GHC/Hs/Decls.hs

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

    {-# LANGUAGE DeriveDataTypeable, DeriveFunctor, DeriveFoldable,
                 DeriveTraversable #-}
    {-# LANGUAGE StandaloneDeriving #-}
    {-# LANGUAGE FlexibleContexts #-}
    {-# LANGUAGE FlexibleInstances #-}
    {-# LANGUAGE UndecidableInstances #-} -- Note [Pass sensitive types]
                                          -- in module GHC.Hs.PlaceHolder
    {-# LANGUAGE ConstraintKinds #-}
    {-# LANGUAGE TypeFamilies #-}

    -- | Abstract syntax of global declarations.
    --
    -- Definitions for: @SynDecl@ and @ConDecl@, @ClassDecl@,
    -- @InstDecl@, @DefaultDecl@ and @ForeignDecl@.
    module GHC.Hs.Decls (
      -- * Toplevel declarations
      HsDecl(..), LHsDecl, HsDataDefn(..), HsDeriving, LHsFunDep,
      HsDerivingClause(..), LHsDerivingClause, NewOrData(..), newOrDataToFlavour,
      StandaloneKindSig(..), LStandaloneKindSig, standaloneKindSigName,

      -- ** Class or type declarations
      TyClDecl(..), LTyClDecl, DataDeclRn(..),
      TyClGroup(..),
      tyClGroupTyClDecls, tyClGroupInstDecls, tyClGroupRoleDecls,
      tyClGroupKindSigs,
      isClassDecl, isDataDecl, isSynDecl, tcdName,
      isFamilyDecl, isTypeFamilyDecl, isDataFamilyDecl,
      isOpenTypeFamilyInfo, isClosedTypeFamilyInfo,
      tyFamInstDeclName, tyFamInstDeclLName,
      countTyClDecls, pprTyClDeclFlavour,
      tyClDeclLName, tyClDeclTyVars,
      hsDeclHasCusk, famResultKindSignature,
      FamilyDecl(..), LFamilyDecl,

      -- ** Instance declarations
      InstDecl(..), LInstDecl, FamilyInfo(..),
      TyFamInstDecl(..), LTyFamInstDecl, instDeclDataFamInsts,
      TyFamDefltDecl, LTyFamDefltDecl,
      DataFamInstDecl(..), LDataFamInstDecl,
      pprDataFamInstFlavour, pprTyFamInstDecl, pprHsFamInstLHS,
      FamInstEqn, LFamInstEqn, FamEqn(..),
      TyFamInstEqn, LTyFamInstEqn, HsTyPats,
      LClsInstDecl, ClsInstDecl(..),

      -- ** Standalone deriving declarations
      DerivDecl(..), LDerivDecl,
      -- ** Deriving strategies
      DerivStrategy(..), LDerivStrategy,
      derivStrategyName, foldDerivStrategy, mapDerivStrategy,
      -- ** @RULE@ declarations
      LRuleDecls,RuleDecls(..),RuleDecl(..),LRuleDecl,HsRuleRn(..),
      RuleBndr(..),LRuleBndr,
      collectRuleBndrSigTys,
      flattenRuleDecls, pprFullRuleName,
      -- ** @default@ declarations
      DefaultDecl(..), LDefaultDecl,
      -- ** Template haskell declaration splice
      SpliceExplicitFlag(..),
      SpliceDecl(..), LSpliceDecl,
      -- ** Foreign function interface declarations
      ForeignDecl(..), LForeignDecl, ForeignImport(..), ForeignExport(..),
      CImportSpec(..),
      -- ** Data-constructor declarations
      ConDecl(..), LConDecl,
      HsConDeclDetails, hsConDeclArgTys, hsConDeclTheta,
      getConNames, getConArgs,
      -- ** Document comments
      DocDecl(..), LDocDecl, docDeclDoc,
      -- ** Deprecations
      WarnDecl(..),  LWarnDecl,
      WarnDecls(..), LWarnDecls,
      -- ** Annotations
      AnnDecl(..), LAnnDecl,
      AnnProvenance(..), annProvenanceName_maybe,
      -- ** Role annotations
      RoleAnnotDecl(..), LRoleAnnotDecl, roleAnnotDeclName,
      -- ** Injective type families
      FamilyResultSig(..), LFamilyResultSig, InjectivityAnn(..), LInjectivityAnn,
      resultVariableName,

      -- * Grouping
      HsGroup(..),  emptyRdrGroup, emptyRnGroup, appendGroups, hsGroupInstDecls

        ) where

    -- friends:
    import GhcPrelude

    import {-# SOURCE #-} GHC.Hs.Expr( HsExpr, HsSplice, pprExpr,
                                       pprSpliceDecl )
            -- Because Expr imports Decls via HsBracket

    import GHC.Hs.Binds
    import GHC.Hs.Types
    import GHC.Hs.Doc
    import TyCon
    import BasicTypes
    import Coercion
    import ForeignCall
    import GHC.Hs.Extension
    import NameSet

    -- others:
    import Class
    import Outputable
    import Util
    import SrcLoc
    import Type

    import Bag
    import Maybes
    import Data.Data        hiding (TyCon,Fixity, Infix)

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

    type LHsDecl p = Located (HsDecl p)
            -- ^ When in a list this may have
            --
            --  - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnSemi'
            --

    -- For details on above see note [Api annotations] in ApiAnnotation

    -- | 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)  -- ^ Documentation comment declaration
      | RoleAnnotD (XRoleAnnotD p) (RoleAnnotDecl p) -- ^Role annotation declaration
      | XHsDecl    (XXHsDecl p)

    type instance XTyClD      (GhcPass _) = NoExtField
    type instance XInstD      (GhcPass _) = NoExtField
    type instance XDerivD     (GhcPass _) = NoExtField
    type instance XValD       (GhcPass _) = NoExtField
    type instance XSigD       (GhcPass _) = NoExtField
    type instance XKindSigD   (GhcPass _) = NoExtField
    type instance XDefD       (GhcPass _) = NoExtField
    type instance XForD       (GhcPass _) = NoExtField
    type instance XWarningD   (GhcPass _) = NoExtField
    type instance XAnnD       (GhcPass _) = NoExtField
    type instance XRuleD      (GhcPass _) = NoExtField
    type instance XSpliceD    (GhcPass _) = NoExtField
    type instance XDocD       (GhcPass _) = NoExtField
    type instance XRoleAnnotD (GhcPass _) = NoExtField
    type instance XXHsDecl    (GhcPass _) = NoExtCon

    -- NB: all top-level fixity decls are contained EITHER
    -- EITHER SigDs
    -- OR     in the ClassDecls in TyClDs
    --
    -- The former covers
    --      a) data constructors
    --      b) class methods (but they can be also done in the
    --              signatures of class decls)
    --      c) imported functions (that have an IfacSig)
    --      d) top level decls
    --
    -- The latter is for class methods only

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

            hs_derivds :: [LDerivDecl p],

            hs_fixds  :: [LFixitySig p],
                    -- Snaffled out of both top-level fixity signatures,
                    -- and those in class declarations

            hs_defds  :: [LDefaultDecl p],
            hs_fords  :: [LForeignDecl p],
            hs_warnds :: [LWarnDecls p],
            hs_annds  :: [LAnnDecl p],
            hs_ruleds :: [LRuleDecls p],

            hs_docs   :: [LDocDecl]
        }
      | XHsGroup (XXHsGroup p)

    type instance XCHsGroup (GhcPass _) = NoExtField
    type instance XXHsGroup (GhcPass _) = NoExtCon

    emptyGroup, emptyRdrGroup, emptyRnGroup :: HsGroup (GhcPass p)
    emptyRdrGroup = emptyGroup { hs_valds = emptyValBindsIn }
    emptyRnGroup  = emptyGroup { hs_valds = emptyValBindsOut }

    hsGroupInstDecls :: HsGroup id -> [LInstDecl id]
    hsGroupInstDecls = (=<<) group_instds . hs_tyclds

    emptyGroup = HsGroup { hs_ext = noExtField,
                           hs_tyclds = [],
                           hs_derivds = [],
                           hs_fixds = [], hs_defds = [], hs_annds = [],
                           hs_fords = [], hs_warnds = [], hs_ruleds = [],
                           hs_valds = error "emptyGroup hs_valds: Can't happen",
                           hs_splcds = [],
                           hs_docs = [] }

    appendGroups :: HsGroup (GhcPass p) -> HsGroup (GhcPass p)
                 -> HsGroup (GhcPass p)
    appendGroups
        HsGroup {
            hs_valds  = val_groups1,
            hs_splcds = spliceds1,
            hs_tyclds = tyclds1,
            hs_derivds = derivds1,
            hs_fixds  = fixds1,
            hs_defds  = defds1,
            hs_annds  = annds1,
            hs_fords  = fords1,
            hs_warnds = warnds1,
            hs_ruleds = rulds1,
            hs_docs   = docs1 }
        HsGroup {
            hs_valds  = val_groups2,
            hs_splcds = spliceds2,
            hs_tyclds = tyclds2,
            hs_derivds = derivds2,
            hs_fixds  = fixds2,
            hs_defds  = defds2,
            hs_annds  = annds2,
            hs_fords  = fords2,
            hs_warnds = warnds2,
            hs_ruleds = rulds2,
            hs_docs   = docs2 }
      =
        HsGroup {
            hs_ext    = noExtField,
            hs_valds  = val_groups1 `plusHsValBinds` val_groups2,
            hs_splcds = spliceds1 ++ spliceds2,
            hs_tyclds = tyclds1 ++ tyclds2,
            hs_derivds = derivds1 ++ derivds2,
            hs_fixds  = fixds1 ++ fixds2,
            hs_annds  = annds1 ++ annds2,
            hs_defds  = defds1 ++ defds2,
            hs_fords  = fords1 ++ fords2,
            hs_warnds = warnds1 ++ warnds2,
            hs_ruleds = rulds1 ++ rulds2,
            hs_docs   = docs1  ++ docs2 }
    appendGroups _ _ = panic "appendGroups"

