Code Inspection: '??' condition is known to be null or not null
If you want to assign a value, pass an argument, or return from a method based on the nullability of an identifier, the clearest syntax you can use in these cases is the ?? (null-coalescing) operator.
A null-coalescing expression works as follows. The left-hand operand is evaluated first, and if it is null, the right-hand operand is evaluated and the result becomes the result of the whole expression.
However, redundant null-coalescing expressions produce dead code and impede readability. As it follows from the logic of the
?? operator, using
null as the right-hand operand does not make sense. Below, ReSharper suggests removing the right-hand operand
null together with the
?? operator, because if the
newCategory is null, then null will be assigned to the
Another situation when the null-coalescing operator is redundant is when the left-hand operand can never be null. In this case, the right-hand operand never gets reached and ReSharper suggests removing the unreachable code: