Compiler support for switch-case error detection

Not adding a default label to the switch-case statement improves the C++ code quality. The normal use case for a switch-case is over an enum like in the example below.

enum class Op {
	Addition,
	Subtraction,
};

double execute(Op op, double left, double right) {
	switch (op) {
	case Op::Addition:
		return left + right;
	case Op::Subtraction:
		return left - right;
	}
	return {};
}

All the enum options have to be considered in the switch-case (if this is not the case then probably something else is a bit smelly in the code). The compiler is telling us whenever we missed an enum options. In gcc it is the -Wswitch flag, this comes for free with -Wall. The benefits are:

• Whenever we extending the enum the compiler is helping by telling us where we missed a code change.
• The intent of the code is clear because the normal case is separated from the error case (the error case should be unreachable, but this is a different topic).

• C++
• Software Development
• Software Quality