    instance (OutputableBndrId p) => Outputable (HsDecl (GhcPass p)) where
        ppr (TyClD _ dcl)             = ppr dcl
        ppr (ValD _ binds)            = ppr binds
        ppr (DefD _ def)              = ppr def
        ppr (InstD _ inst)            = ppr inst
        ppr (DerivD _ deriv)          = ppr deriv
        ppr (ForD _ fd)               = ppr fd
        ppr (SigD _ sd)               = ppr sd
        ppr (KindSigD _ ksd)          = ppr ksd
        ppr (RuleD _ rd)              = ppr rd
        ppr (WarningD _ wd)           = ppr wd
        ppr (AnnD _ ad)               = ppr ad
        ppr (SpliceD _ dd)            = ppr dd
        ppr (DocD _ doc)              = ppr doc
        ppr (RoleAnnotD _ ra)         = ppr ra
        ppr (XHsDecl x)               = ppr x

    instance (OutputableBndrId p) => Outputable (HsGroup (GhcPass p)) where
        ppr (HsGroup { hs_valds  = val_decls,
                       hs_tyclds = tycl_decls,
                       hs_derivds = deriv_decls,
                       hs_fixds  = fix_decls,
                       hs_warnds = deprec_decls,
                       hs_annds  = ann_decls,
                       hs_fords  = foreign_decls,
                       hs_defds  = default_decls,
                       hs_ruleds = rule_decls })
            = vcat_mb empty
                [ppr_ds fix_decls, ppr_ds default_decls,
                 ppr_ds deprec_decls, ppr_ds ann_decls,
                 ppr_ds rule_decls,
                 if isEmptyValBinds val_decls
                    then Nothing
                    else Just (ppr val_decls),
                 ppr_ds (tyClGroupRoleDecls tycl_decls),
                 ppr_ds (tyClGroupKindSigs  tycl_decls),
                 ppr_ds (tyClGroupTyClDecls tycl_decls),
                 ppr_ds (tyClGroupInstDecls tycl_decls),
                 ppr_ds deriv_decls,
                 ppr_ds foreign_decls]
            where
              ppr_ds :: Outputable a => [a] -> Maybe SDoc
              ppr_ds [] = Nothing
              ppr_ds ds = Just (vcat (map ppr ds))

              vcat_mb :: SDoc -> [Maybe SDoc] -> SDoc
              -- Concatenate vertically with white-space between non-blanks
              vcat_mb _    []             = empty
              vcat_mb gap (Nothing : ds) = vcat_mb gap ds
              vcat_mb gap (Just d  : ds) = gap $$ d $$ vcat_mb blankLine ds
        ppr (XHsGroup x) = ppr x

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

    -- | Splice Declaration
    data SpliceDecl p
      = SpliceDecl                  -- Top level splice
            (XSpliceDecl p)
            (Located (HsSplice p))
            SpliceExplicitFlag
      | XSpliceDecl (XXSpliceDecl p)

    type instance XSpliceDecl      (GhcPass _) = NoExtField
    type instance XXSpliceDecl     (GhcPass _) = NoExtCon

    instance OutputableBndrId p
           => Outputable (SpliceDecl (GhcPass p)) where
       ppr (SpliceDecl _ (L _ e) f) = pprSpliceDecl e f
       ppr (XSpliceDecl x) = ppr x

    {-
    ************************************************************************
    *                                                                      *
                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 (RnEnv.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 OccName.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 Class.hs)

    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 RdrHsSyn.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
    TcInstDcls.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 = Located (TyClDecl pass)

    -- | A type or class declaration.
    data TyClDecl pass
      = -- | @type/data family T :: *->*@
        --
        --  - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnType',
        --             'ApiAnnotation.AnnData',
        --             'ApiAnnotation.AnnFamily','ApiAnnotation.AnnDcolon',
        --             'ApiAnnotation.AnnWhere','ApiAnnotation.AnnOpenP',
        --             'ApiAnnotation.AnnDcolon','ApiAnnotation.AnnCloseP',
        --             'ApiAnnotation.AnnEqual','ApiAnnotation.AnnRarrow',
        --             'ApiAnnotation.AnnVbar'

        -- For details on above see note [Api annotations] in ApiAnnotation
        FamDecl { tcdFExt :: XFamDecl pass, tcdFam :: FamilyDecl pass }

      | -- | @type@ declaration
        --
        --  - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnType',
        --             'ApiAnnotation.AnnEqual',

        -- For details on above see note [Api annotations] in ApiAnnotation
        SynDecl { tcdSExt   :: XSynDecl pass          -- ^ Post renameer, FVs
                , tcdLName  :: Located (IdP pass)     -- ^ Type constructor
                , tcdTyVars :: LHsQTyVars pass        -- ^ Type variables; for an
                                                      -- associated type these
                                                      -- include outer binders
                , tcdFixity :: LexicalFixity    -- ^ Fixity used in the declaration
                , tcdRhs    :: LHsType pass }         -- ^ RHS of type declaration

      | -- | @data@ declaration
        --
        --  - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnData',
        --              'ApiAnnotation.AnnFamily',
        --              'ApiAnnotation.AnnNewType',
        --              'ApiAnnotation.AnnNewType','ApiAnnotation.AnnDcolon'
        --              'ApiAnnotation.AnnWhere',

        -- For details on above see note [Api annotations] in ApiAnnotation
        DataDecl { tcdDExt     :: XDataDecl pass       -- ^ Post renamer, CUSK flag, FVs
                 , tcdLName    :: Located (IdP pass)   -- ^ Type constructor
                 , tcdTyVars   :: LHsQTyVars pass      -- ^ Type variables
                                  -- See Note [TyVar binders for associated declarations]
                 , tcdFixity   :: LexicalFixity        -- ^ Fixity used in the declaration
                 , tcdDataDefn :: HsDataDefn pass }

      | ClassDecl { tcdCExt    :: XClassDecl pass,         -- ^ Post renamer, FVs
                    tcdCtxt    :: LHsContext pass,         -- ^ Context...
                    tcdLName   :: Located (IdP pass),      -- ^ Name of the class
                    tcdTyVars  :: LHsQTyVars pass,         -- ^ Class type variables
                    tcdFixity  :: LexicalFixity, -- ^ Fixity used in the declaration
                    tcdFDs     :: [LHsFunDep pass],         -- ^ Functional deps
                    tcdSigs    :: [LSig pass],              -- ^ Methods' signatures
                    tcdMeths   :: LHsBinds pass,            -- ^ Default methods
                    tcdATs     :: [LFamilyDecl pass],       -- ^ Associated types;
                    tcdATDefs  :: [LTyFamDefltDecl pass],   -- ^ Associated type defaults
                    tcdDocs    :: [LDocDecl]                -- ^ Haddock docs
        }
            -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnClass',
            --           'ApiAnnotation.AnnWhere','ApiAnnotation.AnnOpen',
            --           'ApiAnnotation.AnnClose'
            --   - The tcdFDs will have 'ApiAnnotation.AnnVbar',
            --                          'ApiAnnotation.AnnComma'
            --                          'ApiAnnotation.AnnRarrow'

            -- For details on above see note [Api annotations] in ApiAnnotation
      | XTyClDecl (XXTyClDecl pass)

    type LHsFunDep pass = Located (FunDep (Located (IdP pass)))

    data DataDeclRn = DataDeclRn
                 { tcdDataCusk :: Bool    -- ^ does this have a CUSK?
                     -- See Note [CUSKs: complete user-supplied kind signatures]
                 , tcdFVs      :: NameSet }
      deriving Data

    {- 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 Class.hs
         Note [Family instance declaration binders]
    -}

    type instance XFamDecl      (GhcPass _) = NoExtField

    type instance XSynDecl      GhcPs = NoExtField
    type instance XSynDecl      GhcRn = NameSet -- FVs
    type instance XSynDecl      GhcTc = NameSet -- FVs

    type instance XDataDecl     GhcPs = NoExtField
    type instance XDataDecl     GhcRn = DataDeclRn
    type instance XDataDecl     GhcTc = DataDeclRn

    type instance XClassDecl    GhcPs = NoExtField
    type instance XClassDecl    GhcRn = NameSet -- FVs
    type instance XClassDecl    GhcTc = NameSet -- FVs

    type instance XXTyClDecl    (GhcPass _) = NoExtCon

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

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

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

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

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

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

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

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

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

    -- Dealing with names

    tyFamInstDeclName :: TyFamInstDecl (GhcPass p) -> IdP (GhcPass p)
    tyFamInstDeclName = unLoc . tyFamInstDeclLName

    tyFamInstDeclLName :: TyFamInstDecl (GhcPass p) -> Located (IdP (GhcPass p))
    tyFamInstDeclLName (TyFamInstDecl { tfid_eqn =
                         (HsIB { hsib_body = FamEqn { feqn_tycon = ln }}) })
      = ln
    tyFamInstDeclLName (TyFamInstDecl (HsIB _ (XFamEqn nec)))
      = noExtCon nec
    tyFamInstDeclLName (TyFamInstDecl (XHsImplicitBndrs nec))
      = noExtCon nec

    tyClDeclLName :: TyClDecl pass -> Located (IdP pass)
    tyClDeclLName (FamDecl { tcdFam = FamilyDecl { fdLName = ln } }) = ln
    tyClDeclLName decl = tcdLName decl

    tcdName :: TyClDecl pass -> IdP pass
    tcdName = unLoc . tyClDeclLName

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

    countTyClDecls :: [TyClDecl pass] -> (Int, Int, Int, Int, Int)
            -- class, synonym decls, data, newtype, family decls
    countTyClDecls decls
     = (count isClassDecl    decls,
        count isSynDecl      decls,  -- excluding...
        count isDataTy       decls,  -- ...family...
        count isNewTy        decls,  -- ...instances
        count isFamilyDecl   decls)
     where
       isDataTy DataDecl{ tcdDataDefn = HsDataDefn { dd_ND = DataType } } = True
       isDataTy _                                                       = False

       isNewTy DataDecl{ tcdDataDefn = HsDataDefn { dd_ND = NewType } } = True
       isNewTy _                                                      = False

