    {-# LANGUAGE ConstraintKinds #-}
    {-# LANGUAGE DataKinds #-}
    {-# LANGUAGE DeriveDataTypeable #-}
    {-# LANGUAGE DeriveTraversable #-}
    {-# LANGUAGE FlexibleContexts #-}
    {-# LANGUAGE FlexibleInstances #-}
    {-# LANGUAGE LambdaCase #-}
    {-# LANGUAGE ScopedTypeVariables #-}
    {-# LANGUAGE TypeApplications #-}
    {-# LANGUAGE TypeFamilies #-}
    {-# LANGUAGE StandaloneDeriving #-}
    {-# LANGUAGE UndecidableInstances #-} -- Wrinkle in Note [Trees That Grow]
                                          -- in module Language.Haskell.Syntax.Extension
    {-# LANGUAGE ViewPatterns #-}

    {-
    (c) The University of Glasgow 2006
    (c) The GRASP/@type@AQUA Project, Glasgow University, 1992-1998
    -}

    -- See Note [Language.Haskell.Syntax.* Hierarchy] for why not GHC.Hs.*

    -- | Abstract syntax of global declarations.
    --
    -- Definitions for: @SynDecl@ and @ConDecl@, @ClassDecl@,
    -- @InstDecl@, @DefaultDecl@ and @ForeignDecl@.
    module Language.Haskell.Syntax.Decls (
      -- * Toplevel declarations
      HsDecl(..), LHsDecl, HsDataDefn(..), HsDeriving, LHsFunDep, FunDep(..),
      HsDerivingClause(..), LHsDerivingClause, DerivClauseTys(..), LDerivClauseTys,
      NewOrData(..), DataDefnCons(..), dataDefnConsNewOrData,
      isTypeDataDefnCons, firstDataDefnCon,
      StandaloneKindSig(..), LStandaloneKindSig,

      -- ** Class or type declarations
      TyClDecl(..), LTyClDecl,
      TyClGroup(..),
      tyClGroupTyClDecls, tyClGroupInstDecls, tyClGroupRoleDecls,
      tyClGroupKindSigs,
      isClassDecl, isDataDecl, isSynDecl,
      isFamilyDecl, isTypeFamilyDecl, isDataFamilyDecl,
      isOpenTypeFamilyInfo, isClosedTypeFamilyInfo,
      tyClDeclTyVars,
      FamilyDecl(..), LFamilyDecl,

      -- ** Instance declarations
      InstDecl(..), LInstDecl, FamilyInfo(..), familyInfoTyConFlavour,
      TyFamInstDecl(..), LTyFamInstDecl,
      TyFamDefltDecl, LTyFamDefltDecl,
      DataFamInstDecl(..), LDataFamInstDecl,
      FamEqn(..), TyFamInstEqn, LTyFamInstEqn, HsFamEqnPats,
      LClsInstDecl, ClsInstDecl(..),

      -- ** Standalone deriving declarations
      DerivDecl(..), LDerivDecl,
      -- ** Deriving strategies
      DerivStrategy(..), LDerivStrategy,
      -- ** @RULE@ declarations
      LRuleDecls,RuleDecls(..),RuleDecl(..),LRuleDecl,
      RuleBndr(..),LRuleBndr,
      collectRuleBndrSigTys,
      -- ** @default@ declarations
      DefaultDecl(..), LDefaultDecl,
      -- ** Template haskell declaration splice
      SpliceDecoration(..),
      SpliceDecl(..), LSpliceDecl,
      -- ** Foreign function interface declarations
      ForeignDecl(..), LForeignDecl, ForeignImport(..), ForeignExport(..),
      CImportSpec(..),
      -- ** Data-constructor declarations
      ConDecl(..), LConDecl,
      HsConDeclH98Details,
      HsConDeclGADTDetails(..), XPrefixConGADT, XRecConGADT, XXConDeclGADTDetails,
      -- ** Document comments
      DocDecl(..), LDocDecl, docDeclDoc,
      -- ** Deprecations
      WarnDecl(..),  LWarnDecl,
      WarnDecls(..), LWarnDecls,
      -- ** Annotations
      AnnDecl(..), LAnnDecl,
      AnnProvenance(..), annProvenanceName_maybe,
      -- ** Role annotations
      RoleAnnotDecl(..), LRoleAnnotDecl,
      -- ** Injective type families
      FamilyResultSig(..), LFamilyResultSig, InjectivityAnn(..), LInjectivityAnn,

      -- * Grouping
      HsGroup(..), hsGroupInstDecls,
        ) where

    -- friends:
    import {-# SOURCE #-} Language.Haskell.Syntax.Expr
      ( HsExpr, HsUntypedSplice )
            -- Because Expr imports Decls via HsBracket

    import Language.Haskell.Syntax.Binds
    import Language.Haskell.Syntax.Extension
    import Language.Haskell.Syntax.Type
    import Language.Haskell.Syntax.Basic (Role)
    import Language.Haskell.Syntax.Specificity (Specificity)

    import GHC.Types.Basic (TopLevelFlag, OverlapMode, RuleName, Activation
                           ,TyConFlavour(..), TypeOrData(..))
    import GHC.Types.ForeignCall (CType, CCallConv, Safety, Header, CLabelString, CCallTarget, CExportSpec)
    import GHC.Types.Fixity (LexicalFixity)

    import GHC.Unit.Module.Warnings (WarningTxt)

    import GHC.Hs.Doc (LHsDoc) -- ROMES:TODO Discuss in #21592 whether this is parsed AST or base AST

    import Control.Monad
    import Control.Exception (assert)
    import Data.Data        hiding (TyCon, Fixity, Infix)
    import Data.Void
    import Data.Maybe
    import Data.String
    import Data.Function
    import Data.Eq
    import Data.Int
    import Data.Bool
    import Prelude (Show)
    import qualified Data.List
    import Data.Foldable
    import Data.Traversable
    import Data.List.NonEmpty (NonEmpty (..))

    {-
    ************************************************************************
    *                                                                      *
    \subsection[HsDecl]{Declarations}
    *                                                                      *
    ************************************************************************
    -}

    type LHsDecl p = XRec p (HsDecl p)
            -- ^ When in a list this may have

    -- | A Haskell Declaration
    data HsDecl p
      = TyClD      (XTyClD p)      (TyClDecl p)      -- ^ Type or Class Declaration
      | InstD      (XInstD p)      (InstDecl  p)     -- ^ Instance declaration
      | DerivD     (XDerivD p)     (DerivDecl p)     -- ^ Deriving declaration
      | ValD       (XValD p)       (HsBind p)        -- ^ Value declaration
      | SigD       (XSigD p)       (Sig p)           -- ^ Signature declaration
      | KindSigD   (XKindSigD p)   (StandaloneKindSig p) -- ^ Standalone kind signature
      | DefD       (XDefD p)       (DefaultDecl p)   -- ^ 'default' declaration
      | ForD       (XForD p)       (ForeignDecl p)   -- ^ Foreign declaration
      | WarningD   (XWarningD p)   (WarnDecls p)     -- ^ Warning declaration
      | AnnD       (XAnnD p)       (AnnDecl p)       -- ^ Annotation declaration
      | RuleD      (XRuleD p)      (RuleDecls p)     -- ^ Rule declaration
      | SpliceD    (XSpliceD p)    (SpliceDecl p)    -- ^ Splice declaration
                                                     -- (Includes quasi-quotes)
      | DocD       (XDocD p)       (DocDecl p)       -- ^ Documentation comment
                                                     -- declaration
      | RoleAnnotD (XRoleAnnotD p) (RoleAnnotDecl p) -- ^Role annotation declaration
      | XHsDecl    !(XXHsDecl p)

    {-
    Note [Top-level fixity signatures in an HsGroup]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    An `HsGroup p` stores every top-level fixity declarations in one of two places:

    1. hs_fixds :: [LFixitySig p]

       This stores fixity signatures for top-level declarations (e.g., functions,
       data constructors, classes, type families, etc.) as well as fixity
       signatures for class methods written outside of the class, as in this
       example:

         infixl 4 `m1`
         class C1 a where
           m1 :: a -> a -> a

    2. hs_tyclds :: [TyClGroup p]

       Each type class can be found in a TyClDecl inside a TyClGroup, and that
       TyClDecl stores the fixity signatures for its methods written inside of the
       class, as in this example:

         class C2 a where
           infixl 4 `m2`
           m2 :: a -> a -> a

    The story for fixity signatures for class methods is made slightly complicated
    by the fact that they can appear both inside and outside of the class itself,
    and both forms of fixity signatures are considered top-level. This matters
    in `GHC.Rename.Module.rnSrcDecls`, which must create a fixity environment out
    of all top-level fixity signatures before doing anything else. Therefore,
    `rnSrcDecls` must be aware of both (1) and (2) above. The
    `hsGroupTopLevelFixitySigs` function is responsible for collecting this
    information from an `HsGroup`.

    One might wonder why we even bother separating top-level fixity signatures
    into two places at all. That is, why not just take the fixity signatures
    from `hs_tyclds` and put them into `hs_fixds` so that they are all in one
    location? This ends up causing problems for `GHC.HsToCore.Quote.repTopDs`,
    which translates each fixity signature in `hs_fixds` and `hs_tyclds` into a
    Template Haskell `Dec`. If there are any duplicate signatures between the two
    fields, this will result in an error (#17608).
    -}

    -- | Haskell Group
    --
    -- A 'HsDecl' is categorised into a 'HsGroup' before being
    -- fed to the renamer.
    data HsGroup p
      = HsGroup {
            forall p. HsGroup p -> XCHsGroup p
    hs_ext    :: XCHsGroup p,
            forall p. HsGroup p -> HsValBinds p
    hs_valds  :: HsValBinds p,
            forall p. HsGroup p -> [LSpliceDecl p]
    hs_splcds :: [LSpliceDecl p],

            forall p. HsGroup p -> [TyClGroup p]
    hs_tyclds :: [TyClGroup p],
                    -- A list of mutually-recursive groups;
                    -- This includes `InstDecl`s as well;
                    -- Parser generates a singleton list;
                    -- renamer does dependency analysis

            forall p. HsGroup p -> [LDerivDecl p]
    hs_derivds :: [LDerivDecl p],

            forall p. HsGroup p -> [LFixitySig p]
    hs_fixds  :: [LFixitySig p],
                    -- A list of fixity signatures defined for top-level
                    -- declarations and class methods (defined outside of the class
                    -- itself).
                    -- See Note [Top-level fixity signatures in an HsGroup]

            forall p. HsGroup p -> [LDefaultDecl p]
    hs_defds  :: [LDefaultDecl p],
            forall p. HsGroup p -> [LForeignDecl p]
    hs_fords  :: [LForeignDecl p],
            forall p. HsGroup p -> [LWarnDecls p]
    hs_warnds :: [LWarnDecls p],
            forall p. HsGroup p -> [LAnnDecl p]
    hs_annds  :: [LAnnDecl p],
            forall p. HsGroup p -> [LRuleDecls p]
    hs_ruleds :: [LRuleDecls p],

            forall p. HsGroup p -> [LDocDecl p]
    hs_docs   :: [LDocDecl p]
        }
      | XHsGroup !(XXHsGroup p)

    hsGroupInstDecls :: HsGroup id -> [LInstDecl id]
    hsGroupInstDecls :: forall id. HsGroup id -> [LInstDecl id]
    hsGroupInstDecls = (TyClGroup id -> [XRec id (InstDecl id)])
    -> [TyClGroup id] -> [XRec id (InstDecl id)]
    forall (m :: * -> *) a b. Monad m => (a -> m b) -> m a -> m b
    (=<<) TyClGroup id -> [XRec id (InstDecl id)]
    forall pass. TyClGroup pass -> [LInstDecl pass]
    group_instds ([TyClGroup id] -> [XRec id (InstDecl id)])
    -> (HsGroup id -> [TyClGroup id])
    -> HsGroup id
    -> [XRec id (InstDecl id)]
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . HsGroup id -> [TyClGroup id]
    forall p. HsGroup p -> [TyClGroup p]
    hs_tyclds

    -- | Located Splice Declaration
    type LSpliceDecl pass = XRec pass (SpliceDecl pass)

    -- | Splice Declaration
    data SpliceDecl p
      = SpliceDecl                  -- Top level splice
            (XSpliceDecl p)
            (XRec p (HsUntypedSplice p))
            SpliceDecoration -- Whether $( ) variant found, for pretty printing
      | XSpliceDecl !(XXSpliceDecl p)

