path: root/compiler/hsSyn/HsDecls.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 UndecidableInstances #-} -- Note [Pass sensitive types]
                                      -- in module PlaceHolder
{-# LANGUAGE ConstraintKinds #-}
{-# LANGUAGE FlexibleInstances #-}

-- | Abstract syntax of global declarations.
--
-- Definitions for: @SynDecl@ and @ConDecl@, @ClassDecl@,
-- @InstDecl@, @DefaultDecl@ and @ForeignDecl@.
module HsDecls (
  -- * Toplevel declarations
  HsDecl(..), LHsDecl, HsDataDefn(..), HsDeriving,
  HsDerivingClause(..), LHsDerivingClause,

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

  -- ** Instance declarations
  InstDecl(..), LInstDecl, NewOrData(..), FamilyInfo(..),
  TyFamInstDecl(..), LTyFamInstDecl, instDeclDataFamInsts,
  DataFamInstDecl(..), LDataFamInstDecl, pprDataFamInstFlavour, pprFamInstLHS,
  TyFamEqn(..), TyFamInstEqn, LTyFamInstEqn, TyFamDefltEqn, LTyFamDefltEqn,
  HsTyPats,
  LClsInstDecl, ClsInstDecl(..),

  -- ** Standalone deriving declarations
  DerivDecl(..), LDerivDecl,
  -- ** @RULE@ declarations
  LRuleDecls,RuleDecls(..),RuleDecl(..), LRuleDecl, RuleBndr(..),LRuleBndr,
  collectRuleBndrSigTys,
  flattenRuleDecls, pprFullRuleName,
  -- ** @VECTORISE@ declarations
  VectDecl(..), LVectDecl,
  lvectDeclName, lvectInstDecl,
  -- ** @default@ declarations
  DefaultDecl(..), LDefaultDecl,
  -- ** Template haskell declaration splice
  SpliceExplicitFlag(..),
  SpliceDecl(..), LSpliceDecl,
  -- ** Foreign function interface declarations
  ForeignDecl(..), LForeignDecl, ForeignImport(..), ForeignExport(..),
  noForeignImportCoercionYet, noForeignExportCoercionYet,
  CImportSpec(..),
  -- ** Data-constructor declarations
  ConDecl(..), LConDecl,
  HsConDeclDetails, hsConDeclArgTys,
  getConNames,
  getConDetails,
  gadtDeclDetails,
  -- ** 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 {-# SOURCE #-}   HsExpr( LHsExpr, HsExpr, HsSplice, pprExpr,
                                pprSpliceDecl )
        -- Because Expr imports Decls via HsBracket

import HsBinds
import HsTypes
import HsDoc
import TyCon
import Name
import BasicTypes
import Coercion
import ForeignCall
import PlaceHolder ( PlaceHolder(..) )
import HsExtension
import NameSet

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

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

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

type LHsDecl id = Located (HsDecl id)
        -- ^ 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 id
  = TyClD       (TyClDecl id)      -- ^ Type or Class Declaration
  | InstD       (InstDecl  id)     -- ^ Instance declaration
  | DerivD      (DerivDecl id)     -- ^ Deriving declaration
  | ValD        (HsBind id)        -- ^ Value declaration
  | SigD        (Sig id)           -- ^ Signature declaration
  | DefD        (DefaultDecl id)   -- ^ 'default' declaration
  | ForD        (ForeignDecl id)   -- ^ Foreign declaration
  | WarningD    (WarnDecls id)     -- ^ Warning declaration
  | AnnD        (AnnDecl id)       -- ^ Annotation declaration
  | RuleD       (RuleDecls id)     -- ^ Rule declaration
  | VectD       (VectDecl id)      -- ^ Vectorise declaration
  | SpliceD     (SpliceDecl id)    -- ^ Splice declaration
                                   -- (Includes quasi-quotes)
  | DocD        (DocDecl)          -- ^ Documentation comment declaration
  | RoleAnnotD  (RoleAnnotDecl id) -- ^ Role annotation declaration
deriving instance (DataId id) => Data (HsDecl id)


-- 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 id
  = HsGroup {
        hs_valds  :: HsValBinds id,
        hs_splcds :: [LSpliceDecl id],

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

        hs_derivds :: [LDerivDecl id],

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

        hs_defds  :: [LDefaultDecl id],
        hs_fords  :: [LForeignDecl id],
        hs_warnds :: [LWarnDecls id],
        hs_annds  :: [LAnnDecl id],
        hs_ruleds :: [LRuleDecls id],
        hs_vects  :: [LVectDecl id],

        hs_docs   :: [LDocDecl]
  }
deriving instance (DataId id) => Data (HsGroup id)

emptyGroup, emptyRdrGroup, emptyRnGroup :: HsGroup a
emptyRdrGroup = emptyGroup { hs_valds = emptyValBindsIn }
emptyRnGroup  = emptyGroup { hs_valds = emptyValBindsOut }