    -- | Does this declaration have a complete, user-supplied kind signature?
    -- See Note [CUSKs: complete user-supplied kind signatures]
    hsDeclHasCusk :: TyClDecl GhcRn -> Bool
    hsDeclHasCusk (FamDecl { tcdFam =
        FamilyDecl { fdInfo      = fam_info
                   , fdTyVars    = tyvars
                   , fdResultSig = L _ resultSig } }) =
        case fam_info of
          ClosedTypeFamily {} -> hsTvbAllKinded tyvars
                              && isJust (famResultKindSignature resultSig)
          _ -> True -- Un-associated open type/data families have CUSKs
    hsDeclHasCusk (SynDecl { tcdTyVars = tyvars, tcdRhs = rhs })
      = hsTvbAllKinded tyvars && isJust (hsTyKindSig rhs)
    hsDeclHasCusk (DataDecl { tcdDExt = DataDeclRn { tcdDataCusk = cusk }}) = cusk
    hsDeclHasCusk (ClassDecl { tcdTyVars = tyvars }) = hsTvbAllKinded tyvars
    hsDeclHasCusk (FamDecl { tcdFam = XFamilyDecl nec }) = noExtCon nec
    hsDeclHasCusk (XTyClDecl nec) = noExtCon nec

    -- Pretty-printing TyClDecl
    -- ~~~~~~~~~~~~~~~~~~~~~~~~

    instance (OutputableBndrId p) => Outputable (TyClDecl (GhcPass p)) where

        ppr (FamDecl { tcdFam = decl }) = ppr decl
        ppr (SynDecl { tcdLName = ltycon, tcdTyVars = tyvars, tcdFixity = fixity
                     , tcdRhs = rhs })
          = hang (text "type" <+>
                  pp_vanilla_decl_head ltycon tyvars fixity noLHsContext <+> equals)
              4 (ppr rhs)

        ppr (DataDecl { tcdLName = ltycon, tcdTyVars = tyvars, tcdFixity = fixity
                      , tcdDataDefn = defn })
          = pp_data_defn (pp_vanilla_decl_head ltycon tyvars fixity) defn

        ppr (ClassDecl {tcdCtxt = context, tcdLName = lclas, tcdTyVars = tyvars,
                        tcdFixity = fixity,
                        tcdFDs  = fds,
                        tcdSigs = sigs, tcdMeths = methods,
                        tcdATs = ats, tcdATDefs = at_defs})
          | null sigs && isEmptyBag methods && null ats && null at_defs -- No "where" part
          = top_matter

          | otherwise       -- Laid out
          = vcat [ top_matter <+> text "where"
                 , nest 2 $ pprDeclList (map (pprFamilyDecl NotTopLevel . unLoc) ats ++
                                         map (pprTyFamDefltDecl . unLoc) at_defs ++
                                         pprLHsBindsForUser methods sigs) ]
          where
            top_matter = text "class"
                        <+> pp_vanilla_decl_head lclas tyvars fixity context
                        <+> pprFundeps (map unLoc fds)

        ppr (XTyClDecl x) = ppr x

    instance OutputableBndrId p
           => Outputable (TyClGroup (GhcPass p)) where
      ppr (TyClGroup { group_tyclds = tyclds
                     , group_roles = roles
                     , group_kisigs = kisigs
                     , group_instds = instds
                     }
          )
        = hang (text "TyClGroup") 2 $
          ppr kisigs $$
          ppr tyclds $$
          ppr roles $$
          ppr instds
      ppr (XTyClGroup x) = ppr x

    pp_vanilla_decl_head :: (OutputableBndrId p)
       => Located (IdP (GhcPass p))
       -> LHsQTyVars (GhcPass p)
       -> LexicalFixity
       -> LHsContext (GhcPass p)
       -> SDoc
    pp_vanilla_decl_head thing (HsQTvs { hsq_explicit = tyvars }) fixity context
     = hsep [pprLHsContext context, pp_tyvars tyvars]
      where
        pp_tyvars (varl:varsr)
          | fixity == Infix && length varsr > 1
             = hsep [char '(',ppr (unLoc varl), pprInfixOcc (unLoc thing)
                    , (ppr.unLoc) (head varsr), char ')'
                    , hsep (map (ppr.unLoc) (tail varsr))]
          | fixity == Infix
             = hsep [ppr (unLoc varl), pprInfixOcc (unLoc thing)
             , hsep (map (ppr.unLoc) varsr)]
          | otherwise = hsep [ pprPrefixOcc (unLoc thing)
                      , hsep (map (ppr.unLoc) (varl:varsr))]
        pp_tyvars [] = pprPrefixOcc (unLoc thing)
    pp_vanilla_decl_head _ (XLHsQTyVars x) _ _ = ppr x

    pprTyClDeclFlavour :: TyClDecl (GhcPass p) -> SDoc
    pprTyClDeclFlavour (ClassDecl {})   = text "class"
    pprTyClDeclFlavour (SynDecl {})     = text "type"
    pprTyClDeclFlavour (FamDecl { tcdFam = FamilyDecl { fdInfo = info }})
      = pprFlavour info <+> text "family"
    pprTyClDeclFlavour (FamDecl { tcdFam = XFamilyDecl nec })
      = noExtCon nec
    pprTyClDeclFlavour (DataDecl { tcdDataDefn = HsDataDefn { dd_ND = nd } })
      = ppr nd
    pprTyClDeclFlavour (DataDecl { tcdDataDefn = XHsDataDefn x })
      = ppr x
    pprTyClDeclFlavour (XTyClDecl x) = ppr x

    {- 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 on by default.
    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; equivalant 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 do 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 whethher 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 analsis of type, class, and instance decls]
    in RnSource for more info.
    -}

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

    type instance XCTyClGroup (GhcPass _) = NoExtField
    type instance XXTyClGroup (GhcPass _) = NoExtCon

    tyClGroupTyClDecls :: [TyClGroup pass] -> [LTyClDecl pass]
    tyClGroupTyClDecls = concatMap group_tyclds

    tyClGroupInstDecls :: [TyClGroup pass] -> [LInstDecl pass]
    tyClGroupInstDecls = concatMap group_instds

    tyClGroupRoleDecls :: [TyClGroup pass] -> [LRoleAnnotDecl pass]
    tyClGroupRoleDecls = concatMap group_roles

    tyClGroupKindSigs :: [TyClGroup pass] -> [LStandaloneKindSig pass]
    tyClGroupKindSigs = concatMap 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 TyCon
    -}

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

    -- | type Family Result Signature
    data FamilyResultSig pass = -- see Note [FamilyResultSig]
        NoSig (XNoSig pass)
      -- ^ - 'ApiAnnotation.AnnKeywordId' :

      -- For details on above see note [Api annotations] in ApiAnnotation

      | KindSig  (XCKindSig pass) (LHsKind pass)
      -- ^ - 'ApiAnnotation.AnnKeywordId' :
      --             'ApiAnnotation.AnnOpenP','ApiAnnotation.AnnDcolon',
      --             'ApiAnnotation.AnnCloseP'

      -- For details on above see note [Api annotations] in ApiAnnotation

      | TyVarSig (XTyVarSig pass) (LHsTyVarBndr pass)
      -- ^ - 'ApiAnnotation.AnnKeywordId' :
      --             'ApiAnnotation.AnnOpenP','ApiAnnotation.AnnDcolon',
      --             'ApiAnnotation.AnnCloseP', 'ApiAnnotation.AnnEqual'
      | XFamilyResultSig (XXFamilyResultSig pass)

      -- For details on above see note [Api annotations] in ApiAnnotation

    type instance XNoSig            (GhcPass _) = NoExtField
    type instance XCKindSig         (GhcPass _) = NoExtField

    type instance XTyVarSig         (GhcPass _) = NoExtField
    type instance XXFamilyResultSig (GhcPass _) = NoExtCon

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

    -- | type Family Declaration
    data FamilyDecl pass = FamilyDecl
      { fdExt            :: XCFamilyDecl pass
      , fdInfo           :: FamilyInfo pass              -- type/data, closed/open
      , fdLName          :: Located (IdP pass)           -- type constructor
      , fdTyVars         :: LHsQTyVars pass              -- type variables
                           -- See Note [TyVar binders for associated declarations]
      , fdFixity         :: LexicalFixity                -- Fixity used in the declaration
      , fdResultSig      :: LFamilyResultSig pass        -- result signature
      , fdInjectivityAnn :: Maybe (LInjectivityAnn pass) -- optional injectivity ann
      }
      | XFamilyDecl (XXFamilyDecl pass)
      -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnType',
      --             'ApiAnnotation.AnnData', 'ApiAnnotation.AnnFamily',
      --             'ApiAnnotation.AnnWhere', 'ApiAnnotation.AnnOpenP',
      --             'ApiAnnotation.AnnDcolon', 'ApiAnnotation.AnnCloseP',
      --             'ApiAnnotation.AnnEqual', 'ApiAnnotation.AnnRarrow',
      --             'ApiAnnotation.AnnVbar'

