Field-less enums: an issue potentially introduced with the version bump to 1.79

[y1ca1]

I'm pretty excited about this version bump as Rust 1.79 stabilized the inline const expressions. Thanks for the efforts!

However, my existing codebase breaks at a field-less enum declaration:

 enum FieldLess {
    A = 0,
    B = 1,
    C = 2,
}

Verus reports:

error: constant evaluation of enum discriminant resulted in non-integer

A repro link to the playground: https://aurorar8-eb5c.andrew.cmu.edu/?version=stable&mode=basic&edition=2021&gist=e87455afc0f418ffddbf2d5b7a2bb149

Hope this is fairly straightforward to resolve!

[tjhance]

probably the same root cause as: #1334