{-
(c) The University of Glasgow 2006
(c) The AQUA Project, Glasgow University, 1996-1998


TcTyClsDecls: Typecheck type and class declarations
-}

{-# LANGUAGE CPP, TupleSections, ScopedTypeVariables, MultiWayIf #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE ViewPatterns #-}

{-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-}

module TcTyClsDecls (
        tcTyAndClassDecls,

        -- Functions used by TcInstDcls to check
        -- data/type family instance declarations
        kcConDecls, tcConDecls, dataDeclChecks, checkValidTyCon,
        tcFamTyPats, tcTyFamInstEqn,
        tcAddTyFamInstCtxt, tcMkDataFamInstCtxt, tcAddDataFamInstCtxt,
        unravelFamInstPats, addConsistencyConstraints,
        wrongKindOfFamily
    ) where

#include "HsVersions.h"

import GhcPrelude

import GHC.Hs
import HscTypes
import BuildTyCl
import TcRnMonad
import TcEnv
import TcValidity
import TcHsSyn
import TcTyDecls
import TcClassDcl
import {-# SOURCE #-} TcInstDcls( tcInstDecls1 )
import TcDeriv (DerivInfo(..))
import TcUnify ( unifyKind, checkTvConstraints )
import TcHsType
import ClsInst( AssocInstInfo(..) )
import TcMType
import TysWiredIn ( unitTy, makeRecoveryTyCon )
import TcType
import RnEnv( lookupConstructorFields )
import FamInst
import FamInstEnv
import Coercion
import TcOrigin
import Type
import TyCoRep   -- for checkValidRoles
import TyCoPpr( pprTyVars, pprWithExplicitKindsWhen )
import Class
import CoAxiom
import TyCon
import DataCon
import Id
import Var
import VarEnv
import VarSet
import Module
import Name
import NameSet
import NameEnv
import Outputable
import Maybes
import Unify
import Util
import SrcLoc
import ListSetOps
import DynFlags
import Unique
import ConLike( ConLike(..) )
import BasicTypes
import qualified GHC.LanguageExtensions as LangExt

import Control.Monad
import Data.Foldable
import Data.Function ( on )
import Data.Functor.Identity
import Data.List
import qualified Data.List.NonEmpty as NE
import Data.List.NonEmpty ( NonEmpty(..) )
import qualified Data.Set as Set
import Data.Tuple( swap )

{-
************************************************************************
*                                                                      *
\subsection{Type checking for type and class declarations}
*                                                                      *
************************************************************************

Note [Grouping of type and class declarations]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
tcTyAndClassDecls is called on a list of `TyClGroup`s. Each group is a strongly
connected component of mutually dependent types and classes. We kind check and
type check each group separately to enhance kind polymorphism. Take the
following example:

  type Id a = a
  data X = X (Id Int)

If we were to kind check the two declarations together, we would give Id the
kind * -> *, since we apply it to an Int in the definition of X. But we can do
better than that, since Id really is kind polymorphic, and should get kind
forall (k::*). k -> k. Since it does not depend on anything else, it can be
kind-checked by itself, hence getting the most general kind. We then kind check
X, which works fine because we then know the polymorphic kind of Id, and simply
instantiate k to *.

Note [Check role annotations in a second pass]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Role inference potentially depends on the types of all of the datacons declared
in a mutually recursive group. The validity of a role annotation, in turn,
depends on the result of role inference. Because the types of datacons might
be ill-formed (see #7175 and Note [Checking GADT return types]) we must check
*all* the tycons in a group for validity before checking *any* of the roles.
Thus, we take two passes over the resulting tycons, first checking for general
validity and then checking for valid role annotations.
-}

tcTyAndClassDecls :: [TyClGroup GhcRn]      -- Mutually-recursive groups in
                                            -- dependency order
                  -> TcM ( TcGblEnv         -- Input env extended by types and
                                            -- classes
                                            -- and their implicit Ids,DataCons
                         , [InstInfo GhcRn] -- Source-code instance decls info
                         , [DerivInfo]      -- Deriving info
                         )
-- Fails if there are any errors
tcTyAndClassDecls :: [TyClGroup GhcRn] -> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo])
tcTyAndClassDecls [TyClGroup GhcRn]
tyclds_s
  -- The code recovers internally, but if anything gave rise to
  -- an error we'd better stop now, to avoid a cascade
  -- Type check each group in dependency order folding the global env
  = TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo])
-> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo])
forall r. TcM r -> TcM r
checkNoErrs (TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo])
 -> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo]))
-> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo])
-> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo])
forall a b. (a -> b) -> a -> b
$ [InstInfo GhcRn]
-> [DerivInfo]
-> [TyClGroup GhcRn]
-> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo])
fold_env [] [] [TyClGroup GhcRn]
tyclds_s
  where
    fold_env :: [InstInfo GhcRn]
             -> [DerivInfo]
             -> [TyClGroup GhcRn]
             -> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo])
    fold_env :: [InstInfo GhcRn]
-> [DerivInfo]
-> [TyClGroup GhcRn]
-> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo])
fold_env [InstInfo GhcRn]
inst_info [DerivInfo]
deriv_info []
      = do { TcGblEnv
gbl_env <- TcRnIf TcGblEnv TcLclEnv TcGblEnv
forall gbl lcl. TcRnIf gbl lcl gbl
getGblEnv
           ; (TcGblEnv, [InstInfo GhcRn], [DerivInfo])
-> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo])
forall (m :: * -> *) a. Monad m => a -> m a
return (TcGblEnv
gbl_env, [InstInfo GhcRn]
inst_info, [DerivInfo]
deriv_info) }
    fold_env [InstInfo GhcRn]
inst_info [DerivInfo]
deriv_info (TyClGroup GhcRn
tyclds:[TyClGroup GhcRn]
tyclds_s)
      = do { (TcGblEnv
tcg_env, [InstInfo GhcRn]
inst_info', [DerivInfo]
deriv_info') <- TyClGroup GhcRn -> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo])
tcTyClGroup TyClGroup GhcRn
tyclds
           ; TcGblEnv
-> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo])
-> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo])
forall gbl lcl a. gbl -> TcRnIf gbl lcl a -> TcRnIf gbl lcl a
setGblEnv TcGblEnv
tcg_env (TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo])
 -> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo]))
-> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo])
-> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo])
forall a b. (a -> b) -> a -> b
$
               -- remaining groups are typechecked in the extended global env.
             [InstInfo GhcRn]
-> [DerivInfo]
-> [TyClGroup GhcRn]
-> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo])
fold_env ([InstInfo GhcRn]
inst_info' [InstInfo GhcRn] -> [InstInfo GhcRn] -> [InstInfo GhcRn]
forall a. [a] -> [a] -> [a]
++ [InstInfo GhcRn]
inst_info)
                      ([DerivInfo]
deriv_info' [DerivInfo] -> [DerivInfo] -> [DerivInfo]
forall a. [a] -> [a] -> [a]
++ [DerivInfo]
deriv_info)
                      [TyClGroup GhcRn]
tyclds_s }

tcTyClGroup :: TyClGroup GhcRn
            -> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo])
-- Typecheck one strongly-connected component of type, class, and instance decls
-- See Note [TyClGroups and dependency analysis] in GHC.Hs.Decls
tcTyClGroup :: TyClGroup GhcRn -> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo])
tcTyClGroup (TyClGroup { group_tyclds :: forall pass. TyClGroup pass -> [LTyClDecl pass]
group_tyclds = [LTyClDecl GhcRn]
tyclds
                       , group_roles :: forall pass. TyClGroup pass -> [LRoleAnnotDecl pass]
group_roles  = [LRoleAnnotDecl GhcRn]
roles
                       , group_kisigs :: forall pass. TyClGroup pass -> [LStandaloneKindSig pass]
group_kisigs = [LStandaloneKindSig GhcRn]
kisigs
                       , group_instds :: forall pass. TyClGroup pass -> [LInstDecl pass]
group_instds = [LInstDecl GhcRn]
instds })
  = do { let role_annots :: RoleAnnotEnv
role_annots = [LRoleAnnotDecl GhcRn] -> RoleAnnotEnv
mkRoleAnnotEnv [LRoleAnnotDecl GhcRn]
roles

           -- Step 1: Typecheck the standalone kind signatures and type/class declarations
       ; String -> SDoc -> TcRn ()
traceTc String
"---- tcTyClGroup ---- {" SDoc
empty
       ; String -> SDoc -> TcRn ()
traceTc String
"Decls for" ([Name] -> SDoc
forall a. Outputable a => a -> SDoc
ppr ((LTyClDecl GhcRn -> Name) -> [LTyClDecl GhcRn] -> [Name]
forall a b. (a -> b) -> [a] -> [b]
map (TyClDecl GhcRn -> Name
forall (p :: Pass). TyClDecl (GhcPass p) -> IdP (GhcPass p)
tcdName (TyClDecl GhcRn -> Name)
-> (LTyClDecl GhcRn -> TyClDecl GhcRn) -> LTyClDecl GhcRn -> Name
forall b c a. (b -> c) -> (a -> b) -> a -> c
. LTyClDecl GhcRn -> TyClDecl GhcRn
forall a. HasSrcSpan a => a -> SrcSpanLess a
unLoc) [LTyClDecl GhcRn]
tyclds))
       ; ([TyCon]
tyclss, [DerivInfo]
data_deriv_info) <-
           NameEnv TcTyThing
-> TcM ([TyCon], [DerivInfo]) -> TcM ([TyCon], [DerivInfo])
forall r. NameEnv TcTyThing -> TcM r -> TcM r
tcExtendKindEnv ([LTyClDecl GhcRn] -> NameEnv TcTyThing
mkPromotionErrorEnv [LTyClDecl GhcRn]
tyclds) (TcM ([TyCon], [DerivInfo]) -> TcM ([TyCon], [DerivInfo]))
-> TcM ([TyCon], [DerivInfo]) -> TcM ([TyCon], [DerivInfo])
forall a b. (a -> b) -> a -> b
$ -- See Note [Type environment evolution]
           do { NameEnv Kind
kisig_env <- [(Name, Kind)] -> NameEnv Kind
forall a. [(Name, a)] -> NameEnv a
mkNameEnv ([(Name, Kind)] -> NameEnv Kind)
-> IOEnv (Env TcGblEnv TcLclEnv) [(Name, Kind)]
-> IOEnv (Env TcGblEnv TcLclEnv) (NameEnv Kind)
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> (LStandaloneKindSig GhcRn
 -> IOEnv (Env TcGblEnv TcLclEnv) (Name, Kind))
-> [LStandaloneKindSig GhcRn]
-> IOEnv (Env TcGblEnv TcLclEnv) [(Name, Kind)]
forall (t :: * -> *) (f :: * -> *) a b.
(Traversable t, Applicative f) =>
(a -> f b) -> t a -> f (t b)
traverse LStandaloneKindSig GhcRn
-> IOEnv (Env TcGblEnv TcLclEnv) (Name, Kind)
tcStandaloneKindSig [LStandaloneKindSig GhcRn]
kisigs
              ; [LTyClDecl GhcRn]
-> NameEnv Kind -> RoleAnnotEnv -> TcM ([TyCon], [DerivInfo])
tcTyClDecls [LTyClDecl GhcRn]
tyclds NameEnv Kind
kisig_env RoleAnnotEnv
role_annots }

           -- Step 1.5: Make sure we don't have any type synonym cycles
       ; String -> SDoc -> TcRn ()
traceTc String
"Starting synonym cycle check" ([TyCon] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TyCon]
tyclss)
       ; UnitId
this_uid <- (DynFlags -> UnitId)
-> IOEnv (Env TcGblEnv TcLclEnv) DynFlags
-> IOEnv (Env TcGblEnv TcLclEnv) UnitId
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap DynFlags -> UnitId
thisPackage IOEnv (Env TcGblEnv TcLclEnv) DynFlags
forall (m :: * -> *). HasDynFlags m => m DynFlags
getDynFlags
       ; UnitId -> [TyCon] -> [LTyClDecl GhcRn] -> TcRn ()
checkSynCycles UnitId
this_uid [TyCon]
tyclss [LTyClDecl GhcRn]
tyclds
       ; String -> SDoc -> TcRn ()
traceTc String
"Done synonym cycle check" ([TyCon] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TyCon]
tyclss)

           -- Step 2: Perform the validity check on those types/classes
           -- We can do this now because we are done with the recursive knot
           -- Do it before Step 3 (adding implicit things) because the latter
           -- expects well-formed TyCons
       ; String -> SDoc -> TcRn ()
traceTc String
"Starting validity check" ([TyCon] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TyCon]
tyclss)
       ; [TyCon]
tyclss <- (TyCon -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon])
-> [TyCon] -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall (m :: * -> *) a b. Monad m => (a -> m [b]) -> [a] -> m [b]
concatMapM TyCon -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
checkValidTyCl [TyCon]
tyclss
       ; String -> SDoc -> TcRn ()
traceTc String
"Done validity check" ([TyCon] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TyCon]
tyclss)
       ; (TyCon -> TcRn ()) -> [TyCon] -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ (TcRn () -> TcRn () -> TcRn ()
forall r. TcRn r -> TcRn r -> TcRn r
recoverM (() -> TcRn ()
forall (m :: * -> *) a. Monad m => a -> m a
return ()) (TcRn () -> TcRn ()) -> (TyCon -> TcRn ()) -> TyCon -> TcRn ()
forall b c a. (b -> c) -> (a -> b) -> a -> c
. RoleAnnotEnv -> TyCon -> TcRn ()
checkValidRoleAnnots RoleAnnotEnv
role_annots) [TyCon]
tyclss
           -- See Note [Check role annotations in a second pass]

       ; String -> SDoc -> TcRn ()
traceTc String
"---- end tcTyClGroup ---- }" SDoc
empty

           -- Step 3: Add the implicit things;
           -- we want them in the environment because
           -- they may be mentioned in interface files
       ; TcGblEnv
gbl_env <- [TyCon] -> TcRnIf TcGblEnv TcLclEnv TcGblEnv
addTyConsToGblEnv [TyCon]
tyclss

           -- Step 4: check instance declarations
       ; (TcGblEnv
gbl_env', [InstInfo GhcRn]
inst_info, [DerivInfo]
datafam_deriv_info) <-
         TcGblEnv
-> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo])
-> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo])
forall gbl lcl a. gbl -> TcRnIf gbl lcl a -> TcRnIf gbl lcl a
setGblEnv TcGblEnv
gbl_env (TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo])
 -> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo]))
-> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo])
-> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo])
forall a b. (a -> b) -> a -> b
$
         [LInstDecl GhcRn] -> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo])
tcInstDecls1 [LInstDecl GhcRn]
instds

       ; let deriv_info :: [DerivInfo]
deriv_info = [DerivInfo]
datafam_deriv_info [DerivInfo] -> [DerivInfo] -> [DerivInfo]
forall a. [a] -> [a] -> [a]
++ [DerivInfo]
data_deriv_info
       ; (TcGblEnv, [InstInfo GhcRn], [DerivInfo])
-> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo])
forall (m :: * -> *) a. Monad m => a -> m a
return (TcGblEnv
gbl_env', [InstInfo GhcRn]
inst_info, [DerivInfo]
deriv_info) }


tcTyClGroup (XTyClGroup XXTyClGroup GhcRn
nec) = NoExtCon -> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo])
forall a. NoExtCon -> a
noExtCon XXTyClGroup GhcRn
NoExtCon
nec