      -- For details on above see note [Api annotations] in ApiAnnotation

    type instance XCFamilyDecl    (GhcPass _) = NoExtField
    type instance XXFamilyDecl    (GhcPass _) = NoExtCon

    -- | Located Injectivity Annotation
    type LInjectivityAnn pass = Located (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 (Located (IdP pass)) [Located (IdP pass)]
      -- ^ - 'ApiAnnotation.AnnKeywordId' :
      --             'ApiAnnotation.AnnRarrow', 'ApiAnnotation.AnnVbar'

      -- For details on above see note [Api annotations] in ApiAnnotation

    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])

    famResultKindSignature :: FamilyResultSig (GhcPass p) -> Maybe (LHsKind (GhcPass p))
    famResultKindSignature (NoSig _) = Nothing
    famResultKindSignature (KindSig _ ki) = Just ki
    famResultKindSignature (TyVarSig _ bndr) =
      case unLoc bndr of
        UserTyVar _ _ -> Nothing
        KindedTyVar _ _ ki -> Just ki
        XTyVarBndr nec -> noExtCon nec
    famResultKindSignature (XFamilyResultSig nec) = noExtCon nec

    -- | Maybe return name of the result type variable
    resultVariableName :: FamilyResultSig (GhcPass a) -> Maybe (IdP (GhcPass a))
    resultVariableName (TyVarSig _ sig) = Just $ hsLTyVarName sig
    resultVariableName _                = Nothing

    instance OutputableBndrId p
           => Outputable (FamilyDecl (GhcPass p)) where
      ppr = pprFamilyDecl TopLevel

    pprFamilyDecl :: (OutputableBndrId p)
                  => TopLevelFlag -> FamilyDecl (GhcPass p) -> SDoc
    pprFamilyDecl top_level (FamilyDecl { fdInfo = info, fdLName = ltycon
                                        , fdTyVars = tyvars
                                        , fdFixity = fixity
                                        , fdResultSig = L _ result
                                        , fdInjectivityAnn = mb_inj })
      = vcat [ pprFlavour info <+> pp_top_level <+>
               pp_vanilla_decl_head ltycon tyvars fixity noLHsContext <+>
               pp_kind <+> pp_inj <+> pp_where
             , nest 2 $ pp_eqns ]
      where
        pp_top_level = case top_level of
                         TopLevel    -> text "family"
                         NotTopLevel -> empty

        pp_kind = case result of
                    NoSig    _         -> empty
                    KindSig  _ kind    -> dcolon <+> ppr kind
                    TyVarSig _ tv_bndr -> text "=" <+> ppr tv_bndr
                    XFamilyResultSig nec -> noExtCon nec
        pp_inj = case mb_inj of
                   Just (L _ (InjectivityAnn lhs rhs)) ->
                     hsep [ vbar, ppr lhs, text "->", hsep (map ppr rhs) ]
                   Nothing -> empty
        (pp_where, pp_eqns) = case info of
          ClosedTypeFamily mb_eqns ->
            ( text "where"
            , case mb_eqns of
                Nothing   -> text ".."
                Just eqns -> vcat $ map (ppr_fam_inst_eqn . unLoc) eqns )
          _ -> (empty, empty)
    pprFamilyDecl _ (XFamilyDecl nec) = noExtCon nec

    pprFlavour :: FamilyInfo pass -> SDoc
    pprFlavour DataFamily            = text "data"
    pprFlavour OpenTypeFamily        = text "type"
    pprFlavour (ClosedTypeFamily {}) = text "type"

    instance Outputable (FamilyInfo pass) where
      ppr info = pprFlavour info <+> text "family"

    {- *********************************************************************
    *                                                                      *
                   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 { dd_ext    :: XCHsDataDefn pass,
                     dd_ND     :: NewOrData,
                     dd_ctxt   :: LHsContext pass,           -- ^ Context
                     dd_cType  :: Maybe (Located CType),
                     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

                     dd_cons   :: [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'.

                     dd_derivs :: HsDeriving pass  -- ^ Optional 'deriving' claues

                 -- For details on above see note [Api annotations] in ApiAnnotation
       }
      | XHsDataDefn (XXHsDataDefn pass)

    type instance XCHsDataDefn    (GhcPass _) = NoExtField

    type instance XXHsDataDefn    (GhcPass _) = NoExtCon

    -- | Haskell Deriving clause
    type HsDeriving pass = Located [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 = Located (HsDerivingClause pass)

    -- | A single @deriving@ clause of a data declaration.
    --
    --  - 'ApiAnnotation.AnnKeywordId' :
    --       'ApiAnnotation.AnnDeriving', 'ApiAnnotation.AnnStock',
    --       'ApiAnnotation.AnnAnyClass', 'Api.AnnNewtype',
    --       'ApiAnnotation.AnnOpen','ApiAnnotation.AnnClose'
    data HsDerivingClause pass
      -- See Note [Deriving strategies] in TcDeriv
      = HsDerivingClause
        { deriv_clause_ext :: XCHsDerivingClause pass
        , deriv_clause_strategy :: Maybe (LDerivStrategy pass)
          -- ^ The user-specified strategy (if any) to use when deriving
          -- 'deriv_clause_tys'.
        , deriv_clause_tys :: Located [LHsSigType pass]
          -- ^ The types to derive.
          --
          -- It uses 'LHsSigType's because, with @-XGeneralizedNewtypeDeriving@,
          -- we 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)@.
        }
      | XHsDerivingClause (XXHsDerivingClause pass)

    type instance XCHsDerivingClause    (GhcPass _) = NoExtField
    type instance XXHsDerivingClause    (GhcPass _) = NoExtCon

    instance OutputableBndrId p
           => Outputable (HsDerivingClause (GhcPass p)) where
      ppr (HsDerivingClause { deriv_clause_strategy = dcs
                            , deriv_clause_tys      = L _ dct })
        = hsep [ text "deriving"
               , pp_strat_before
               , pp_dct dct
               , pp_strat_after ]
          where
            -- This complexity is to distinguish between
            --    deriving Show
            --    deriving (Show)
            pp_dct [HsIB { hsib_body = ty }]
                     = ppr (parenthesizeHsType appPrec ty)
            pp_dct _ = parens (interpp'SP dct)

            -- @via@ is unique in that in comes /after/ the class being derived,
            -- so we must special-case it.
            (pp_strat_before, pp_strat_after) =
              case dcs of
                Just (L _ via@ViaStrategy{}) -> (empty, ppr via)
                _                            -> (ppDerivStrategy dcs, empty)
      ppr (XHsDerivingClause x) = ppr x

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

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

    type instance XStandaloneKindSig (GhcPass p) = NoExtField
    type instance XXStandaloneKindSig (GhcPass p) = NoExtCon

    standaloneKindSigName :: StandaloneKindSig (GhcPass p) -> IdP (GhcPass p)
    standaloneKindSigName (StandaloneKindSig _ lname _) = unLoc lname
    standaloneKindSigName (XStandaloneKindSig nec) = noExtCon nec

    {- 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.
    -}

    data NewOrData
      = NewType                     -- ^ @newtype Blah ...@
      | DataType                    -- ^ @data Blah ...@
      deriving( Eq, Data )                -- Needed because Demand derives Eq

    -- | Convert a 'NewOrData' to a 'TyConFlavour'
    newOrDataToFlavour :: NewOrData -> TyConFlavour
    newOrDataToFlavour NewType  = NewtypeFlavour
    newOrDataToFlavour DataType = DataTypeFlavour

    -- | Located data Constructor Declaration
    type LConDecl pass = Located (ConDecl pass)
          -- ^ May have 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnSemi' when
          --   in a GADT constructor list

      -- For details on above see note [Api annotations] in ApiAnnotation

    -- |
    --
    -- @
    -- 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
    -- @
    --
    -- - 'ApiAnnotation.AnnKeywordId's : 'ApiAnnotation.AnnOpen',
    --            'ApiAnnotation.AnnDotdot','ApiAnnotation.AnnCLose',
    --            'ApiAnnotation.AnnEqual','ApiAnnotation.AnnVbar',
    --            'ApiAnnotation.AnnDarrow','ApiAnnotation.AnnDarrow',
    --            'ApiAnnotation.AnnForall','ApiAnnotation.AnnDot'

    -- For details on above see note [Api annotations] in ApiAnnotation

    -- | data Constructor Declaration
    data ConDecl pass
      = ConDeclGADT
          { con_g_ext   :: XConDeclGADT pass
          , con_names   :: [Located (IdP pass)]

          -- The next four fields describe the type after the '::'
          -- See Note [GADT abstract syntax]
          -- The following field is Located to anchor API Annotations,
          -- AnnForall and AnnDot.
          , con_forall  :: Located Bool      -- ^ True <=> explicit forall
                                             --   False => hsq_explicit is empty
          , con_qvars   :: LHsQTyVars pass
                           -- Whether or not there is an /explicit/ forall, we still
                           -- need to capture the implicitly-bound type/kind variables