    -- | A splice can appear with various decorations wrapped around it. This data
    -- type captures explicitly how it was originally written, for use in the pretty
    -- printer.
    data SpliceDecoration
      = DollarSplice  -- ^ $splice
      | BareSplice    -- ^ bare splice
      deriving (Typeable SpliceDecoration
    Typeable SpliceDecoration =>
    (forall (c :: * -> *).
     (forall d b. Data d => c (d -> b) -> d -> c b)
     -> (forall g. g -> c g) -> SpliceDecoration -> c SpliceDecoration)
    -> (forall (c :: * -> *).
        (forall b r. Data b => c (b -> r) -> c r)
        -> (forall r. r -> c r) -> Constr -> c SpliceDecoration)
    -> (SpliceDecoration -> Constr)
    -> (SpliceDecoration -> DataType)
    -> (forall (t :: * -> *) (c :: * -> *).
        Typeable t =>
        (forall d. Data d => c (t d)) -> Maybe (c SpliceDecoration))
    -> (forall (t :: * -> * -> *) (c :: * -> *).
        Typeable t =>
        (forall d e. (Data d, Data e) => c (t d e))
        -> Maybe (c SpliceDecoration))
    -> ((forall b. Data b => b -> b)
        -> SpliceDecoration -> SpliceDecoration)
    -> (forall r r'.
        (r -> r' -> r)
        -> r -> (forall d. Data d => d -> r') -> SpliceDecoration -> r)
    -> (forall r r'.
        (r' -> r -> r)
        -> r -> (forall d. Data d => d -> r') -> SpliceDecoration -> r)
    -> (forall u.
        (forall d. Data d => d -> u) -> SpliceDecoration -> [u])
    -> (forall u.
        Int -> (forall d. Data d => d -> u) -> SpliceDecoration -> u)
    -> (forall (m :: * -> *).
        Monad m =>
        (forall d. Data d => d -> m d)
        -> SpliceDecoration -> m SpliceDecoration)
    -> (forall (m :: * -> *).
        MonadPlus m =>
        (forall d. Data d => d -> m d)
        -> SpliceDecoration -> m SpliceDecoration)
    -> (forall (m :: * -> *).
        MonadPlus m =>
        (forall d. Data d => d -> m d)
        -> SpliceDecoration -> m SpliceDecoration)
    -> Data SpliceDecoration
    SpliceDecoration -> Constr
    SpliceDecoration -> DataType
    (forall b. Data b => b -> b)
    -> SpliceDecoration -> SpliceDecoration
    forall a.
    Typeable a =>
    (forall (c :: * -> *).
     (forall d b. Data d => c (d -> b) -> d -> c b)
     -> (forall g. g -> c g) -> a -> c a)
    -> (forall (c :: * -> *).
        (forall b r. Data b => c (b -> r) -> c r)
        -> (forall r. r -> c r) -> Constr -> c a)
    -> (a -> Constr)
    -> (a -> DataType)
    -> (forall (t :: * -> *) (c :: * -> *).
        Typeable t =>
        (forall d. Data d => c (t d)) -> Maybe (c a))
    -> (forall (t :: * -> * -> *) (c :: * -> *).
        Typeable t =>
        (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c a))
    -> ((forall b. Data b => b -> b) -> a -> a)
    -> (forall r r'.
        (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> a -> r)
    -> (forall r r'.
        (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> a -> r)
    -> (forall u. (forall d. Data d => d -> u) -> a -> [u])
    -> (forall u. Int -> (forall d. Data d => d -> u) -> a -> u)
    -> (forall (m :: * -> *).
        Monad m =>
        (forall d. Data d => d -> m d) -> a -> m a)
    -> (forall (m :: * -> *).
        MonadPlus m =>
        (forall d. Data d => d -> m d) -> a -> m a)
    -> (forall (m :: * -> *).
        MonadPlus m =>
        (forall d. Data d => d -> m d) -> a -> m a)
    -> Data a
    forall u.
    Int -> (forall d. Data d => d -> u) -> SpliceDecoration -> u
    forall u. (forall d. Data d => d -> u) -> SpliceDecoration -> [u]
    forall r r'.
    (r -> r' -> r)
    -> r -> (forall d. Data d => d -> r') -> SpliceDecoration -> r
    forall r r'.
    (r' -> r -> r)
    -> r -> (forall d. Data d => d -> r') -> SpliceDecoration -> r
    forall (m :: * -> *).
    Monad m =>
    (forall d. Data d => d -> m d)
    -> SpliceDecoration -> m SpliceDecoration
    forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d)
    -> SpliceDecoration -> m SpliceDecoration
    forall (c :: * -> *).
    (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c SpliceDecoration
    forall (c :: * -> *).
    (forall d b. Data d => c (d -> b) -> d -> c b)
    -> (forall g. g -> c g) -> SpliceDecoration -> c SpliceDecoration
    forall (t :: * -> *) (c :: * -> *).
    Typeable t =>
    (forall d. Data d => c (t d)) -> Maybe (c SpliceDecoration)
    forall (t :: * -> * -> *) (c :: * -> *).
    Typeable t =>
    (forall d e. (Data d, Data e) => c (t d e))
    -> Maybe (c SpliceDecoration)
    $cgfoldl :: forall (c :: * -> *).
    (forall d b. Data d => c (d -> b) -> d -> c b)
    -> (forall g. g -> c g) -> SpliceDecoration -> c SpliceDecoration
    gfoldl :: forall (c :: * -> *).
    (forall d b. Data d => c (d -> b) -> d -> c b)
    -> (forall g. g -> c g) -> SpliceDecoration -> c SpliceDecoration
    $cgunfold :: forall (c :: * -> *).
    (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c SpliceDecoration
    gunfold :: forall (c :: * -> *).
    (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c SpliceDecoration
    $ctoConstr :: SpliceDecoration -> Constr
    toConstr :: SpliceDecoration -> Constr
    $cdataTypeOf :: SpliceDecoration -> DataType
    dataTypeOf :: SpliceDecoration -> DataType
    $cdataCast1 :: forall (t :: * -> *) (c :: * -> *).
    Typeable t =>
    (forall d. Data d => c (t d)) -> Maybe (c SpliceDecoration)
    dataCast1 :: forall (t :: * -> *) (c :: * -> *).
    Typeable t =>
    (forall d. Data d => c (t d)) -> Maybe (c SpliceDecoration)
    $cdataCast2 :: forall (t :: * -> * -> *) (c :: * -> *).
    Typeable t =>
    (forall d e. (Data d, Data e) => c (t d e))
    -> Maybe (c SpliceDecoration)
    dataCast2 :: forall (t :: * -> * -> *) (c :: * -> *).
    Typeable t =>
    (forall d e. (Data d, Data e) => c (t d e))
    -> Maybe (c SpliceDecoration)
    $cgmapT :: (forall b. Data b => b -> b)
    -> SpliceDecoration -> SpliceDecoration
    gmapT :: (forall b. Data b => b -> b)
    -> SpliceDecoration -> SpliceDecoration
    $cgmapQl :: forall r r'.
    (r -> r' -> r)
    -> r -> (forall d. Data d => d -> r') -> SpliceDecoration -> r
    gmapQl :: forall r r'.
    (r -> r' -> r)
    -> r -> (forall d. Data d => d -> r') -> SpliceDecoration -> r
    $cgmapQr :: forall r r'.
    (r' -> r -> r)
    -> r -> (forall d. Data d => d -> r') -> SpliceDecoration -> r
    gmapQr :: forall r r'.
    (r' -> r -> r)
    -> r -> (forall d. Data d => d -> r') -> SpliceDecoration -> r
    $cgmapQ :: forall u. (forall d. Data d => d -> u) -> SpliceDecoration -> [u]
    gmapQ :: forall u. (forall d. Data d => d -> u) -> SpliceDecoration -> [u]
    $cgmapQi :: forall u.
    Int -> (forall d. Data d => d -> u) -> SpliceDecoration -> u
    gmapQi :: forall u.
    Int -> (forall d. Data d => d -> u) -> SpliceDecoration -> u
    $cgmapM :: forall (m :: * -> *).
    Monad m =>
    (forall d. Data d => d -> m d)
    -> SpliceDecoration -> m SpliceDecoration
    gmapM :: forall (m :: * -> *).
    Monad m =>
    (forall d. Data d => d -> m d)
    -> SpliceDecoration -> m SpliceDecoration
    $cgmapMp :: forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d)
    -> SpliceDecoration -> m SpliceDecoration
    gmapMp :: forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d)
    -> SpliceDecoration -> m SpliceDecoration
    $cgmapMo :: forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d)
    -> SpliceDecoration -> m SpliceDecoration
    gmapMo :: forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d)
    -> SpliceDecoration -> m SpliceDecoration
    Data, SpliceDecoration -> SpliceDecoration -> Bool
    (SpliceDecoration -> SpliceDecoration -> Bool)
    -> (SpliceDecoration -> SpliceDecoration -> Bool)
    -> Eq SpliceDecoration
    forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
    $c== :: SpliceDecoration -> SpliceDecoration -> Bool
    == :: SpliceDecoration -> SpliceDecoration -> Bool
    $c/= :: SpliceDecoration -> SpliceDecoration -> Bool
    /= :: SpliceDecoration -> SpliceDecoration -> Bool
    Eq, Int -> SpliceDecoration -> ShowS
    [SpliceDecoration] -> ShowS
    SpliceDecoration -> String
    (Int -> SpliceDecoration -> ShowS)
    -> (SpliceDecoration -> String)
    -> ([SpliceDecoration] -> ShowS)
    -> Show SpliceDecoration
    forall a.
    (Int -> a -> ShowS) -> (a -> String) -> ([a] -> ShowS) -> Show a
    $cshowsPrec :: Int -> SpliceDecoration -> ShowS
    showsPrec :: Int -> SpliceDecoration -> ShowS
    $cshow :: SpliceDecoration -> String
    show :: SpliceDecoration -> String
    $cshowList :: [SpliceDecoration] -> ShowS
    showList :: [SpliceDecoration] -> ShowS
    Show)

    {-
    ************************************************************************
    *                                                                      *
                Type and class declarations
    *                                                                      *
    ************************************************************************

    Note [The Naming story]
    ~~~~~~~~~~~~~~~~~~~~~~~
    Here is the story about the implicit names that go with type, class,
    and instance decls.  It's a bit tricky, so pay attention!

    "Implicit" (or "system") binders
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      Each data type decl defines
            a worker name for each constructor
            to-T and from-T convertors
      Each class decl defines
            a tycon for the class
            a data constructor for that tycon
            the worker for that constructor
            a selector for each superclass

    All have occurrence names that are derived uniquely from their parent
    declaration.

    None of these get separate definitions in an interface file; they are
    fully defined by the data or class decl.  But they may *occur* in
    interface files, of course.  Any such occurrence must haul in the
    relevant type or class decl.

    Plan of attack:
     - Ensure they "point to" the parent data/class decl
       when loading that decl from an interface file
       (See RnHiFiles.getSysBinders)

     - When typechecking the decl, we build the implicit TyCons and Ids.
       When doing so we look them up in the name cache (GHC.Rename.Env.lookupSysName),
       to ensure correct module and provenance is set

    These are the two places that we have to conjure up the magic derived
    names.  (The actual magic is in GHC.Types.Name.Occurrence.mkWorkerOcc, etc.)

    Default methods
    ~~~~~~~~~~~~~~~
     - Occurrence name is derived uniquely from the method name
       E.g. $dmmax

     - If there is a default method name at all, it's recorded in
       the ClassOpSig (in GHC.Hs.Binds), in the DefMethInfo field.
       (DefMethInfo is defined in GHC.Core.Class)

    Source-code class decls and interface-code class decls are treated subtly
    differently, which has given me a great deal of confusion over the years.
    Here's the deal.  (We distinguish the two cases because source-code decls
    have (Just binds) in the tcdMeths field, whereas interface decls have Nothing.

    In *source-code* class declarations:

     - When parsing, every ClassOpSig gets a DefMeth with a suitable RdrName
       This is done by GHC.Parser.PostProcess.mkClassOpSigDM

     - The renamer renames it to a Name

     - During typechecking, we generate a binding for each $dm for
       which there's a programmer-supplied default method:
            class Foo a where
              op1 :: <type>
              op2 :: <type>
              op1 = ...
       We generate a binding for $dmop1 but not for $dmop2.
       The Class for Foo has a Nothing for op2 and
                             a Just ($dm_op1, VanillaDM) for op1.
       The Name for $dmop2 is simply discarded.

    In *interface-file* class declarations:
      - When parsing, we see if there's an explicit programmer-supplied default method
        because there's an '=' sign to indicate it:
            class Foo a where
              op1 = :: <type>       -- NB the '='
              op2   :: <type>
        We use this info to generate a DefMeth with a suitable RdrName for op1,
        and a NoDefMeth for op2
      - The interface file has a separate definition for $dmop1, with unfolding etc.
      - The renamer renames it to a Name.
      - The renamer treats $dmop1 as a free variable of the declaration, so that
        the binding for $dmop1 will be sucked in.  (See RnHsSyn.tyClDeclFVs)
        This doesn't happen for source code class decls, because they *bind* the default method.

    Dictionary functions
    ~~~~~~~~~~~~~~~~~~~~
    Each instance declaration gives rise to one dictionary function binding.

    The type checker makes up new source-code instance declarations
    (e.g. from 'deriving' or generic default methods --- see
    GHC.Tc.TyCl.Instance.tcInstDecls1).  So we can't generate the names for
    dictionary functions in advance (we don't know how many we need).

    On the other hand for interface-file instance declarations, the decl
    specifies the name of the dictionary function, and it has a binding elsewhere
    in the interface file:
            instance {Eq Int} = dEqInt
            dEqInt :: {Eq Int} <pragma info>

    So again we treat source code and interface file code slightly differently.

    Source code:
      - Source code instance decls have a Nothing in the (Maybe name) field
        (see data InstDecl below)

      - The typechecker makes up a Local name for the dict fun for any source-code
        instance decl, whether it comes from a source-code instance decl, or whether
        the instance decl is derived from some other construct (e.g. 'deriving').

      - The occurrence name it chooses is derived from the instance decl (just for
        documentation really) --- e.g. dNumInt.  Two dict funs may share a common
        occurrence name, but will have different uniques.  E.g.
            instance Foo [Int]  where ...
            instance Foo [Bool] where ...
        These might both be dFooList

      - The CoreTidy phase externalises the name, and ensures the occurrence name is
        unique (this isn't special to dict funs).  So we'd get dFooList and dFooList1.

      - We can take this relaxed approach (changing the occurrence name later)
        because dict fun Ids are not captured in a TyCon or Class (unlike default
        methods, say).  Instead, they are kept separately in the InstEnv.  This
        makes it easy to adjust them after compiling a module.  (Once we've finished
        compiling that module, they don't change any more.)