-- Gives the kind for every TyCon that has a standalone kind signature
type KindSigEnv = NameEnv Kind

tcTyClDecls
  :: [LTyClDecl GhcRn]
  -> KindSigEnv
  -> RoleAnnotEnv
  -> TcM ([TyCon], [DerivInfo])
tcTyClDecls :: [LTyClDecl GhcRn]
-> NameEnv Kind -> RoleAnnotEnv -> TcM ([TyCon], [DerivInfo])
tcTyClDecls [LTyClDecl GhcRn]
tyclds NameEnv Kind
kisig_env RoleAnnotEnv
role_annots
  = do {    -- Step 1: kind-check this group and returns the final
            -- (possibly-polymorphic) kind of each TyCon and Class
            -- See Note [Kind checking for type and class decls]
         [TyCon]
tc_tycons <- NameEnv Kind
-> [LTyClDecl GhcRn] -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
kcTyClGroup NameEnv Kind
kisig_env [LTyClDecl GhcRn]
tyclds
       ; String -> SDoc -> TcRn ()
traceTc String
"tcTyAndCl generalized kinds" ([SDoc] -> SDoc
vcat ((TyCon -> SDoc) -> [TyCon] -> [SDoc]
forall a b. (a -> b) -> [a] -> [b]
map TyCon -> SDoc
ppr_tc_tycon [TyCon]
tc_tycons))

            -- Step 2: type-check all groups together, returning
            -- the final TyCons and Classes
            --
            -- NB: We have to be careful here to NOT eagerly unfold
            -- type synonyms, as we have not tested for type synonym
            -- loops yet and could fall into a black hole.
       ; (([TyCon], [DerivInfo]) -> TcM ([TyCon], [DerivInfo]))
-> TcM ([TyCon], [DerivInfo])
forall a env. (a -> IOEnv env a) -> IOEnv env a
fixM ((([TyCon], [DerivInfo]) -> TcM ([TyCon], [DerivInfo]))
 -> TcM ([TyCon], [DerivInfo]))
-> (([TyCon], [DerivInfo]) -> TcM ([TyCon], [DerivInfo]))
-> TcM ([TyCon], [DerivInfo])
forall a b. (a -> b) -> a -> b
$ \ ~([TyCon]
rec_tyclss, [DerivInfo]
_) -> do
           { TcGblEnv
tcg_env <- TcRnIf TcGblEnv TcLclEnv TcGblEnv
forall gbl lcl. TcRnIf gbl lcl gbl
getGblEnv
           ; let roles :: Name -> [Role]
roles = HscSource -> RoleAnnotEnv -> [TyCon] -> Name -> [Role]
inferRoles (TcGblEnv -> HscSource
tcg_src TcGblEnv
tcg_env) RoleAnnotEnv
role_annots [TyCon]
rec_tyclss

                 -- Populate environment with knot-tied ATyCon for TyCons
                 -- NB: if the decls mention any ill-staged data cons
                 -- (see Note [Recursion and promoting data constructors])
                 -- we will have failed already in kcTyClGroup, so no worries here
           ; ([TyCon]
tycons, [[DerivInfo]]
data_deriv_infos) <-
             [(Name, TyThing)]
-> TcM ([TyCon], [[DerivInfo]]) -> TcM ([TyCon], [[DerivInfo]])
forall r. [(Name, TyThing)] -> TcM r -> TcM r
tcExtendRecEnv ([TyCon] -> [TyCon] -> [(Name, TyThing)]
zipRecTyClss [TyCon]
tc_tycons [TyCon]
rec_tyclss) (TcM ([TyCon], [[DerivInfo]]) -> TcM ([TyCon], [[DerivInfo]]))
-> TcM ([TyCon], [[DerivInfo]]) -> TcM ([TyCon], [[DerivInfo]])
forall a b. (a -> b) -> a -> b
$

                 -- Also extend the local type envt with bindings giving
                 -- a TcTyCon for each each knot-tied TyCon or Class
                 -- See Note [Type checking recursive type and class declarations]
                 -- and Note [Type environment evolution]
             [TyCon]
-> TcM ([TyCon], [[DerivInfo]]) -> TcM ([TyCon], [[DerivInfo]])
forall a. [TyCon] -> TcM a -> TcM a
tcExtendKindEnvWithTyCons [TyCon]
tc_tycons (TcM ([TyCon], [[DerivInfo]]) -> TcM ([TyCon], [[DerivInfo]]))
-> TcM ([TyCon], [[DerivInfo]]) -> TcM ([TyCon], [[DerivInfo]])
forall a b. (a -> b) -> a -> b
$

                 -- Kind and type check declarations for this group
               (LTyClDecl GhcRn
 -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo]))
-> [LTyClDecl GhcRn] -> TcM ([TyCon], [[DerivInfo]])
forall (m :: * -> *) a b c.
Applicative m =>
(a -> m (b, c)) -> [a] -> m ([b], [c])
mapAndUnzipM ((Name -> [Role])
-> LTyClDecl GhcRn
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
tcTyClDecl Name -> [Role]
roles) [LTyClDecl GhcRn]
tyclds
           ; ([TyCon], [DerivInfo]) -> TcM ([TyCon], [DerivInfo])
forall (m :: * -> *) a. Monad m => a -> m a
return ([TyCon]
tycons, [[DerivInfo]] -> [DerivInfo]
forall (t :: * -> *) a. Foldable t => t [a] -> [a]
concat [[DerivInfo]]
data_deriv_infos)
           } }
  where
    ppr_tc_tycon :: TyCon -> SDoc
ppr_tc_tycon TyCon
tc = SDoc -> SDoc
parens ([SDoc] -> SDoc
sep [ Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyCon -> Name
tyConName TyCon
tc) SDoc -> SDoc -> SDoc
<> SDoc
comma
                                  , [TyConBinder] -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyCon -> [TyConBinder]
tyConBinders TyCon
tc) SDoc -> SDoc -> SDoc
<> SDoc
comma
                                  , Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyCon -> Kind
tyConResKind TyCon
tc)
                                  , Bool -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyCon -> Bool
isTcTyCon TyCon
tc) ])

zipRecTyClss :: [TcTyCon]
             -> [TyCon]           -- Knot-tied
             -> [(Name,TyThing)]
-- Build a name-TyThing mapping for the TyCons bound by decls
-- being careful not to look at the knot-tied [TyThing]
-- The TyThings in the result list must have a visible ATyCon,
-- because typechecking types (in, say, tcTyClDecl) looks at
-- this outer constructor
zipRecTyClss :: [TyCon] -> [TyCon] -> [(Name, TyThing)]
zipRecTyClss [TyCon]
tc_tycons [TyCon]
rec_tycons
  = [ (Name
name, TyCon -> TyThing
ATyCon (Name -> TyCon
get Name
name)) | TyCon
tc_tycon <- [TyCon]
tc_tycons, let name :: Name
name = TyCon -> Name
forall a. NamedThing a => a -> Name
getName TyCon
tc_tycon ]
  where
    rec_tc_env :: NameEnv TyCon
    rec_tc_env :: NameEnv TyCon
rec_tc_env = (TyCon -> NameEnv TyCon -> NameEnv TyCon)
-> NameEnv TyCon -> [TyCon] -> NameEnv TyCon
forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr TyCon -> NameEnv TyCon -> NameEnv TyCon
add_tc NameEnv TyCon
forall a. NameEnv a
emptyNameEnv [TyCon]
rec_tycons

    add_tc :: TyCon -> NameEnv TyCon -> NameEnv TyCon
    add_tc :: TyCon -> NameEnv TyCon -> NameEnv TyCon
add_tc TyCon
tc NameEnv TyCon
env = (TyCon -> NameEnv TyCon -> NameEnv TyCon)
-> NameEnv TyCon -> [TyCon] -> NameEnv TyCon
forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr TyCon -> NameEnv TyCon -> NameEnv TyCon
add_one_tc NameEnv TyCon
env (TyCon
tc TyCon -> [TyCon] -> [TyCon]
forall a. a -> [a] -> [a]
: TyCon -> [TyCon]
tyConATs TyCon
tc)

    add_one_tc :: TyCon -> NameEnv TyCon -> NameEnv TyCon
    add_one_tc :: TyCon -> NameEnv TyCon -> NameEnv TyCon
add_one_tc TyCon
tc NameEnv TyCon
env = NameEnv TyCon -> Name -> TyCon -> NameEnv TyCon
forall a. NameEnv a -> Name -> a -> NameEnv a
extendNameEnv NameEnv TyCon
env (TyCon -> Name
tyConName TyCon
tc) TyCon
tc

    get :: Name -> TyCon
get Name
name = case NameEnv TyCon -> Name -> Maybe TyCon
forall a. NameEnv a -> Name -> Maybe a
lookupNameEnv NameEnv TyCon
rec_tc_env Name
name of
                 Just TyCon
tc -> TyCon
tc
                 Maybe TyCon
other   -> String -> SDoc -> TyCon
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"zipRecTyClss" (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
name SDoc -> SDoc -> SDoc
<+> Maybe TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr Maybe TyCon
other)

{-
************************************************************************
*                                                                      *
                Kind checking
*                                                                      *
************************************************************************

Note [Kind checking for type and class decls]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Kind checking is done thus:

   1. Make up a kind variable for each parameter of the declarations,
      and extend the kind environment (which is in the TcLclEnv)

   2. Kind check the declarations

We need to kind check all types in the mutually recursive group
before we know the kind of the type variables.  For example:

  class C a where
     op :: D b => a -> b -> b

  class D c where
     bop :: (Monad c) => ...

Here, the kind of the locally-polymorphic type variable "b"
depends on *all the uses of class D*.  For example, the use of
Monad c in bop's type signature means that D must have kind Type->Type.

Note: we don't treat type synonyms specially (we used to, in the past);
in particular, even if we have a type synonym cycle, we still kind check
it normally, and test for cycles later (checkSynCycles).  The reason
we can get away with this is because we have more systematic TYPE r
inference, which means that we can do unification between kinds that
aren't lifted (this historically was not true.)

The downside of not directly reading off the kinds of the RHS of
type synonyms in topological order is that we don't transparently
support making synonyms of types with higher-rank kinds.  But
you can always specify a CUSK directly to make this work out.
See tc269 for an example.

Note [CUSKs and PolyKinds]
~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider

    data T (a :: *) = MkT (S a)   -- Has CUSK
    data S a = MkS (T Int) (S a)  -- No CUSK

Via inferInitialKinds we get
  T :: * -> *
  S :: kappa -> *

Then we call kcTyClDecl on each decl in the group, to constrain the
kind unification variables.  BUT we /skip/ the RHS of any decl with
a CUSK.  Here we skip the RHS of T, so we eventually get
  S :: forall k. k -> *

This gets us more polymorphism than we would otherwise get, similar
(but implemented strangely differently from) the treatment of type
signatures in value declarations.

However, we only want to do so when we have PolyKinds.
When we have NoPolyKinds, we don't skip those decls, because we have defaulting
(#16609). Skipping won't bring us more polymorphism when we have defaulting.
Consider

  data T1 a = MkT1 T2        -- No CUSK
  data T2 = MkT2 (T1 Maybe)  -- Has CUSK

If we skip the rhs of T2 during kind-checking, the kind of a remains unsolved.
With PolyKinds, we do generalization to get T1 :: forall a. a -> *. And the
program type-checks.
But with NoPolyKinds, we do defaulting to get T1 :: * -> *. Defaulting happens
in quantifyTyVars, which is called from generaliseTcTyCon. Then type-checking
(T1 Maybe) will throw a type error.

Summary: with PolyKinds, we must skip; with NoPolyKinds, we must /not/ skip.

Open type families
~~~~~~~~~~~~~~~~~~
This treatment of type synonyms only applies to Haskell 98-style synonyms.
General type functions can be recursive, and hence, appear in `alg_decls'.

The kind of an open type family is solely determinded by its kind signature;
hence, only kind signatures participate in the construction of the initial
kind environment (as constructed by `inferInitialKind'). In fact, we ignore
instances of families altogether in the following. However, we need to include
the kinds of *associated* families into the construction of the initial kind
environment. (This is handled by `allDecls').

See also Note [Kind checking recursive type and class declarations]

Note [How TcTyCons work]
~~~~~~~~~~~~~~~~~~~~~~~~
TcTyCons are used for two distinct purposes

1.  When recovering from a type error in a type declaration,
    we want to put the erroneous TyCon in the environment in a
    way that won't lead to more errors.  We use a TcTyCon for this;
    see makeRecoveryTyCon.

2.  When checking a type/class declaration (in module TcTyClsDecls), we come
    upon knowledge of the eventual tycon in bits and pieces.

      S1) First, we use inferInitialKinds to look over the user-provided
          kind signature of a tycon (including, for example, the number
          of parameters written to the tycon) to get an initial shape of
          the tycon's kind.  We record that shape in a TcTyCon.

          For CUSK tycons, the TcTyCon has the final, generalised kind.
          For non-CUSK tycons, the TcTyCon has as its tyConBinders only
          the explicit arguments given -- no kind variables, etc.

      S2) Then, using these initial kinds, we kind-check the body of the
          tycon (class methods, data constructors, etc.), filling in the
          metavariables in the tycon's initial kind.

      S3) We then generalize to get the (non-CUSK) tycon's final, fixed
          kind. Finally, once this has happened for all tycons in a
          mutually recursive group, we can desugar the lot.

    For convenience, we store partially-known tycons in TcTyCons, which
    might store meta-variables. These TcTyCons are stored in the local
    environment in TcTyClsDecls, until the real full TyCons can be created
    during desugaring. A desugared program should never have a TcTyCon.

3.  In a TcTyCon, everything is zonked after the kind-checking pass (S2).

4.  tyConScopedTyVars.  A challenging piece in all of this is that we
    end up taking three separate passes over every declaration:
      - one in inferInitialKind (this pass look only at the head, not the body)
      - one in kcTyClDecls (to kind-check the body)
      - a final one in tcTyClDecls (to desugar)

    In the latter two passes, we need to connect the user-written type
    variables in an LHsQTyVars with the variables in the tycon's
    inferred kind. Because the tycon might not have a CUSK, this
    matching up is, in general, quite hard to do.  (Look through the
    git history between Dec 2015 and Apr 2016 for
    TcHsType.splitTelescopeTvs!)

    Instead of trying, we just store the list of type variables to
    bring into scope, in the tyConScopedTyVars field of the TcTyCon.
    These tyvars are brought into scope in TcHsType.bindTyClTyVars.

    In a TcTyCon, why is tyConScopedTyVars :: [(Name,TcTyVar)] rather
    than just [TcTyVar]?  Consider these mutually-recursive decls
       data T (a :: k1) b = MkT (S a b)
       data S (c :: k2) d = MkS (T c d)
    We start with k1 bound to kappa1, and k2 to kappa2; so initially
    in the (Name,TcTyVar) pairs the Name is that of the TcTyVar. But
    then kappa1 and kappa2 get unified; so after the zonking in
    'generalise' in 'kcTyClGroup' the Name and TcTyVar may differ.

See also Note [Type checking recursive type and class declarations].

Note [Swizzling the tyvars before generaliseTcTyCon]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This Note only applies when /inferring/ the kind of a TyCon.
If there is a separate kind signature, or a CUSK, we take an entirely
different code path.

For inference, consider
   class C (f :: k) x where
      type T f
      op :: D f => blah
   class D (g :: j) y where
      op :: C g => y -> blah

Here C and D are considered mutually recursive.  Neither has a CUSK.
Just before generalisation we have the (un-quantified) kinds
   C :: k1 -> k2 -> Constraint
   T :: k1 -> Type
   D :: k1 -> Type -> Constraint
Notice that f's kind and g's kind have been unified to 'k1'. We say
that k1 is the "representative" of k in C's decl, and of j in D's decl.

Now when quantifying, we'd like to end up with
   C :: forall {k2}. forall k. k -> k2 -> Constraint
   T :: forall k. k -> Type
   D :: forall j. j -> Type -> Constraint

That is, we want to swizzle the representative to have the Name given
by the user. Partly this is to improve error messages and the output of
:info in GHCi.  But it is /also/ important because the code for a
default method may mention the class variable(s), but at that point
(tcClassDecl2), we only have the final class tyvars available.
(Alternatively, we could record the scoped type variables in the
TyCon, but it's a nuisance to do so.)

Notes:

* On the input to generaliseTyClDecl, the mapping between the
  user-specified Name and the representative TyVar is recorded in the
  tyConScopedTyVars of the TcTyCon.  NB: you first need to zonk to see
  this representative TyVar.

