Code Inspection: Heuristically unreachable case due to integer analysis

tip

You can suppress this inspection to ignore specific issues, change its severity level to make the issues less or more noticeable, or disable it altogether.

This inspection reports cases of switch statements that will never be executed according to the results of integer value analysis. The inspection only works if Analyze integer arithmetic is enabled on the Editor | Inspection Settings page of JetBrains Rider settings Ctrl+Alt+S.

Here is an example of annotating the method parameter with [NonNegativeValueAttribute] to refine the analysis within the method body. Knowing that the parameter is non-negative, JetBrains Rider can report redundant cases:

void TestSwitch([NonNegativeValue] int input)
{
    int newValue;
    switch (input)
    {
        case 0:
            newValue = 1;
            break;
        case -1:  // Case is heuristically unavailable
            newValue = 0;
            break;
        default:
            newValue = input;
            break;
    }
}