Describe how to emulate a C gap enum best

[lerno]

typedef enum
{
  ABC = -3,
  DEF = 100
} Foo;

void update(Foo x);
Foo get_value(void);

Convert this to:

typedef FooType = int;
enum Foo : (inline FooType val)
{
  ABC = -3,
  DEF = 100
}
extern fn void update(FooType x);
extern fn FooType get_value();

Now we can use this as:

update(Foo.ABC); // But no inference.
if (Foo.DEF == get_value()) { ... }
Foo f = Foo.lookup(get_value());