* The swizzling is actually performed by swizzleTcTyConBndrs

* We must do the swizzling across the whole class decl. Consider
     class C f where
       type S (f :: k)
       type T f
  Here f's kind k is a parameter of C, and its identity is shared
  with S and T.  So if we swizzle the representative k at all, we
  must do so consistently for the entire declaration.

  Hence the call to check_duplicate_tc_binders is in generaliseTyClDecl,
  rather than in generaliseTcTyCon.

There are errors to catch here.  Suppose we had
   class E (f :: j) (g :: k) where
     op :: SameKind f g -> blah

Then, just before generalisation we will have the (unquantified)
   E :: k1 -> k1 -> Constraint

That's bad!  Two distinctly-named tyvars (j and k) have ended up with
the same representative k1.  So when swizzling, we check (in
check_duplicate_tc_binders) that two distinct source names map
to the same representative.

Here's an interesting case:
    class C1 f where
      type S (f :: k1)
      type T (f :: k2)
Here k1 and k2 are different Names, but they end up mapped to the
same representative TyVar.  To make the swizzling consistent (remember
we must have a single k across C1, S and T) we reject the program.

Another interesting case
    class C2 f where
      type S (f :: k) (p::Type)
      type T (f :: k) (p::Type->Type)

Here the two k's (and the two p's) get distinct Uniques, because they
are seen by the renamer as locally bound in S and T resp.  But again
the two (distinct) k's end up bound to the same representative TyVar.
You might argue that this should be accepted, but it's definitely
rejected (via an entirely different code path) if you add a kind sig:
    type C2' :: j -> Constraint
    class C2' f where
      type S (f :: k) (p::Type)
We get
    • Expected kind ‘j’, but ‘f’ has kind ‘k’
    • In the associated type family declaration for ‘S’

So we reject C2 too, even without the kind signature.  We have
to do a bit of work to get a good error message, since both k's
look the same to the user.

Another case
    class C3 (f :: k1) where
      type S (f :: k2)

This will be rejected too.


Note [Type environment evolution]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
As we typecheck a group of declarations the type environment evolves.
Consider for example:
  data B (a :: Type) = MkB (Proxy 'MkB)

We do the following steps:

  1. Start of tcTyClDecls: use mkPromotionErrorEnv to initialise the
     type env with promotion errors
            B   :-> TyConPE
            MkB :-> DataConPE

  2. kcTyCLGroup
      - Do inferInitialKinds, which will signal a promotion
        error if B is used in any of the kinds needed to initialise
        B's kind (e.g. (a :: Type)) here

      - Extend the type env with these initial kinds (monomorphic for
        decls that lack a CUSK)
            B :-> TcTyCon <initial kind>
        (thereby overriding the B :-> TyConPE binding)
        and do kcLTyClDecl on each decl to get equality constraints on
        all those initial kinds

      - Generalise the initial kind, making a poly-kinded TcTyCon

  3. Back in tcTyDecls, extend the envt with bindings of the poly-kinded
     TcTyCons, again overriding the promotion-error bindings.

     But note that the data constructor promotion errors are still in place
     so that (in our example) a use of MkB will still be signalled as
     an error.

  4. Typecheck the decls.

  5. In tcTyClGroup, extend the envt with bindings for TyCon and DataCons


Note [Missed opportunity to retain higher-rank kinds]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In 'kcTyClGroup', there is a missed opportunity to make kind
inference work in a few more cases.  The idea is analogous
to Note [Single function non-recursive binding special-case]:

     * If we have an SCC with a single decl, which is non-recursive,
       instead of creating a unification variable representing the
       kind of the decl and unifying it with the rhs, we can just
       read the type directly of the rhs.

     * Furthermore, we can update our SCC analysis to ignore
       dependencies on declarations which have CUSKs: we don't
       have to kind-check these all at once, since we can use
       the CUSK to initialize the kind environment.

Unfortunately this requires reworking a bit of the code in
'kcLTyClDecl' so I've decided to punt unless someone shouts about it.

Note [Don't process associated types in getInitialKind]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Previously, we processed associated types in the thing_inside in getInitialKind,
but this was wrong -- we want to do ATs sepearately.
The consequence for not doing it this way is #15142:

  class ListTuple (tuple :: Type) (as :: [(k, Type)]) where
    type ListToTuple as :: Type

We assign k a kind kappa[1]. When checking the tuple (k, Type), we try to unify
kappa ~ Type, but this gets deferred because we bumped the TcLevel as we bring
`tuple` into scope. Thus, when we check ListToTuple, kappa[1] still hasn't
unified with Type. And then, when we generalize the kind of ListToTuple (which
indeed has a CUSK, according to the rules), we skolemize the free metavariable
kappa. Note that we wouldn't skolemize kappa when generalizing the kind of ListTuple,
because the solveEqualities in kcInferDeclHeader is at TcLevel 1 and so kappa[1]
will unify with Type.

Bottom line: as associated types should have no effect on a CUSK enclosing class,
we move processing them to a separate action, run after the outer kind has
been generalized.

-}

kcTyClGroup :: KindSigEnv -> [LTyClDecl GhcRn] -> TcM [TcTyCon]

-- Kind check this group, kind generalize, and return the resulting local env
-- This binds the TyCons and Classes of the group, but not the DataCons
-- See Note [Kind checking for type and class decls]
-- and Note [Inferring kinds for type declarations]
kcTyClGroup :: NameEnv Kind
-> [LTyClDecl GhcRn] -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
kcTyClGroup NameEnv Kind
kisig_env [LTyClDecl GhcRn]
decls
  = do  { Module
mod <- IOEnv (Env TcGblEnv TcLclEnv) Module
forall (m :: * -> *). HasModule m => m Module
getModule
        ; String -> SDoc -> TcRn ()
traceTc String
"---- kcTyClGroup ---- {"
                  (String -> SDoc
text String
"module" SDoc -> SDoc -> SDoc
<+> Module -> SDoc
forall a. Outputable a => a -> SDoc
ppr Module
mod SDoc -> SDoc -> SDoc
$$ [SDoc] -> SDoc
vcat ((LTyClDecl GhcRn -> SDoc) -> [LTyClDecl GhcRn] -> [SDoc]
forall a b. (a -> b) -> [a] -> [b]
map LTyClDecl GhcRn -> SDoc
forall a. Outputable a => a -> SDoc
ppr [LTyClDecl GhcRn]
decls))

          -- Kind checking;
          --    1. Bind kind variables for decls
          --    2. Kind-check decls
          --    3. Generalise the inferred kinds
          -- See Note [Kind checking for type and class decls]

        ; Bool
cusks_enabled <- Extension -> TcRnIf TcGblEnv TcLclEnv Bool
forall gbl lcl. Extension -> TcRnIf gbl lcl Bool
xoptM Extension
LangExt.CUSKs TcRnIf TcGblEnv TcLclEnv Bool
-> TcRnIf TcGblEnv TcLclEnv Bool -> TcRnIf TcGblEnv TcLclEnv Bool
forall (f :: * -> *). Applicative f => f Bool -> f Bool -> f Bool
<&&> Extension -> TcRnIf TcGblEnv TcLclEnv Bool
forall gbl lcl. Extension -> TcRnIf gbl lcl Bool
xoptM Extension
LangExt.PolyKinds
                    -- See Note [CUSKs and PolyKinds]
        ; let ([LTyClDecl GhcRn]
kindless_decls, [(LTyClDecl GhcRn, SAKS_or_CUSK)]
kinded_decls) = (LTyClDecl GhcRn
 -> Either (LTyClDecl GhcRn) (LTyClDecl GhcRn, SAKS_or_CUSK))
-> [LTyClDecl GhcRn]
-> ([LTyClDecl GhcRn], [(LTyClDecl GhcRn, SAKS_or_CUSK)])
forall a b c. (a -> Either b c) -> [a] -> ([b], [c])
partitionWith LTyClDecl GhcRn
-> Either (LTyClDecl GhcRn) (LTyClDecl GhcRn, SAKS_or_CUSK)
get_kind [LTyClDecl GhcRn]
decls

              get_kind :: LTyClDecl GhcRn
-> Either (LTyClDecl GhcRn) (LTyClDecl GhcRn, SAKS_or_CUSK)
get_kind LTyClDecl GhcRn
d
                | Just Kind
ki <- NameEnv Kind -> Name -> Maybe Kind
forall a. NameEnv a -> Name -> Maybe a
lookupNameEnv NameEnv Kind
kisig_env (TyClDecl GhcRn -> IdP GhcRn
forall (p :: Pass). TyClDecl (GhcPass p) -> IdP (GhcPass p)
tcdName (LTyClDecl GhcRn -> SrcSpanLess (LTyClDecl GhcRn)
forall a. HasSrcSpan a => a -> SrcSpanLess a
unLoc LTyClDecl GhcRn
d))
                = (LTyClDecl GhcRn, SAKS_or_CUSK)
-> Either (LTyClDecl GhcRn) (LTyClDecl GhcRn, SAKS_or_CUSK)
forall a b. b -> Either a b
Right (LTyClDecl GhcRn
d, Kind -> SAKS_or_CUSK
SAKS Kind
ki)

                | Bool
cusks_enabled Bool -> Bool -> Bool
&& TyClDecl GhcRn -> Bool
hsDeclHasCusk (LTyClDecl GhcRn -> SrcSpanLess (LTyClDecl GhcRn)
forall a. HasSrcSpan a => a -> SrcSpanLess a
unLoc LTyClDecl GhcRn
d)
                = (LTyClDecl GhcRn, SAKS_or_CUSK)
-> Either (LTyClDecl GhcRn) (LTyClDecl GhcRn, SAKS_or_CUSK)
forall a b. b -> Either a b
Right (LTyClDecl GhcRn
d, SAKS_or_CUSK
CUSK)

                | Bool
otherwise = LTyClDecl GhcRn
-> Either (LTyClDecl GhcRn) (LTyClDecl GhcRn, SAKS_or_CUSK)
forall a b. a -> Either a b
Left LTyClDecl GhcRn
d

        ; [TyCon]
checked_tcs <- [(LTyClDecl GhcRn, SAKS_or_CUSK)]
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
checkInitialKinds [(LTyClDecl GhcRn, SAKS_or_CUSK)]
kinded_decls
        ; [TyCon]
inferred_tcs
            <- [TyCon]
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall a. [TyCon] -> TcM a -> TcM a
tcExtendKindEnvWithTyCons [TyCon]
checked_tcs (IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
 -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon])
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall a b. (a -> b) -> a -> b
$
               IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall r. TcM r -> TcM r
pushTcLevelM_   (IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
 -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon])
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall a b. (a -> b) -> a -> b
$  -- We are going to kind-generalise, so
                                  -- unification variables in here must
                                  -- be one level in
               IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall r. TcM r -> TcM r
solveEqualities (IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
 -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon])
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall a b. (a -> b) -> a -> b
$
               do {  -- Step 1: Bind kind variables for all decls
                    [TyCon]
mono_tcs <- [LTyClDecl GhcRn] -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
inferInitialKinds [LTyClDecl GhcRn]
kindless_decls

                  ; String -> SDoc -> TcRn ()
traceTc String
"kcTyClGroup: initial kinds" (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$
                    [TyCon] -> SDoc
ppr_tc_kinds [TyCon]
mono_tcs

                    -- Step 2: Set extended envt, kind-check the decls
                    -- NB: the environment extension overrides the tycon
                    --     promotion-errors bindings
                    --     See Note [Type environment evolution]
                  ; [TyCon] -> TcRn () -> TcRn ()
forall a. [TyCon] -> TcM a -> TcM a
tcExtendKindEnvWithTyCons [TyCon]
mono_tcs (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
                    (LTyClDecl GhcRn -> TcRn ()) -> [LTyClDecl GhcRn] -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ LTyClDecl GhcRn -> TcRn ()
kcLTyClDecl [LTyClDecl GhcRn]
kindless_decls

                  ; [TyCon] -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall (m :: * -> *) a. Monad m => a -> m a
return [TyCon]
mono_tcs }

        -- Step 3: generalisation
        -- Finally, go through each tycon and give it its final kind,
        -- with all the required, specified, and inferred variables
        -- in order.
        ; let inferred_tc_env :: NameEnv TyCon
inferred_tc_env = [(Name, TyCon)] -> NameEnv TyCon
forall a. [(Name, a)] -> NameEnv a
mkNameEnv ([(Name, TyCon)] -> NameEnv TyCon)
-> [(Name, TyCon)] -> NameEnv TyCon
forall a b. (a -> b) -> a -> b
$
                                (TyCon -> (Name, TyCon)) -> [TyCon] -> [(Name, TyCon)]
forall a b. (a -> b) -> [a] -> [b]
map (\TyCon
tc -> (TyCon -> Name
tyConName TyCon
tc, TyCon
tc)) [TyCon]
inferred_tcs
        ; [TyCon]
generalized_tcs <- (LTyClDecl GhcRn -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon])
-> [LTyClDecl GhcRn] -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall (m :: * -> *) a b. Monad m => (a -> m [b]) -> [a] -> m [b]
concatMapM (NameEnv TyCon
-> LTyClDecl GhcRn -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
generaliseTyClDecl NameEnv TyCon
inferred_tc_env)
                                        [LTyClDecl GhcRn]
kindless_decls

        ; let poly_tcs :: [TyCon]
poly_tcs = [TyCon]
checked_tcs [TyCon] -> [TyCon] -> [TyCon]
forall a. [a] -> [a] -> [a]
++ [TyCon]
generalized_tcs
        ; String -> SDoc -> TcRn ()
traceTc String
"---- kcTyClGroup end ---- }" ([TyCon] -> SDoc
ppr_tc_kinds [TyCon]
poly_tcs)
        ; [TyCon] -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall (m :: * -> *) a. Monad m => a -> m a
return [TyCon]
poly_tcs }
  where
    ppr_tc_kinds :: [TyCon] -> SDoc
ppr_tc_kinds [TyCon]
tcs = [SDoc] -> SDoc
vcat ((TyCon -> SDoc) -> [TyCon] -> [SDoc]
forall a b. (a -> b) -> [a] -> [b]
map TyCon -> SDoc
pp_tc [TyCon]
tcs)
    pp_tc :: TyCon -> SDoc
pp_tc TyCon
tc = Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyCon -> Name
tyConName TyCon
tc) SDoc -> SDoc -> SDoc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
<+> Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyCon -> Kind
tyConKind TyCon
tc)

type ScopedPairs = [(Name, TcTyVar)]
  -- The ScopedPairs for a TcTyCon are precisely
  --    specified-tvs ++ required-tvs
  -- You can distinguish them because there are tyConArity required-tvs

generaliseTyClDecl :: NameEnv TcTyCon -> LTyClDecl GhcRn -> TcM [TcTyCon]
-- See Note [Swizzling the tyvars before generaliseTcTyCon]
generaliseTyClDecl :: NameEnv TyCon
-> LTyClDecl GhcRn -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
generaliseTyClDecl NameEnv TyCon
inferred_tc_env (L SrcSpan
_ TyClDecl GhcRn
decl)
  = do { let names_in_this_decl :: [Name]
             names_in_this_decl :: [Name]
names_in_this_decl = TyClDecl GhcRn -> [Name]
tycld_names TyClDecl GhcRn
decl

       -- Extract the specified/required binders and skolemise them
       ; [(TyCon, ScopedPairs)]
tc_with_tvs  <- (Name -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, ScopedPairs))
-> [Name] -> IOEnv (Env TcGblEnv TcLclEnv) [(TyCon, ScopedPairs)]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM Name -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, ScopedPairs)
skolemise_tc_tycon [Name]
names_in_this_decl

       -- Zonk, to manifest the side-effects of skolemisation to the swizzler
       -- NB: it's important to skolemise them all before this step. E.g.
       --         class C f where { type T (f :: k) }
       --     We only skolemise k when looking at T's binders,
       --     but k appears in f's kind in C's binders.
       ; [(TyCon, ScopedPairs, Kind)]
tc_infos <- ((TyCon, ScopedPairs)
 -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, ScopedPairs, Kind))
-> [(TyCon, ScopedPairs)]
-> IOEnv (Env TcGblEnv TcLclEnv) [(TyCon, ScopedPairs, Kind)]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM (TyCon, ScopedPairs)
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, ScopedPairs, Kind)
zonk_tc_tycon [(TyCon, ScopedPairs)]
tc_with_tvs