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

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

appendGroups :: HsGroup a -> HsGroup a -> HsGroup a
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_vects = vects1,
  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_vects  = vects2,
        hs_docs   = docs2 }
  =
    HsGroup {
        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_vects  = vects1 ++ vects2,
        hs_docs   = docs1  ++ docs2 }

instance (SourceTextX pass, OutputableBndrId pass)
       => Outputable (HsDecl pass) 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 (RuleD rd)              = ppr rd
    ppr (VectD vect)            = ppr vect
    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

instance (SourceTextX pass, OutputableBndrId pass)
      => Outputable (HsGroup pass) 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,
                   hs_vects  = vect_decls })
        = vcat_mb empty
            [ppr_ds fix_decls, ppr_ds default_decls,
             ppr_ds deprec_decls, ppr_ds ann_decls,
             ppr_ds rule_decls,
             ppr_ds vect_decls,
             if isEmptyValBinds val_decls
                then Nothing
                else Just (ppr val_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

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

-- | Splice Declaration
data SpliceDecl id
  = SpliceDecl                  -- Top level splice
        (Located (HsSplice id))
        SpliceExplicitFlag
deriving instance (DataId id) => Data (SpliceDecl id)

instance (SourceTextX pass, OutputableBndrId pass)
       => Outputable (SpliceDecl pass) where
   ppr (SpliceDecl (L _ e) f) = pprSpliceDecl e f

{-
************************************************************************
*                                                                      *
            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 HsBinds), 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 { tcdFam :: FamilyDecl pass }

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

    -- For details on above see note [Api annotations] in ApiAnnotation
    SynDecl { 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
            , tcdFVs    :: PostRn pass NameSet }

  | -- | @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 { tcdLName    :: Located (IdP pass) -- ^ Type constructor
             , tcdTyVars   :: LHsQTyVars pass  -- ^ Type variables; for an
                                               -- associated type
                                               --   these include outer binders
                                               -- Eg  class T a where
                                               --       type F a :: *
                                               --       type F a = a -> a
                                               -- Here the type decl for 'f'
                                               -- includes 'a' in its tcdTyVars
             , tcdFixity  :: LexicalFixity -- ^ Fixity used in the declaration
             , tcdDataDefn :: HsDataDefn pass
             , tcdDataCusk :: PostRn pass Bool    -- ^ does this have a CUSK?
             , tcdFVs      :: PostRn pass NameSet }

  | ClassDecl { 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     :: [Located (FunDep (Located (IdP pass)))],
                                                        -- ^ Functional deps
                tcdSigs    :: [LSig pass],              -- ^ Methods' signatures
                tcdMeths   :: LHsBinds pass,            -- ^ Default methods
                tcdATs     :: [LFamilyDecl pass],       -- ^ Associated types;
                tcdATDefs  :: [LTyFamDefltEqn pass],
                                                   -- ^ Associated type defaults
                tcdDocs    :: [LDocDecl],               -- ^ Haddock docs
                tcdFVs     :: PostRn pass NameSet
    }
        -- ^ - '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

deriving instance (DataId id) => Data (TyClDecl id)


-- 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 pass -> (IdP pass)
tyFamInstDeclName = unLoc . tyFamInstDeclLName

tyFamInstDeclLName :: TyFamInstDecl pass -> Located (IdP pass)
tyFamInstDeclLName (TyFamInstDecl { tfid_eqn =
                     (L _ (TyFamEqn { tfe_tycon = ln })) })
  = ln

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 [Complete user-supplied kind signatures]
hsDeclHasCusk :: TyClDecl GhcRn -> Bool
hsDeclHasCusk (FamDecl { tcdFam = fam_decl }) = famDeclHasCusk Nothing fam_decl
hsDeclHasCusk (SynDecl { tcdTyVars = tyvars, tcdRhs = rhs })
  -- NB: Keep this synchronized with 'getInitialKind'
  = hsTvbAllKinded tyvars && rhs_annotated rhs
  where
    rhs_annotated (L _ ty) = case ty of
      HsParTy lty  -> rhs_annotated lty
      HsKindSig {} -> True
      _            -> False
hsDeclHasCusk (DataDecl { tcdDataCusk = cusk }) = cusk
hsDeclHasCusk (ClassDecl { tcdTyVars = tyvars }) = hsTvbAllKinded tyvars

