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1. DerivErrMustBeEnumType :: TyCon -> DeriveInstanceErrReason

   ghc	GHC.Tc.Errors.Types

   The given TyCon must be an enumeration. See Note [Enumeration types] in GHC.Core.TyCon

2. TcRnNegativeNumTypeLiteral :: HsTyLit GhcPs -> TcRnMessage

   ghc	GHC.Tc.Errors.Types

   TcRnNegativeNumTypeLiteral is an error that occurs whenever a type-level number literal is negative. type Neg = -1 Test cases: th/T8412 typecheckshould_failT8306

3. TcRnTagToEnumMissingValArg :: TcRnMessage

   ghc	GHC.Tc.Errors.Types

   TcRnTagToEnumMissingValArg is an error that occurs when the 'tagToEnum#' function is not applied to a single value argument. Example(s): tagToEnum# 1 2 Test cases: None

4. TcRnTagToEnumResTyNotAnEnum :: Type -> TcRnMessage

   ghc	GHC.Tc.Errors.Types

   TcRnTagToEnumResTyNotAnEnum is an error that occurs when the 'tagToEnum#' function is given a result type that is not an enumeration type. Example(s): foo :: Int -- not an enumeration TyCon foo = tagToEnum# 0# Test cases: typecheckshould_failtcfail164

5. TcRnTagToEnumResTyTypeData :: Type -> TcRnMessage

   ghc	GHC.Tc.Errors.Types

   TcRnTagToEnumResTyTypeData is an error that occurs when the 'tagToEnum#' function is given a result type that is headed by a type data type, as the data constructors of a type data do not exist at the term level. Example(s): type data Letter = A | B | C foo :: Letter foo = tagToEnum# 0# Test cases: type-datashould_failTDTagToEnum.hs

6. TcRnTagToEnumUnspecifiedResTy :: Type -> TcRnMessage

   ghc	GHC.Tc.Errors.Types

   TcRnTagToEnumUnspecifiedResTy is an error that occurs when the 'tagToEnum#' function is not given a concrete result type. Example(s): foo :: forall a. a foo = tagToEnum# 0# Test cases: typecheckshould_failtcfail164

7. type PhaseNum = Int

   ghc	GHC.Types.Basic

   Phase Number

8. diagnosticCodeNumber :: DiagnosticCode -> Natural

   ghc	GHC.Types.Error

   the actual diagnostic code

9. fromPersistValueEnum :: (Enum a, Bounded a) => PersistValue -> Either Text a

   persistent	Database.Persist.Class.PersistEntity

   Convenience function for getting a free PersistField instance from a type with an Enum instance. This function also requires a Bounded instance to improve the reporting of errors. Example usage in combination with toPersistValueEnum:

   data SeverityLevel = Low | Medium | Critical | High
   deriving (Enum, Bounded)
   instance PersistField SeverityLevel where
   fromPersistValue = fromPersistValueEnum
   toPersistValue = toPersistValueEnum
   

10. toPersistValueEnum :: Enum a => a -> PersistValue

    persistent	Database.Persist.Class.PersistEntity

    Convenience function for getting a free PersistField instance from a type with an Enum instance. The function derivePersistField from the persistent-template package should generally be preferred. However, if you want to ensure that an ORDER BY clause that uses your field will order rows by the data constructor order, this is a better choice. Example usage in combination with fromPersistValueEnum:

    data SeverityLevel = Low | Medium | Critical | High
    deriving (Enum, Bounded)
    instance PersistField SeverityLevel where
    fromPersistValue = fromPersistValueEnum
    toPersistValue = toPersistValueEnum
    

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