    Interface file code:
      - The instance decl gives the dict fun name, so the InstDecl has a (Just name)
        in the (Maybe name) field.

      - RnHsSyn.instDeclFVs treats the dict fun name as free in the decl, so that we
        suck in the dfun binding
    -}

    -- | Located Declaration of a Type or Class
    type LTyClDecl pass = XRec pass (TyClDecl pass)

    -- | A type or class declaration.
    data TyClDecl pass
      = -- | @type/data family T :: *->*@
        FamDecl { forall pass. TyClDecl pass -> XFamDecl pass
    tcdFExt :: XFamDecl pass, forall pass. TyClDecl pass -> FamilyDecl pass
    tcdFam :: FamilyDecl pass }

      | -- | @type@ declaration
        SynDecl { forall pass. TyClDecl pass -> XSynDecl pass
    tcdSExt   :: XSynDecl pass          -- ^ Post renamer, FVs
                , forall pass. TyClDecl pass -> LIdP pass
    tcdLName  :: LIdP pass              -- ^ Type constructor
                , forall pass. TyClDecl pass -> LHsQTyVars pass
    tcdTyVars :: LHsQTyVars pass        -- ^ Type variables; for an
                                                      -- associated type these
                                                      -- include outer binders
                , forall pass. TyClDecl pass -> LexicalFixity
    tcdFixity :: LexicalFixity          -- ^ Fixity used in the declaration
                , forall pass. TyClDecl pass -> LHsType pass
    tcdRhs    :: LHsType pass }         -- ^ RHS of type declaration

      | -- | @data@ declaration
        DataDecl { forall pass. TyClDecl pass -> XDataDecl pass
    tcdDExt     :: XDataDecl pass       -- ^ Post renamer, CUSK flag, FVs
                 , tcdLName    :: LIdP pass             -- ^ Type constructor
                 , tcdTyVars   :: LHsQTyVars pass      -- ^ Type variables
                                  -- See Note [TyVar binders for associated decls]
                 , tcdFixity   :: LexicalFixity        -- ^ Fixity used in the declaration
                 , forall pass. TyClDecl pass -> HsDataDefn pass
    tcdDataDefn :: HsDataDefn pass }

      | ClassDecl { forall pass. TyClDecl pass -> XClassDecl pass
    tcdCExt    :: XClassDecl pass,         -- ^ Post renamer, FVs
                    forall pass. TyClDecl pass -> Maybe (LHsContext pass)
    tcdCtxt    :: Maybe (LHsContext pass), -- ^ Context...
                    tcdLName   :: LIdP pass,               -- ^ Name of the class
                    tcdTyVars  :: LHsQTyVars pass,         -- ^ Class type variables
                    tcdFixity  :: LexicalFixity, -- ^ Fixity used in the declaration
                    forall pass. TyClDecl pass -> [LHsFunDep pass]
    tcdFDs     :: [LHsFunDep pass],         -- ^ Functional deps
                    forall pass. TyClDecl pass -> [LSig pass]
    tcdSigs    :: [LSig pass],              -- ^ Methods' signatures
                    forall pass. TyClDecl pass -> LHsBinds pass
    tcdMeths   :: LHsBinds pass,            -- ^ Default methods
                    forall pass. TyClDecl pass -> [LFamilyDecl pass]
    tcdATs     :: [LFamilyDecl pass],       -- ^ Associated types;
                    forall pass. TyClDecl pass -> [LTyFamDefltDecl pass]
    tcdATDefs  :: [LTyFamDefltDecl pass],   -- ^ Associated type defaults
                    forall pass. TyClDecl pass -> [LDocDecl pass]
    tcdDocs    :: [LDocDecl pass]           -- ^ Haddock docs
        }
      | XTyClDecl !(XXTyClDecl pass)

    data FunDep pass
      = FunDep (XCFunDep pass)
               [LIdP pass]
               [LIdP pass]
      | XFunDep !(XXFunDep pass)

    type LHsFunDep pass = XRec pass (FunDep pass)

    {- Note [TyVar binders for associated decls]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    For an /associated/ data, newtype, or type-family decl, the LHsQTyVars
    /includes/ outer binders.  For example
        class T a where
           data D a c
           type F a b :: *
           type F a b = a -> a
    Here the data decl for 'D', and type-family decl for 'F', both include 'a'
    in their LHsQTyVars (tcdTyVars and fdTyVars resp).

    Ditto any implicit binders in the hsq_implicit field of the LHSQTyVars.

    The idea is that the associated type is really a top-level decl in its
    own right.  However we are careful to use the same name 'a', so that
    we can match things up.

    c.f. Note [Associated type tyvar names] in GHC.Core.Class
         Note [Family instance declaration binders]
    -}

    {- Note [Class EpLayout]
    ~~~~~~~~~~~~~~~~~~~~~~~~
    The EpLayout is used to associate Haddock comments with parts of the declaration.
    Compare the following examples:

        class C a where
          f :: a -> Int
          -- ^ comment on f

        class C a where
          f :: a -> Int
        -- ^ comment on C

    Notice how "comment on f" and "comment on C" differ only by indentation level.
    Thus we have to record the indentation level of the class declarations.

    See also Note [Adding Haddock comments to the syntax tree] in GHC.Parser.PostProcess.Haddock
    -}

    -- Simple classifiers for TyClDecl
    -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    -- | @True@ <=> argument is a @data@\/@newtype@
    -- declaration.
    isDataDecl :: TyClDecl pass -> Bool
    isDataDecl :: forall pass. TyClDecl pass -> Bool
    isDataDecl (DataDecl {}) = Bool
    True
    isDataDecl TyClDecl pass
    _other        = Bool
    False

    -- | type or type instance declaration
    isSynDecl :: TyClDecl pass -> Bool
    isSynDecl :: forall pass. TyClDecl pass -> Bool
    isSynDecl (SynDecl {})   = Bool
    True
    isSynDecl TyClDecl pass
    _other        = Bool
    False

    -- | type class
    isClassDecl :: TyClDecl pass -> Bool
    isClassDecl :: forall pass. TyClDecl pass -> Bool
    isClassDecl (ClassDecl {}) = Bool
    True
    isClassDecl TyClDecl pass
    _              = Bool
    False

    -- | type/data family declaration
    isFamilyDecl :: TyClDecl pass -> Bool
    isFamilyDecl :: forall pass. TyClDecl pass -> Bool
    isFamilyDecl (FamDecl {})  = Bool
    True
    isFamilyDecl TyClDecl pass
    _other        = Bool
    False

    -- | type family declaration
    isTypeFamilyDecl :: TyClDecl pass -> Bool
    isTypeFamilyDecl :: forall pass. TyClDecl pass -> Bool
    isTypeFamilyDecl (FamDecl XFamDecl pass
    _ (FamilyDecl { fdInfo :: forall pass. FamilyDecl pass -> FamilyInfo pass
    fdInfo = FamilyInfo pass
    info })) = case FamilyInfo pass
    info of
      FamilyInfo pass
    OpenTypeFamily      -> Bool
    True
      ClosedTypeFamily {} -> Bool
    True
      FamilyInfo pass
    _                   -> Bool
    False
    isTypeFamilyDecl TyClDecl pass
    _ = Bool
    False

    -- | open type family info
    isOpenTypeFamilyInfo :: FamilyInfo pass -> Bool
    isOpenTypeFamilyInfo :: forall pass. FamilyInfo pass -> Bool
    isOpenTypeFamilyInfo FamilyInfo pass
    OpenTypeFamily = Bool
    True
    isOpenTypeFamilyInfo FamilyInfo pass
    _              = Bool
    False

    -- | closed type family info
    isClosedTypeFamilyInfo :: FamilyInfo pass -> Bool
    isClosedTypeFamilyInfo :: forall pass. FamilyInfo pass -> Bool
    isClosedTypeFamilyInfo (ClosedTypeFamily {}) = Bool
    True
    isClosedTypeFamilyInfo FamilyInfo pass
    _                     = Bool
    False

    -- | data family declaration
    isDataFamilyDecl :: TyClDecl pass -> Bool
    isDataFamilyDecl :: forall pass. TyClDecl pass -> Bool
    isDataFamilyDecl (FamDecl XFamDecl pass
    _ (FamilyDecl { fdInfo :: forall pass. FamilyDecl pass -> FamilyInfo pass
    fdInfo = FamilyInfo pass
    DataFamily })) = Bool
    True
    isDataFamilyDecl TyClDecl pass
    _other      = Bool
    False

    -- Dealing with names

    tyClDeclTyVars :: TyClDecl pass -> LHsQTyVars pass
    tyClDeclTyVars :: forall pass. TyClDecl pass -> LHsQTyVars pass
    tyClDeclTyVars (FamDecl { tcdFam :: forall pass. TyClDecl pass -> FamilyDecl pass
    tcdFam = FamilyDecl { fdTyVars :: forall pass. FamilyDecl pass -> LHsQTyVars pass
    fdTyVars = LHsQTyVars pass
    tvs } }) = LHsQTyVars pass
    tvs
    tyClDeclTyVars TyClDecl pass
    d = TyClDecl pass -> LHsQTyVars pass
    forall pass. TyClDecl pass -> LHsQTyVars pass
    tcdTyVars TyClDecl pass
    d

    {- Note [CUSKs: complete user-supplied kind signatures]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    We kind-check declarations differently if they have a complete, user-supplied
    kind signature (CUSK). This is because we can safely generalise a CUSKed
    declaration before checking all of the others, supporting polymorphic recursion.
    See https://gitlab.haskell.org/ghc/ghc/wikis/ghc-kinds/kind-inference#proposed-new-strategy
    and #9200 for lots of discussion of how we got here.

    The detection of CUSKs is enabled by the -XCUSKs extension, switched off by default
    in GHC2021 and on in Haskell98/2010.
    Under -XNoCUSKs, all declarations are treated as if they have no CUSK.
    See https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0036-kind-signatures.rst

    PRINCIPLE:
      a type declaration has a CUSK iff we could produce a separate kind signature
      for it, just like a type signature for a function,
      looking only at the header of the declaration.

    Examples:
      * data T1 (a :: *->*) (b :: *) = ....
        -- Has CUSK; equivalent to   T1 :: (*->*) -> * -> *

     * data T2 a b = ...
       -- No CUSK; we do not want to guess T2 :: * -> * -> *
       -- because the full decl might be   data T a b = MkT (a b)

      * data T3 (a :: k -> *) (b :: *) = ...
        -- CUSK; equivalent to   T3 :: (k -> *) -> * -> *
        -- We lexically generalise over k to get
        --    T3 :: forall k. (k -> *) -> * -> *
        -- The generalisation is here is purely lexical, just like
        --    f3 :: a -> a
        -- means
        --    f3 :: forall a. a -> a

      * data T4 (a :: j k) = ...
         -- CUSK; equivalent to   T4 :: j k -> *
         -- which we lexically generalise to  T4 :: forall j k. j k -> *
         -- and then, if PolyKinds is on, we further generalise to
         --   T4 :: forall kk (j :: kk -> *) (k :: kk). j k -> *
         -- Again this is exactly like what happens as the term level
         -- when you write
         --    f4 :: forall a b. a b -> Int

    NOTE THAT
      * A CUSK does /not/ mean that everything about the kind signature is
        fully specified by the user.  Look at T4 and f4: we had to do kind
        inference to figure out the kind-quantification.  But in both cases
        (T4 and f4) that inference is done looking /only/ at the header of T4
        (or signature for f4), not at the definition thereof.

      * The CUSK completely fixes the kind of the type constructor, forever.

      * The precise rules, for each declaration form, for whether a declaration
        has a CUSK are given in the user manual section "Complete user-supplied
        kind signatures and polymorphic recursion".  But they simply implement
        PRINCIPLE above.

      * Open type families are interesting:
          type family T5 a b :: *
        There simply /is/ no accompanying declaration, so that info is all
        we'll ever get.  So we it has a CUSK by definition, and we default
        any un-fixed kind variables to *.

      * Associated types are a bit tricker:
          class C6 a where
             type family T6 a b :: *
             op :: a Int -> Int
        Here C6 does not have a CUSK (in fact we ultimately discover that
        a :: * -> *).  And hence neither does T6, the associated family,
        because we can't fix its kind until we have settled C6.  Another
        way to say it: unlike a top-level, we /may/ discover more about
        a's kind from C6's definition.

      * A data definition with a top-level :: must explicitly bind all
        kind variables to the right of the ::. See test
        dependent/should_compile/KindLevels, which requires this
        case. (Naturally, any kind variable mentioned before the :: should
        not be bound after it.)

        This last point is much more debatable than the others; see
        #15142 comment:22

        Because this is fiddly to check, there is a field in the DataDeclRn
        structure (included in a DataDecl after the renamer) that stores whether
        or not the declaration has a CUSK.
    -}

    {- *********************************************************************
    *                                                                      *
                             TyClGroup
            Strongly connected components of
          type, class, instance, and role declarations
    *                                                                      *
    ********************************************************************* -}

    {- Note [TyClGroups and dependency analysis]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    A TyClGroup represents a strongly connected components of type/class/instance
    decls, together with the role annotations for the type/class declarations.

    The hs_tyclds :: [TyClGroup] field of a HsGroup is a dependency-order
    sequence of strongly-connected components.

    Invariants
     * The type and class declarations, group_tyclds, may depend on each
       other, or earlier TyClGroups, but not on later ones

     * The role annotations, group_roles, are role-annotations for some or
       all of the types and classes in group_tyclds (only).

     * The instance declarations, group_instds, may (and usually will)
       depend on group_tyclds, or on earlier TyClGroups, but not on later
       ones.