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

instance (SourceTextX pass, OutputableBndrId pass)
       => Outputable (TyClDecl pass) 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 [] <+> 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 ppr_fam_deflt_eqn at_defs ++
                                     pprLHsBindsForUser methods sigs) ]
      where
        top_matter = text "class"
                    <+> pp_vanilla_decl_head lclas tyvars fixity (unLoc context)
                    <+> pprFundeps (map unLoc fds)

instance (SourceTextX pass, OutputableBndrId pass)
       => Outputable (TyClGroup pass) where
  ppr (TyClGroup { group_tyclds = tyclds
                 , group_roles = roles
                 , group_instds = instds
                 }
      )
    = ppr tyclds $$
      ppr roles $$
      ppr instds

pp_vanilla_decl_head :: (SourceTextX pass, OutputableBndrId pass)
   => Located (IdP pass)
   -> LHsQTyVars pass
   -> LexicalFixity
   -> HsContext pass
   -> SDoc
pp_vanilla_decl_head thing (HsQTvs { hsq_explicit = tyvars }) fixity context
 = hsep [pprHsContext context, pp_tyvars tyvars]
  where
    pp_tyvars (varl: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 [] = ppr thing

pprTyClDeclFlavour :: TyClDecl a -> SDoc
pprTyClDeclFlavour (ClassDecl {})   = text "class"
pprTyClDeclFlavour (SynDecl {})     = text "type"
pprTyClDeclFlavour (FamDecl { tcdFam = FamilyDecl { fdInfo = info }})
  = pprFlavour info <+> text "family"
pprTyClDeclFlavour (DataDecl { tcdDataDefn = HsDataDefn { dd_ND = nd } })
  = ppr nd


{- Note [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 ghc.haskell.org/trac/ghc/wiki/GhcKinds/KindInference#Proposednewstrategy
and #9200 for lots of discussion of how we got here.

A declaration has a CUSK if we can know its complete kind without doing any
inference, at all. Here are the rules:

 - A class or datatype is said to have a CUSK if and only if all of its type
variables are annotated. Its result kind is, by construction, Constraint or *
respectively.

 - A type synonym has a CUSK if and only if all of its type variables and its
RHS are annotated with kinds.

 - A closed type family is said to have a CUSK if and only if all of its type
variables and its return type are annotated.

 - An open type family always has a CUSK -- unannotated type variables (and
return type) default to *.

 - Additionally, if -XTypeInType is on, then 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.)
-}


{- *********************************************************************
*                                                                      *
                         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_tyclds :: [LTyClDecl pass]
              , group_roles  :: [LRoleAnnotDecl pass]
              , group_instds :: [LInstDecl pass] }
deriving instance (DataId id) => Data (TyClGroup id)

emptyTyClGroup :: TyClGroup pass
emptyTyClGroup = TyClGroup [] [] []

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

mkTyClGroup :: [LTyClDecl pass] -> [LInstDecl pass] -> TyClGroup pass
mkTyClGroup decls instds = TyClGroup
  { group_tyclds = decls
  , group_roles = []
  , group_instds = instds
  }



{- *********************************************************************
*                                                                      *
               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
  -- ^ - 'ApiAnnotation.AnnKeywordId' :

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

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

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

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

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

deriving instance (DataId pass) => Data (FamilyResultSig pass)

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

-- | type Family Declaration
data FamilyDecl pass = FamilyDecl
  { fdInfo           :: FamilyInfo pass              -- type/data, closed/open
  , fdLName          :: Located (IdP pass)           -- type constructor
  , fdTyVars         :: LHsQTyVars pass              -- type variables
  , fdFixity         :: LexicalFixity         -- Fixity used in the declaration
  , fdResultSig      :: LFamilyResultSig pass        -- result signature
  , fdInjectivityAnn :: Maybe (LInjectivityAnn pass) -- optional injectivity ann
  }
  -- ^ - '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

deriving instance (DataId id) => Data (FamilyDecl id)

-- | 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
deriving instance (DataId pass) => Data (InjectivityAnn pass)

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

-- | Does this family declaration have a complete, user-supplied kind signature?
famDeclHasCusk :: Maybe Bool
                   -- ^ if associated, does the enclosing class have a CUSK?
               -> FamilyDecl pass -> Bool
famDeclHasCusk _ (FamilyDecl { fdInfo      = ClosedTypeFamily _
                             , fdTyVars    = tyvars
                             , fdResultSig = L _ resultSig })
  = hsTvbAllKinded tyvars && hasReturnKindSignature resultSig
famDeclHasCusk mb_class_cusk _ = mb_class_cusk `orElse` True
        -- all un-associated open families have CUSKs!