       -- Swizzle
       ; [(TyCon, ScopedPairs, Kind)]
swizzled_infos <- TyClDecl GhcRn
-> IOEnv (Env TcGblEnv TcLclEnv) [(TyCon, ScopedPairs, Kind)]
-> IOEnv (Env TcGblEnv TcLclEnv) [(TyCon, ScopedPairs, Kind)]
forall a. TyClDecl GhcRn -> TcM a -> TcM a
tcAddDeclCtxt TyClDecl GhcRn
decl ([(TyCon, ScopedPairs, Kind)]
-> IOEnv (Env TcGblEnv TcLclEnv) [(TyCon, ScopedPairs, Kind)]
swizzleTcTyConBndrs [(TyCon, ScopedPairs, Kind)]
tc_infos)

       -- And finally generalise
       ; ((TyCon, ScopedPairs, Kind) -> TcRn TyCon)
-> [(TyCon, ScopedPairs, Kind)]
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall a b. (a -> TcRn b) -> [a] -> TcRn [b]
mapAndReportM (TyCon, ScopedPairs, Kind) -> TcRn TyCon
generaliseTcTyCon [(TyCon, ScopedPairs, Kind)]
swizzled_infos }
  where
    tycld_names :: TyClDecl GhcRn -> [Name]
    tycld_names :: TyClDecl GhcRn -> [Name]
tycld_names TyClDecl GhcRn
decl = TyClDecl GhcRn -> IdP GhcRn
forall (p :: Pass). TyClDecl (GhcPass p) -> IdP (GhcPass p)
tcdName TyClDecl GhcRn
decl Name -> [Name] -> [Name]
forall a. a -> [a] -> [a]
: TyClDecl GhcRn -> [Name]
at_names TyClDecl GhcRn
decl

    at_names :: TyClDecl GhcRn -> [Name]
    at_names :: TyClDecl GhcRn -> [Name]
at_names (ClassDecl { tcdATs :: forall pass. TyClDecl pass -> [LFamilyDecl pass]
tcdATs = [LFamilyDecl GhcRn]
ats }) = (LFamilyDecl GhcRn -> Name) -> [LFamilyDecl GhcRn] -> [Name]
forall a b. (a -> b) -> [a] -> [b]
map (FamilyDecl GhcRn -> Name
forall (p :: Pass). FamilyDecl (GhcPass p) -> IdP (GhcPass p)
familyDeclName (FamilyDecl GhcRn -> Name)
-> (LFamilyDecl GhcRn -> FamilyDecl GhcRn)
-> LFamilyDecl GhcRn
-> Name
forall b c a. (b -> c) -> (a -> b) -> a -> c
. LFamilyDecl GhcRn -> FamilyDecl GhcRn
forall a. HasSrcSpan a => a -> SrcSpanLess a
unLoc) [LFamilyDecl GhcRn]
ats
    at_names TyClDecl GhcRn
_ = []  -- Only class decls have associated types

    skolemise_tc_tycon :: Name -> TcM (TcTyCon, ScopedPairs)
    -- Zonk and skolemise the Specified and Required binders
    skolemise_tc_tycon :: Name -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, ScopedPairs)
skolemise_tc_tycon Name
tc_name
      = do { let tc :: TyCon
tc = NameEnv TyCon -> Name -> TyCon
forall a. NameEnv a -> Name -> a
lookupNameEnv_NF NameEnv TyCon
inferred_tc_env Name
tc_name
                      -- This lookup should not fail
           ; ScopedPairs
scoped_prs <- (TcTyCoVar -> IOEnv (Env TcGblEnv TcLclEnv) TcTyCoVar)
-> ScopedPairs -> IOEnv (Env TcGblEnv TcLclEnv) ScopedPairs
forall (m :: * -> *) b c a.
Monad m =>
(b -> m c) -> [(a, b)] -> m [(a, c)]
mapSndM TcTyCoVar -> IOEnv (Env TcGblEnv TcLclEnv) TcTyCoVar
zonkAndSkolemise (TyCon -> ScopedPairs
tcTyConScopedTyVars TyCon
tc)
           ; (TyCon, ScopedPairs)
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, ScopedPairs)
forall (m :: * -> *) a. Monad m => a -> m a
return (TyCon
tc, ScopedPairs
scoped_prs) }

    zonk_tc_tycon :: (TcTyCon, ScopedPairs) -> TcM (TcTyCon, ScopedPairs, TcKind)
    zonk_tc_tycon :: (TyCon, ScopedPairs)
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, ScopedPairs, Kind)
zonk_tc_tycon (TyCon
tc, ScopedPairs
scoped_prs)
      = do { ScopedPairs
scoped_prs <- (TcTyCoVar -> IOEnv (Env TcGblEnv TcLclEnv) TcTyCoVar)
-> ScopedPairs -> IOEnv (Env TcGblEnv TcLclEnv) ScopedPairs
forall (m :: * -> *) b c a.
Monad m =>
(b -> m c) -> [(a, b)] -> m [(a, c)]
mapSndM HasDebugCallStack =>
TcTyCoVar -> IOEnv (Env TcGblEnv TcLclEnv) TcTyCoVar
TcTyCoVar -> IOEnv (Env TcGblEnv TcLclEnv) TcTyCoVar
zonkTcTyVarToTyVar ScopedPairs
scoped_prs
                           -- We really have to do this again, even though
                           -- we have just done zonkAndSkolemise
           ; Kind
res_kind   <- Kind -> TcM Kind
zonkTcType (TyCon -> Kind
tyConResKind TyCon
tc)
           ; (TyCon, ScopedPairs, Kind)
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, ScopedPairs, Kind)
forall (m :: * -> *) a. Monad m => a -> m a
return (TyCon
tc, ScopedPairs
scoped_prs, Kind
res_kind) }

swizzleTcTyConBndrs :: [(TcTyCon, ScopedPairs, TcKind)]
                -> TcM [(TcTyCon, ScopedPairs, TcKind)]
swizzleTcTyConBndrs :: [(TyCon, ScopedPairs, Kind)]
-> IOEnv (Env TcGblEnv TcLclEnv) [(TyCon, ScopedPairs, Kind)]
swizzleTcTyConBndrs [(TyCon, ScopedPairs, Kind)]
tc_infos
  | ((Name, TcTyCoVar) -> Bool) -> ScopedPairs -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
all (Name, TcTyCoVar) -> Bool
no_swizzle ScopedPairs
swizzle_prs
    -- This fast path happens almost all the time
    -- See Note [Non-cloning for tyvar binders] in TcHsType
  = do { String -> SDoc -> TcRn ()
traceTc String
"Skipping swizzleTcTyConBndrs for" ([TyCon] -> SDoc
forall a. Outputable a => a -> SDoc
ppr (((TyCon, ScopedPairs, Kind) -> TyCon)
-> [(TyCon, ScopedPairs, Kind)] -> [TyCon]
forall a b. (a -> b) -> [a] -> [b]
map (TyCon, ScopedPairs, Kind) -> TyCon
forall a b c. (a, b, c) -> a
fstOf3 [(TyCon, ScopedPairs, Kind)]
tc_infos))
       ; [(TyCon, ScopedPairs, Kind)]
-> IOEnv (Env TcGblEnv TcLclEnv) [(TyCon, ScopedPairs, Kind)]
forall (m :: * -> *) a. Monad m => a -> m a
return [(TyCon, ScopedPairs, Kind)]
tc_infos }

  | Bool
otherwise
  = do { TcRn ()
check_duplicate_tc_binders

       ; String -> SDoc -> TcRn ()
traceTc String
"swizzleTcTyConBndrs" (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$
         [SDoc] -> SDoc
vcat [ String -> SDoc
text String
"before" SDoc -> SDoc -> SDoc
<+> [(TyCon, ScopedPairs, Kind)] -> SDoc
forall a a c. Outputable a => [(a, [(a, TcTyCoVar)], c)] -> SDoc
ppr_infos [(TyCon, ScopedPairs, Kind)]
tc_infos
              , String -> SDoc
text String
"swizzle_prs" SDoc -> SDoc -> SDoc
<+> ScopedPairs -> SDoc
forall a. Outputable a => a -> SDoc
ppr ScopedPairs
swizzle_prs
              , String -> SDoc
text String
"after" SDoc -> SDoc -> SDoc
<+> [(TyCon, ScopedPairs, Kind)] -> SDoc
forall a a c. Outputable a => [(a, [(a, TcTyCoVar)], c)] -> SDoc
ppr_infos [(TyCon, ScopedPairs, Kind)]
swizzled_infos ]

       ; [(TyCon, ScopedPairs, Kind)]
-> IOEnv (Env TcGblEnv TcLclEnv) [(TyCon, ScopedPairs, Kind)]
forall (m :: * -> *) a. Monad m => a -> m a
return [(TyCon, ScopedPairs, Kind)]
swizzled_infos }

  where
    swizzled_infos :: [(TyCon, ScopedPairs, Kind)]
swizzled_infos =  [ (TyCon
tc, (TcTyCoVar -> TcTyCoVar) -> ScopedPairs -> ScopedPairs
forall b c a. (b -> c) -> [(a, b)] -> [(a, c)]
mapSnd TcTyCoVar -> TcTyCoVar
swizzle_var ScopedPairs
scoped_prs, Kind -> Kind
swizzle_ty Kind
kind)
                      | (TyCon
tc, ScopedPairs
scoped_prs, Kind
kind) <- [(TyCon, ScopedPairs, Kind)]
tc_infos ]

    swizzle_prs :: [(Name,TyVar)]
    -- Pairs the user-specifed Name with its representative TyVar
    -- See Note [Swizzling the tyvars before generaliseTcTyCon]
    swizzle_prs :: ScopedPairs
swizzle_prs = [ (Name, TcTyCoVar)
pr | (TyCon
_, ScopedPairs
prs, Kind
_) <- [(TyCon, ScopedPairs, Kind)]
tc_infos, (Name, TcTyCoVar)
pr <- ScopedPairs
prs ]

    no_swizzle :: (Name,TyVar) -> Bool
    no_swizzle :: (Name, TcTyCoVar) -> Bool
no_swizzle (Name
nm, TcTyCoVar
tv) = Name
nm Name -> Name -> Bool
forall a. Eq a => a -> a -> Bool
== TcTyCoVar -> Name
tyVarName TcTyCoVar
tv

    ppr_infos :: [(a, [(a, TcTyCoVar)], c)] -> SDoc
ppr_infos [(a, [(a, TcTyCoVar)], c)]
infos = [SDoc] -> SDoc
vcat [ a -> SDoc
forall a. Outputable a => a -> SDoc
ppr a
tc SDoc -> SDoc -> SDoc
<+> [TcTyCoVar] -> SDoc
pprTyVars (((a, TcTyCoVar) -> TcTyCoVar) -> [(a, TcTyCoVar)] -> [TcTyCoVar]
forall a b. (a -> b) -> [a] -> [b]
map (a, TcTyCoVar) -> TcTyCoVar
forall a b. (a, b) -> b
snd [(a, TcTyCoVar)]
prs)
                           | (a
tc, [(a, TcTyCoVar)]
prs, c
_) <- [(a, [(a, TcTyCoVar)], c)]
infos ]

    -- Check for duplicates
    -- E.g. data SameKind (a::k) (b::k)
    --      data T (a::k1) (b::k2) = MkT (SameKind a b)
    -- Here k1 and k2 start as TyVarTvs, and get unified with each other
    -- If this happens, things get very confused later, so fail fast
    check_duplicate_tc_binders :: TcM ()
    check_duplicate_tc_binders :: TcRn ()
check_duplicate_tc_binders = Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
unless ([(Name, Name)] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [(Name, Name)]
err_prs) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
                                 do { ((Name, Name) -> TcRn ()) -> [(Name, Name)] -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ (Name, Name) -> TcRn ()
report_dup [(Name, Name)]
err_prs; TcRn ()
forall env a. IOEnv env a
failM }

    -------------- Error reporting ------------
    err_prs :: [(Name,Name)]
    err_prs :: [(Name, Name)]
err_prs = [ (Name
n1,Name
n2)
              | (Name, TcTyCoVar)
pr :| ScopedPairs
prs <- ((Name, TcTyCoVar) -> (Name, TcTyCoVar) -> Bool)
-> ScopedPairs -> [NonEmpty (Name, TcTyCoVar)]
forall a. (a -> a -> Bool) -> [a] -> [NonEmpty a]
findDupsEq (TcTyCoVar -> TcTyCoVar -> Bool
forall a. Eq a => a -> a -> Bool
(==) (TcTyCoVar -> TcTyCoVar -> Bool)
-> ((Name, TcTyCoVar) -> TcTyCoVar)
-> (Name, TcTyCoVar)
-> (Name, TcTyCoVar)
-> Bool
forall b c a. (b -> b -> c) -> (a -> b) -> a -> a -> c
`on` (Name, TcTyCoVar) -> TcTyCoVar
forall a b. (a, b) -> b
snd) ScopedPairs
swizzle_prs
              , (Name
n1,TcTyCoVar
_):(Name
n2,TcTyCoVar
_):ScopedPairs
_ <- [((Name, TcTyCoVar) -> (Name, TcTyCoVar) -> Bool)
-> ScopedPairs -> ScopedPairs
forall a. (a -> a -> Bool) -> [a] -> [a]
nubBy (Name -> Name -> Bool
forall a. Eq a => a -> a -> Bool
(==) (Name -> Name -> Bool)
-> ((Name, TcTyCoVar) -> Name)
-> (Name, TcTyCoVar)
-> (Name, TcTyCoVar)
-> Bool
forall b c a. (b -> b -> c) -> (a -> b) -> a -> a -> c
`on` (Name, TcTyCoVar) -> Name
forall a b. (a, b) -> a
fst) ((Name, TcTyCoVar)
pr(Name, TcTyCoVar) -> ScopedPairs -> ScopedPairs
forall a. a -> [a] -> [a]
:ScopedPairs
prs)] ]
              -- This nubBy avoids bogus error reports when we have
              --    [("f", f), ..., ("f",f)....] in swizzle_prs
              -- which happens with  class C f where { type T f }

    report_dup :: (Name,Name) -> TcM ()
    report_dup :: (Name, Name) -> TcRn ()
report_dup (Name
n1,Name
n2)
      = SrcSpan -> TcRn () -> TcRn ()
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan (Name -> SrcSpan
forall a. NamedThing a => a -> SrcSpan
getSrcSpan Name
n2) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$ SDoc -> TcRn ()
addErrTc (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$
        SDoc -> Int -> SDoc -> SDoc
hang (String -> SDoc
text String
"Different names for the same type variable:") Int
2 SDoc
info
      where
        info :: SDoc
info | Name -> OccName
nameOccName Name
n1 OccName -> OccName -> Bool
forall a. Eq a => a -> a -> Bool
/= Name -> OccName
nameOccName Name
n2
             = SDoc -> SDoc
quotes (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
n1) SDoc -> SDoc -> SDoc
<+> String -> SDoc
text String
"and" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
n2)
             | Bool
otherwise -- Same OccNames! See C2 in
                         -- Note [Swizzling the tyvars before generaliseTcTyCon]
             = [SDoc] -> SDoc
vcat [ SDoc -> SDoc
quotes (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
n1) SDoc -> SDoc -> SDoc
<+> String -> SDoc
text String
"bound at" SDoc -> SDoc -> SDoc
<+> SrcLoc -> SDoc
forall a. Outputable a => a -> SDoc
ppr (Name -> SrcLoc
forall a. NamedThing a => a -> SrcLoc
getSrcLoc Name
n1)
                    , SDoc -> SDoc
quotes (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
n2) SDoc -> SDoc -> SDoc
<+> String -> SDoc
text String
"bound at" SDoc -> SDoc -> SDoc
<+> SrcLoc -> SDoc
forall a. Outputable a => a -> SDoc
ppr (Name -> SrcLoc
forall a. NamedThing a => a -> SrcLoc
getSrcLoc Name
n2) ]

