Some test cases for arg-less enums.
(Ext1 x)
(Ext2 =x)))
(C #t))
+
+(type Opcode (enum A B C))
+(type MachInst (enum D E F))
+(decl Lower2 (Opcode) MachInst)
+(rule
+ (Lower2 (Opcode.A))
+ (MachInst.D))
+(rule
+ (Lower2 (Opcode.B))
+ (MachInst.E))
+(rule
+ (Lower2 (Opcode.C))
+ (MachInst.F))