    See Note [Dependency analysis of type, class, and instance decls]
    in GHC.Rename.Module for more info.
    -}

    -- | Type or Class Group
    data TyClGroup pass  -- See Note [TyClGroups and dependency analysis]
      = TyClGroup { forall pass. TyClGroup pass -> XCTyClGroup pass
    group_ext    :: XCTyClGroup pass
                  , forall pass. TyClGroup pass -> [LTyClDecl pass]
    group_tyclds :: [LTyClDecl pass]
                  , forall pass. TyClGroup pass -> [LRoleAnnotDecl pass]
    group_roles  :: [LRoleAnnotDecl pass]
                  , forall pass. TyClGroup pass -> [LStandaloneKindSig pass]
    group_kisigs :: [LStandaloneKindSig pass]
                  , forall pass. TyClGroup pass -> [LInstDecl pass]
    group_instds :: [LInstDecl pass] }
      | XTyClGroup !(XXTyClGroup pass)

    tyClGroupTyClDecls :: [TyClGroup pass] -> [LTyClDecl pass]
    tyClGroupTyClDecls :: forall pass. [TyClGroup pass] -> [LTyClDecl pass]
    tyClGroupTyClDecls = (TyClGroup pass -> [XRec pass (TyClDecl pass)])
    -> [TyClGroup pass] -> [XRec pass (TyClDecl pass)]
    forall (t :: * -> *) a b. Foldable t => (a -> [b]) -> t a -> [b]
    Data.List.concatMap TyClGroup pass -> [XRec pass (TyClDecl pass)]
    forall pass. TyClGroup pass -> [LTyClDecl pass]
    group_tyclds

    tyClGroupInstDecls :: [TyClGroup pass] -> [LInstDecl pass]
    tyClGroupInstDecls :: forall pass. [TyClGroup pass] -> [LInstDecl pass]
    tyClGroupInstDecls = (TyClGroup pass -> [XRec pass (InstDecl pass)])
    -> [TyClGroup pass] -> [XRec pass (InstDecl pass)]
    forall (t :: * -> *) a b. Foldable t => (a -> [b]) -> t a -> [b]
    Data.List.concatMap TyClGroup pass -> [XRec pass (InstDecl pass)]
    forall pass. TyClGroup pass -> [LInstDecl pass]
    group_instds

    tyClGroupRoleDecls :: [TyClGroup pass] -> [LRoleAnnotDecl pass]
    tyClGroupRoleDecls :: forall pass. [TyClGroup pass] -> [LRoleAnnotDecl pass]
    tyClGroupRoleDecls = (TyClGroup pass -> [XRec pass (RoleAnnotDecl pass)])
    -> [TyClGroup pass] -> [XRec pass (RoleAnnotDecl pass)]
    forall (t :: * -> *) a b. Foldable t => (a -> [b]) -> t a -> [b]
    Data.List.concatMap TyClGroup pass -> [XRec pass (RoleAnnotDecl pass)]
    forall pass. TyClGroup pass -> [LRoleAnnotDecl pass]
    group_roles

    tyClGroupKindSigs :: [TyClGroup pass] -> [LStandaloneKindSig pass]
    tyClGroupKindSigs :: forall pass. [TyClGroup pass] -> [LStandaloneKindSig pass]
    tyClGroupKindSigs = (TyClGroup pass -> [XRec pass (StandaloneKindSig pass)])
    -> [TyClGroup pass] -> [XRec pass (StandaloneKindSig pass)]
    forall (t :: * -> *) a b. Foldable t => (a -> [b]) -> t a -> [b]
    Data.List.concatMap TyClGroup pass -> [XRec pass (StandaloneKindSig pass)]
    forall pass. TyClGroup pass -> [LStandaloneKindSig pass]
    group_kisigs

    {- *********************************************************************
    *                                                                      *
                   Data and type family declarations
    *                                                                      *
    ********************************************************************* -}

    {- Note [FamilyResultSig]
    ~~~~~~~~~~~~~~~~~~~~~~~~~

    This data type represents the return signature of a type family.  Possible
    values are:

     * NoSig - the user supplied no return signature:
          type family Id a where ...

     * KindSig - the user supplied the return kind:
          type family Id a :: * where ...

     * TyVarSig - user named the result with a type variable and possibly
       provided a kind signature for that variable:
          type family Id a = r where ...
          type family Id a = (r :: *) where ...

       Naming result of a type family is required if we want to provide
       injectivity annotation for a type family:
          type family Id a = r | r -> a where ...

    See also: Note [Injectivity annotation]

    Note [Injectivity annotation]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    A user can declare a type family to be injective:

       type family Id a = r | r -> a where ...

     * The part after the "|" is called "injectivity annotation".
     * "r -> a" part is called "injectivity condition"; at the moment terms
       "injectivity annotation" and "injectivity condition" are synonymous
       because we only allow a single injectivity condition.
     * "r" is the "LHS of injectivity condition". LHS can only contain the
       variable naming the result of a type family.

     * "a" is the "RHS of injectivity condition". RHS contains space-separated
       type and kind variables representing the arguments of a type
       family. Variables can be omitted if a type family is not injective in
       these arguments. Example:
             type family Foo a b c = d | d -> a c where ...

    Note that:
     (a) naming of type family result is required to provide injectivity
         annotation
     (b) for associated types if the result was named then injectivity annotation
         is mandatory. Otherwise result type variable is indistinguishable from
         associated type default.

    It is possible that in the future this syntax will be extended to support
    more complicated injectivity annotations. For example we could declare that
    if we know the result of Plus and one of its arguments we can determine the
    other argument:

       type family Plus a b = (r :: Nat) | r a -> b, r b -> a where ...

    Here injectivity annotation would consist of two comma-separated injectivity
    conditions.

    See also Note [Injective type families] in GHC.Core.TyCon
    -}

    -- | Located type Family Result Signature
    type LFamilyResultSig pass = XRec pass (FamilyResultSig pass)

    -- | type Family Result Signature
    data FamilyResultSig pass = -- see Note [FamilyResultSig]
        NoSig (XNoSig pass)
      | KindSig  (XCKindSig pass) (LHsKind pass)
      | TyVarSig (XTyVarSig pass) (LHsTyVarBndr () pass)
      | XFamilyResultSig !(XXFamilyResultSig pass)

    -- | Located type Family Declaration
    type LFamilyDecl pass = XRec pass (FamilyDecl pass)

    -- | type Family Declaration
    data FamilyDecl pass = FamilyDecl
      { forall pass. FamilyDecl pass -> XCFamilyDecl pass
    fdExt            :: XCFamilyDecl pass
      , forall pass. FamilyDecl pass -> FamilyInfo pass
    fdInfo           :: FamilyInfo pass              -- type/data, closed/open
      , forall pass. FamilyDecl pass -> TopLevelFlag
    fdTopLevel       :: TopLevelFlag                 -- used for printing only
      , forall pass. FamilyDecl pass -> LIdP pass
    fdLName          :: LIdP pass                    -- type constructor
      , forall pass. FamilyDecl pass -> LHsQTyVars pass
    fdTyVars         :: LHsQTyVars pass              -- type variables
                           -- See Note [TyVar binders for associated decls]
      , forall pass. FamilyDecl pass -> LexicalFixity
    fdFixity         :: LexicalFixity                -- Fixity used in the declaration
      , forall pass. FamilyDecl pass -> LFamilyResultSig pass
    fdResultSig      :: LFamilyResultSig pass        -- result signature
      , forall pass. FamilyDecl pass -> Maybe (LInjectivityAnn pass)
    fdInjectivityAnn :: Maybe (LInjectivityAnn pass) -- optional injectivity ann
      }
      | XFamilyDecl !(XXFamilyDecl pass)

    -- | Located Injectivity Annotation
    type LInjectivityAnn pass = XRec pass (InjectivityAnn pass)

    -- | If the user supplied an injectivity annotation it is represented using
    -- InjectivityAnn. At the moment this is a single injectivity condition - see
    -- Note [Injectivity annotation]. `Located name` stores the LHS of injectivity
    -- condition. `[Located name]` stores the RHS of injectivity condition. Example:
    --
    --   type family Foo a b c = r | r -> a c where ...
    --
    -- This will be represented as "InjectivityAnn `r` [`a`, `c`]"
    data InjectivityAnn pass
      = InjectivityAnn (XCInjectivityAnn pass)
                       (LIdP pass) [LIdP pass]
      | XInjectivityAnn !(XXInjectivityAnn pass)

    data FamilyInfo pass
      = DataFamily
      | OpenTypeFamily
         -- | 'Nothing' if we're in an hs-boot file and the user
         -- said "type family Foo x where .."
      | ClosedTypeFamily (Maybe [LTyFamInstEqn pass])

    familyInfoTyConFlavour
      :: Maybe tc    -- ^ Just cls <=> this is an associated family of class cls
      -> FamilyInfo pass
      -> TyConFlavour tc
    familyInfoTyConFlavour :: forall tc pass. Maybe tc -> FamilyInfo pass -> TyConFlavour tc
    familyInfoTyConFlavour Maybe tc
    mb_parent_tycon FamilyInfo pass
    info =
      case FamilyInfo pass
    info of
        FamilyInfo pass
    DataFamily         -> TypeOrData -> Maybe tc -> TyConFlavour tc
    forall tc. TypeOrData -> Maybe tc -> TyConFlavour tc
    OpenFamilyFlavour TypeOrData
    IAmData Maybe tc
    mb_parent_tycon
        FamilyInfo pass
    OpenTypeFamily     -> TypeOrData -> Maybe tc -> TyConFlavour tc
    forall tc. TypeOrData -> Maybe tc -> TyConFlavour tc
    OpenFamilyFlavour TypeOrData
    IAmType Maybe tc
    mb_parent_tycon
        ClosedTypeFamily Maybe [LTyFamInstEqn pass]
    _ -> Bool -> TyConFlavour tc -> TyConFlavour tc
    forall a. (?callStack::CallStack) => Bool -> a -> a
    assert (Maybe tc -> Bool
    forall a. Maybe a -> Bool
    isNothing Maybe tc
    mb_parent_tycon)
                              -- See Note [Closed type family mb_parent_tycon]
                              TyConFlavour tc
    forall tc. TyConFlavour tc
    ClosedTypeFamilyFlavour

    {- Note [Closed type family mb_parent_tycon]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    There's no way to write a closed type family inside a class declaration:

      class C a where
        type family F a where  -- error: parse error on input ‘where’

    In fact, it is not clear what the meaning of such a declaration would be.
    Therefore, 'mb_parent_tycon' of any closed type family has to be Nothing.
    -}

    {- *********************************************************************
    *                                                                      *
                   Data types and data constructors
    *                                                                      *
    ********************************************************************* -}

    -- | Haskell Data type Definition
    data HsDataDefn pass   -- The payload of a data type defn
                           -- Used *both* for vanilla data declarations,
                           --       *and* for data family instances
      = -- | Declares a data type or newtype, giving its constructors
        -- @
        --  data/newtype T a = <constrs>
        --  data/newtype instance T [a] = <constrs>
        -- @
        HsDataDefn { forall pass. HsDataDefn pass -> XCHsDataDefn pass
    dd_ext    :: XCHsDataDefn pass,
                     forall pass. HsDataDefn pass -> Maybe (LHsContext pass)
    dd_ctxt   :: Maybe (LHsContext pass), -- ^ Context
                     forall pass. HsDataDefn pass -> Maybe (XRec pass CType)
    dd_cType  :: Maybe (XRec pass CType),
                     forall pass. HsDataDefn pass -> Maybe (LHsKind pass)
    dd_kindSig:: Maybe (LHsKind pass),
                         -- ^ Optional kind signature.
                         --
                         -- @(Just k)@ for a GADT-style @data@,
                         -- or @data instance@ decl, with explicit kind sig
                         --
                         -- Always @Nothing@ for H98-syntax decls

                     forall pass. HsDataDefn pass -> DataDefnCons (LConDecl pass)
    dd_cons   :: DataDefnCons (LConDecl pass),
                         -- ^ Data constructors
                         --
                         -- For @data T a = T1 | T2 a@
                         --   the 'LConDecl's all have 'ConDeclH98'.
                         -- For @data T a where { T1 :: T a }@
                         --   the 'LConDecls' all have 'ConDeclGADT'.

                     forall pass. HsDataDefn pass -> HsDeriving pass
    dd_derivs :: HsDeriving pass  -- ^ Optional 'deriving' clause

                 -- For details on above see Note [exact print annotations] in GHC.Parser.Annotation
       }
      | XHsDataDefn !(XXHsDataDefn pass)

    -- | Haskell Deriving clause
    type HsDeriving pass = [LHsDerivingClause pass]
      -- ^ The optional @deriving@ clauses of a data declaration. "Clauses" is
      -- plural because one can specify multiple deriving clauses using the
      -- @-XDerivingStrategies@ language extension.
      --
      -- The list of 'LHsDerivingClause's corresponds to exactly what the user
      -- requested to derive, in order. If no deriving clauses were specified,
      -- the list is empty.

    type LHsDerivingClause pass = XRec pass (HsDerivingClause pass)

    -- | A single @deriving@ clause of a data declaration.
    data HsDerivingClause pass
      -- See Note [Deriving strategies] in GHC.Tc.Deriv
      = HsDerivingClause
        { forall pass. HsDerivingClause pass -> XCHsDerivingClause pass
    deriv_clause_ext :: XCHsDerivingClause pass
        , forall pass. HsDerivingClause pass -> Maybe (LDerivStrategy pass)
    deriv_clause_strategy :: Maybe (LDerivStrategy pass)
          -- ^ The user-specified strategy (if any) to use when deriving
          -- 'deriv_clause_tys'.
        , forall pass. HsDerivingClause pass -> LDerivClauseTys pass
    deriv_clause_tys :: LDerivClauseTys pass
          -- ^ The types to derive.
        }
      | XHsDerivingClause !(XXHsDerivingClause pass)

    type LDerivClauseTys pass = XRec pass (DerivClauseTys pass)