    -------------- The swizzler ------------
    -- This does a deep traverse, simply doing a
    -- Name-to-Name change, governed by swizzle_env
    -- The 'swap' is what gets from the representative TyVar
    -- back to the original user-specified Name
    swizzle_env :: VarEnv Name
swizzle_env = [(TcTyCoVar, Name)] -> VarEnv Name
forall a. [(TcTyCoVar, a)] -> VarEnv a
mkVarEnv (((Name, TcTyCoVar) -> (TcTyCoVar, Name))
-> ScopedPairs -> [(TcTyCoVar, Name)]
forall a b. (a -> b) -> [a] -> [b]
map (Name, TcTyCoVar) -> (TcTyCoVar, Name)
forall a b. (a, b) -> (b, a)
swap ScopedPairs
swizzle_prs)

    swizzleMapper :: TyCoMapper () Identity
    swizzleMapper :: TyCoMapper () Identity
swizzleMapper = TyCoMapper :: forall env (m :: * -> *).
(env -> TcTyCoVar -> m Kind)
-> (env -> TcTyCoVar -> m Coercion)
-> (env -> CoercionHole -> m Coercion)
-> (env -> TcTyCoVar -> ArgFlag -> m (env, TcTyCoVar))
-> (TyCon -> m TyCon)
-> TyCoMapper env m
TyCoMapper { tcm_tyvar :: () -> TcTyCoVar -> Identity Kind
tcm_tyvar = () -> TcTyCoVar -> Identity Kind
forall (m :: * -> *) p. Monad m => p -> TcTyCoVar -> m Kind
swizzle_tv
                               , tcm_covar :: () -> TcTyCoVar -> Identity Coercion
tcm_covar = () -> TcTyCoVar -> Identity Coercion
forall (m :: * -> *) p. Monad m => p -> TcTyCoVar -> m Coercion
swizzle_cv
                               , tcm_hole :: () -> CoercionHole -> Identity Coercion
tcm_hole  = () -> CoercionHole -> Identity Coercion
forall a p a. Outputable a => p -> a -> a
swizzle_hole
                               , tcm_tycobinder :: () -> TcTyCoVar -> ArgFlag -> Identity ((), TcTyCoVar)
tcm_tycobinder = () -> TcTyCoVar -> ArgFlag -> Identity ((), TcTyCoVar)
forall (m :: * -> *) p p.
Monad m =>
p -> TcTyCoVar -> p -> m ((), TcTyCoVar)
swizzle_bndr
                               , tcm_tycon :: TyCon -> Identity TyCon
tcm_tycon      = TyCon -> Identity TyCon
forall a a. Outputable a => a -> a
swizzle_tycon }
    swizzle_hole :: p -> a -> a
swizzle_hole  p
_ a
hole = String -> SDoc -> a
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"swizzle_hole" (a -> SDoc
forall a. Outputable a => a -> SDoc
ppr a
hole)
       -- These types are pre-zonked
    swizzle_tycon :: a -> a
swizzle_tycon a
tc = String -> SDoc -> a
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"swizzle_tc" (a -> SDoc
forall a. Outputable a => a -> SDoc
ppr a
tc)
       -- TcTyCons can't appear in kinds (yet)
    swizzle_tv :: p -> TcTyCoVar -> m Kind
swizzle_tv p
_ TcTyCoVar
tv = Kind -> m Kind
forall (m :: * -> *) a. Monad m => a -> m a
return (TcTyCoVar -> Kind
mkTyVarTy (TcTyCoVar -> TcTyCoVar
swizzle_var TcTyCoVar
tv))
    swizzle_cv :: p -> TcTyCoVar -> m Coercion
swizzle_cv p
_ TcTyCoVar
cv = Coercion -> m Coercion
forall (m :: * -> *) a. Monad m => a -> m a
return (TcTyCoVar -> Coercion
mkCoVarCo (TcTyCoVar -> TcTyCoVar
swizzle_var TcTyCoVar
cv))

    swizzle_bndr :: p -> TcTyCoVar -> p -> m ((), TcTyCoVar)
swizzle_bndr p
_ TcTyCoVar
tcv p
_
      = ((), TcTyCoVar) -> m ((), TcTyCoVar)
forall (m :: * -> *) a. Monad m => a -> m a
return ((), TcTyCoVar -> TcTyCoVar
swizzle_var TcTyCoVar
tcv)

    swizzle_var :: Var -> Var
    swizzle_var :: TcTyCoVar -> TcTyCoVar
swizzle_var TcTyCoVar
v
      | Just Name
nm <- VarEnv Name -> TcTyCoVar -> Maybe Name
forall a. VarEnv a -> TcTyCoVar -> Maybe a
lookupVarEnv VarEnv Name
swizzle_env TcTyCoVar
v
      = (Kind -> Kind) -> TcTyCoVar -> TcTyCoVar
updateVarType Kind -> Kind
swizzle_ty (TcTyCoVar
v TcTyCoVar -> Name -> TcTyCoVar
`setVarName` Name
nm)
      | Bool
otherwise
      = (Kind -> Kind) -> TcTyCoVar -> TcTyCoVar
updateVarType Kind -> Kind
swizzle_ty TcTyCoVar
v

    swizzle_ty :: Kind -> Kind
swizzle_ty Kind
ty = Identity Kind -> Kind
forall a. Identity a -> a
runIdentity (TyCoMapper () Identity -> () -> Kind -> Identity Kind
forall (m :: * -> *) env.
Monad m =>
TyCoMapper env m -> env -> Kind -> m Kind
mapType TyCoMapper () Identity
swizzleMapper () Kind
ty)


generaliseTcTyCon :: (TcTyCon, ScopedPairs, TcKind) -> TcM TcTyCon
generaliseTcTyCon :: (TyCon, ScopedPairs, Kind) -> TcRn TyCon
generaliseTcTyCon (TyCon
tc, ScopedPairs
scoped_prs, Kind
tc_res_kind)
  -- See Note [Required, Specified, and Inferred for types]
  = SrcSpan -> TcRn TyCon -> TcRn TyCon
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan (TyCon -> SrcSpan
forall a. NamedThing a => a -> SrcSpan
getSrcSpan TyCon
tc) (TcRn TyCon -> TcRn TyCon) -> TcRn TyCon -> TcRn TyCon
forall a b. (a -> b) -> a -> b
$
    TyCon -> TcRn TyCon -> TcRn TyCon
forall a. TyCon -> TcM a -> TcM a
addTyConCtxt TyCon
tc (TcRn TyCon -> TcRn TyCon) -> TcRn TyCon -> TcRn TyCon
forall a b. (a -> b) -> a -> b
$
    do { -- Step 1: Separate Specified from Required variables
         -- NB: spec_req_tvs = spec_tvs ++ req_tvs
         --     And req_tvs is 1-1 with tyConTyVars
         --     See Note [Scoped tyvars in a TcTyCon] in TyCon
       ; let spec_req_tvs :: [TcTyCoVar]
spec_req_tvs        = ((Name, TcTyCoVar) -> TcTyCoVar) -> ScopedPairs -> [TcTyCoVar]
forall a b. (a -> b) -> [a] -> [b]
map (Name, TcTyCoVar) -> TcTyCoVar
forall a b. (a, b) -> b
snd ScopedPairs
scoped_prs
             n_spec :: Int
n_spec              = [TcTyCoVar] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length [TcTyCoVar]
spec_req_tvs Int -> Int -> Int
forall a. Num a => a -> a -> a
- TyCon -> Int
tyConArity TyCon
tc
             ([TcTyCoVar]
spec_tvs, [TcTyCoVar]
req_tvs) = Int -> [TcTyCoVar] -> ([TcTyCoVar], [TcTyCoVar])
forall a. Int -> [a] -> ([a], [a])
splitAt Int
n_spec [TcTyCoVar]
spec_req_tvs
             sorted_spec_tvs :: [TcTyCoVar]
sorted_spec_tvs     = [TcTyCoVar] -> [TcTyCoVar]
scopedSort [TcTyCoVar]
spec_tvs
                 -- NB: We can't do the sort until we've zonked
                 --     Maintain the L-R order of scoped_tvs

       -- Step 2a: find all the Inferred variables we want to quantify over
       ; CandidatesQTvs
dvs1 <- [Kind] -> TcM CandidatesQTvs
candidateQTyVarsOfKinds ([Kind] -> TcM CandidatesQTvs) -> [Kind] -> TcM CandidatesQTvs
forall a b. (a -> b) -> a -> b
$
                 (Kind
tc_res_kind Kind -> [Kind] -> [Kind]
forall a. a -> [a] -> [a]
: (TcTyCoVar -> Kind) -> [TcTyCoVar] -> [Kind]
forall a b. (a -> b) -> [a] -> [b]
map TcTyCoVar -> Kind
tyVarKind [TcTyCoVar]
spec_req_tvs)
       ; let dvs2 :: CandidatesQTvs
dvs2 = CandidatesQTvs
dvs1 CandidatesQTvs -> [TcTyCoVar] -> CandidatesQTvs
`delCandidates` [TcTyCoVar]
spec_req_tvs

       -- Step 2b: quantify, mainly meaning skolemise the free variables
       -- Returned 'inferred' are scope-sorted and skolemised
       ; [TcTyCoVar]
inferred <- CandidatesQTvs -> TcM [TcTyCoVar]
quantifyTyVars CandidatesQTvs
dvs2

       ; String -> SDoc -> TcRn ()
traceTc String
"generaliseTcTyCon: pre zonk"
           ([SDoc] -> SDoc
vcat [ String -> SDoc
text String
"tycon =" SDoc -> SDoc -> SDoc
<+> TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tc
                 , String -> SDoc
text String
"spec_req_tvs =" SDoc -> SDoc -> SDoc
<+> [TcTyCoVar] -> SDoc
pprTyVars [TcTyCoVar]
spec_req_tvs
                 , String -> SDoc
text String
"tc_res_kind =" SDoc -> SDoc -> SDoc
<+> Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr Kind
tc_res_kind
                 , String -> SDoc
text String
"dvs1 =" SDoc -> SDoc -> SDoc
<+> CandidatesQTvs -> SDoc
forall a. Outputable a => a -> SDoc
ppr CandidatesQTvs
dvs1
                 , String -> SDoc
text String
"inferred =" SDoc -> SDoc -> SDoc
<+> [TcTyCoVar] -> SDoc
pprTyVars [TcTyCoVar]
inferred ])

       -- Step 3: Final zonk (following kind generalisation)
       -- See Note [Swizzling the tyvars before generaliseTcTyCon]
       ; ZonkEnv
ze <- TcM ZonkEnv
emptyZonkEnv
       ; (ZonkEnv
ze, [TcTyCoVar]
inferred)        <- ZonkEnv -> [TcTyCoVar] -> TcM (ZonkEnv, [TcTyCoVar])
zonkTyBndrsX ZonkEnv
ze [TcTyCoVar]
inferred
       ; (ZonkEnv
ze, [TcTyCoVar]
sorted_spec_tvs) <- ZonkEnv -> [TcTyCoVar] -> TcM (ZonkEnv, [TcTyCoVar])
zonkTyBndrsX ZonkEnv
ze [TcTyCoVar]
sorted_spec_tvs
       ; (ZonkEnv
ze, [TcTyCoVar]
req_tvs)         <- ZonkEnv -> [TcTyCoVar] -> TcM (ZonkEnv, [TcTyCoVar])
zonkTyBndrsX ZonkEnv
ze [TcTyCoVar]
req_tvs
       ; Kind
tc_res_kind           <- ZonkEnv -> Kind -> TcM Kind
zonkTcTypeToTypeX ZonkEnv
ze Kind
tc_res_kind

       ; String -> SDoc -> TcRn ()
traceTc String
"generaliseTcTyCon: post zonk" (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$
         [SDoc] -> SDoc
vcat [ String -> SDoc
text String
"tycon =" SDoc -> SDoc -> SDoc
<+> TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tc
              , String -> SDoc
text String
"inferred =" SDoc -> SDoc -> SDoc
<+> [TcTyCoVar] -> SDoc
pprTyVars [TcTyCoVar]
inferred
              , String -> SDoc
text String
"spec_req_tvs =" SDoc -> SDoc -> SDoc
<+> [TcTyCoVar] -> SDoc
pprTyVars [TcTyCoVar]
spec_req_tvs
              , String -> SDoc
text String
"sorted_spec_tvs =" SDoc -> SDoc -> SDoc
<+> [TcTyCoVar] -> SDoc
pprTyVars [TcTyCoVar]
sorted_spec_tvs
              , String -> SDoc
text String
"req_tvs =" SDoc -> SDoc -> SDoc
<+> [TcTyCoVar] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TcTyCoVar]
req_tvs
              , String -> SDoc
text String
"zonk-env =" SDoc -> SDoc -> SDoc
<+> ZonkEnv -> SDoc
forall a. Outputable a => a -> SDoc
ppr ZonkEnv
ze ]

       -- Step 4: Make the TyConBinders.
       ; let dep_fv_set :: TyVarSet
dep_fv_set     = CandidatesQTvs -> TyVarSet
candidateKindVars CandidatesQTvs
dvs1
             inferred_tcbs :: [TyConBinder]
inferred_tcbs  = ArgFlag -> [TcTyCoVar] -> [TyConBinder]
mkNamedTyConBinders ArgFlag
Inferred [TcTyCoVar]
inferred
             specified_tcbs :: [TyConBinder]
specified_tcbs = ArgFlag -> [TcTyCoVar] -> [TyConBinder]
mkNamedTyConBinders ArgFlag
Specified [TcTyCoVar]
sorted_spec_tvs
             required_tcbs :: [TyConBinder]
required_tcbs  = (TcTyCoVar -> TyConBinder) -> [TcTyCoVar] -> [TyConBinder]
forall a b. (a -> b) -> [a] -> [b]
map (TyVarSet -> TcTyCoVar -> TyConBinder
mkRequiredTyConBinder TyVarSet
dep_fv_set) [TcTyCoVar]
req_tvs

       -- Step 5: Assemble the final list.
             final_tcbs :: [TyConBinder]
final_tcbs = [[TyConBinder]] -> [TyConBinder]
forall (t :: * -> *) a. Foldable t => t [a] -> [a]
concat [ [TyConBinder]
inferred_tcbs
                                 , [TyConBinder]
specified_tcbs
                                 , [TyConBinder]
required_tcbs ]

       -- Step 6: Make the result TcTyCon
             tycon :: TyCon
tycon = Name
-> [TyConBinder]
-> Kind
-> ScopedPairs
-> Bool
-> TyConFlavour
-> TyCon
mkTcTyCon (TyCon -> Name
tyConName TyCon
tc) [TyConBinder]
final_tcbs Kind
tc_res_kind
                            ([TcTyCoVar] -> ScopedPairs
mkTyVarNamePairs ([TcTyCoVar]
sorted_spec_tvs [TcTyCoVar] -> [TcTyCoVar] -> [TcTyCoVar]
forall a. [a] -> [a] -> [a]
++ [TcTyCoVar]
req_tvs))
                            Bool
True {- it's generalised now -}
                            (TyCon -> TyConFlavour
tyConFlavour TyCon
tc)

       ; String -> SDoc -> TcRn ()
traceTc String
"generaliseTcTyCon done" (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$
         [SDoc] -> SDoc
vcat [ String -> SDoc
text String
"tycon =" SDoc -> SDoc -> SDoc
<+> TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tc
              , String -> SDoc
text String
"tc_res_kind =" SDoc -> SDoc -> SDoc
<+> Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr Kind
tc_res_kind
              , String -> SDoc
text String
"dep_fv_set =" SDoc -> SDoc -> SDoc
<+> TyVarSet -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyVarSet
dep_fv_set
              , String -> SDoc
text String
"inferred_tcbs =" SDoc -> SDoc -> SDoc
<+> [TyConBinder] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TyConBinder]
inferred_tcbs
              , String -> SDoc
text String
"specified_tcbs =" SDoc -> SDoc -> SDoc
<+> [TyConBinder] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TyConBinder]
specified_tcbs
              , String -> SDoc
text String
"required_tcbs =" SDoc -> SDoc -> SDoc
<+> [TyConBinder] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TyConBinder]
required_tcbs
              , String -> SDoc
text String
"final_tcbs =" SDoc -> SDoc -> SDoc
<+> [TyConBinder] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TyConBinder]
final_tcbs ]

       -- Step 7: Check for validity.
       -- We do this here because we're about to put the tycon into the
       -- the environment, and we don't want anything malformed there
       ; TyCon -> TcRn ()
checkTyConTelescope TyCon
tycon

       ; TyCon -> TcRn TyCon
forall (m :: * -> *) a. Monad m => a -> m a
return TyCon
tycon }

{- Note [Required, Specified, and Inferred for types]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Each forall'd type variable in a type or kind is one of

  * Required: an argument must be provided at every call site

  * Specified: the argument can be inferred at call sites, but
    may be instantiated with visible type/kind application

  * Inferred: the must be inferred at call sites; it
    is unavailable for use with visible type/kind application.