-- | Does this family declaration have user-supplied return kind signature?
hasReturnKindSignature :: FamilyResultSig a -> Bool
hasReturnKindSignature NoSig                          = False
hasReturnKindSignature (TyVarSig (L _ (UserTyVar _))) = False
hasReturnKindSignature _                              = True

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

instance (SourceTextX pass, OutputableBndrId pass)
       => Outputable (FamilyDecl pass) where
  ppr = pprFamilyDecl TopLevel

pprFamilyDecl :: (SourceTextX pass, OutputableBndrId pass)
              => TopLevelFlag -> FamilyDecl pass -> 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 [] <+>
           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
    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 eqns )
      _ -> (empty, empty)

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_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
   }
deriving instance (DataId id) => Data (HsDataDefn id)

-- | 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_strategy :: Maybe (Located DerivStrategy)
      -- ^ 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)@.
    }
deriving instance (DataId id) => Data (HsDerivingClause id)

instance (SourceTextX pass, OutputableBndrId pass)
       => Outputable (HsDerivingClause pass) where
  ppr (HsDerivingClause { deriv_clause_strategy = dcs
                        , deriv_clause_tys      = L _ dct })
    = hsep [ text "deriving"
           , ppDerivStrategy dcs
           , pp_dct dct ]
      where
        -- This complexity is to distinguish between
        --    deriving Show
        --    deriving (Show)
        pp_dct [a@(HsIB { hsib_body = L _ HsAppsTy{} })] = parens (ppr a)
        pp_dct [a] = ppr a
        pp_dct _   = parens (interpp'SP dct)

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

-- | 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_names   :: [Located (IdP pass)]
      , con_type    :: LHsSigType pass
        -- ^ The type after the ‘::’
      , con_doc     :: Maybe LHsDocString
          -- ^ A possible Haddock comment.
      }

  | ConDeclH98
      { con_name    :: Located (IdP pass)

      , con_qvars     :: Maybe (LHsQTyVars pass)
        -- User-written forall (if any), and its implicit
        -- kind variables
        -- Non-Nothing needs -XExistentialQuantification
        --               e.g. data T a = forall b. MkT b (b->a)
        --               con_qvars = {b}

      , con_cxt       :: Maybe (LHsContext pass)
        -- ^ User-written context (if any)

      , con_details   :: HsConDeclDetails pass
          -- ^ Arguments

      , con_doc       :: Maybe LHsDocString
          -- ^ A possible Haddock comment.
      }
deriving instance (DataId pass) => Data (ConDecl pass)

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

getConNames :: ConDecl pass -> [Located (IdP pass)]
getConNames ConDeclH98  {con_name  = name}  = [name]
getConNames ConDeclGADT {con_names = names} = names

-- don't call with RdrNames, because it can't deal with HsAppsTy
getConDetails :: ConDecl pass -> HsConDeclDetails pass
getConDetails ConDeclH98  {con_details  = details} = details
getConDetails ConDeclGADT {con_type     = ty     } = details
  where
    (details,_,_,_) = gadtDeclDetails ty

-- don't call with RdrNames, because it can't deal with HsAppsTy
gadtDeclDetails :: LHsSigType pass
                -> ( HsConDeclDetails pass
                   , LHsType pass
                   , LHsContext pass
                   , [LHsTyVarBndr pass] )
gadtDeclDetails HsIB {hsib_body = lbody_ty} = (details,res_ty,cxt,tvs)
  where
    (tvs, cxt, tau) = splitLHsSigmaTy lbody_ty
    (details, res_ty)           -- See Note [Sorting out the result type]
      = case tau of
          L _ (HsFunTy (L l (HsRecTy flds)) res_ty')
                  -> (RecCon (L l flds), res_ty')
          _other  -> (PrefixCon [], tau)

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)

pp_data_defn :: (SourceTextX pass, OutputableBndrId pass)
                  => (HsContext pass -> SDoc)   -- Printing the header
                  -> HsDataDefn pass
                  -> SDoc
pp_data_defn pp_hdr (HsDataDefn { dd_ND = new_or_data, dd_ctxt = L _ 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)

instance (SourceTextX pass, OutputableBndrId pass)
       => Outputable (HsDataDefn pass) where
   ppr d = pp_data_defn (\_ -> text "Naked HsDataDefn") d

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

pp_condecls :: (SourceTextX pass, OutputableBndrId pass)
            => [LConDecl pass] -> 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 (SourceTextX pass, OutputableBndrId pass)
       => Outputable (ConDecl pass) where
    ppr = pprConDecl

pprConDecl :: (SourceTextX pass, OutputableBndrId pass) => ConDecl pass -> SDoc
pprConDecl (ConDeclH98 { con_name = L _ con
                       , con_qvars = mtvs
                       , con_cxt = mcxt
                       , con_details = details
                       , con_doc = doc })
  = sep [ppr_mbDoc doc, pprHsForAll tvs cxt,         ppr_details details]
  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)
    tvs = case mtvs of
      Nothing -> []
      Just (HsQTvs { hsq_explicit = tvs }) -> tvs

    cxt = fromMaybe (noLoc []) mcxt

pprConDecl (ConDeclGADT { con_names = cons, con_type = res_ty, con_doc = doc })
  = sep [ppr_mbDoc doc <+> ppr_con_names cons <+> dcolon
         <+> ppr res_ty]

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 TyFamEqn represents one equation of a type family instance.
It is parameterised over its tfe_pats field:

 * An ordinary type family instance declaration looks like this in source Haskell
      type instance T [a] Int = a -> a
   (or something similar for a closed family)
   It is represented by a TyFamInstEqn, with *type* in the tfe_pats field.

