Error for duplicate enum values

[jez]

Input

→ View on sorbet.run

# typed: strict
extend T::Sig

class MyEnum < T::Enum
  enums do
    Foo = new
    Bar = new
    Foo = new
  end
end

Observed output

No errors! Great job.

Expected behavior

Sorbet does not in general report constant redefinition errors, because it does not track code loading order:

https://sorbet.org/docs/unsupported#tracking-code-loading-order

There are a couple limited forms of this problem that Sorbet could nonetheless solve:

1. Warn for duplicate enum values (potentially encoding sorbet-runtime's serialized_val computation to know that Foo1 = new; Foo2 = new('Foo1') is an error as well
2. Warn for re-assigned constants if the redefinition happens within a single file

Either of these would help bring another class of runtime errors into the static checks.

---

This becomes especially useful the larger the enum is, because the two duplicates might be at arbitrary spots in the list of values.