    -- | The types mentioned in a single @deriving@ clause. This can come in two
    -- forms, 'DctSingle' or 'DctMulti', depending on whether the types are
    -- surrounded by enclosing parentheses or not. These parentheses are
    -- semantically different than 'HsParTy'. For example, @deriving ()@ means
    -- \"derive zero classes\" rather than \"derive an instance of the 0-tuple\".
    --
    -- 'DerivClauseTys' use 'LHsSigType' because @deriving@ clauses can mention
    -- type variables that aren't bound by the datatype, e.g.
    --
    -- > data T b = ... deriving (C [a])
    --
    -- should produce a derived instance for @C [a] (T b)@.
    data DerivClauseTys pass
      = -- | A @deriving@ clause with a single type. Moreover, that type can only
        -- be a type constructor without any arguments.
        --
        -- Example: @deriving Eq@
        DctSingle (XDctSingle pass) (LHsSigType pass)

        -- | A @deriving@ clause with a comma-separated list of types, surrounded
        -- by enclosing parentheses.
        --
        -- Example: @deriving (Eq, C a)@
      | DctMulti (XDctMulti pass) [LHsSigType pass]

      | XDerivClauseTys !(XXDerivClauseTys pass)

    -- | Located Standalone Kind Signature
    type LStandaloneKindSig pass = XRec pass (StandaloneKindSig pass)

    data StandaloneKindSig pass
      = StandaloneKindSig (XStandaloneKindSig pass)
          (LIdP pass)           -- Why a single binder? See #16754
          (LHsSigType pass)     -- Why not LHsSigWcType? See Note [Wildcards in standalone kind signatures]
      | XStandaloneKindSig !(XXStandaloneKindSig pass)

    {- Note [Wildcards in standalone kind signatures]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Standalone kind signatures enable polymorphic recursion, and it is unclear how
    to reconcile this with partial type signatures, so we disallow wildcards in
    them.

    We reject wildcards in 'rnStandaloneKindSignature' by returning False for
    'StandaloneKindSigCtx' in 'wildCardsAllowed'.

    The alternative design is to have special treatment for partial standalone kind
    signatures, much like we have special treatment for partial type signatures in
    terms. However, partial standalone kind signatures are not a proper replacement
    for CUSKs, so this would be a separate feature.
    -}

    -- | When we only care whether a data-type declaration is `data` or `newtype`, but not what constructors it has
    data NewOrData
      = NewType                     -- ^ @newtype Blah ...@
      | DataType                    -- ^ @data Blah ...@
      deriving ( NewOrData -> NewOrData -> Bool
    (NewOrData -> NewOrData -> Bool)
    -> (NewOrData -> NewOrData -> Bool) -> Eq NewOrData
    forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
    $c== :: NewOrData -> NewOrData -> Bool
    == :: NewOrData -> NewOrData -> Bool
    $c/= :: NewOrData -> NewOrData -> Bool
    /= :: NewOrData -> NewOrData -> Bool
    Eq, Typeable NewOrData
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    (forall (c :: * -> *).
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        (r -> r' -> r)
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    -> Data NewOrData
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    Data )                -- Needed because Demand derives Eq

    -- | Whether a data-type declaration is @data@ or @newtype@, and its constructors.
    data DataDefnCons a
      = NewTypeCon          -- @newtype N x = MkN blah@
          a      -- Info about the single data constructor @MkN@

      | DataTypeCons
          Bool   -- True  <=> type data T x = ...
                 --           See Note [Type data declarations] in GHC.Rename.Module
                 -- False <=> data T x = ...
          [a]    -- The (possibly empty) list of data constructors
      deriving ( DataDefnCons a -> DataDefnCons a -> Bool
    (DataDefnCons a -> DataDefnCons a -> Bool)
    -> (DataDefnCons a -> DataDefnCons a -> Bool)
    -> Eq (DataDefnCons a)
    forall a. Eq a => DataDefnCons a -> DataDefnCons a -> Bool
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    $c== :: forall a. Eq a => DataDefnCons a -> DataDefnCons a -> Bool
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    /= :: DataDefnCons a -> DataDefnCons a -> Bool
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    -> (forall a b. (a -> b -> b) -> b -> DataDefnCons a -> b)
    -> (forall b a. (b -> a -> b) -> b -> DataDefnCons a -> b)
    -> (forall b a. (b -> a -> b) -> b -> DataDefnCons a -> b)
    -> (forall a. (a -> a -> a) -> DataDefnCons a -> a)
    -> (forall a. (a -> a -> a) -> DataDefnCons a -> a)
    -> (forall a. DataDefnCons a -> [a])
    -> (forall a. DataDefnCons a -> Bool)
    -> (forall a. DataDefnCons a -> Int)
    -> (forall a. Eq a => a -> DataDefnCons a -> Bool)
    -> (forall a. Ord a => DataDefnCons a -> a)
    -> (forall a. Ord a => DataDefnCons a -> a)
    -> (forall a. Num a => DataDefnCons a -> a)
    -> (forall a. Num a => DataDefnCons a -> a)
    -> Foldable DataDefnCons
    forall a. Eq a => a -> DataDefnCons a -> Bool
    forall a. Num a => DataDefnCons a -> a
    forall a. Ord a => DataDefnCons a -> a
    forall m. Monoid m => DataDefnCons m -> m
    forall a. DataDefnCons a -> Bool
    forall a. DataDefnCons a -> Int
    forall a. DataDefnCons a -> [a]
    forall a. (a -> a -> a) -> DataDefnCons a -> a
    forall m a. Monoid m => (a -> m) -> DataDefnCons a -> m
    forall b a. (b -> a -> b) -> b -> DataDefnCons a -> b
    forall a b. (a -> b -> b) -> b -> DataDefnCons a -> b
    forall (t :: * -> *).
    (forall m. Monoid m => t m -> m)
    -> (forall m a. Monoid m => (a -> m) -> t a -> m)
    -> (forall m a. Monoid m => (a -> m) -> t a -> m)
    -> (forall a b. (a -> b -> b) -> b -> t a -> b)
    -> (forall a b. (a -> b -> b) -> b -> t a -> b)
    -> (forall b a. (b -> a -> b) -> b -> t a -> b)
    -> (forall b a. (b -> a -> b) -> b -> t a -> b)
    -> (forall a. (a -> a -> a) -> t a -> a)
    -> (forall a. (a -> a -> a) -> t a -> a)
    -> (forall a. t a -> [a])
    -> (forall a. t a -> Bool)
    -> (forall a. t a -> Int)
    -> (forall a. Eq a => a -> t a -> Bool)
    -> (forall a. Ord a => t a -> a)
    -> (forall a. Ord a => t a -> a)
    -> (forall a. Num a => t a -> a)
    -> (forall a. Num a => t a -> a)
    -> Foldable t
    $cfold :: forall m. Monoid m => DataDefnCons m -> m
    fold :: forall m. Monoid m => DataDefnCons m -> m
    $cfoldMap :: forall m a. Monoid m => (a -> m) -> DataDefnCons a -> m
    foldMap :: forall m a. Monoid m => (a -> m) -> DataDefnCons a -> m
    $cfoldMap' :: forall m a. Monoid m => (a -> m) -> DataDefnCons a -> m
    foldMap' :: forall m a. Monoid m => (a -> m) -> DataDefnCons a -> m
    $cfoldr :: forall a b. (a -> b -> b) -> b -> DataDefnCons a -> b
    foldr :: forall a b. (a -> b -> b) -> b -> DataDefnCons a -> b
    $cfoldr' :: forall a b. (a -> b -> b) -> b -> DataDefnCons a -> b
    foldr' :: forall a b. (a -> b -> b) -> b -> DataDefnCons a -> b
    $cfoldl :: forall b a. (b -> a -> b) -> b -> DataDefnCons a -> b
    foldl :: forall b a. (b -> a -> b) -> b -> DataDefnCons a -> b
    $cfoldl' :: forall b a. (b -> a -> b) -> b -> DataDefnCons a -> b
    foldl' :: forall b a. (b -> a -> b) -> b -> DataDefnCons a -> b
    $cfoldr1 :: forall a. (a -> a -> a) -> DataDefnCons a -> a
    foldr1 :: forall a. (a -> a -> a) -> DataDefnCons a -> a
    $cfoldl1 :: forall a. (a -> a -> a) -> DataDefnCons a -> a
    foldl1 :: forall a. (a -> a -> a) -> DataDefnCons a -> a
    $ctoList :: forall a. DataDefnCons a -> [a]
    toList :: forall a. DataDefnCons a -> [a]
    $cnull :: forall a. DataDefnCons a -> Bool
    null :: forall a. DataDefnCons a -> Bool
    $clength :: forall a. DataDefnCons a -> Int
    length :: forall a. DataDefnCons a -> Int
    $celem :: forall a. Eq a => a -> DataDefnCons a -> Bool
    elem :: forall a. Eq a => a -> DataDefnCons a -> Bool
    $cmaximum :: forall a. Ord a => DataDefnCons a -> a
    maximum :: forall a. Ord a => DataDefnCons a -> a
    $cminimum :: forall a. Ord a => DataDefnCons a -> a
    minimum :: forall a. Ord a => DataDefnCons a -> a
    $csum :: forall a. Num a => DataDefnCons a -> a
    sum :: forall a. Num a => DataDefnCons a -> a
    $cproduct :: forall a. Num a => DataDefnCons a -> a
    product :: forall a. Num a => DataDefnCons a -> a
    Foldable, (forall a b. (a -> b) -> DataDefnCons a -> DataDefnCons b)
    -> (forall a b. a -> DataDefnCons b -> DataDefnCons a)
    -> Functor DataDefnCons
    forall a b. a -> DataDefnCons b -> DataDefnCons a
    forall a b. (a -> b) -> DataDefnCons a -> DataDefnCons b
    forall (f :: * -> *).
    (forall a b. (a -> b) -> f a -> f b)
    -> (forall a b. a -> f b -> f a) -> Functor f
    $cfmap :: forall a b. (a -> b) -> DataDefnCons a -> DataDefnCons b
    fmap :: forall a b. (a -> b) -> DataDefnCons a -> DataDefnCons b
    $c<$ :: forall a b. a -> DataDefnCons b -> DataDefnCons a
    <$ :: forall a b. a -> DataDefnCons b -> DataDefnCons a
    Functor, Functor DataDefnCons
    Foldable DataDefnCons
    (Functor DataDefnCons, Foldable DataDefnCons) =>
    (forall (f :: * -> *) a b.
     Applicative f =>
     (a -> f b) -> DataDefnCons a -> f (DataDefnCons b))
    -> (forall (f :: * -> *) a.
        Applicative f =>
        DataDefnCons (f a) -> f (DataDefnCons a))
    -> (forall (m :: * -> *) a b.
        Monad m =>
        (a -> m b) -> DataDefnCons a -> m (DataDefnCons b))
    -> (forall (m :: * -> *) a.
        Monad m =>
        DataDefnCons (m a) -> m (DataDefnCons a))
    -> Traversable DataDefnCons
    forall (t :: * -> *).
    (Functor t, Foldable t) =>
    (forall (f :: * -> *) a b.
     Applicative f =>
     (a -> f b) -> t a -> f (t b))
    -> (forall (f :: * -> *) a. Applicative f => t (f a) -> f (t a))
    -> (forall (m :: * -> *) a b.
        Monad m =>
        (a -> m b) -> t a -> m (t b))
    -> (forall (m :: * -> *) a. Monad m => t (m a) -> m (t a))
    -> Traversable t
    forall (m :: * -> *) a.
    Monad m =>
    DataDefnCons (m a) -> m (DataDefnCons a)
    forall (f :: * -> *) a.
    Applicative f =>
    DataDefnCons (f a) -> f (DataDefnCons a)
    forall (m :: * -> *) a b.
    Monad m =>
    (a -> m b) -> DataDefnCons a -> m (DataDefnCons b)
    forall (f :: * -> *) a b.
    Applicative f =>
    (a -> f b) -> DataDefnCons a -> f (DataDefnCons b)
    $ctraverse :: forall (f :: * -> *) a b.
    Applicative f =>
    (a -> f b) -> DataDefnCons a -> f (DataDefnCons b)
    traverse :: forall (f :: * -> *) a b.
    Applicative f =>
    (a -> f b) -> DataDefnCons a -> f (DataDefnCons b)
    $csequenceA :: forall (f :: * -> *) a.
    Applicative f =>
    DataDefnCons (f a) -> f (DataDefnCons a)
    sequenceA :: forall (f :: * -> *) a.
    Applicative f =>
    DataDefnCons (f a) -> f (DataDefnCons a)
    $cmapM :: forall (m :: * -> *) a b.
    Monad m =>
    (a -> m b) -> DataDefnCons a -> m (DataDefnCons b)
    mapM :: forall (m :: * -> *) a b.
    Monad m =>
    (a -> m b) -> DataDefnCons a -> m (DataDefnCons b)
    $csequence :: forall (m :: * -> *) a.
    Monad m =>
    DataDefnCons (m a) -> m (DataDefnCons a)
    sequence :: forall (m :: * -> *) a.
    Monad m =>
    DataDefnCons (m a) -> m (DataDefnCons a)
    Traversable )                -- Needed because Demand derives Eq

    dataDefnConsNewOrData :: DataDefnCons a -> NewOrData
    dataDefnConsNewOrData :: forall a. DataDefnCons a -> NewOrData
    dataDefnConsNewOrData = \ case
        NewTypeCon a
    _ -> NewOrData
    NewType
        DataTypeCons Bool
    _ [a]
    _ -> NewOrData
    DataType