          , con_mb_cxt  :: Maybe (LHsContext pass) -- ^ User-written context (if any)
          , con_args    :: HsConDeclDetails pass   -- ^ Arguments; never InfixCon
          , con_res_ty  :: LHsType pass            -- ^ Result type

          , con_doc     :: Maybe LHsDocString
              -- ^ A possible Haddock comment.
          }

      | ConDeclH98
          { con_ext     :: XConDeclH98 pass
          , con_name    :: Located (IdP pass)

          , con_forall  :: Located 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
          , con_ex_tvs :: [LHsTyVarBndr pass]      -- ^ Existentials only
          , con_mb_cxt :: Maybe (LHsContext pass)  -- ^ User-written context (if any)
          , con_args   :: HsConDeclDetails pass    -- ^ Arguments; can be InfixCon

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

    type instance XConDeclGADT (GhcPass _) = NoExtField
    type instance XConDeclH98  (GhcPass _) = NoExtField
    type instance XXConDecl    (GhcPass _) = NoExtCon

    {- Note [GADT abstract syntax]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    There's a wrinkle in ConDeclGADT

    * For record syntax, it's all uniform.  Given:
          data T a where
            K :: forall a. Ord a => { x :: [a], ... } -> T a
        we make the a ConDeclGADT for K with
           con_qvars  = {a}
           con_mb_cxt = Just [Ord a]
           con_args   = RecCon <the record fields>
           con_res_ty = T a

      We need the RecCon before the reanmer, so we can find the record field
      binders in GHC.Hs.Utils.hsConDeclsBinders.

    * However for a GADT constr declaration which is not a record, it can
      be hard parse until we know operator fixities. Consider for example
         C :: a :*: b -> a :*: b -> a :+: b
      Initially this type will parse as
          a :*: (b -> (a :*: (b -> (a :+: b))))
      so it's hard to split up the arguments until we've done the precedence
      resolution (in the renamer).

      So:  - In the parser (RdrHsSyn.mkGadtDecl), we put the whole constr
             type into the res_ty for a ConDeclGADT for now, and use
             PrefixCon []
                con_args   = PrefixCon []
                con_res_ty = a :*: (b -> (a :*: (b -> (a :+: b))))

           - In the renamer (RnSource.rnConDecl), we unravel it afer
             operator fixities are sorted. So we generate. So we end
             up with
                con_args   = PrefixCon [ a :*: b, a :*: b ]
                con_res_ty = a :+: b
    -}

    -- | Haskell data Constructor Declaration Details
    type HsConDeclDetails pass
       = HsConDetails (LBangType pass) (Located [LConDeclField pass])

    getConNames :: ConDecl (GhcPass p) -> [Located (IdP (GhcPass p))]
    getConNames ConDeclH98  {con_name  = name}  = [name]
    getConNames ConDeclGADT {con_names = names} = names
    getConNames (XConDecl nec) = noExtCon nec

    getConArgs :: ConDecl pass -> HsConDeclDetails pass
    getConArgs d = con_args d

    hsConDeclArgTys :: HsConDeclDetails pass -> [LBangType pass]
    hsConDeclArgTys (PrefixCon tys)    = tys
    hsConDeclArgTys (InfixCon ty1 ty2) = [ty1,ty2]
    hsConDeclArgTys (RecCon flds)      = map (cd_fld_type . unLoc) (unLoc flds)

    hsConDeclTheta :: Maybe (LHsContext pass) -> [LHsType pass]
    hsConDeclTheta Nothing            = []
    hsConDeclTheta (Just (L _ theta)) = theta

    pp_data_defn :: (OutputableBndrId p)
                      => (LHsContext (GhcPass p) -> SDoc)   -- Printing the header
                      -> HsDataDefn (GhcPass p)
                      -> SDoc
    pp_data_defn pp_hdr (HsDataDefn { dd_ND = new_or_data, dd_ctxt = context
                                    , dd_cType = mb_ct
                                    , dd_kindSig = mb_sig
                                    , dd_cons = condecls, dd_derivs = derivings })
      | null condecls
      = ppr new_or_data <+> pp_ct <+> pp_hdr context <+> pp_sig
        <+> pp_derivings derivings

      | otherwise
      = hang (ppr new_or_data <+> pp_ct  <+> pp_hdr context <+> pp_sig)
           2 (pp_condecls condecls $$ pp_derivings derivings)
      where
        pp_ct = case mb_ct of
                   Nothing   -> empty
                   Just ct -> ppr ct
        pp_sig = case mb_sig of
                   Nothing   -> empty
                   Just kind -> dcolon <+> ppr kind
        pp_derivings (L _ ds) = vcat (map ppr ds)
    pp_data_defn _ (XHsDataDefn x) = ppr x

    instance OutputableBndrId p
           => Outputable (HsDataDefn (GhcPass p)) where
       ppr d = pp_data_defn (\_ -> text "Naked HsDataDefn") d

    instance OutputableBndrId p
           => Outputable (StandaloneKindSig (GhcPass p)) where
      ppr (StandaloneKindSig _ v ki)
        = text "type" <+> pprPrefixOcc (unLoc v) <+> text "::" <+> ppr ki
      ppr (XStandaloneKindSig nec) = noExtCon nec

    instance Outputable NewOrData where
      ppr NewType  = text "newtype"
      ppr DataType = text "data"

    pp_condecls :: (OutputableBndrId p) => [LConDecl (GhcPass p)] -> SDoc
    pp_condecls cs@(L _ ConDeclGADT{} : _) -- In GADT syntax
      = hang (text "where") 2 (vcat (map ppr cs))
    pp_condecls cs                    -- In H98 syntax
      = equals <+> sep (punctuate (text " |") (map ppr cs))

    instance (OutputableBndrId p) => Outputable (ConDecl (GhcPass p)) where
        ppr = pprConDecl

    pprConDecl :: (OutputableBndrId p) => ConDecl (GhcPass p) -> SDoc
    pprConDecl (ConDeclH98 { con_name = L _ con
                           , con_ex_tvs = ex_tvs
                           , con_mb_cxt = mcxt
                           , con_args = args
                           , con_doc = doc })
      = sep [ppr_mbDoc doc, pprHsForAll ForallInvis ex_tvs cxt, ppr_details args]
      where
        ppr_details (InfixCon t1 t2) = hsep [ppr t1, pprInfixOcc con, ppr t2]
        ppr_details (PrefixCon tys)  = hsep (pprPrefixOcc con
                                       : map (pprHsType . unLoc) tys)
        ppr_details (RecCon fields)  = pprPrefixOcc con
                                     <+> pprConDeclFields (unLoc fields)
        cxt = fromMaybe noLHsContext mcxt

    pprConDecl (ConDeclGADT { con_names = cons, con_qvars = qvars
                            , con_mb_cxt = mcxt, con_args = args
                            , con_res_ty = res_ty, con_doc = doc })
      = ppr_mbDoc doc <+> ppr_con_names cons <+> dcolon
        <+> (sep [pprHsForAll ForallInvis (hsq_explicit qvars) cxt,
                  ppr_arrow_chain (get_args args ++ [ppr res_ty]) ])
      where
        get_args (PrefixCon args) = map ppr args
        get_args (RecCon fields)  = [pprConDeclFields (unLoc fields)]
        get_args (InfixCon {})    = pprPanic "pprConDecl:GADT" (ppr cons)

        cxt = fromMaybe noLHsContext mcxt

        ppr_arrow_chain (a:as) = sep (a : map (arrow <+>) as)
        ppr_arrow_chain []     = empty

    pprConDecl (XConDecl x) = ppr x

    ppr_con_names :: (OutputableBndr a) => [Located a] -> SDoc
    ppr_con_names = pprWithCommas (pprPrefixOcc . unLoc)

    {-
    ************************************************************************
    *                                                                      *
                    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 = Located (TyFamInstEqn pass)
      -- ^ May have 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnSemi'
      --   when in a list

    -- For details on above see note [Api annotations] in ApiAnnotation

    -- | Haskell Type Patterns
    type HsTyPats 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 hsib_vars field of the HsImplicitBndrs
    in FamInstEqn depending on whether or not an explicit forall is present. In
    the case of an explicit forall, the hsib_vars only includes kind variables not
    bound in the forall. Otherwise, all type (and kind) variables are bound in
    the hsib_vars. In the latter case, note that in particular

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

    * The hsib_vars *includes* 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 hsib_vars of the F decl are {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 = FamInstEqn pass (LHsType pass)

    -- | 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 = Located (TyFamDefltDecl pass)

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

    -- | Type Family Instance Declaration
    newtype TyFamInstDecl pass = TyFamInstDecl { tfid_eqn :: TyFamInstEqn pass }
        -- ^
        --  - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnType',
        --           'ApiAnnotation.AnnInstance',

        -- For details on above see note [Api annotations] in ApiAnnotation

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

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

    -- | Data Family Instance Declaration
    newtype DataFamInstDecl pass
      = DataFamInstDecl { dfid_eqn :: FamInstEqn pass (HsDataDefn pass) }
        -- ^
        --  - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnData',
        --           'ApiAnnotation.AnnNewType','ApiAnnotation.AnnInstance',
        --           'ApiAnnotation.AnnDcolon'
        --           'ApiAnnotation.AnnWhere','ApiAnnotation.AnnOpen',
        --           'ApiAnnotation.AnnClose'

        -- For details on above see note [Api annotations] in ApiAnnotation

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

    -- | Located Family Instance Equation
    type LFamInstEqn pass rhs = Located (FamInstEqn pass rhs)