 * On the other hand, the *default instance* of an associated type looks like
   this in source Haskell
      class C a where
        type T a b
        type T a b = a -> b   -- The default instance
   It is represented by a TyFamDefltEqn, with *type variables* in the tfe_pats
   field.
-}

----------------- 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

-- | Located Type Family Default Equation
type LTyFamDefltEqn pass = Located (TyFamDefltEqn pass)

-- | Haskell Type Patterns
type HsTyPats pass = HsImplicitBndrs pass [LHsType pass]
            -- ^ Type patterns (with kind and type bndrs)
            -- See Note [Family instance declaration binders]

{- Note [Family instance declaration binders]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The HsTyPats field is LHS patterns or a type/data family instance.

The hsib_vars of the HsImplicitBndrs are the template variables of the
type patterns, i.e. fv(pat_tys).  Note 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
-}

-- | Type Family Instance Equation
type TyFamInstEqn  pass = TyFamEqn pass (HsTyPats pass)

-- | Type Family Default Equation
type TyFamDefltEqn pass = TyFamEqn pass (LHsQTyVars pass)
  -- See Note [Type family instance declarations in HsSyn]

-- | Type Family Equation
--
-- One equation in a type family instance declaration
-- See Note [Type family instance declarations in HsSyn]
data TyFamEqn pass pats
  = TyFamEqn
       { tfe_tycon  :: Located (IdP pass)
       , tfe_pats   :: pats
       , tfe_fixity :: LexicalFixity    -- ^ Fixity used in the declaration
       , tfe_rhs    :: LHsType pass }
    -- ^
    --  - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnEqual'

    -- For details on above see note [Api annotations] in ApiAnnotation
deriving instance (DataId pass, Data pats) => Data (TyFamEqn pass pats)

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

-- | Type Family Instance Declaration
data TyFamInstDecl pass
  = TyFamInstDecl
       { tfid_eqn  :: LTyFamInstEqn pass
       , tfid_fvs  :: PostRn pass NameSet }
    -- ^
    --  - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnType',
    --           'ApiAnnotation.AnnInstance',

    -- For details on above see note [Api annotations] in ApiAnnotation
deriving instance (DataId pass) => Data (TyFamInstDecl pass)

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

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

-- | Data Family Instance Declaration
data DataFamInstDecl pass
  = DataFamInstDecl
       { dfid_tycon     :: Located (IdP pass)
       , dfid_pats      :: HsTyPats   pass       -- LHS
       , dfid_fixity    :: LexicalFixity    -- ^ Fixity used in the declaration
       , dfid_defn      :: HsDataDefn pass       -- RHS
       , dfid_fvs       :: PostRn pass NameSet }
                                           -- Free vars for dependency analysis
    -- ^
    --  - '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
deriving instance (DataId pass) => Data (DataFamInstDecl pass)

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

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

-- | Class Instance Declaration
data ClsInstDecl pass
  = ClsInstDecl
      { 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
deriving instance (DataId id) => Data (ClsInstDecl id)


----------------- 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_inst  :: ClsInstDecl pass }
  | DataFamInstD              -- data family instance
      { dfid_inst :: DataFamInstDecl pass }
  | TyFamInstD              -- type family instance
      { tfid_inst :: TyFamInstDecl pass }
deriving instance (DataId id) => Data (InstDecl id)

instance (SourceTextX pass, OutputableBndrId pass)
       => Outputable (TyFamInstDecl pass) where
  ppr = pprTyFamInstDecl TopLevel

pprTyFamInstDecl :: (SourceTextX pass, OutputableBndrId pass)
                 => TopLevelFlag -> TyFamInstDecl pass -> 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

ppr_fam_inst_eqn :: (SourceTextX pass, OutputableBndrId pass)
                 => LTyFamInstEqn pass -> SDoc
ppr_fam_inst_eqn (L _ (TyFamEqn { tfe_tycon = tycon
                                , tfe_pats  = pats
                                , tfe_fixity = fixity
                                , tfe_rhs   = rhs }))
    = pprFamInstLHS tycon pats fixity [] Nothing <+> equals <+> ppr rhs

ppr_fam_deflt_eqn :: (SourceTextX pass, OutputableBndrId pass)
                  => LTyFamDefltEqn pass -> SDoc
ppr_fam_deflt_eqn (L _ (TyFamEqn { tfe_tycon = tycon
                                 , tfe_pats  = tvs
                                 , tfe_fixity = fixity
                                 , tfe_rhs   = rhs }))
    = text "type" <+> pp_vanilla_decl_head tycon tvs fixity []
                  <+> equals <+> ppr rhs

