Enum serialization spike

Sorbet runtime 0.6.13583 accepts integer serialized values in T::Enum. An enum with One = new(1) and Two = new(2) passed these checks:

deserialize(1) returns the same object as One.
Two.serialize returns the integer 2.
The enum and a bidirectional coerce method pass strict type checking.

The check used Ruby 3.4.6 and the Sorbet static binary directly. The srb wrapper loaded an unrelated installed Prism RBI with an unresolved Prism::LexCompat constant.

Tapioca 0.20.0’s SorbetEnums listener emits member declarations inside an RBI::TEnumBlock. Rendering its tree produces this shape:

class IntegerEnumSpike < T::Enum
  enums do
    One = new
    Two = new
  end
end

No integer serialization fallback is needed. Member names that start with digits use the resolver’s N prefix. An underscore prefix would not form a valid Ruby constant.

Member name equal to the class name

Sorbet cannot type a member whose constant name equals its enclosing enum class’s leaf name. The problematic shape is:

class Affiliation < T::Enum
  enums do
    Affiliation = new("affiliation")
    External = new("external")
  end
end

The inner Affiliation denotes a member, not a type. Qualifying type references does not make this member declaration usable by Sorbet. The chosen limit is to reject this shape in sorbet_ruby_enums and rbi_enums with Schematrix::OutputCollisionError. The check compares the folded member name with the enclosing class leaf, so it also applies to nested classes and differently spelled values that fold to that name. Plain Ruby and RBS permit it.

This restriction is separate from namespace shadowing in consumers. Partial and DSL signatures use absolute class references to select the shared enum class outside their Partial and Dsl namespaces. They do not create another enum family.