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

    -- | 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
           { feqn_ext    :: XCFamEqn pass rhs
           , feqn_tycon  :: Located (IdP pass)
           , feqn_bndrs  :: Maybe [LHsTyVarBndr pass] -- ^ Optional quantified type vars
           , feqn_pats   :: HsTyPats pass
           , feqn_fixity :: LexicalFixity -- ^ Fixity used in the declaration
           , feqn_rhs    :: rhs
           }
        -- ^
        --  - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnEqual'
      | XFamEqn (XXFamEqn pass rhs)

        -- For details on above see note [Api annotations] in ApiAnnotation

    type instance XCFamEqn    (GhcPass _) r = NoExtField
    type instance XXFamEqn    (GhcPass _) r = NoExtCon

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

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

    -- | Class Instance Declaration
    data ClsInstDecl pass
      = ClsInstDecl
          { cid_ext     :: XCClsInstDecl 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.
          , cid_binds         :: LHsBinds pass       -- Class methods
          , cid_sigs          :: [LSig pass]         -- User-supplied pragmatic info
          , cid_tyfam_insts   :: [LTyFamInstDecl pass]   -- Type family instances
          , cid_datafam_insts :: [LDataFamInstDecl pass] -- Data family instances
          , cid_overlap_mode  :: Maybe (Located OverlapMode)
             -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen',
             --                                    'ApiAnnotation.AnnClose',

            -- For details on above see note [Api annotations] in ApiAnnotation
          }
        -- ^
        --  - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnInstance',
        --           'ApiAnnotation.AnnWhere',
        --           'ApiAnnotation.AnnOpen','ApiAnnotation.AnnClose',

        -- For details on above see note [Api annotations] in ApiAnnotation
      | XClsInstDecl (XXClsInstDecl pass)

    type instance XCClsInstDecl    (GhcPass _) = NoExtField
    type instance XXClsInstDecl    (GhcPass _) = NoExtCon

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

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

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

    type instance XClsInstD     (GhcPass _) = NoExtField
    type instance XDataFamInstD (GhcPass _) = NoExtField
    type instance XTyFamInstD   (GhcPass _) = NoExtField
    type instance XXInstDecl    (GhcPass _) = NoExtCon

    instance OutputableBndrId p
           => Outputable (TyFamInstDecl (GhcPass p)) where
      ppr = pprTyFamInstDecl TopLevel

    pprTyFamInstDecl :: (OutputableBndrId p)
                     => TopLevelFlag -> TyFamInstDecl (GhcPass p) -> SDoc
    pprTyFamInstDecl top_lvl (TyFamInstDecl { tfid_eqn = eqn })
       = text "type" <+> ppr_instance_keyword top_lvl <+> ppr_fam_inst_eqn eqn

    ppr_instance_keyword :: TopLevelFlag -> SDoc
    ppr_instance_keyword TopLevel    = text "instance"
    ppr_instance_keyword NotTopLevel = empty

    pprTyFamDefltDecl :: (OutputableBndrId p)
                      => TyFamDefltDecl (GhcPass p) -> SDoc
    pprTyFamDefltDecl = pprTyFamInstDecl NotTopLevel

    ppr_fam_inst_eqn :: (OutputableBndrId p)
                     => TyFamInstEqn (GhcPass p) -> SDoc
    ppr_fam_inst_eqn (HsIB { hsib_body = FamEqn { feqn_tycon  = L _ tycon
                                                , feqn_bndrs  = bndrs
                                                , feqn_pats   = pats
                                                , feqn_fixity = fixity
                                                , feqn_rhs    = rhs }})
        = pprHsFamInstLHS tycon bndrs pats fixity noLHsContext <+> equals <+> ppr rhs
    ppr_fam_inst_eqn (HsIB { hsib_body = XFamEqn x }) = ppr x
    ppr_fam_inst_eqn (XHsImplicitBndrs x) = ppr x

    instance OutputableBndrId p
           => Outputable (DataFamInstDecl (GhcPass p)) where
      ppr = pprDataFamInstDecl TopLevel

    pprDataFamInstDecl :: (OutputableBndrId p)
                       => TopLevelFlag -> DataFamInstDecl (GhcPass p) -> SDoc
    pprDataFamInstDecl top_lvl (DataFamInstDecl { dfid_eqn = HsIB { hsib_body =
                                 FamEqn { feqn_tycon  = L _ tycon
                                        , feqn_bndrs  = bndrs
                                        , feqn_pats   = pats
                                        , feqn_fixity = fixity
                                        , feqn_rhs    = defn }}})
      = pp_data_defn pp_hdr defn
      where
        pp_hdr ctxt = ppr_instance_keyword top_lvl
                  <+> pprHsFamInstLHS tycon bndrs pats fixity ctxt
                      -- pp_data_defn pretty-prints the kind sig. See #14817.

    pprDataFamInstDecl _ (DataFamInstDecl (HsIB _ (XFamEqn x)))
      = ppr x
    pprDataFamInstDecl _ (DataFamInstDecl (XHsImplicitBndrs x))
      = ppr x

    pprDataFamInstFlavour :: DataFamInstDecl (GhcPass p) -> SDoc
    pprDataFamInstFlavour (DataFamInstDecl { dfid_eqn = HsIB { hsib_body =
                            FamEqn { feqn_rhs = HsDataDefn { dd_ND = nd }}}})
      = ppr nd
    pprDataFamInstFlavour (DataFamInstDecl { dfid_eqn = HsIB { hsib_body =
                            FamEqn { feqn_rhs = XHsDataDefn x}}})
      = ppr x
    pprDataFamInstFlavour (DataFamInstDecl (HsIB _ (XFamEqn x)))
      = ppr x
    pprDataFamInstFlavour (DataFamInstDecl (XHsImplicitBndrs x))
      = ppr x

    pprHsFamInstLHS :: (OutputableBndrId p)
       => IdP (GhcPass p)
       -> Maybe [LHsTyVarBndr (GhcPass p)]
       -> HsTyPats (GhcPass p)
       -> LexicalFixity
       -> LHsContext (GhcPass p)
       -> SDoc
    pprHsFamInstLHS thing bndrs typats fixity mb_ctxt
       = hsep [ pprHsExplicitForAll ForallInvis bndrs
              , pprLHsContext mb_ctxt
              , pp_pats typats ]
       where
         pp_pats (patl:patr:pats)
           | Infix <- fixity
           = let pp_op_app = hsep [ ppr patl, pprInfixOcc thing, ppr patr ] in
             case pats of
               [] -> pp_op_app
               _  -> hsep (parens pp_op_app : map ppr pats)

         pp_pats pats = hsep [ pprPrefixOcc thing
                             , hsep (map ppr pats)]

    instance OutputableBndrId p
           => Outputable (ClsInstDecl (GhcPass p)) where
        ppr (ClsInstDecl { cid_poly_ty = inst_ty, cid_binds = binds
                         , cid_sigs = sigs, cid_tyfam_insts = ats
                         , cid_overlap_mode = mbOverlap
                         , cid_datafam_insts = adts })
          | null sigs, null ats, null adts, isEmptyBag binds  -- No "where" part
          = top_matter

          | otherwise       -- Laid out
          = vcat [ top_matter <+> text "where"
                 , nest 2 $ pprDeclList $
                   map (pprTyFamInstDecl NotTopLevel . unLoc)   ats ++
                   map (pprDataFamInstDecl NotTopLevel . unLoc) adts ++
                   pprLHsBindsForUser binds sigs ]
          where
            top_matter = text "instance" <+> ppOverlapPragma mbOverlap
                                                 <+> ppr inst_ty
        ppr (XClsInstDecl x) = ppr x

    ppDerivStrategy :: OutputableBndrId p
                    => Maybe (LDerivStrategy (GhcPass p)) -> SDoc
    ppDerivStrategy mb =
      case mb of
        Nothing       -> empty
        Just (L _ ds) -> ppr ds

    ppOverlapPragma :: Maybe (Located OverlapMode) -> SDoc
    ppOverlapPragma mb =
      case mb of
        Nothing           -> empty
        Just (L _ (NoOverlap s))    -> maybe_stext s "{-# NO_OVERLAP #-}"
        Just (L _ (Overlappable s)) -> maybe_stext s "{-# OVERLAPPABLE #-}"
        Just (L _ (Overlapping s))  -> maybe_stext s "{-# OVERLAPPING #-}"
        Just (L _ (Overlaps s))     -> maybe_stext s "{-# OVERLAPS #-}"
        Just (L _ (Incoherent s))   -> maybe_stext s "{-# INCOHERENT #-}"
      where
        maybe_stext NoSourceText     alt = text alt
        maybe_stext (SourceText src) _   = text src <+> text "#-}"

    instance (OutputableBndrId p) => Outputable (InstDecl (GhcPass p)) where
        ppr (ClsInstD     { cid_inst  = decl }) = ppr decl
        ppr (TyFamInstD   { tfid_inst = decl }) = ppr decl
        ppr (DataFamInstD { dfid_inst = decl }) = ppr decl
        ppr (XInstDecl x) = ppr x

    -- Extract the declarations of associated data types from an instance

    instDeclDataFamInsts :: [LInstDecl (GhcPass p)] -> [DataFamInstDecl (GhcPass p)]
    instDeclDataFamInsts inst_decls
      = concatMap do_one inst_decls
      where
        do_one (L _ (ClsInstD { cid_inst = ClsInstDecl { cid_datafam_insts = fam_insts } }))
          = map unLoc fam_insts
        do_one (L _ (DataFamInstD { dfid_inst = fam_inst }))      = [fam_inst]
        do_one (L _ (TyFamInstD {}))                              = []
        do_one (L _ (ClsInstD _ (XClsInstDecl nec))) = noExtCon nec
        do_one (L _ (XInstDecl nec))                 = noExtCon nec

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

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

    -- | Stand-alone 'deriving instance' declaration
    data DerivDecl pass = DerivDecl
            { deriv_ext          :: XCDerivDecl 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 TcDerivInfer.