instance (SourceTextX pass, OutputableBndrId pass)
       => Outputable (DataFamInstDecl pass) where
  ppr = pprDataFamInstDecl TopLevel

pprDataFamInstDecl :: (SourceTextX pass, OutputableBndrId pass)
                   => TopLevelFlag -> DataFamInstDecl pass -> SDoc
pprDataFamInstDecl top_lvl (DataFamInstDecl { dfid_tycon = tycon
                                            , dfid_pats  = pats
                                            , dfid_fixity = fixity
                                            , dfid_defn  = defn })
  = pp_data_defn pp_hdr defn
  where
    pp_hdr ctxt = ppr_instance_keyword top_lvl
              <+> pprFamInstLHS tycon pats fixity ctxt (dd_kindSig defn)

pprDataFamInstFlavour :: DataFamInstDecl pass -> SDoc
pprDataFamInstFlavour (DataFamInstDecl { dfid_defn = (HsDataDefn { dd_ND = nd }) })
  = ppr nd

pprFamInstLHS :: (SourceTextX pass, OutputableBndrId pass)
   => Located (IdP pass)
   -> HsTyPats pass
   -> LexicalFixity
   -> HsContext pass
   -> Maybe (LHsKind pass)
   -> SDoc
pprFamInstLHS thing (HsIB { hsib_body = typats }) fixity context mb_kind_sig
                                              -- explicit type patterns
   = hsep [ pprHsContext context, pp_pats typats, pp_kind_sig ]
   where
     pp_pats (patl:patsr)
       | fixity == Infix
          = hsep [pprHsType (unLoc patl), pprInfixOcc (unLoc thing)
          , hsep (map (pprHsType.unLoc) patsr)]
       | otherwise = hsep [ pprPrefixOcc (unLoc thing)
                   , hsep (map (pprHsType.unLoc) (patl:patsr))]
     pp_pats [] = pprPrefixOcc (unLoc thing)

     pp_kind_sig
       | Just k <- mb_kind_sig
       = dcolon <+> ppr k
       | otherwise
       = empty

instance (SourceTextX pass, OutputableBndrId pass)
       => Outputable (ClsInstDecl pass) 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

ppDerivStrategy :: Maybe (Located DerivStrategy) -> 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 (SourceTextX pass, OutputableBndrId pass)
       => Outputable (InstDecl pass) where
    ppr (ClsInstD     { cid_inst  = decl }) = ppr decl
    ppr (TyFamInstD   { tfid_inst = decl }) = ppr decl
    ppr (DataFamInstD { dfid_inst = decl }) = ppr decl

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

instDeclDataFamInsts :: [LInstDecl pass] -> [DataFamInstDecl pass]
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 {}))                              = []

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

-- | Located Deriving Declaration
type LDerivDecl pass = Located (DerivDecl pass)

-- | Deriving Declaration
data DerivDecl pass = DerivDecl
        { deriv_type         :: LHsSigType pass
        , deriv_strategy     :: Maybe (Located DerivStrategy)
        , 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
        }
deriving instance (DataId pass) => Data (DerivDecl pass)

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

{-
************************************************************************
*                                                                      *
\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 [LHsType pass]
        -- ^ - 'ApiAnnotation.AnnKeywordId's : 'ApiAnnotation.AnnDefault',
        --          'ApiAnnotation.AnnOpen','ApiAnnotation.AnnClose'

        -- For details on above see note [Api annotations] in ApiAnnotation
deriving instance (DataId pass) => Data (DefaultDecl pass)

instance (SourceTextX pass, OutputableBndrId pass)
       => Outputable (DefaultDecl pass) where

    ppr (DefaultDecl tys)
      = text "default" <+> parens (interpp'SP tys)

{-
************************************************************************
*                                                                      *
\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_name   :: Located (IdP pass)    -- defines this name
      , fd_sig_ty :: LHsSigType pass       -- sig_ty
      , fd_co     :: PostTc pass Coercion  -- rep_ty ~ sig_ty
      , fd_fi     :: ForeignImport }

  | ForeignExport
      { fd_name   :: Located (IdP pass)    -- uses this name
      , fd_sig_ty :: LHsSigType pass       -- sig_ty
      , fd_co     :: PostTc pass Coercion  -- rep_ty ~ 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

deriving instance (DataId pass) => Data (ForeignDecl 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.
-}

noForeignImportCoercionYet :: PlaceHolder
noForeignImportCoercionYet = PlaceHolder

noForeignExportCoercionYet :: PlaceHolder
noForeignExportCoercionYet = PlaceHolder

-- 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 (SourceTextX pass, OutputableBndrId pass)
       => Outputable (ForeignDecl pass) 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)

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_src   :: SourceText
                              , rds_rules :: [LRuleDecl pass] }
deriving instance (DataId pass) => Data (RuleDecls pass)

