Been asked for a few times, submitting it here for posterity.

enum Enum {
	A = 0, B, C
}

void main() {
	with (Enum) {
		assert (A == 0);
		assert (B == A+1);
		assert (C == B+1);
	}
}

It would be handy if the above worked. A common use case is switching on an enum:

enum Enum {
	A = 0, B, C
}

void main() {
	Enum e;
	with (Enum) switch (e) {
		case A:
		case B:
		case C:
		default: break;
	}
	// the above looks much better than:
	switch (e) {
		case Enum.A:
		case Enum.B:
		case Enum.C:
		default: break;
	}
}