            , deriv_strategy     :: Maybe (LDerivStrategy pass)
            , deriv_overlap_mode :: Maybe (Located OverlapMode)
             -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnDeriving',
             --        'ApiAnnotation.AnnInstance', 'ApiAnnotation.AnnStock',
             --        'ApiAnnotation.AnnAnyClass', 'Api.AnnNewtype',
             --        'ApiAnnotation.AnnOpen','ApiAnnotation.AnnClose'

      -- For details on above see note [Api annotations] in ApiAnnotation
            }
      | XDerivDecl (XXDerivDecl pass)

    type instance XCDerivDecl    (GhcPass _) = NoExtField
    type instance XXDerivDecl    (GhcPass _) = NoExtCon

    instance OutputableBndrId p
           => Outputable (DerivDecl (GhcPass p)) where
        ppr (DerivDecl { deriv_type = ty
                       , deriv_strategy = ds
                       , deriv_overlap_mode = o })
            = hsep [ text "deriving"
                   , ppDerivStrategy ds
                   , text "instance"
                   , ppOverlapPragma o
                   , ppr ty ]
        ppr (XDerivDecl x) = ppr x

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

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

    -- | Which technique the user explicitly requested when deriving an instance.
    data DerivStrategy pass
      -- See Note [Deriving strategies] in TcDeriv
      = StockStrategy    -- ^ 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 -- ^ @-XDeriveAnyClass@
      | NewtypeStrategy  -- ^ @-XGeneralizedNewtypeDeriving@
      | ViaStrategy (XViaStrategy pass)
                         -- ^ @-XDerivingVia@

    type instance XViaStrategy GhcPs = LHsSigType GhcPs
    type instance XViaStrategy GhcRn = LHsSigType GhcRn
    type instance XViaStrategy GhcTc = Type

    instance OutputableBndrId p
            => Outputable (DerivStrategy (GhcPass p)) where
        ppr StockStrategy    = text "stock"
        ppr AnyclassStrategy = text "anyclass"
        ppr NewtypeStrategy  = text "newtype"
        ppr (ViaStrategy ty) = text "via" <+> ppr ty

    -- | A short description of a @DerivStrategy'@.
    derivStrategyName :: DerivStrategy a -> SDoc
    derivStrategyName = text . go
      where
        go StockStrategy    = "stock"
        go AnyclassStrategy = "anyclass"
        go NewtypeStrategy  = "newtype"
        go (ViaStrategy {}) = "via"

    -- | Eliminate a 'DerivStrategy'.
    foldDerivStrategy :: (p ~ GhcPass pass)
                      => r -> (XViaStrategy p -> r) -> DerivStrategy p -> r
    foldDerivStrategy other _   StockStrategy    = other
    foldDerivStrategy other _   AnyclassStrategy = other
    foldDerivStrategy other _   NewtypeStrategy  = other
    foldDerivStrategy _     via (ViaStrategy t)  = via t

    -- | Map over the @via@ type if dealing with 'ViaStrategy'. Otherwise,
    -- return the 'DerivStrategy' unchanged.
    mapDerivStrategy :: (p ~ GhcPass pass)
                     => (XViaStrategy p -> XViaStrategy p)
                     -> DerivStrategy p -> DerivStrategy p
    mapDerivStrategy f ds = foldDerivStrategy ds (ViaStrategy . f) ds

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

    There can only be one default declaration per module, but it is hard
    for the parser to check that; we pass them all through in the abstract
    syntax, and that restriction must be checked in the front end.
    -}

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

    -- | Default Declaration
    data DefaultDecl pass
      = DefaultDecl (XCDefaultDecl pass) [LHsType pass]
            -- ^ - 'ApiAnnotation.AnnKeywordId's : 'ApiAnnotation.AnnDefault',
            --          'ApiAnnotation.AnnOpen','ApiAnnotation.AnnClose'

            -- For details on above see note [Api annotations] in ApiAnnotation
      | XDefaultDecl (XXDefaultDecl pass)

    type instance XCDefaultDecl    (GhcPass _) = NoExtField
    type instance XXDefaultDecl    (GhcPass _) = NoExtCon

    instance OutputableBndrId p
           => Outputable (DefaultDecl (GhcPass p)) where
        ppr (DefaultDecl _ tys)
          = text "default" <+> parens (interpp'SP tys)
        ppr (XDefaultDecl x) = ppr x

    {-
    ************************************************************************
    *                                                                      *
    \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 = Located (ForeignDecl pass)

    -- | Foreign Declaration
    data ForeignDecl pass
      = ForeignImport
          { fd_i_ext  :: XForeignImport pass   -- Post typechecker, rep_ty ~ sig_ty
          , fd_name   :: Located (IdP pass)    -- defines this name
          , fd_sig_ty :: LHsSigType pass       -- sig_ty
          , fd_fi     :: ForeignImport }

      | ForeignExport
          { fd_e_ext  :: XForeignExport pass   -- Post typechecker, rep_ty ~ sig_ty
          , fd_name   :: Located (IdP pass)    -- uses this name
          , fd_sig_ty :: LHsSigType pass       -- sig_ty
          , fd_fe     :: ForeignExport }
            -- ^
            --  - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnForeign',
            --           'ApiAnnotation.AnnImport','ApiAnnotation.AnnExport',
            --           'ApiAnnotation.AnnDcolon'

            -- For details on above see note [Api annotations] in ApiAnnotation
      | 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.
    -}

    type instance XForeignImport   GhcPs = NoExtField
    type instance XForeignImport   GhcRn = NoExtField
    type instance XForeignImport   GhcTc = Coercion

    type instance XForeignExport   GhcPs = NoExtField
    type instance XForeignExport   GhcRn = NoExtField
    type instance XForeignExport   GhcTc = Coercion

    type instance XXForeignDecl    (GhcPass _) = NoExtCon

    -- Specification Of an imported external entity in dependence on the calling
    -- convention
    --
    data ForeignImport = -- 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  (Located CCallConv) -- ccall or stdcall
                                  (Located Safety)  -- interruptible, safe or unsafe
                                  (Maybe Header)       -- name of C header
                                  CImportSpec          -- details of the C entity
                                  (Located SourceText) -- original source text for
                                                       -- the C entity
      deriving Data

    -- 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 Data

    -- specification of an externally exported entity in dependence on the calling
    -- convention
    --
    data ForeignExport = CExport  (Located CExportSpec) -- contains the calling
                                                        -- convention
                                  (Located SourceText)  -- original source text for
                                                        -- the C entity
      deriving Data

    -- pretty printing of foreign declarations
    --

    instance OutputableBndrId p
           => Outputable (ForeignDecl (GhcPass p)) where
      ppr (ForeignImport { fd_name = n, fd_sig_ty = ty, fd_fi = fimport })
        = hang (text "foreign import" <+> ppr fimport <+> ppr n)
             2 (dcolon <+> ppr ty)
      ppr (ForeignExport { fd_name = n, fd_sig_ty = ty, fd_fe = fexport }) =
        hang (text "foreign export" <+> ppr fexport <+> ppr n)
           2 (dcolon <+> ppr ty)
      ppr (XForeignDecl x) = ppr x

    instance Outputable ForeignImport where
      ppr (CImport  cconv safety mHeader spec (L _ srcText)) =
        ppr cconv <+> ppr safety
          <+> pprWithSourceText srcText (pprCEntity spec "")
        where
          pp_hdr = case mHeader of
                   Nothing -> empty
                   Just (Header _ header) -> ftext header

          pprCEntity (CLabel lbl) _ =
            doubleQuotes $ text "static" <+> pp_hdr <+> char '&' <> ppr lbl
          pprCEntity (CFunction (StaticTarget st _lbl _ isFun)) src =
            if dqNeeded then doubleQuotes ce else empty
              where
                dqNeeded = (take 6 src == "static")
                        || isJust mHeader
                        || not isFun
                        || st /= NoSourceText
                ce =
                      -- We may need to drop leading spaces first
                      (if take 6 src == "static" then text "static" else empty)
                  <+> pp_hdr
                  <+> (if isFun then empty else text "value")
                  <+> (pprWithSourceText st empty)
          pprCEntity (CFunction DynamicTarget) _ =
            doubleQuotes $ text "dynamic"
          pprCEntity CWrapper _ = doubleQuotes $ text "wrapper"

    instance Outputable ForeignExport where
      ppr (CExport  (L _ (CExportStatic _ lbl cconv)) _) =
        ppr cconv <+> char '"' <> ppr lbl <> char '"'

    {-
    ************************************************************************
    *                                                                      *
    \subsection{Transformation rules}
    *                                                                      *
    ************************************************************************
    -}

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

      -- Note [Pragma source text] in BasicTypes
    -- | Rule Declarations
    data RuleDecls pass = HsRules { rds_ext   :: XCRuleDecls pass
                                  , rds_src   :: SourceText
                                  , rds_rules :: [LRuleDecl pass] }
      | XRuleDecls (XXRuleDecls pass)

    type instance XCRuleDecls    (GhcPass _) = NoExtField
    type instance XXRuleDecls    (GhcPass _) = NoExtCon