Why have Inferred at all? Because we just can't make user-facing
promises about the ordering of some variables. These might swizzle
around even between minor released. By forbidding visible type
application, we ensure users aren't caught unawares.

Go read Note [VarBndrs, TyCoVarBinders, TyConBinders, and visibility] in TyCoRep.

The question for this Note is this:
   given a TyClDecl, how are its quantified type variables classified?
Much of the debate is memorialized in #15743.

Here is our design choice. When inferring the ordering of variables
for a TyCl declaration (that is, for those variables that he user
has not specified the order with an explicit `forall`), we use the
following order:

 1. Inferred variables
 2. Specified variables; in the left-to-right order in which
    the user wrote them, modified by scopedSort (see below)
    to put them in depdendency order.
 3. Required variables before a top-level ::
 4. All variables after a top-level ::

If this ordering does not make a valid telescope, we reject the definition.

Example:
  data SameKind :: k -> k -> *
  data Bad a (c :: Proxy b) (d :: Proxy a) (x :: SameKind b d)

For Bad:
  - a, c, d, x are Required; they are explicitly listed by the user
    as the positional arguments of Bad
  - b is Specified; it appears explicitly in a kind signature
  - k, the kind of a, is Inferred; it is not mentioned explicitly at all

Putting variables in the order Inferred, Specified, Required
gives us this telescope:
  Inferred:  k
  Specified: b : Proxy a
  Required : (a : k) (c : Proxy b) (d : Proxy a) (x : SameKind b d)

But this order is ill-scoped, because b's kind mentions a, which occurs
after b in the telescope. So we reject Bad.

Associated types
~~~~~~~~~~~~~~~~
For associated types everything above is determined by the
associated-type declaration alone, ignoring the class header.
Here is an example (#15592)
  class C (a :: k) b where
    type F (x :: b a)

In the kind of C, 'k' is Specified.  But what about F?
In the kind of F,

 * Should k be Inferred or Specified?  It's Specified for C,
   but not mentioned in F's declaration.

 * In which order should the Specified variables a and b occur?
   It's clearly 'a' then 'b' in C's declaration, but the L-R ordering
   in F's declaration is 'b' then 'a'.

In both cases we make the choice by looking at F's declaration alone,
so it gets the kind
   F :: forall {k}. forall b a. b a -> Type

How it works
~~~~~~~~~~~~
These design choices are implemented by two completely different code
paths for

  * Declarations with a standalone kind signature or a complete user-specified
    kind signature (CUSK). Handled by the kcCheckDeclHeader.

  * Declarations without a kind signature (standalone or CUSK) are handled by
    kcInferDeclHeader; see Note [Inferring kinds for type declarations].

Note that neither code path worries about point (4) above, as this
is nicely handled by not mangling the res_kind. (Mangling res_kinds is done
*after* all this stuff, in tcDataDefn's call to etaExpandAlgTyCon.)

We can tell Inferred apart from Specified by looking at the scoped
tyvars; Specified are always included there.