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

-- | Rule Declaration
data RuleDecl pass
  = HsRule                             -- Source rule
        (Located (SourceText,RuleName)) -- Rule name
               -- Note [Pragma source text] in BasicTypes
        Activation
        [LRuleBndr pass]        -- Forall'd vars; after typechecking this
                                --   includes tyvars
        (Located (HsExpr pass)) -- LHS
        (PostRn pass NameSet)   -- Free-vars from the LHS
        (Located (HsExpr pass)) -- RHS
        (PostRn pass NameSet)   -- Free-vars from the RHS
        -- ^
        --  - 'ApiAnnotation.AnnKeywordId' :
        --           'ApiAnnotation.AnnOpen','ApiAnnotation.AnnTilde',
        --           'ApiAnnotation.AnnVal',
        --           'ApiAnnotation.AnnClose',
        --           'ApiAnnotation.AnnForall','ApiAnnotation.AnnDot',
        --           'ApiAnnotation.AnnEqual',

        -- For details on above see note [Api annotations] in ApiAnnotation
deriving instance (DataId pass) => Data (RuleDecl pass)

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 (Located (IdP pass))
  | RuleBndrSig (Located (IdP pass)) (LHsSigWcType pass)
        -- ^
        --  - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen',
        --     'ApiAnnotation.AnnDcolon','ApiAnnotation.AnnClose'

        -- For details on above see note [Api annotations] in ApiAnnotation
deriving instance (DataId pass) => Data (RuleBndr pass)

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 (SourceTextX pass, OutputableBndrId pass)
       => Outputable (RuleDecls pass) where
  ppr (HsRules st rules)
    = pprWithSourceText st (text "{-# RULES")
          <+> vcat (punctuate semi (map ppr rules)) <+> text "#-}"

instance (SourceTextX pass, OutputableBndrId pass)
       => Outputable (RuleDecl pass) where
  ppr (HsRule name act ns lhs _fv_lhs rhs _fv_rhs)
        = sep [pprFullRuleName name <+> ppr act,
               nest 4 (pp_forall <+> pprExpr (unLoc lhs)),
               nest 6 (equals <+> pprExpr (unLoc rhs)) ]
        where
          pp_forall | null ns   = empty
                    | otherwise = forAllLit <+> fsep (map ppr ns) <> dot

instance (SourceTextX pass, OutputableBndrId pass)
       => Outputable (RuleBndr pass) where
   ppr (RuleBndr name) = ppr name
   ppr (RuleBndrSig name ty) = parens (ppr name <> dcolon <> ppr ty)

{-
************************************************************************
*                                                                      *
\subsection{Vectorisation declarations}
*                                                                      *
************************************************************************

A vectorisation pragma, one of

  {-# VECTORISE f = closure1 g (scalar_map g) #-}
  {-# VECTORISE SCALAR f #-}
  {-# NOVECTORISE f #-}

  {-# VECTORISE type T = ty #-}
  {-# VECTORISE SCALAR type T #-}
-}

-- | Located Vectorise Declaration
type LVectDecl pass = Located (VectDecl pass)

-- | Vectorise Declaration
data VectDecl pass
  = HsVect
      SourceText   -- Note [Pragma source text] in BasicTypes
      (Located (IdP pass))
      (LHsExpr pass)
        -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen',
        --           'ApiAnnotation.AnnEqual','ApiAnnotation.AnnClose'

        -- For details on above see note [Api annotations] in ApiAnnotation
  | HsNoVect
      SourceText   -- Note [Pragma source text] in BasicTypes
      (Located (IdP pass))
        -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen',
        --                                    'ApiAnnotation.AnnClose'

        -- For details on above see note [Api annotations] in ApiAnnotation
  | HsVectTypeIn                -- pre type-checking
      SourceText                -- Note [Pragma source text] in BasicTypes
      Bool                      -- 'TRUE' => SCALAR declaration
      (Located (IdP pass))
      (Maybe (Located (IdP pass))) -- 'Nothing' => no right-hand side
        -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen',
        --           'ApiAnnotation.AnnType','ApiAnnotation.AnnClose',
        --           'ApiAnnotation.AnnEqual'

        -- For details on above see note [Api annotations] in ApiAnnotation
  | HsVectTypeOut               -- post type-checking
      Bool                      -- 'TRUE' => SCALAR declaration
      TyCon
      (Maybe TyCon)             -- 'Nothing' => no right-hand side
  | HsVectClassIn               -- pre type-checking
      SourceText                -- Note [Pragma source text] in BasicTypes
      (Located (IdP pass))
        -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen',
        --           'ApiAnnotation.AnnClass','ApiAnnotation.AnnClose',