    -- | Are the constructors within a @type data@ declaration?
    -- See Note [Type data declarations] in GHC.Rename.Module.
    isTypeDataDefnCons :: DataDefnCons a -> Bool
    isTypeDataDefnCons :: forall a. DataDefnCons a -> Bool
    isTypeDataDefnCons (NewTypeCon a
    _) = Bool
    False
    isTypeDataDefnCons (DataTypeCons Bool
    is_type_data [a]
    _) = Bool
    is_type_data

    -- | Retrieve the first data constructor in a 'DataDefnCons' (if one exists).
    firstDataDefnCon :: DataDefnCons a -> Maybe a
    firstDataDefnCon :: forall a. DataDefnCons a -> Maybe a
    firstDataDefnCon (NewTypeCon a
    con) = a -> Maybe a
    forall a. a -> Maybe a
    Just a
    con
    firstDataDefnCon (DataTypeCons Bool
    _ [a]
    cons) = [a] -> Maybe a
    forall a. [a] -> Maybe a
    listToMaybe [a]
    cons

    -- | Located data Constructor Declaration
    type LConDecl pass = XRec pass (ConDecl pass)

    -- |
    --
    -- @
    -- data T b = forall a. Eq a => MkT a b
    --   MkT :: forall b a. Eq a => MkT a b
    --
    -- data T b where
    --      MkT1 :: Int -> T Int
    --
    -- data T = Int `MkT` Int
    --        | MkT2
    --
    -- data T a where
    --      Int `MkT` Int :: T Int
    -- @

    -- | data Constructor Declaration
    data ConDecl pass
      = ConDeclGADT
          { forall pass. ConDecl pass -> XConDeclGADT pass
    con_g_ext   :: XConDeclGADT pass
          , forall pass. ConDecl pass -> NonEmpty (LIdP pass)
    con_names   :: NonEmpty (LIdP pass)
          -- The following fields describe the type after the '::'
          -- See Note [GADT abstract syntax]
          , forall pass. ConDecl pass -> XRec pass (HsOuterSigTyVarBndrs pass)
    con_bndrs   :: XRec pass (HsOuterSigTyVarBndrs pass)
            -- ^ The outermost type variable binders, be they explicit or
            --   implicit.  The 'XRec' is used to anchor exact print
            --   annotations, AnnForall and AnnDot.
          , forall pass. ConDecl pass -> Maybe (LHsContext pass)
    con_mb_cxt  :: Maybe (LHsContext pass)   -- ^ User-written context (if any)
          , forall pass. ConDecl pass -> HsConDeclGADTDetails pass
    con_g_args  :: HsConDeclGADTDetails pass -- ^ Arguments; never infix
          , forall pass. ConDecl pass -> LHsType pass
    con_res_ty  :: LHsType pass              -- ^ Result type

          , forall pass. ConDecl pass -> Maybe (LHsDoc pass)
    con_doc     :: Maybe (LHsDoc pass) -- ^ A possible Haddock
                                                     -- comment.
          }

      | ConDeclH98
          { forall pass. ConDecl pass -> XConDeclH98 pass
    con_ext     :: XConDeclH98 pass
          , forall pass. ConDecl pass -> LIdP pass
    con_name    :: LIdP pass

          , forall pass. ConDecl pass -> Bool
    con_forall  :: Bool
                                  -- ^ True <=> explicit user-written forall
                                  --     e.g. data T a = forall b. MkT b (b->a)
                                  --     con_ex_tvs = {b}
                                  -- False => con_ex_tvs is empty
          , forall pass. ConDecl pass -> [LHsTyVarBndr Specificity pass]
    con_ex_tvs :: [LHsTyVarBndr Specificity pass] -- ^ Existentials only
          , con_mb_cxt :: Maybe (LHsContext pass)         -- ^ User-written context (if any)
          , forall pass. ConDecl pass -> HsConDeclH98Details pass
    con_args   :: HsConDeclH98Details pass        -- ^ Arguments; can be infix

          , con_doc    :: Maybe (LHsDoc pass) -- ^ A possible Haddock comment.
          }
      | XConDecl !(XXConDecl pass)

    {- Note [GADT abstract syntax]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    The types of both forms of GADT constructors are very structured, as they
    must consist of the quantified type variables (if provided), followed by the
    context (if provided), followed by the argument types (if provided), followed
    by the result type. (See "Wrinkle: No nested foralls or contexts" below for
    more discussion on the restrictions imposed here.) As a result, instead of
    storing the type of a GADT constructor as a single LHsType, we split it up
    into its constituent components for easier access.

    There are two broad ways to classify GADT constructors:

    * Record-syntax constructors. For example:

        data T a where
          K :: forall a. Ord a => { x :: [a], ... } -> T a

    * Prefix constructors, which do not use record syntax. For example:

        data T a where
          K :: forall a. Ord a => [a] -> ... -> T a

    This distinction is recorded in the `con_args :: HsConDetails pass`, which
    tracks if we're dealing with a RecCon or PrefixCon. It is easy to distinguish
    the two in the AST since record GADT constructors use HsRecTy. This distinction
    is made in GHC.Parser.PostProcess.mkGadtDecl.

    It is worth elaborating a bit more on the process of splitting the argument
    types of a GADT constructor, since there are some non-obvious details involved.
    While splitting the argument types of a record GADT constructor is easy (they
    are stored in an HsRecTy), splitting the arguments of a prefix GADT constructor
    is trickier. The basic idea is that we must split along the outermost function
    arrows ((->) and (%1 ->)) in the type, which GHC.Hs.Type.splitHsFunType
    accomplishes. But what about type operators? Consider:

      C :: a :*: b -> a :*: b -> a :+: b

    This could parse in many different ways depending on the precedences of each
    type operator. In particular, if (:*:) were to have lower precedence than (->),
    then it could very well parse like this:

      a :*: ((b -> a) :*: ((b -> a) :+: b)))

    This would give the false impression that the whole type is part of one large
    return type, with no arguments. Note that we do not fully resolve the exact
    precedences of each user-defined type operator until the renamer, so this a
    more difficult task for the parser.

    Fortunately, there is no risk of the above happening. GHC's parser gives
    special treatment to function arrows, and as a result, they are always parsed
    with a lower precedence than any other type operator. As a result, the type
    above is actually parsed like this:

      (a :*: b) -> ((a :*: b) -> (a :+: b))

    While we won't know the exact precedences of (:*:) and (:+:) until the renamer,
    all we are concerned about in the parser is identifying the overall shape of
    the argument and result types, which we can accomplish by piggybacking on the
    special treatment given to function arrows. In a future where function arrows
    aren't given special status in the parser, we will likely have to modify
    GHC.Parser.PostProcess.mkHsOpTyPV to preserve this trick.

    -----
    -- Wrinkle: No nested foralls or contexts
    -----

    GADT constructors provide some freedom to change the order of foralls in their
    types (see Note [DataCon user type variable binders] in GHC.Core.DataCon), but
    this freedom is still limited. GADTs still require that all quantification
    occurs "prenex". That is, any explicitly quantified type variables must occur
    at the front of the GADT type, followed by any contexts, followed by the body of
    the GADT type, in precisely that order. For instance:

      data T where
        MkT1 :: forall a b. (Eq a, Eq b) => a -> b -> T
          -- OK
        MkT2 :: forall a. Eq a => forall b. a -> b -> T
          -- Rejected, `forall b` is nested
        MkT3 :: forall a b. Eq a => Eq b => a -> b -> T
          -- Rejected, `Eq b` is nested
        MkT4 :: Int -> forall a. a -> T
          -- Rejected, `forall a` is nested
        MkT5 :: forall a. Int -> Eq a => a -> T
          -- Rejected, `Eq a` is nested
        MkT6 :: (forall a. a -> T)
          -- Rejected, `forall a` is nested due to the surrounding parentheses
        MkT7 :: (Eq a => a -> t)
          -- Rejected, `Eq a` is nested due to the surrounding parentheses

    For the full details, see the "Formal syntax for GADTs" section of the GHC
    User's Guide. GHC enforces that GADT constructors do not have nested `forall`s
    or contexts in two parts:

    1. GHC, in the process of splitting apart a GADT's type,
       extracts out the leading `forall` and context (if they are provided). To
       accomplish this splitting, the renamer uses the
       GHC.Hs.Type.splitLHsGADTPrefixTy function, which is careful not to remove
       parentheses surrounding the leading `forall` or context (as these
       parentheses can be syntactically significant). If the third result returned
       by splitLHsGADTPrefixTy contains any `forall`s or contexts, then they must
       be nested, so they will be rejected.

       Note that this step applies to both prefix and record GADTs alike, as they
       both have syntax which permits `forall`s and contexts. The difference is
       where this step happens:

       * For prefix GADTs, this happens in the renamer (in rnConDecl), as we cannot
         split until after the type operator fixities have been resolved.
       * For record GADTs, this happens in the parser (in mkGadtDecl).
    2. If the GADT type is prefix, the renamer (in the ConDeclGADTPrefixPs case of
       rnConDecl) will then check for nested `forall`s/contexts in the body of a
       prefix GADT type, after it has determined what all of the argument types are.
       This step is necessary to catch examples like MkT4 above, where the nested
       quantification occurs after a visible argument type.
    -}

    -- | The arguments in a Haskell98-style data constructor.
    type HsConDeclH98Details pass
       = HsConDetails Void (HsScaled pass (LBangType pass)) (XRec pass [LConDeclField pass])
    -- The Void argument to HsConDetails here is a reflection of the fact that
    -- type applications are not allowed in data constructor declarations.

    -- | The arguments in a GADT constructor. Unlike Haskell98-style constructors,
    -- GADT constructors cannot be declared with infix syntax. As a result, we do
    -- not use 'HsConDetails' here, as 'InfixCon' would be an unrepresentable
    -- state. (There is a notion of infix GADT constructors for the purposes of
    -- derived Show instances—see Note [Infix GADT constructors] in
    -- GHC.Tc.TyCl—but that is an orthogonal concern.)
    data HsConDeclGADTDetails pass
       = PrefixConGADT !(XPrefixConGADT pass) [HsScaled pass (LBangType pass)]
       | RecConGADT !(XRecConGADT pass) (XRec pass [LConDeclField pass])
       | XConDeclGADTDetails !(XXConDeclGADTDetails pass)

    type family XPrefixConGADT       p
    type family XRecConGADT          p
    type family XXConDeclGADTDetails p

    {-
    ************************************************************************
    *                                                                      *
                    Instance declarations
    *                                                                      *
    ************************************************************************

    Note [Type family instance declarations in HsSyn]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    The data type FamEqn represents one equation of a type family instance.
    Aside from the pass, it is also parameterised over another field, feqn_rhs.
    feqn_rhs is either an HsDataDefn (for data family instances) or an LHsType
    (for type family instances).

    Type family instances also include associated type family default equations.
    That is because a default for a type family looks like this:

      class C a where
        type family F a b :: Type
        type F c d = (c,d)   -- Default instance

    The default declaration is really just a `type instance` declaration, but one
    with particularly simple patterns: they must all be distinct type variables.
    That's because we will instantiate it (in an instance declaration for `C`) if
    we don't give an explicit instance for `F`. Note that the names of the
    variables don't need to match those of the class: it really is like a
    free-standing `type instance` declaration.
    -}

    ----------------- Type synonym family instances -------------

    -- | Located Type Family Instance Equation
    type LTyFamInstEqn pass = XRec pass (TyFamInstEqn pass)

    -- | HsFamEqnPats represents patterns on the left-hand side of a type instance,
    -- e.g. `type instance F @k (a :: k) = a` has patterns `@k` and `(a :: k)`.
    --
    -- HsFamEqnPats used to be called HsTyPats but it was renamed to avoid confusion
    -- with a different notion of type patterns, see #23657.
    type HsFamEqnPats pass = [LHsTypeArg pass]

    {- Note [Family instance declaration binders]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    The feqn_pats field of FamEqn (family instance equation) stores the LHS type
    (and kind) patterns. Any type (and kind) variables contained
    in these type patterns are bound in the feqn_bndrs field.
    Note that in particular:

    * The feqn_bndrs *include* any anonymous wildcards.  For example
         type instance F a _ = a
      The feqn_bndrs will be HsOuterImplicit {a, _}.  Remember that each separate
      wildcard '_' gets its own unique.  In this context wildcards behave just like
      an ordinary type variable, only anonymous.

    * The feqn_bndrs *include* type variables that are already in scope

       Eg   class C s t where
              type F t p :: *
            instance C w (a,b) where
              type F (a,b) x = x->a
       The feqn_bndrs of the F decl is HsOuterImplicit {a,b,x}, even though the
       F decl is nested inside the 'instance' decl.