Design alternatives
~~~~~~~~~~~~~~~~~~~
* For associated types we considered putting the class variables
  before the local variables, in a nod to the treatment for class
  methods. But it got too compilicated; see #15592, comment:21ff.

* We rigidly require the ordering above, even though we could be much more
  permissive. Relevant musings are at
  https://gitlab.haskell.org/ghc/ghc/issues/15743#note_161623
  The bottom line conclusion is that, if the user wants a different ordering,
  then can specify it themselves, and it is better to be predictable and dumb
  than clever and capricious.

  I (Richard) conjecture we could be fully permissive, allowing all classes
  of variables to intermix. We would have to augment ScopedSort to refuse to
  reorder Required variables (or check that it wouldn't have). But this would
  allow more programs. See #15743 for examples. Interestingly, Idris seems
  to allow this intermixing. The intermixing would be fully specified, in that
  we can be sure that inference wouldn't change between versions. However,
  would users be able to predict it? That I cannot answer.

Test cases (and tickets) relevant to these design decisions
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  T15591*
  T15592*
  T15743*

Note [Inferring kinds for type declarations]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This note deals with /inference/ for type declarations
that do not have a CUSK.  Consider
  data T (a :: k1) k2 (x :: k2) = MkT (S a k2 x)
  data S (b :: k3) k4 (y :: k4) = MkS (T b k4 y)

We do kind inference as follows:

* Step 1: inferInitialKinds, and in particular kcInferDeclHeader.
  Make a unification variable for each of the Required and Specified
  type variables in the header.

  Record the connection between the Names the user wrote and the
  fresh unification variables in the tcTyConScopedTyVars field
  of the TcTyCon we are making
      [ (a,  aa)
      , (k1, kk1)
      , (k2, kk2)
      , (x,  xx) ]
  (I'm using the convention that double letter like 'aa' or 'kk'
  mean a unification variable.)

  These unification variables
    - Are TyVarTvs: that is, unification variables that can
      unify only with other type variables.
      See Note [Signature skolems] in TcType

    - Have complete fresh Names; see TcMType
      Note [Unification variables need fresh Names]

  Assign initial monomorophic kinds to S, T
          T :: kk1 -> * -> kk2 -> *
          S :: kk3 -> * -> kk4 -> *

* Step 2: kcTyClDecl. Extend the environment with a TcTyCon for S and
  T, with these monomorphic kinds.  Now kind-check the declarations,
  and solve the resulting equalities.  The goal here is to discover
  constraints on all these unification variables.

  Here we find that kk1 := kk3, and kk2 := kk4.

  This is why we can't use skolems for kk1 etc; they have to
  unify with each other.

* Step 3: generaliseTcTyCon. Generalise each TyCon in turn.
  We find the free variables of the kind, skolemise them,
  sort them out into Inferred/Required/Specified (see the above
  Note [Required, Specified, and Inferred for types]),
  and perform some validity checks.

  This makes the utterly-final TyConBinders for the TyCon.

  All this is very similar at the level of terms: see TcBinds
  Note [Quantified variables in partial type signatures]

  But there some tricky corners: Note [Tricky scoping in generaliseTcTyCon]

* Step 4.  Extend the type environment with a TcTyCon for S and T, now
  with their utterly-final polymorphic kinds (needed for recursive
  occurrences of S, T).  Now typecheck the declarations, and build the
  final AlgTyCOn for S and T resp.

The first three steps are in kcTyClGroup; the fourth is in
tcTyClDecls.

There are some wrinkles

* Do not default TyVarTvs.  We always want to kind-generalise over
  TyVarTvs, and /not/ default them to Type. By definition a TyVarTv is
  not allowed to unify with a type; it must stand for a type
  variable. Hence the check in TcSimplify.defaultTyVarTcS, and
  TcMType.defaultTyVar.  Here's another example (#14555):
     data Exp :: [TYPE rep] -> TYPE rep -> Type where
        Lam :: Exp (a:xs) b -> Exp xs (a -> b)
  We want to kind-generalise over the 'rep' variable.
  #14563 is another example.

* Duplicate type variables. Consider #11203
    data SameKind :: k -> k -> *
    data Q (a :: k1) (b :: k2) c = MkQ (SameKind a b)
  Here we will unify k1 with k2, but this time doing so is an error,
  because k1 and k2 are bound in the same declaration.

  We spot this during validity checking (findDupTyVarTvs),
  in generaliseTcTyCon.

* Required arguments.  Even the Required arguments should be made
  into TyVarTvs, not skolems.  Consider
    data T k (a :: k)
  Here, k is a Required, dependent variable. For uniformity, it is helpful
  to have k be a TyVarTv, in parallel with other dependent variables.

* Duplicate skolemisation is expected.  When generalising in Step 3,
  we may find that one of the variables we want to quantify has
  already been skolemised.  For example, suppose we have already
  generalise S. When we come to T we'll find that kk1 (now the same as
  kk3) has already been skolemised.

  That's fine -- but it means that
    a) when collecting quantification candidates, in
       candidateQTyVarsOfKind, we must collect skolems
    b) quantifyTyVars should be a no-op on such a skolem

Note [Tricky scoping in generaliseTcTyCon]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider #16342
  class C (a::ka) x where
    cop :: D a x => x -> Proxy a -> Proxy a
    cop _ x = x :: Proxy (a::ka)

  class D (b::kb) y where
    dop :: C b y => y -> Proxy b -> Proxy b
    dop _ x = x :: Proxy (b::kb)

C and D are mutually recursive, by the time we get to
generaliseTcTyCon we'll have unified kka := kkb.

But when typechecking the default declarations for 'cop' and 'dop' in
tcDlassDecl2 we need {a, ka} and {b, kb} respectively to be in scope.
But at that point all we have is the utterly-final Class itself.

Conclusion: the classTyVars of a class must have the same Name as
that originally assigned by the user.  In our example, C must have
classTyVars {a, ka, x} while D has classTyVars {a, kb, y}.  Despite
the fact that kka and kkb got unified!

We achieve this sleight of hand in generaliseTcTyCon, using
the specialised function zonkRecTyVarBndrs.  We make the call
   zonkRecTyVarBndrs [ka,a,x] [kkb,aa,xxx]
where the [ka,a,x] are the Names originally assigned by the user, and
[kkb,aa,xx] are the corresponding (post-zonking, skolemised) TcTyVars.
zonkRecTyVarBndrs builds a recursive ZonkEnv that binds
   kkb :-> (ka :: <zonked kind of kkb>)
   aa  :-> (a  :: <konked kind of aa>)
   etc
That is, it maps each skolemised TcTyVars to the utterly-final
TyVar to put in the class, with its correct user-specified name.
When generalising D we'll do the same thing, but the ZonkEnv will map
   kkb :-> (kb :: <zonked kind of kkb>)
   bb  :-> (b  :: <konked kind of bb>)
   etc
Note that 'kkb' again appears in the domain of the mapping, but this
time mapped to 'kb'.  That's how C and D end up with differently-named
final TyVars despite the fact that we unified kka:=kkb

zonkRecTyVarBndrs we need to do knot-tying because of the need to
apply this same substitution to the kind of each.

Note [Inferring visible dependent quantification]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider

  data T k :: k -> Type where
    MkT1 :: T Type Int
    MkT2 :: T (Type -> Type) Maybe

This looks like it should work. However, it is polymorphically recursive,
as the uses of T in the constructor types specialize the k in the kind
of T. This trips up our dear users (#17131, #17541), and so we add
a "landmark" context (which cannot be suppressed) whenever we
spot inferred visible dependent quantification (VDQ).

It's hard to know when we've actually been tripped up by polymorphic recursion
specifically, so we just include a note to users whenever we infer VDQ. The
testsuite did not show up a single spurious inclusion of this message.

The context is added in addVDQNote, which looks for a visible TyConBinder
that also appears in the TyCon's kind. (I first looked at the kind for
a visible, dependent quantifier, but Note [No polymorphic recursion] in
TcHsType defeats that approach.) addVDQNote is used in kcTyClDecl,
which is used only when inferring the kind of a tycon (never with a CUSK or
SAK).

Once upon a time, I (Richard E) thought that the tycon-kind could
not be a forall-type. But this is wrong: data T :: forall k. k -> Type
(with -XNoCUSKs) could end up here. And this is all OK.


-}

--------------
tcExtendKindEnvWithTyCons :: [TcTyCon] -> TcM a -> TcM a
tcExtendKindEnvWithTyCons :: [TyCon] -> TcM a -> TcM a
tcExtendKindEnvWithTyCons [TyCon]
tcs
  = [(Name, TcTyThing)] -> TcM a -> TcM a
forall r. [(Name, TcTyThing)] -> TcM r -> TcM r
tcExtendKindEnvList [ (TyCon -> Name
tyConName TyCon
tc, TyCon -> TcTyThing
ATcTyCon TyCon
tc) | TyCon
tc <- [TyCon]
tcs ]

--------------
mkPromotionErrorEnv :: [LTyClDecl GhcRn] -> TcTypeEnv
-- Maps each tycon/datacon to a suitable promotion error
--    tc :-> APromotionErr TyConPE
--    dc :-> APromotionErr RecDataConPE
--    See Note [Recursion and promoting data constructors]

mkPromotionErrorEnv :: [LTyClDecl GhcRn] -> NameEnv TcTyThing
mkPromotionErrorEnv [LTyClDecl GhcRn]
decls
  = (LTyClDecl GhcRn -> NameEnv TcTyThing -> NameEnv TcTyThing)
-> NameEnv TcTyThing -> [LTyClDecl GhcRn] -> NameEnv TcTyThing
forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr (NameEnv TcTyThing -> NameEnv TcTyThing -> NameEnv TcTyThing
forall a. NameEnv a -> NameEnv a -> NameEnv a
plusNameEnv (NameEnv TcTyThing -> NameEnv TcTyThing -> NameEnv TcTyThing)
-> (LTyClDecl GhcRn -> NameEnv TcTyThing)
-> LTyClDecl GhcRn
-> NameEnv TcTyThing
-> NameEnv TcTyThing
forall b c a. (b -> c) -> (a -> b) -> a -> c
. TyClDecl GhcRn -> NameEnv TcTyThing
mk_prom_err_env (TyClDecl GhcRn -> NameEnv TcTyThing)
-> (LTyClDecl GhcRn -> TyClDecl GhcRn)
-> LTyClDecl GhcRn
-> NameEnv TcTyThing
forall b c a. (b -> c) -> (a -> b) -> a -> c
. LTyClDecl GhcRn -> TyClDecl GhcRn
forall a. HasSrcSpan a => a -> SrcSpanLess a
unLoc)
          NameEnv TcTyThing
forall a. NameEnv a
emptyNameEnv [LTyClDecl GhcRn]
decls

mk_prom_err_env :: TyClDecl GhcRn -> TcTypeEnv
mk_prom_err_env :: TyClDecl GhcRn -> NameEnv TcTyThing
mk_prom_err_env (ClassDecl { tcdLName :: forall pass. TyClDecl pass -> Located (IdP pass)
tcdLName = L SrcSpan
_ IdP GhcRn
nm, tcdATs :: forall pass. TyClDecl pass -> [LFamilyDecl pass]
tcdATs = [LFamilyDecl GhcRn]
ats })
  = Name -> TcTyThing -> NameEnv TcTyThing
forall a. Name -> a -> NameEnv a
unitNameEnv Name
IdP GhcRn
nm (PromotionErr -> TcTyThing
APromotionErr PromotionErr
ClassPE)
    NameEnv TcTyThing -> NameEnv TcTyThing -> NameEnv TcTyThing
forall a. NameEnv a -> NameEnv a -> NameEnv a
`plusNameEnv`
    [(Name, TcTyThing)] -> NameEnv TcTyThing
forall a. [(Name, a)] -> NameEnv a
mkNameEnv [ (FamilyDecl GhcRn -> IdP GhcRn
forall (p :: Pass). FamilyDecl (GhcPass p) -> IdP (GhcPass p)
familyDeclName FamilyDecl GhcRn
at, PromotionErr -> TcTyThing
APromotionErr PromotionErr
TyConPE)
              | L SrcSpan
_ FamilyDecl GhcRn
at <- [LFamilyDecl GhcRn]
ats ]

mk_prom_err_env (DataDecl { tcdLName :: forall pass. TyClDecl pass -> Located (IdP pass)
tcdLName = L SrcSpan
_ IdP GhcRn
name
                          , tcdDataDefn :: forall pass. TyClDecl pass -> HsDataDefn pass
tcdDataDefn = HsDataDefn { dd_cons :: forall pass. HsDataDefn pass -> [LConDecl pass]
dd_cons = [LConDecl GhcRn]
cons } })
  = Name -> TcTyThing -> NameEnv TcTyThing
forall a. Name -> a -> NameEnv a
unitNameEnv Name
IdP GhcRn
name (PromotionErr -> TcTyThing
APromotionErr PromotionErr
TyConPE)
    NameEnv TcTyThing -> NameEnv TcTyThing -> NameEnv TcTyThing
forall a. NameEnv a -> NameEnv a -> NameEnv a
`plusNameEnv`
    [(Name, TcTyThing)] -> NameEnv TcTyThing
forall a. [(Name, a)] -> NameEnv a
mkNameEnv [ (Name
con, PromotionErr -> TcTyThing
APromotionErr PromotionErr
RecDataConPE)
              | L SrcSpan
_ ConDecl GhcRn
con' <- [LConDecl GhcRn]
cons
              , L SrcSpan
_ Name
con  <- ConDecl GhcRn -> [GenLocated SrcSpan (IdP GhcRn)]
forall (p :: Pass).
ConDecl (GhcPass p) -> [Located (IdP (GhcPass p))]
getConNames ConDecl GhcRn
con' ]

mk_prom_err_env TyClDecl GhcRn
decl
  = Name -> TcTyThing -> NameEnv TcTyThing
forall a. Name -> a -> NameEnv a
unitNameEnv (TyClDecl GhcRn -> IdP GhcRn
forall (p :: Pass). TyClDecl (GhcPass p) -> IdP (GhcPass p)
tcdName TyClDecl GhcRn
decl) (PromotionErr -> TcTyThing
APromotionErr PromotionErr
TyConPE)
    -- Works for family declarations too

--------------
inferInitialKinds :: [LTyClDecl GhcRn] -> TcM [TcTyCon]
-- Returns a TcTyCon for each TyCon bound by the decls,
-- each with its initial kind

inferInitialKinds :: [LTyClDecl GhcRn] -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
inferInitialKinds [LTyClDecl GhcRn]
decls
  = do { String -> SDoc -> TcRn ()
traceTc String
"inferInitialKinds {" (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$ [Name] -> SDoc
forall a. Outputable a => a -> SDoc
ppr ((LTyClDecl GhcRn -> Name) -> [LTyClDecl GhcRn] -> [Name]
forall a b. (a -> b) -> [a] -> [b]
map (TyClDecl GhcRn -> Name
forall (p :: Pass). TyClDecl (GhcPass p) -> IdP (GhcPass p)
tcdName (TyClDecl GhcRn -> Name)
-> (LTyClDecl GhcRn -> TyClDecl GhcRn) -> LTyClDecl GhcRn -> Name
forall b c a. (b -> c) -> (a -> b) -> a -> c
. LTyClDecl GhcRn -> TyClDecl GhcRn
forall a. HasSrcSpan a => a -> SrcSpanLess a
unLoc) [LTyClDecl GhcRn]
decls)
       ; [TyCon]
tcs <- (LTyClDecl GhcRn -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon])
-> [LTyClDecl GhcRn] -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall (m :: * -> *) a b. Monad m => (a -> m [b]) -> [a] -> m [b]
concatMapM LTyClDecl GhcRn -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
infer_initial_kind [LTyClDecl GhcRn]
decls
       ; String -> SDoc -> TcRn ()
traceTc String
"inferInitialKinds done }" SDoc
empty
       ; [TyCon] -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall (m :: * -> *) a. Monad m => a -> m a
return [TyCon]
tcs }
  where
    infer_initial_kind :: LTyClDecl GhcRn -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
infer_initial_kind = (SrcSpanLess (LTyClDecl GhcRn)
 -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon])
-> LTyClDecl GhcRn -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall a b. HasSrcSpan a => (SrcSpanLess a -> TcM b) -> a -> TcM b
addLocM (InitialKindStrategy
-> TyClDecl GhcRn -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
getInitialKind InitialKindStrategy
InitialKindInfer)

-- Check type/class declarations against their standalone kind signatures or
-- CUSKs, producing a generalized TcTyCon for each.
checkInitialKinds :: [(LTyClDecl GhcRn, SAKS_or_CUSK)] -> TcM [TcTyCon]
checkInitialKinds :: [(LTyClDecl GhcRn, SAKS_or_CUSK)]
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
checkInitialKinds [(LTyClDecl GhcRn, SAKS_or_CUSK)]
decls
  = do { String -> SDoc -> TcRn ()
traceTc String
"checkInitialKinds {" (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$ [(Name, SAKS_or_CUSK)] -> SDoc
forall a. Outputable a => a -> SDoc
ppr ((LTyClDecl GhcRn -> Name)
-> [(LTyClDecl GhcRn, SAKS_or_CUSK)] -> [(Name, SAKS_or_CUSK)]
forall a c b. (a -> c) -> [(a, b)] -> [(c, b)]
mapFst (TyClDecl GhcRn -> Name
forall (p :: Pass). TyClDecl (GhcPass p) -> IdP (GhcPass p)
tcdName (TyClDecl GhcRn -> Name)
-> (LTyClDecl GhcRn -> TyClDecl GhcRn) -> LTyClDecl GhcRn -> Name
forall b c a. (b -> c) -> (a -> b) -> a -> c
. LTyClDecl GhcRn -> TyClDecl GhcRn
forall a. HasSrcSpan a => a -> SrcSpanLess a
unLoc) [(LTyClDecl GhcRn, SAKS_or_CUSK)]
decls)
       ; [TyCon]
tcs <- ((LTyClDecl GhcRn, SAKS_or_CUSK)
 -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon])
-> [(LTyClDecl GhcRn, SAKS_or_CUSK)]
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall (m :: * -> *) a b. Monad m => (a -> m [b]) -> [a] -> m [b]
concatMapM (LTyClDecl GhcRn, SAKS_or_CUSK)
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall a.
(HasSrcSpan a, SrcSpanLess a ~ TyClDecl GhcRn) =>
(a, SAKS_or_CUSK) -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
check_initial_kind [(LTyClDecl GhcRn, SAKS_or_CUSK)]
decls
       ; String -> SDoc -> TcRn ()
traceTc String
"checkInitialKinds done }" SDoc
empty
       ; [TyCon] -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall (m :: * -> *) a. Monad m => a -> m a
return [TyCon]
tcs }
  where
    check_initial_kind :: (a, SAKS_or_CUSK) -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
check_initial_kind (a
ldecl, SAKS_or_CUSK
msig) =
      (SrcSpanLess a -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon])
-> a -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall a b. HasSrcSpan a => (SrcSpanLess a -> TcM b) -> a -> TcM b
addLocM (InitialKindStrategy
-> TyClDecl GhcRn -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
getInitialKind (SAKS_or_CUSK -> InitialKindStrategy
InitialKindCheck SAKS_or_CUSK
msig)) a
ldecl

-- | Get the initial kind of a TyClDecl, either generalized or non-generalized,
-- depending on the 'InitialKindStrategy'.
getInitialKind :: InitialKindStrategy -> TyClDecl GhcRn -> TcM [TcTyCon]

-- Allocate a fresh kind variable for each TyCon and Class
-- For each tycon, return a TcTyCon with kind k
-- where k is the kind of tc, derived from the LHS
--         of the definition (and probably including
--         kind unification variables)
--      Example: data T a b = ...
--      return (T, kv1 -> kv2 -> kv3)
--
-- This pass deals with (ie incorporates into the kind it produces)
--   * The kind signatures on type-variable binders
--   * The result kinds signature on a TyClDecl
--
-- No family instances are passed to checkInitialKinds/inferInitialKinds
getInitialKind :: InitialKindStrategy
-> TyClDecl GhcRn -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
getInitialKind InitialKindStrategy
strategy
    (ClassDecl { tcdLName :: forall pass. TyClDecl pass -> Located (IdP pass)
tcdLName = L SrcSpan
_ IdP GhcRn
name
               , tcdTyVars :: forall pass. TyClDecl pass -> LHsQTyVars pass
tcdTyVars = LHsQTyVars GhcRn
ktvs
               , tcdATs :: forall pass. TyClDecl pass -> [LFamilyDecl pass]
