Is there a way to get the C# compiler to emit an error if a switch(enum_val) is missing a case statement?

Question

I just realized I added a value to the list of \"must-handle\" values in my enum, but I didn\'t catch it until runtime. I know the C# compiler is really powerful when it com

Answer 1

The C# compiler doesn't have this check built-in, but there's a code contracts checker for .Net that does: https://blogs.msdn.microsoft.com/francesco/2014/09/12/how-to-use-cccheck-to-prove-no-case-is-forgotten/

The technique is to use a code contract assertion to tell the checker that the default case should never be reachable:

switch (c) {
  case Colors.Red: break;
  case Colors.Blue:
  case Colors.Green: break;
  default:
    Contract.Assert(false); // Tell static checker this shouldn't happen
}

Then, if the checker sees that it is reachable (because one of the enum values is not handled), it will warn you:

warning : CodeContracts: This assert, always leading to an error, may be reachable.
Are you missing an enum case?