Remove empty defaults from switch statements and expressions

[spacey-sooty]

This is actually an anti pattern for switch statements as it prevents compile time checking of exhaustiveness. For switch expressions this is functionally equivalent to having no default.

[rzblue]

In java switch statements are not checked for exhaustiveness, and non-enum values generally can't be checked for exhaustiveness. It's generally considered good practice to have a default to make it clear what happens with all other values. Switch expressions obviously must be exhaustive, so for non-enum values you need a default case.

Is this for c++ specifically?

[spacey-sooty]

No this is also for Java, by adding an empty default to a switch expression you add absolutely nothing to the expression. If you were to instead add a default which does something (eg logs an invalid state) this would make sense but this is not what WPILib does right now.

[rzblue]

Perhaps instead of removing all default cases we should throw an exception or log a warning where appropriate, or add a comment indicating why it's ok that the default was reached. IMO not having a default is only fine where it's obvious why unhandled cases can be safely ignored.

by adding an empty default to a switch expression you add absolutely nothing to the expression.

Are you referring to a statement here instead? Expressions can't have empty cases