       However after the renamer, the uniques will match up:
            instance C w7 (a8,b9) where
              type F (a8,b9) x10 = x10->a8
       so that we can compare the type pattern in the 'instance' decl and
       in the associated 'type' decl

    c.f. Note [TyVar binders for associated decls]
    -}

    -- | Type Family Instance Equation
    type TyFamInstEqn pass = FamEqn pass (LHsType pass)
                -- Here, the @pats@ are type patterns (with kind and type bndrs).
                -- See Note [Family instance declaration binders]

    -- | Type family default declarations.
    -- A convenient synonym for 'TyFamInstDecl'.
    -- See @Note [Type family instance declarations in HsSyn]@.
    type TyFamDefltDecl = TyFamInstDecl

    -- | Located type family default declarations.
    type LTyFamDefltDecl pass = XRec pass (TyFamDefltDecl pass)

    -- | Located Type Family Instance Declaration
    type LTyFamInstDecl pass = XRec pass (TyFamInstDecl pass)

    -- | Type Family Instance Declaration
    data TyFamInstDecl pass
      = TyFamInstDecl { forall pass. TyFamInstDecl pass -> XCTyFamInstDecl pass
    tfid_xtn :: XCTyFamInstDecl pass
                      , forall pass. TyFamInstDecl pass -> TyFamInstEqn pass
    tfid_eqn :: TyFamInstEqn pass }
      | XTyFamInstDecl !(XXTyFamInstDecl pass)

    ----------------- Data family instances -------------

    -- | Located Data Family Instance Declaration
    type LDataFamInstDecl pass = XRec pass (DataFamInstDecl pass)

    -- | Data Family Instance Declaration
    newtype DataFamInstDecl pass
      = DataFamInstDecl { forall pass. DataFamInstDecl pass -> FamEqn pass (HsDataDefn pass)
    dfid_eqn :: FamEqn pass (HsDataDefn pass) }

    ----------------- Family instances (common types) -------------

    -- | Family Equation
    --
    -- One equation in a type family instance declaration, data family instance
    -- declaration, or type family default.
    -- See Note [Type family instance declarations in HsSyn]
    -- See Note [Family instance declaration binders]
    data FamEqn pass rhs
      = FamEqn
           { forall pass rhs. FamEqn pass rhs -> XCFamEqn pass rhs
    feqn_ext    :: XCFamEqn pass rhs
           , forall pass rhs. FamEqn pass rhs -> LIdP pass
    feqn_tycon  :: LIdP pass
           , forall pass rhs. FamEqn pass rhs -> HsOuterFamEqnTyVarBndrs pass
    feqn_bndrs  :: HsOuterFamEqnTyVarBndrs pass -- ^ Optional quantified type vars
           , forall pass rhs. FamEqn pass rhs -> HsFamEqnPats pass
    feqn_pats   :: HsFamEqnPats pass
           , forall pass rhs. FamEqn pass rhs -> LexicalFixity
    feqn_fixity :: LexicalFixity -- ^ Fixity used in the declaration
           , forall pass rhs. FamEqn pass rhs -> rhs
    feqn_rhs    :: rhs
           }
      | XFamEqn !(XXFamEqn pass rhs)

    ----------------- Class instances -------------

    -- | Located Class Instance Declaration
    type LClsInstDecl pass = XRec pass (ClsInstDecl pass)

    -- | Class Instance Declaration
    data ClsInstDecl pass
      = ClsInstDecl
          { forall pass. ClsInstDecl pass -> XCClsInstDecl pass
    cid_ext     :: XCClsInstDecl pass
          , forall pass. ClsInstDecl pass -> LHsSigType pass
    cid_poly_ty :: LHsSigType pass    -- Context => Class Instance-type
                                              -- Using a polytype means that the renamer conveniently
                                              -- figures out the quantified type variables for us.
          , forall pass. ClsInstDecl pass -> LHsBinds pass
    cid_binds         :: LHsBinds pass       -- Class methods
          , forall pass. ClsInstDecl pass -> [LSig pass]
    cid_sigs          :: [LSig pass]         -- User-supplied pragmatic info
          , forall pass. ClsInstDecl pass -> [LTyFamInstDecl pass]
    cid_tyfam_insts   :: [LTyFamInstDecl pass]   -- Type family instances
          , forall pass. ClsInstDecl pass -> [LDataFamInstDecl pass]
    cid_datafam_insts :: [LDataFamInstDecl pass] -- Data family instances
          , forall pass. ClsInstDecl pass -> Maybe (XRec pass OverlapMode)
    cid_overlap_mode  :: Maybe (XRec pass OverlapMode)
          }
      | XClsInstDecl !(XXClsInstDecl pass)

    ----------------- Instances of all kinds -------------

    -- | Located Instance Declaration
    type LInstDecl pass = XRec pass (InstDecl pass)

    -- | Instance Declaration
    data InstDecl pass  -- Both class and family instances
      = ClsInstD
          { forall pass. InstDecl pass -> XClsInstD pass
    cid_d_ext :: XClsInstD pass
          , forall pass. InstDecl pass -> ClsInstDecl pass
    cid_inst  :: ClsInstDecl pass }
      | DataFamInstD              -- data family instance
          { forall pass. InstDecl pass -> XDataFamInstD pass
    dfid_ext  :: XDataFamInstD pass
          , forall pass. InstDecl pass -> DataFamInstDecl pass
    dfid_inst :: DataFamInstDecl pass }
      | TyFamInstD              -- type family instance
          { forall pass. InstDecl pass -> XTyFamInstD pass
    tfid_ext  :: XTyFamInstD pass
          , forall pass. InstDecl pass -> TyFamInstDecl pass
    tfid_inst :: TyFamInstDecl pass }
      | XInstDecl !(XXInstDecl pass)

    {-
    ************************************************************************
    *                                                                      *
    \subsection[DerivDecl]{A stand-alone instance deriving declaration}
    *                                                                      *
    ************************************************************************
    -}

    -- | Located stand-alone 'deriving instance' declaration
    type LDerivDecl pass = XRec pass (DerivDecl pass)

    -- | Stand-alone 'deriving instance' declaration
    data DerivDecl pass = DerivDecl
            { forall pass. DerivDecl pass -> XCDerivDecl pass
    deriv_ext          :: XCDerivDecl pass
            , forall pass. DerivDecl pass -> LHsSigWcType pass
    deriv_type         :: LHsSigWcType pass
              -- ^ The instance type to derive.
              --
              -- It uses an 'LHsSigWcType' because the context is allowed to be a
              -- single wildcard:
              --
              -- > deriving instance _ => Eq (Foo a)
              --
              -- Which signifies that the context should be inferred.

              -- See Note [Inferring the instance context] in GHC.Tc.Deriv.Infer.

            , forall pass. DerivDecl pass -> Maybe (LDerivStrategy pass)
    deriv_strategy     :: Maybe (LDerivStrategy pass)
            , forall pass. DerivDecl pass -> Maybe (XRec pass OverlapMode)
    deriv_overlap_mode :: Maybe (XRec pass OverlapMode)
            }
      | XDerivDecl !(XXDerivDecl pass)

    {-
    ************************************************************************
    *                                                                      *
                    Deriving strategies
    *                                                                      *
    ************************************************************************
    -}

    -- | A 'Located' 'DerivStrategy'.
    type LDerivStrategy pass = XRec pass (DerivStrategy pass)

    -- | Which technique the user explicitly requested when deriving an instance.
    data DerivStrategy pass
      -- See Note [Deriving strategies] in GHC.Tc.Deriv
      = StockStrategy (XStockStrategy pass)
                         -- ^ GHC's \"standard\" strategy, which is to implement a
                         --   custom instance for the data type. This only works
                         --   for certain types that GHC knows about (e.g., 'Eq',
                         --   'Show', 'Functor' when @-XDeriveFunctor@ is enabled,
                         --   etc.)
      | AnyclassStrategy (XAnyClassStrategy pass) -- ^ @-XDeriveAnyClass@
      | NewtypeStrategy  (XNewtypeStrategy pass)  -- ^ @-XGeneralizedNewtypeDeriving@
      | ViaStrategy (XViaStrategy pass)
                         -- ^ @-XDerivingVia@

    {-
    ************************************************************************
    *                                                                      *
    \subsection[DefaultDecl]{A @default@ declaration}
    *                                                                      *
    ************************************************************************
    -}

    -- | Located Default Declaration
    type LDefaultDecl pass = XRec pass (DefaultDecl pass)

    -- See Note [Named default declarations] in GHC.Tc.Gen.Default
    -- | Default Declaration
    data DefaultDecl pass
      = DefaultDecl
          { forall pass. DefaultDecl pass -> XCDefaultDecl pass
    defd_ext      :: XCDefaultDecl pass
          , forall pass. DefaultDecl pass -> Maybe (LIdP pass)
    defd_class    :: Maybe (LIdP pass)  -- Nothing in absence of NamedDefaults
          , forall pass. DefaultDecl pass -> [LHsType pass]
    defd_defaults :: [LHsType pass] }
      | XDefaultDecl !(XXDefaultDecl pass)

    {-
    ************************************************************************
    *                                                                      *
    \subsection{Foreign function interface declaration}
    *                                                                      *
    ************************************************************************
    -}

    -- foreign declarations are distinguished as to whether they define or use a
    -- Haskell name
    --
    --  * the Boolean value indicates whether the pre-standard deprecated syntax
    --   has been used

    -- | Located Foreign Declaration
    type LForeignDecl pass = XRec pass (ForeignDecl pass)

    -- | Foreign Declaration
    data ForeignDecl pass
      = ForeignImport
          { forall pass. ForeignDecl pass -> XForeignImport pass
    fd_i_ext  :: XForeignImport pass   -- Post typechecker, rep_ty ~ sig_ty
          , forall pass. ForeignDecl pass -> LIdP pass
    fd_name   :: LIdP pass             -- defines this name
          , forall pass. ForeignDecl pass -> LHsSigType pass
    fd_sig_ty :: LHsSigType pass       -- sig_ty
          , forall pass. ForeignDecl pass -> ForeignImport pass
    fd_fi     :: ForeignImport pass }

      | ForeignExport
          { forall pass. ForeignDecl pass -> XForeignExport pass
    fd_e_ext  :: XForeignExport pass   -- Post typechecker, rep_ty ~ sig_ty
          , fd_name   :: LIdP pass             -- uses this name
          , fd_sig_ty :: LHsSigType pass       -- sig_ty
          , forall pass. ForeignDecl pass -> ForeignExport pass
    fd_fe     :: ForeignExport pass }
      | XForeignDecl !(XXForeignDecl pass)

    {-
        In both ForeignImport and ForeignExport:
            sig_ty is the type given in the Haskell code
            rep_ty is the representation for this type, i.e. with newtypes
                   coerced away and type functions evaluated.
        Thus if the declaration is valid, then rep_ty will only use types
        such as Int and IO that we know how to make foreign calls with.
    -}

    -- Specification Of an imported external entity in dependence on the calling
    -- convention
    --
    data ForeignImport pass = -- import of a C entity
                              --
                              --  * the two strings specifying a header file or library
                              --   may be empty, which indicates the absence of a
                              --   header or object specification (both are not used
                              --   in the case of `CWrapper' and when `CFunction'
                              --   has a dynamic target)
                              --
                              --  * the calling convention is irrelevant for code
                              --   generation in the case of `CLabel', but is needed
                              --   for pretty printing
                              --
                              --  * `Safety' is irrelevant for `CLabel' and `CWrapper'
                              --
                              CImport  (XCImport pass)
                                       (XRec pass CCallConv) -- ccall
                                       (XRec pass Safety)  -- interruptible, safe or unsafe
                                       (Maybe Header)       -- name of C header
                                       CImportSpec          -- details of the C entity
                            | XForeignImport !(XXForeignImport pass)

