot be returned by writable reference because it is a readonly variable

Example

The following sample generates CS8334:

// CS8334.cs (5,14)

class Program
{
    static ref int M(in int arg1, in (int Alice, int Bob) arg2)
    {
        return ref arg2.Alice;
    }
}

To correct this error

To return a reference to a read-only member, refactoring to return ref readonly will correct this error:

class Program
{
    static ref readonly int M(in int arg1, in (int Alice, int Bob) arg2)
    {
        return ref arg2.Alice;
    }
}