       -- For details on above see note [Api annotations] in ApiAnnotation
  | HsVectClassOut              -- post type-checking
      Class
  | HsVectInstIn                -- pre type-checking (always SCALAR)  !!!FIXME: should be superfluous now
      (LHsSigType pass)
  | HsVectInstOut               -- post type-checking (always SCALAR) !!!FIXME: should be superfluous now
      ClsInst
deriving instance (DataId pass) => Data (VectDecl pass)

lvectDeclName :: NamedThing (IdP pass) => LVectDecl pass -> Name
lvectDeclName (L _ (HsVect _       (L _ name) _))    = getName name
lvectDeclName (L _ (HsNoVect _     (L _ name)))      = getName name
lvectDeclName (L _ (HsVectTypeIn _  _ (L _ name) _)) = getName name
lvectDeclName (L _ (HsVectTypeOut  _ tycon _))       = getName tycon
lvectDeclName (L _ (HsVectClassIn _ (L _ name)))     = getName name
lvectDeclName (L _ (HsVectClassOut cls))             = getName cls
lvectDeclName (L _ (HsVectInstIn _))
  = panic "HsDecls.lvectDeclName: HsVectInstIn"
lvectDeclName (L _ (HsVectInstOut  _))
  = panic "HsDecls.lvectDeclName: HsVectInstOut"

lvectInstDecl :: LVectDecl pass -> Bool
lvectInstDecl (L _ (HsVectInstIn _))  = True
lvectInstDecl (L _ (HsVectInstOut _)) = True
lvectInstDecl _                       = False

instance (SourceTextX pass, OutputableBndrId pass)
       => Outputable (VectDecl pass) where
  ppr (HsVect _ v rhs)
    = sep [text "{-# VECTORISE" <+> ppr v,
           nest 4 $
             pprExpr (unLoc rhs) <+> text "#-}" ]
  ppr (HsNoVect _ v)
    = sep [text "{-# NOVECTORISE" <+> ppr v <+> text "#-}" ]
  ppr (HsVectTypeIn _ False t Nothing)
    = sep [text "{-# VECTORISE type" <+> ppr t <+> text "#-}" ]
  ppr (HsVectTypeIn _ False t (Just t'))
    = sep [text "{-# VECTORISE type" <+> ppr t, text "=", ppr t', text "#-}" ]
  ppr (HsVectTypeIn _ True t Nothing)
    = sep [text "{-# VECTORISE SCALAR type" <+> ppr t <+> text "#-}" ]
  ppr (HsVectTypeIn _ True t (Just t'))
    = sep [text "{-# VECTORISE SCALAR type" <+> ppr t, text "=", ppr t', text "#-}" ]
  ppr (HsVectTypeOut False t Nothing)
    = sep [text "{-# VECTORISE type" <+> ppr t <+> text "#-}" ]
  ppr (HsVectTypeOut False t (Just t'))
    = sep [text "{-# VECTORISE type" <+> ppr t, text "=", ppr t', text "#-}" ]
  ppr (HsVectTypeOut True t Nothing)
    = sep [text "{-# VECTORISE SCALAR type" <+> ppr t <+> text "#-}" ]
  ppr (HsVectTypeOut True t (Just t'))
    = sep [text "{-# VECTORISE SCALAR type" <+> ppr t, text "=", ppr t', text "#-}" ]
  ppr (HsVectClassIn _ c)
    = sep [text "{-# VECTORISE class" <+> ppr c <+> text "#-}" ]
  ppr (HsVectClassOut c)
    = sep [text "{-# VECTORISE class" <+> ppr c <+> text "#-}" ]
  ppr (HsVectInstIn ty)
    = sep [text "{-# VECTORISE SCALAR instance" <+> ppr ty <+> text "#-}" ]
  ppr (HsVectInstOut i)
    = sep [text "{-# VECTORISE SCALAR instance" <+> ppr i <+> text "#-}" ]

{-
************************************************************************
*                                                                      *
\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_src :: SourceText
                               , wd_warnings :: [LWarnDecl pass]
                               }
deriving instance (DataId pass) => Data (WarnDecls pass)

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

-- | Warning pragma Declaration
data WarnDecl pass = Warning [Located (IdP pass)] WarningTxt
deriving instance (DataId pass) => Data (WarnDecl pass)

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

instance OutputableBndr (IdP pass) => Outputable (WarnDecl pass) where
    ppr (Warning thing txt)
      = hsep ( punctuate comma (map ppr thing))
              <+> ppr txt

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

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

-- | Annotation Declaration
data AnnDecl pass = HsAnnotation
                      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
deriving instance (DataId pass) => Data (AnnDecl pass)

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

-- | 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 (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
deriving instance (DataId pass) => Data (RoleAnnotDecl pass)

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

roleAnnotDeclName :: RoleAnnotDecl pass -> (IdP pass)
roleAnnotDeclName (RoleAnnotDecl (L _ name) _) = name