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

    -- | Rule Declaration
    data RuleDecl pass
      = HsRule -- Source rule
           { rd_ext  :: XHsRule pass
               -- ^ After renamer, free-vars from the LHS and RHS
           , rd_name :: Located (SourceText,RuleName)
               -- ^ Note [Pragma source text] in BasicTypes
           , rd_act  :: Activation
           , rd_tyvs :: Maybe [LHsTyVarBndr (NoGhcTc pass)]
               -- ^ Forall'd type vars
           , rd_tmvs :: [LRuleBndr pass]
               -- ^ Forall'd term vars, before typechecking; after typechecking
               --    this includes all forall'd vars
           , rd_lhs  :: Located (HsExpr pass)
           , rd_rhs  :: Located (HsExpr pass)
           }
        -- ^
        --  - 'ApiAnnotation.AnnKeywordId' :
        --           'ApiAnnotation.AnnOpen','ApiAnnotation.AnnTilde',
        --           'ApiAnnotation.AnnVal',
        --           'ApiAnnotation.AnnClose',
        --           'ApiAnnotation.AnnForall','ApiAnnotation.AnnDot',
        --           'ApiAnnotation.AnnEqual',
      | XRuleDecl (XXRuleDecl pass)

    data HsRuleRn = HsRuleRn NameSet NameSet -- Free-vars from the LHS and RHS
      deriving Data

    type instance XHsRule       GhcPs = NoExtField
    type instance XHsRule       GhcRn = HsRuleRn
    type instance XHsRule       GhcTc = HsRuleRn

    type instance XXRuleDecl    (GhcPass _) = NoExtCon

    flattenRuleDecls :: [LRuleDecls pass] -> [LRuleDecl pass]
    flattenRuleDecls decls = concatMap (rds_rules . unLoc) decls

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

    -- | Rule Binder
    data RuleBndr pass
      = RuleBndr (XCRuleBndr pass)  (Located (IdP pass))
      | RuleBndrSig (XRuleBndrSig pass) (Located (IdP pass)) (LHsSigWcType pass)
      | XRuleBndr (XXRuleBndr pass)
            -- ^
            --  - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen',
            --     'ApiAnnotation.AnnDcolon','ApiAnnotation.AnnClose'

            -- For details on above see note [Api annotations] in ApiAnnotation

    type instance XCRuleBndr    (GhcPass _) = NoExtField
    type instance XRuleBndrSig  (GhcPass _) = NoExtField
    type instance XXRuleBndr    (GhcPass _) = NoExtCon

    collectRuleBndrSigTys :: [RuleBndr pass] -> [LHsSigWcType pass]
    collectRuleBndrSigTys bndrs = [ty | RuleBndrSig _ _ ty <- bndrs]

    pprFullRuleName :: Located (SourceText, RuleName) -> SDoc
    pprFullRuleName (L _ (st, n)) = pprWithSourceText st (doubleQuotes $ ftext n)

    instance (OutputableBndrId p) => Outputable (RuleDecls (GhcPass p)) where
      ppr (HsRules { rds_src = st
                   , rds_rules = rules })
        = pprWithSourceText st (text "{-# RULES")
              <+> vcat (punctuate semi (map ppr rules)) <+> text "#-}"
      ppr (XRuleDecls x) = ppr x

    instance (OutputableBndrId p) => Outputable (RuleDecl (GhcPass p)) where
      ppr (HsRule { rd_name = name
                  , rd_act  = act
                  , rd_tyvs = tys
                  , rd_tmvs = tms
                  , rd_lhs  = lhs
                  , rd_rhs  = rhs })
            = sep [pprFullRuleName name <+> ppr act,
                   nest 4 (pp_forall_ty tys <+> pp_forall_tm tys
                                            <+> pprExpr (unLoc lhs)),
                   nest 6 (equals <+> pprExpr (unLoc rhs)) ]
            where
              pp_forall_ty Nothing     = empty
              pp_forall_ty (Just qtvs) = forAllLit <+> fsep (map ppr qtvs) <> dot
              pp_forall_tm Nothing | null tms = empty
              pp_forall_tm _ = forAllLit <+> fsep (map ppr tms) <> dot
      ppr (XRuleDecl x) = ppr x

    instance (OutputableBndrId p) => Outputable (RuleBndr (GhcPass p)) where
       ppr (RuleBndr _ name) = ppr name
       ppr (RuleBndrSig _ name ty) = parens (ppr name <> dcolon <> ppr ty)
       ppr (XRuleBndr x) = ppr x

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

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

    -- | Documentation comment Declaration
    data DocDecl
      = DocCommentNext HsDocString
      | DocCommentPrev HsDocString
      | DocCommentNamed String HsDocString
      | DocGroup Int HsDocString
      deriving Data

    -- Okay, I need to reconstruct the document comments, but for now:
    instance Outputable DocDecl where
      ppr _ = text "<document comment>"

    docDeclDoc :: DocDecl -> HsDocString
    docDeclDoc (DocCommentNext d) = d
    docDeclDoc (DocCommentPrev d) = d
    docDeclDoc (DocCommentNamed _ d) = d
    docDeclDoc (DocGroup _ d) = d

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

    We use exported entities for things to deprecate.
    -}

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

     -- Note [Pragma source text] in BasicTypes
    -- | Warning pragma Declarations
    data WarnDecls pass = Warnings { wd_ext      :: XWarnings pass
                                   , wd_src      :: SourceText
                                   , wd_warnings :: [LWarnDecl pass]
                                   }
      | XWarnDecls (XXWarnDecls pass)

    type instance XWarnings      (GhcPass _) = NoExtField
    type instance XXWarnDecls    (GhcPass _) = NoExtCon

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

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

    type instance XWarning      (GhcPass _) = NoExtField
    type instance XXWarnDecl    (GhcPass _) = NoExtCon

    instance OutputableBndr (IdP (GhcPass p))
            => Outputable (WarnDecls (GhcPass p)) where
        ppr (Warnings _ (SourceText src) decls)
          = text src <+> vcat (punctuate comma (map ppr decls)) <+> text "#-}"
        ppr (Warnings _ NoSourceText _decls) = panic "WarnDecls"
        ppr (XWarnDecls x) = ppr x

    instance OutputableBndr (IdP (GhcPass p))
           => Outputable (WarnDecl (GhcPass p)) where
        ppr (Warning _ thing txt)
          = hsep ( punctuate comma (map ppr thing))
                  <+> ppr txt
        ppr (XWarnDecl x) = ppr x

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

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

    -- | Annotation Declaration
    data AnnDecl pass = HsAnnotation
                          (XHsAnnotation pass)
                          SourceText -- Note [Pragma source text] in BasicTypes
                          (AnnProvenance (IdP pass)) (Located (HsExpr pass))
          -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen',
          --           'ApiAnnotation.AnnType'
          --           'ApiAnnotation.AnnModule'
          --           'ApiAnnotation.AnnClose'

          -- For details on above see note [Api annotations] in ApiAnnotation
      | XAnnDecl (XXAnnDecl pass)

    type instance XHsAnnotation (GhcPass _) = NoExtField
    type instance XXAnnDecl     (GhcPass _) = NoExtCon

    instance (OutputableBndrId p) => Outputable (AnnDecl (GhcPass p)) where
        ppr (HsAnnotation _ _ provenance expr)
          = hsep [text "{-#", pprAnnProvenance provenance, pprExpr (unLoc expr), text "#-}"]
        ppr (XAnnDecl x) = ppr x

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

    annProvenanceName_maybe :: AnnProvenance name -> Maybe name
    annProvenanceName_maybe (ValueAnnProvenance (L _ name)) = Just name
    annProvenanceName_maybe (TypeAnnProvenance (L _ name))  = Just name
    annProvenanceName_maybe ModuleAnnProvenance       = Nothing

    pprAnnProvenance :: OutputableBndr name => AnnProvenance name -> SDoc
    pprAnnProvenance ModuleAnnProvenance       = text "ANN module"
    pprAnnProvenance (ValueAnnProvenance (L _ name))
      = text "ANN" <+> ppr name
    pprAnnProvenance (TypeAnnProvenance (L _ name))
      = text "ANN type" <+> ppr name

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

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

    -- See #8185 for more info about why role annotations are
    -- top-level declarations
    -- | Role Annotation Declaration
    data RoleAnnotDecl pass
      = RoleAnnotDecl (XCRoleAnnotDecl pass)
                      (Located (IdP pass))   -- type constructor
                      [Located (Maybe Role)] -- optional annotations
          -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnType',
          --           'ApiAnnotation.AnnRole'

          -- For details on above see note [Api annotations] in ApiAnnotation
      | XRoleAnnotDecl (XXRoleAnnotDecl pass)

    type instance XCRoleAnnotDecl (GhcPass _) = NoExtField
    type instance XXRoleAnnotDecl (GhcPass _) = NoExtCon

    instance OutputableBndr (IdP (GhcPass p))
           => Outputable (RoleAnnotDecl (GhcPass p)) where
      ppr (RoleAnnotDecl _ ltycon roles)
        = text "type role" <+> pprPrefixOcc (unLoc ltycon) <+>
          hsep (map (pp_role . unLoc) roles)
        where
          pp_role Nothing  = underscore
          pp_role (Just r) = ppr r
      ppr (XRoleAnnotDecl x) = ppr x

    roleAnnotDeclName :: RoleAnnotDecl (GhcPass p) -> IdP (GhcPass p)
    roleAnnotDeclName (RoleAnnotDecl _ (L _ name) _) = name
    roleAnnotDeclName (XRoleAnnotDecl nec) = noExtCon nec