    -- details of an external C entity
    --
    data CImportSpec = CLabel    CLabelString     -- import address of a C label
                     | CFunction CCallTarget      -- static or dynamic function
                     | CWrapper                   -- wrapper to expose closures
                                                  -- (former f.e.d.)
      deriving Typeable CImportSpec
    Typeable CImportSpec =>
    (forall (c :: * -> *).
     (forall d b. Data d => c (d -> b) -> d -> c b)
     -> (forall g. g -> c g) -> CImportSpec -> c CImportSpec)
    -> (forall (c :: * -> *).
        (forall b r. Data b => c (b -> r) -> c r)
        -> (forall r. r -> c r) -> Constr -> c CImportSpec)
    -> (CImportSpec -> Constr)
    -> (CImportSpec -> DataType)
    -> (forall (t :: * -> *) (c :: * -> *).
        Typeable t =>
        (forall d. Data d => c (t d)) -> Maybe (c CImportSpec))
    -> (forall (t :: * -> * -> *) (c :: * -> *).
        Typeable t =>
        (forall d e. (Data d, Data e) => c (t d e))
        -> Maybe (c CImportSpec))
    -> ((forall b. Data b => b -> b) -> CImportSpec -> CImportSpec)
    -> (forall r r'.
        (r -> r' -> r)
        -> r -> (forall d. Data d => d -> r') -> CImportSpec -> r)
    -> (forall r r'.
        (r' -> r -> r)
        -> r -> (forall d. Data d => d -> r') -> CImportSpec -> r)
    -> (forall u. (forall d. Data d => d -> u) -> CImportSpec -> [u])
    -> (forall u.
        Int -> (forall d. Data d => d -> u) -> CImportSpec -> u)
    -> (forall (m :: * -> *).
        Monad m =>
        (forall d. Data d => d -> m d) -> CImportSpec -> m CImportSpec)
    -> (forall (m :: * -> *).
        MonadPlus m =>
        (forall d. Data d => d -> m d) -> CImportSpec -> m CImportSpec)
    -> (forall (m :: * -> *).
        MonadPlus m =>
        (forall d. Data d => d -> m d) -> CImportSpec -> m CImportSpec)
    -> Data CImportSpec
    CImportSpec -> Constr
    CImportSpec -> DataType
    (forall b. Data b => b -> b) -> CImportSpec -> CImportSpec
    forall a.
    Typeable a =>
    (forall (c :: * -> *).
     (forall d b. Data d => c (d -> b) -> d -> c b)
     -> (forall g. g -> c g) -> a -> c a)
    -> (forall (c :: * -> *).
        (forall b r. Data b => c (b -> r) -> c r)
        -> (forall r. r -> c r) -> Constr -> c a)
    -> (a -> Constr)
    -> (a -> DataType)
    -> (forall (t :: * -> *) (c :: * -> *).
        Typeable t =>
        (forall d. Data d => c (t d)) -> Maybe (c a))
    -> (forall (t :: * -> * -> *) (c :: * -> *).
        Typeable t =>
        (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c a))
    -> ((forall b. Data b => b -> b) -> a -> a)
    -> (forall r r'.
        (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> a -> r)
    -> (forall r r'.
        (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> a -> r)
    -> (forall u. (forall d. Data d => d -> u) -> a -> [u])
    -> (forall u. Int -> (forall d. Data d => d -> u) -> a -> u)
    -> (forall (m :: * -> *).
        Monad m =>
        (forall d. Data d => d -> m d) -> a -> m a)
    -> (forall (m :: * -> *).
        MonadPlus m =>
        (forall d. Data d => d -> m d) -> a -> m a)
    -> (forall (m :: * -> *).
        MonadPlus m =>
        (forall d. Data d => d -> m d) -> a -> m a)
    -> Data a
    forall u. Int -> (forall d. Data d => d -> u) -> CImportSpec -> u
    forall u. (forall d. Data d => d -> u) -> CImportSpec -> [u]
    forall r r'.
    (r -> r' -> r)
    -> r -> (forall d. Data d => d -> r') -> CImportSpec -> r
    forall r r'.
    (r' -> r -> r)
    -> r -> (forall d. Data d => d -> r') -> CImportSpec -> r
    forall (m :: * -> *).
    Monad m =>
    (forall d. Data d => d -> m d) -> CImportSpec -> m CImportSpec
    forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d) -> CImportSpec -> m CImportSpec
    forall (c :: * -> *).
    (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c CImportSpec
    forall (c :: * -> *).
    (forall d b. Data d => c (d -> b) -> d -> c b)
    -> (forall g. g -> c g) -> CImportSpec -> c CImportSpec
    forall (t :: * -> *) (c :: * -> *).
    Typeable t =>
    (forall d. Data d => c (t d)) -> Maybe (c CImportSpec)
    forall (t :: * -> * -> *) (c :: * -> *).
    Typeable t =>
    (forall d e. (Data d, Data e) => c (t d e))
    -> Maybe (c CImportSpec)
    $cgfoldl :: forall (c :: * -> *).
    (forall d b. Data d => c (d -> b) -> d -> c b)
    -> (forall g. g -> c g) -> CImportSpec -> c CImportSpec
    gfoldl :: forall (c :: * -> *).
    (forall d b. Data d => c (d -> b) -> d -> c b)
    -> (forall g. g -> c g) -> CImportSpec -> c CImportSpec
    $cgunfold :: forall (c :: * -> *).
    (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c CImportSpec
    gunfold :: forall (c :: * -> *).
    (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c CImportSpec
    $ctoConstr :: CImportSpec -> Constr
    toConstr :: CImportSpec -> Constr
    $cdataTypeOf :: CImportSpec -> DataType
    dataTypeOf :: CImportSpec -> DataType
    $cdataCast1 :: forall (t :: * -> *) (c :: * -> *).
    Typeable t =>
    (forall d. Data d => c (t d)) -> Maybe (c CImportSpec)
    dataCast1 :: forall (t :: * -> *) (c :: * -> *).
    Typeable t =>
    (forall d. Data d => c (t d)) -> Maybe (c CImportSpec)
    $cdataCast2 :: forall (t :: * -> * -> *) (c :: * -> *).
    Typeable t =>
    (forall d e. (Data d, Data e) => c (t d e))
    -> Maybe (c CImportSpec)
    dataCast2 :: forall (t :: * -> * -> *) (c :: * -> *).
    Typeable t =>
    (forall d e. (Data d, Data e) => c (t d e))
    -> Maybe (c CImportSpec)
    $cgmapT :: (forall b. Data b => b -> b) -> CImportSpec -> CImportSpec
    gmapT :: (forall b. Data b => b -> b) -> CImportSpec -> CImportSpec
    $cgmapQl :: forall r r'.
    (r -> r' -> r)
    -> r -> (forall d. Data d => d -> r') -> CImportSpec -> r
    gmapQl :: forall r r'.
    (r -> r' -> r)
    -> r -> (forall d. Data d => d -> r') -> CImportSpec -> r
    $cgmapQr :: forall r r'.
    (r' -> r -> r)
    -> r -> (forall d. Data d => d -> r') -> CImportSpec -> r
    gmapQr :: forall r r'.
    (r' -> r -> r)
    -> r -> (forall d. Data d => d -> r') -> CImportSpec -> r
    $cgmapQ :: forall u. (forall d. Data d => d -> u) -> CImportSpec -> [u]
    gmapQ :: forall u. (forall d. Data d => d -> u) -> CImportSpec -> [u]
    $cgmapQi :: forall u. Int -> (forall d. Data d => d -> u) -> CImportSpec -> u
    gmapQi :: forall u. Int -> (forall d. Data d => d -> u) -> CImportSpec -> u
    $cgmapM :: forall (m :: * -> *).
    Monad m =>
    (forall d. Data d => d -> m d) -> CImportSpec -> m CImportSpec
    gmapM :: forall (m :: * -> *).
    Monad m =>
    (forall d. Data d => d -> m d) -> CImportSpec -> m CImportSpec
    $cgmapMp :: forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d) -> CImportSpec -> m CImportSpec
    gmapMp :: forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d) -> CImportSpec -> m CImportSpec
    $cgmapMo :: forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d) -> CImportSpec -> m CImportSpec
    gmapMo :: forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d) -> CImportSpec -> m CImportSpec
    Data

    -- specification of an externally exported entity in dependence on the calling
    -- convention
    --
    data ForeignExport pass = CExport  (XCExport pass) (XRec pass CExportSpec) -- contains the calling convention
                            | XForeignExport !(XXForeignExport pass)

    {-
    ************************************************************************
    *                                                                      *
    \subsection{Rewrite rules}
    *                                                                      *
    ************************************************************************
    -}

    -- | Located Rule Declarations
    type LRuleDecls pass = XRec pass (RuleDecls pass)

    -- | Rule Declarations
    data RuleDecls pass = HsRules { forall pass. RuleDecls pass -> XCRuleDecls pass
    rds_ext   :: XCRuleDecls pass
                                  , forall pass. RuleDecls pass -> [LRuleDecl pass]
    rds_rules :: [LRuleDecl pass] }
      | XRuleDecls !(XXRuleDecls pass)

    -- | Located Rule Declaration
    type LRuleDecl pass = XRec pass (RuleDecl pass)

    -- | Rule Declaration
    data RuleDecl pass
      = HsRule -- Source rule
           { forall pass. RuleDecl pass -> XHsRule pass
    rd_ext  :: XHsRule pass
               -- ^ After renamer, free-vars from the LHS and RHS
           , forall pass. RuleDecl pass -> XRec pass CLabelString
    rd_name :: XRec pass RuleName
               -- ^ Note [Pragma source text] in "GHC.Types.SourceText"
           , forall pass. RuleDecl pass -> Activation
    rd_act  :: Activation
           , forall pass.
    RuleDecl pass -> Maybe [LHsTyVarBndr () (NoGhcTc pass)]
    rd_tyvs :: Maybe [LHsTyVarBndr () (NoGhcTc pass)]
               -- ^ Forall'd type vars
           , forall pass. RuleDecl pass -> [LRuleBndr pass]
    rd_tmvs :: [LRuleBndr pass]
               -- ^ Forall'd term vars, before typechecking; after typechecking
               --    this includes all forall'd vars
           , forall pass. RuleDecl pass -> XRec pass (HsExpr pass)
    rd_lhs  :: XRec pass (HsExpr pass)
           , forall pass. RuleDecl pass -> XRec pass (HsExpr pass)
    rd_rhs  :: XRec pass (HsExpr pass)
           }
      | XRuleDecl !(XXRuleDecl pass)

    -- | Located Rule Binder
    type LRuleBndr pass = XRec pass (RuleBndr pass)

    -- | Rule Binder
    data RuleBndr pass
      = RuleBndr (XCRuleBndr pass)  (LIdP pass)
      | RuleBndrSig (XRuleBndrSig pass) (LIdP pass) (HsPatSigType pass)
      | XRuleBndr !(XXRuleBndr pass)

    collectRuleBndrSigTys :: [RuleBndr pass] -> [HsPatSigType pass]
    collectRuleBndrSigTys :: forall pass. [RuleBndr pass] -> [HsPatSigType pass]
    collectRuleBndrSigTys [RuleBndr pass]
    bndrs = [HsPatSigType pass
    ty | RuleBndrSig XRuleBndrSig pass
    _ LIdP pass
    _ HsPatSigType pass
    ty <- [RuleBndr pass]
    bndrs]

    {-
    ************************************************************************
    *                                                                      *
    \subsection[DocDecl]{Document comments}
    *                                                                      *
    ************************************************************************
    -}

    -- | Located Documentation comment Declaration
    type LDocDecl pass = XRec pass (DocDecl pass)

    -- | Documentation comment Declaration
    data DocDecl pass
      = DocCommentNext (LHsDoc pass)
      | DocCommentPrev (LHsDoc pass)
      | DocCommentNamed String (LHsDoc pass)
      | DocGroup Int (LHsDoc pass)

    deriving instance (Data pass, Data (IdP pass)) => Data (DocDecl pass)

    docDeclDoc :: DocDecl pass -> LHsDoc pass
    docDeclDoc :: forall pass. DocDecl pass -> LHsDoc pass
    docDeclDoc (DocCommentNext LHsDoc pass
    d) = LHsDoc pass
    d
    docDeclDoc (DocCommentPrev LHsDoc pass
    d) = LHsDoc pass
    d
    docDeclDoc (DocCommentNamed String
    _ LHsDoc pass
    d) = LHsDoc pass
    d
    docDeclDoc (DocGroup Int
    _ LHsDoc pass
    d) = LHsDoc pass
    d

    {-
    ************************************************************************
    *                                                                      *
    \subsection[DeprecDecl]{Deprecations}
    *                                                                      *
    ************************************************************************

    We use exported entities for things to deprecate.
    -}

    -- | Located Warning Declarations
    type LWarnDecls pass = XRec pass (WarnDecls pass)

    -- | Warning pragma Declarations
    data WarnDecls pass = Warnings { forall pass. WarnDecls pass -> XWarnings pass
    wd_ext      :: XWarnings pass
                                   , forall pass. WarnDecls pass -> [LWarnDecl pass]
    wd_warnings :: [LWarnDecl pass]
                                   }
      | XWarnDecls !(XXWarnDecls pass)

    -- | Located Warning pragma Declaration
    type LWarnDecl pass = XRec pass (WarnDecl pass)

    -- | Warning pragma Declaration
    data WarnDecl pass = Warning (XWarning pass) [LIdP pass] (WarningTxt pass)
                       | XWarnDecl !(XXWarnDecl pass)

    {-
    ************************************************************************
    *                                                                      *
    \subsection[AnnDecl]{Annotations}
    *                                                                      *
    ************************************************************************
    -}

    -- | Located Annotation Declaration
    type LAnnDecl pass = XRec pass (AnnDecl pass)

    -- | Annotation Declaration
    data AnnDecl pass = HsAnnotation
                          (XHsAnnotation pass)
                          (AnnProvenance pass) (XRec pass (HsExpr pass))
      | XAnnDecl !(XXAnnDecl pass)

    -- | Annotation Provenance
    data AnnProvenance pass = ValueAnnProvenance (LIdP pass)
                            | TypeAnnProvenance (LIdP pass)
                            | ModuleAnnProvenance
    -- deriving instance Functor     AnnProvenance
    -- deriving instance Foldable    AnnProvenance
    -- deriving instance Traversable AnnProvenance
    -- deriving instance (Data pass) => Data (AnnProvenance pass)

    annProvenanceName_maybe :: forall p. UnXRec p => AnnProvenance p -> Maybe (IdP p)
    annProvenanceName_maybe :: forall p. UnXRec p => AnnProvenance p -> Maybe (IdP p)
    annProvenanceName_maybe (ValueAnnProvenance (forall p a. UnXRec p => XRec p a -> a
    unXRec @p -> IdP p
    name)) = IdP p -> Maybe (IdP p)
    forall a. a -> Maybe a
    Just IdP p
    name
    annProvenanceName_maybe (TypeAnnProvenance (forall p a. UnXRec p => XRec p a -> a
    unXRec @p -> IdP p
    name))  = IdP p -> Maybe (IdP p)
    forall a. a -> Maybe a
    Just IdP p
    name
    annProvenanceName_maybe AnnProvenance p
    ModuleAnnProvenance                      = Maybe (IdP p)
    forall a. Maybe a
    Nothing

    {-
    ************************************************************************
    *                                                                      *
    \subsection[RoleAnnot]{Role annotations}
    *                                                                      *
    ************************************************************************
    -}

    -- | Located Role Annotation Declaration
    type LRoleAnnotDecl pass = XRec pass (RoleAnnotDecl pass)

    -- See #8185 for more info about why role annotations are
    -- top-level declarations
    -- | Role Annotation Declaration
    data RoleAnnotDecl pass
      = RoleAnnotDecl (XCRoleAnnotDecl pass)
                      (LIdP pass)              -- type constructor
                      [XRec pass (Maybe Role)] -- optional annotations
      | XRoleAnnotDecl !(XXRoleAnnotDecl pass)