tcdATs = [LFamilyDecl GhcRn]
ats })
  = do { TyCon
cls <- InitialKindStrategy
-> Name
-> TyConFlavour
-> LHsQTyVars GhcRn
-> TcM ContextKind
-> TcRn TyCon
kcDeclHeader InitialKindStrategy
strategy Name
IdP GhcRn
name TyConFlavour
ClassFlavour LHsQTyVars GhcRn
ktvs (TcM ContextKind -> TcRn TyCon) -> TcM ContextKind -> TcRn TyCon
forall a b. (a -> b) -> a -> b
$
                ContextKind -> TcM ContextKind
forall (m :: * -> *) a. Monad m => a -> m a
return (Kind -> ContextKind
TheKind Kind
constraintKind)
       ; let parent_tv_prs :: ScopedPairs
parent_tv_prs = TyCon -> ScopedPairs
tcTyConScopedTyVars TyCon
cls
            -- See Note [Don't process associated types in getInitialKind]
       ; [TyCon]
inner_tcs <-
           ScopedPairs
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall r. ScopedPairs -> TcM r -> TcM r
tcExtendNameTyVarEnv ScopedPairs
parent_tv_prs (IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
 -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon])
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall a b. (a -> b) -> a -> b
$
           (LFamilyDecl GhcRn -> TcRn TyCon)
-> [LFamilyDecl GhcRn] -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM ((SrcSpanLess (LFamilyDecl GhcRn) -> TcRn TyCon)
-> LFamilyDecl GhcRn -> TcRn TyCon
forall a b. HasSrcSpan a => (SrcSpanLess a -> TcM b) -> a -> TcM b
addLocM (TyCon -> FamilyDecl GhcRn -> TcRn TyCon
getAssocFamInitialKind TyCon
cls)) [LFamilyDecl GhcRn]
ats
       ; [TyCon] -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall (m :: * -> *) a. Monad m => a -> m a
return (TyCon
cls TyCon -> [TyCon] -> [TyCon]
forall a. a -> [a] -> [a]
: [TyCon]
inner_tcs) }
  where
    getAssocFamInitialKind :: TyCon -> FamilyDecl GhcRn -> TcRn TyCon
getAssocFamInitialKind TyCon
cls =
      case InitialKindStrategy
strategy of
        InitialKindStrategy
InitialKindInfer -> Maybe TyCon -> FamilyDecl GhcRn -> TcRn TyCon
get_fam_decl_initial_kind (TyCon -> Maybe TyCon
forall a. a -> Maybe a
Just TyCon
cls)
        InitialKindCheck SAKS_or_CUSK
_ -> TyCon -> FamilyDecl GhcRn -> TcRn TyCon
check_initial_kind_assoc_fam TyCon
cls

getInitialKind InitialKindStrategy
strategy
    (DataDecl { tcdLName :: forall pass. TyClDecl pass -> Located (IdP pass)
tcdLName = L SrcSpan
_ IdP GhcRn
name
              , tcdTyVars :: forall pass. TyClDecl pass -> LHsQTyVars pass
tcdTyVars = LHsQTyVars GhcRn
ktvs
              , tcdDataDefn :: forall pass. TyClDecl pass -> HsDataDefn pass
tcdDataDefn = HsDataDefn { dd_kindSig :: forall pass. HsDataDefn pass -> Maybe (LHsKind pass)
dd_kindSig = Maybe (LHsKind GhcRn)
m_sig
                                         , dd_ND :: forall pass. HsDataDefn pass -> NewOrData
dd_ND = NewOrData
new_or_data } })
  = do  { let flav :: TyConFlavour
flav = NewOrData -> TyConFlavour
newOrDataToFlavour NewOrData
new_or_data
              ctxt :: UserTypeCtxt
ctxt = Name -> UserTypeCtxt
DataKindCtxt Name
IdP GhcRn
name
        ; TyCon
tc <- InitialKindStrategy
-> Name
-> TyConFlavour
-> LHsQTyVars GhcRn
-> TcM ContextKind
-> TcRn TyCon
kcDeclHeader InitialKindStrategy
strategy Name
IdP GhcRn
name TyConFlavour
flav LHsQTyVars GhcRn
ktvs (TcM ContextKind -> TcRn TyCon) -> TcM ContextKind -> TcRn TyCon
forall a b. (a -> b) -> a -> b
$
                case Maybe (LHsKind GhcRn)
m_sig of
                  Just LHsKind GhcRn
ksig -> Kind -> ContextKind
TheKind (Kind -> ContextKind) -> TcM Kind -> TcM ContextKind
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> UserTypeCtxt -> LHsKind GhcRn -> TcM Kind
tcLHsKindSig UserTypeCtxt
ctxt LHsKind GhcRn
ksig
                  Maybe (LHsKind GhcRn)
Nothing -> NewOrData -> TcM ContextKind
dataDeclDefaultResultKind NewOrData
new_or_data
        ; [TyCon] -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall (m :: * -> *) a. Monad m => a -> m a
return [TyCon
tc] }

getInitialKind InitialKindStrategy
InitialKindInfer (FamDecl { tcdFam :: forall pass. TyClDecl pass -> FamilyDecl pass
tcdFam = FamilyDecl GhcRn
decl })
  = do { TyCon
tc <- Maybe TyCon -> FamilyDecl GhcRn -> TcRn TyCon
get_fam_decl_initial_kind Maybe TyCon
forall a. Maybe a
Nothing FamilyDecl GhcRn
decl
       ; [TyCon] -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall (m :: * -> *) a. Monad m => a -> m a
return [TyCon
tc] }

getInitialKind (InitialKindCheck SAKS_or_CUSK
msig) (FamDecl { tcdFam :: forall pass. TyClDecl pass -> FamilyDecl pass
tcdFam =
  FamilyDecl { fdLName :: forall pass. FamilyDecl pass -> Located (IdP pass)
fdLName     = GenLocated SrcSpan (IdP GhcRn)
-> SrcSpanLess (GenLocated SrcSpan Name)
forall a. HasSrcSpan a => a -> SrcSpanLess a
unLoc -> SrcSpanLess (GenLocated SrcSpan Name)
name
             , fdTyVars :: forall pass. FamilyDecl pass -> LHsQTyVars pass
fdTyVars    = LHsQTyVars GhcRn
ktvs
             , fdResultSig :: forall pass. FamilyDecl pass -> LFamilyResultSig pass
fdResultSig = LFamilyResultSig GhcRn -> SrcSpanLess (LFamilyResultSig GhcRn)
forall a. HasSrcSpan a => a -> SrcSpanLess a
unLoc -> SrcSpanLess (LFamilyResultSig GhcRn)
resultSig
             , fdInfo :: forall pass. FamilyDecl pass -> FamilyInfo pass
fdInfo      = FamilyInfo GhcRn
info } } )
  = do { let flav :: TyConFlavour
flav = Maybe TyCon -> FamilyInfo GhcRn -> TyConFlavour
forall pass. Maybe TyCon -> FamilyInfo pass -> TyConFlavour
getFamFlav Maybe TyCon
forall a. Maybe a
Nothing FamilyInfo GhcRn
info
             ctxt :: UserTypeCtxt
ctxt = Name -> UserTypeCtxt
TyFamResKindCtxt Name
SrcSpanLess (GenLocated SrcSpan Name)
name
       ; TyCon
tc <- InitialKindStrategy
-> Name
-> TyConFlavour
-> LHsQTyVars GhcRn
-> TcM ContextKind
-> TcRn TyCon
kcDeclHeader (SAKS_or_CUSK -> InitialKindStrategy
InitialKindCheck SAKS_or_CUSK
msig) Name
SrcSpanLess (GenLocated SrcSpan Name)
name TyConFlavour
flav LHsQTyVars GhcRn
ktvs (TcM ContextKind -> TcRn TyCon) -> TcM ContextKind -> TcRn TyCon
forall a b. (a -> b) -> a -> b
$
               case FamilyResultSig GhcRn -> Maybe (LHsKind GhcRn)
forall (p :: Pass).
FamilyResultSig (GhcPass p) -> Maybe (LHsKind (GhcPass p))
famResultKindSignature SrcSpanLess (LFamilyResultSig GhcRn)
FamilyResultSig GhcRn
resultSig of
                 Just LHsKind GhcRn
ksig -> Kind -> ContextKind
TheKind (Kind -> ContextKind) -> TcM Kind -> TcM ContextKind
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> UserTypeCtxt -> LHsKind GhcRn -> TcM Kind
tcLHsKindSig UserTypeCtxt
ctxt LHsKind GhcRn
ksig
                 Maybe (LHsKind GhcRn)
Nothing ->
                   case SAKS_or_CUSK
msig of
                     SAKS_or_CUSK
CUSK -> ContextKind -> TcM ContextKind
forall (m :: * -> *) a. Monad m => a -> m a
return (Kind -> ContextKind
TheKind Kind
liftedTypeKind)
                     SAKS Kind
_ -> ContextKind -> TcM ContextKind
forall (m :: * -> *) a. Monad m => a -> m a
return ContextKind
AnyKind
       ; [TyCon] -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall (m :: * -> *) a. Monad m => a -> m a
return [TyCon
tc] }

getInitialKind InitialKindStrategy
strategy
    (SynDecl { tcdLName :: forall pass. TyClDecl pass -> Located (IdP pass)
tcdLName = L SrcSpan
_ IdP GhcRn
name
             , tcdTyVars :: forall pass. TyClDecl pass -> LHsQTyVars pass
tcdTyVars = LHsQTyVars GhcRn
ktvs
             , tcdRhs :: forall pass. TyClDecl pass -> LHsType pass
tcdRhs = LHsKind GhcRn
rhs })
  = do { let ctxt :: UserTypeCtxt
ctxt = Name -> UserTypeCtxt
TySynKindCtxt Name
IdP GhcRn
name
       ; TyCon
tc <- InitialKindStrategy
-> Name
-> TyConFlavour
-> LHsQTyVars GhcRn
-> TcM ContextKind
-> TcRn TyCon
kcDeclHeader InitialKindStrategy
strategy Name
IdP GhcRn
name TyConFlavour
TypeSynonymFlavour LHsQTyVars GhcRn
ktvs (TcM ContextKind -> TcRn TyCon) -> TcM ContextKind -> TcRn TyCon
forall a b. (a -> b) -> a -> b
$
               case LHsKind GhcRn -> Maybe (LHsKind GhcRn)
forall pass. LHsType pass -> Maybe (LHsType pass)
hsTyKindSig LHsKind GhcRn
rhs of
                 Just LHsKind GhcRn
rhs_sig -> Kind -> ContextKind
TheKind (Kind -> ContextKind) -> TcM Kind -> TcM ContextKind
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> UserTypeCtxt -> LHsKind GhcRn -> TcM Kind
tcLHsKindSig UserTypeCtxt
ctxt LHsKind GhcRn
rhs_sig
                 Maybe (LHsKind GhcRn)
Nothing -> ContextKind -> TcM ContextKind
forall (m :: * -> *) a. Monad m => a -> m a
return ContextKind
AnyKind
       ; [TyCon] -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall (m :: * -> *) a. Monad m => a -> m a
return [TyCon
tc] }

getInitialKind InitialKindStrategy
_ (DataDecl XDataDecl GhcRn
_ GenLocated SrcSpan (IdP GhcRn)
_ LHsQTyVars GhcRn
_ LexicalFixity
_ (XHsDataDefn XXHsDataDefn GhcRn
nec)) = NoExtCon -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall a. NoExtCon -> a
noExtCon XXHsDataDefn GhcRn
NoExtCon
nec
getInitialKind InitialKindStrategy
_ (FamDecl {tcdFam :: forall pass. TyClDecl pass -> FamilyDecl pass
tcdFam = XFamilyDecl XXFamilyDecl GhcRn
nec}) = NoExtCon -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall a. NoExtCon -> a
noExtCon XXFamilyDecl GhcRn
NoExtCon
nec
getInitialKind InitialKindStrategy
_ (XTyClDecl XXTyClDecl GhcRn
nec) = NoExtCon -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall a. NoExtCon -> a
noExtCon XXTyClDecl GhcRn
NoExtCon
nec

get_fam_decl_initial_kind
  :: Maybe TcTyCon -- ^ Just cls <=> this is an associated family of class cls
  -> FamilyDecl GhcRn
  -> TcM TcTyCon
get_fam_decl_initial_kind :: Maybe TyCon -> FamilyDecl GhcRn -> TcRn TyCon
get_fam_decl_initial_kind Maybe TyCon
mb_parent_tycon
    FamilyDecl { fdLName :: forall pass. FamilyDecl pass -> Located (IdP pass)
fdLName     = L SrcSpan
_ IdP GhcRn
name
               , fdTyVars :: forall pass. FamilyDecl pass -> LHsQTyVars pass
fdTyVars    = LHsQTyVars GhcRn
ktvs
               , fdResultSig :: forall pass. FamilyDecl pass -> LFamilyResultSig pass
fdResultSig = L SrcSpan
_ FamilyResultSig GhcRn
resultSig
               , fdInfo :: forall pass. FamilyDecl pass -> FamilyInfo pass
fdInfo      = FamilyInfo GhcRn
info }
  = InitialKindStrategy
-> Name
-> TyConFlavour
-> LHsQTyVars GhcRn
-> TcM ContextKind
-> TcRn TyCon
kcDeclHeader InitialKindStrategy
InitialKindInfer Name
IdP GhcRn
name TyConFlavour
flav LHsQTyVars GhcRn
ktvs (TcM ContextKind -> TcRn TyCon) -> TcM ContextKind -> TcRn TyCon
forall a b. (a -> b) -> a -> b
$
    case FamilyResultSig GhcRn
resultSig of
      KindSig XCKindSig GhcRn
_ LHsKind GhcRn
ki                          -> Kind -> ContextKind
TheKind (Kind -> ContextKind) -> TcM Kind -> TcM ContextKind
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> UserTypeCtxt -> LHsKind GhcRn -> TcM Kind
tcLHsKindSig UserTypeCtxt
ctxt LHsKind GhcRn
ki
      TyVarSig XTyVarSig GhcRn
_ (L SrcSpan
_ (KindedTyVar XKindedTyVar GhcRn
_ GenLocated SrcSpan (IdP GhcRn)
_ LHsKind GhcRn
ki)) -> Kind -> ContextKind
TheKind (Kind -> ContextKind) -> TcM Kind -> TcM ContextKind
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> UserTypeCtxt -> LHsKind GhcRn -> TcM Kind
tcLHsKindSig UserTypeCtxt
ctxt LHsKind GhcRn
ki
      FamilyResultSig GhcRn
_ -- open type families have * return kind by default
        | TyConFlavour -> Bool
tcFlavourIsOpen TyConFlavour
flav              -> ContextKind -> TcM ContextKind
forall (m :: * -> *) a. Monad m => a -> m a
return (Kind -> ContextKind
TheKind Kind
liftedTypeKind)
               -- closed type families have their return kind inferred
               -- by default
        | Bool
otherwise                         -> ContextKind -> TcM ContextKind
forall (m :: * -> *) a. Monad m => a -> m a
return ContextKind
AnyKind
  where
    flav :: TyConFlavour
flav = Maybe TyCon -> FamilyInfo GhcRn -> TyConFlavour
forall pass. Maybe TyCon -> FamilyInfo pass -> TyConFlavour
getFamFlav Maybe TyCon
mb_parent_tycon FamilyInfo GhcRn
info
    ctxt :: UserTypeCtxt
ctxt = Name -> UserTypeCtxt
TyFamResKindCtxt Name
IdP GhcRn
name
get_fam_decl_initial_kind Maybe TyCon
_ (XFamilyDecl XXFamilyDecl GhcRn
nec) = NoExtCon -> TcRn TyCon
forall a. NoExtCon -> a
noExtCon XXFamilyDecl GhcRn
NoExtCon
nec

-- See Note [Standalone kind signatures for associated types]
check_initial_kind_assoc_fam
  :: TcTyCon -- parent class
  -> FamilyDecl GhcRn
  -> TcM TcTyCon
check_initial_kind_assoc_fam :: TyCon -> FamilyDecl GhcRn -> TcRn TyCon
check_initial_kind_assoc_fam TyCon
cls
  FamilyDecl
    { fdLName :: forall pass. FamilyDecl pass -> Located (IdP pass)
fdLName     = GenLocated SrcSpan (IdP GhcRn)
-> SrcSpanLess (GenLocated SrcSpan Name)
forall a. HasSrcSpan a => a -> SrcSpanLess a
unLoc -> SrcSpanLess (GenLocated SrcSpan Name)
name
    , fdTyVars :: forall pass. FamilyDecl pass -> LHsQTyVars pass
fdTyVars    = LHsQTyVars GhcRn
ktvs
    , fdResultSig :: forall pass. FamilyDecl pass -> LFamilyResultSig pass
fdResultSig = LFamilyResultSig GhcRn -> SrcSpanLess (LFamilyResultSig GhcRn)
forall a. HasSrcSpan a => a -> SrcSpanLess a
unLoc -> SrcSpanLess (LFamilyResultSig GhcRn)
resultSig
    , fdInfo :: forall pass. FamilyDecl pass -> FamilyInfo pass
fdInfo      = FamilyInfo GhcRn
info }
  = InitialKindStrategy
-> Name
-> TyConFlavour
-> LHsQTyVars GhcRn
-> TcM ContextKind
-> TcRn TyCon
kcDeclHeader (SAKS_or_CUSK -> InitialKindStrategy
InitialKindCheck SAKS_or_CUSK
CUSK) Name
SrcSpanLess (GenLocated SrcSpan Name)
name TyConFlavour
flav LHsQTyVars GhcRn
ktvs (TcM ContextKind -> TcRn TyCon) -> TcM ContextKind -> TcRn TyCon
forall a b. (a -> b) -> a -> b
$
    case FamilyResultSig GhcRn -> Maybe (LHsKind GhcRn)
forall (p :: Pass).
FamilyResultSig (GhcPass p) -> Maybe (LHsKind (GhcPass p))
famResultKindSignature SrcSpanLess (LFamilyResultSig GhcRn)
FamilyResultSig GhcRn
resultSig of
      Just LHsKind GhcRn
ksig -> Kind -> ContextKind
TheKind (Kind -> ContextKind) -> TcM Kind -> TcM ContextKind
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> UserTypeCtxt -> LHsKind GhcRn -> TcM Kind
tcLHsKindSig UserTypeCtxt
ctxt LHsKind GhcRn
ksig
      Maybe (LHsKind GhcRn)
Nothing -> ContextKind -> TcM ContextKind
forall (m :: * -> *) a. Monad m => a -> m a
return (Kind -> ContextKind
TheKind Kind
liftedTypeKind)
  where
    ctxt :: UserTypeCtxt
ctxt = Name -> UserTypeCtxt
TyFamResKindCtxt Name
SrcSpanLess (GenLocated SrcSpan Name)
name
    flav :: TyConFlavour
flav = Maybe TyCon -> FamilyInfo GhcRn -> TyConFlavour
forall pass. Maybe TyCon -> FamilyInfo pass -> TyConFlavour
getFamFlav (TyCon -> Maybe TyCon
forall a. a -> Maybe a
Just TyCon
cls) FamilyInfo GhcRn
info
check_initial_kind_assoc_fam TyCon
_ (XFamilyDecl XXFamilyDecl GhcRn
nec) = NoExtCon -> TcRn TyCon
forall a. NoExtCon -> a
noExtCon XXFamilyDecl GhcRn
NoExtCon
nec

{- Note [Standalone kind signatures for associated types]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

If associated types had standalone kind signatures, would they wear them

---------------------------+------------------------------
  like this? (OUT)         |   or like this? (IN)
---------------------------+------------------------------
  type T :: Type -> Type   |   class C a where
  class C a where          |     type T :: Type -> Type
    type T a               |     type T a

The (IN) variant is syntactically ambiguous:

  class C a where
    type T :: a   -- standalone kind signature?
    type T :: a   -- declaration header?

The (OUT) variant does not suffer from this issue, but it might not be the
direction in which we want to take Haskell: we seek to unify type families and
functions, and, by extension, associated types with class methods. And yet we
give class methods their signatures inside the class, not outside. Neither do
we have the counterpart of InstanceSigs for StandaloneKindSignatures.

For now, we dodge the question by using CUSKs for associated types instead of
standalone kind signatures. This is a simple addition to the rule we used to
have before standalone kind signatures:

  old rule:  associated type has a CUSK iff its parent class has a CUSK
  new rule:  associated type has a CUSK iff its parent class has a CUSK or a standalone kind signature

-}

-- See Note [Data declaration default result kind]
dataDeclDefaultResultKind :: NewOrData -> TcM ContextKind
dataDeclDefaultResultKind :: NewOrData -> TcM ContextKind
dataDeclDefaultResultKind NewOrData
new_or_data = do
  -- See Note [Implementation of UnliftedNewtypes]
  Bool
unlifted_newtypes <- Extension -> TcRnIf TcGblEnv TcLclEnv Bool
forall gbl lcl. Extension -> TcRnIf gbl lcl Bool
xoptM Extension
LangExt.UnliftedNewtypes
  ContextKind -> TcM ContextKind
forall (m :: * -> *) a. Monad m => a -> m a
return (ContextKind -> TcM ContextKind) -> ContextKind -> TcM ContextKind
forall a b. (a -> b) -> a -> b
$ case NewOrData
new_or_data of
    NewOrData
NewType | Bool
unlifted_newtypes -> ContextKind
OpenKind
    NewOrData
_ -> Kind -> ContextKind
TheKind Kind
liftedTypeKind

{- Note [Data declaration default result kind]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

When the user has not written an inline result kind annotation on a data
declaration, we assume it to be 'Type'. That is, the following declarations
D1 and D2 are considered equivalent:

  data D1         where ...
  data D2 :: Type where ...

The consequence of this assumption is that we reject D3 even though we
accept D4:

  data D3 where
    MkD3 :: ... -> D3 param

  data D4 :: Type -> Type where
    MkD4 :: ... -> D4 param

However, there's a twist: when -XUnliftedNewtypes are enabled, we must relax
the assumed result kind to (TYPE r) for newtypes:

  newtype D5 where
    MkD5 :: Int# -> D5

dataDeclDefaultResultKind takes care to produce the appropriate result kind.
-}

---------------------------------
getFamFlav
  :: Maybe TcTyCon    -- ^ Just cls <=> this is an associated family of class cls
  -> FamilyInfo pass
  -> TyConFlavour
getFamFlav :: Maybe TyCon -> FamilyInfo pass -> TyConFlavour
getFamFlav Maybe TyCon
mb_parent_tycon FamilyInfo pass
info =
  case FamilyInfo pass
info of
    FamilyInfo pass
DataFamily         -> Maybe TyCon -> TyConFlavour
DataFamilyFlavour Maybe TyCon
mb_parent_tycon
    FamilyInfo pass
OpenTypeFamily     -> Maybe TyCon -> TyConFlavour
OpenTypeFamilyFlavour Maybe TyCon
mb_parent_tycon
    ClosedTypeFamily Maybe [LTyFamInstEqn pass]
_ -> ASSERT( isNothing mb_parent_tycon ) -- See Note [Closed type family mb_parent_tycon]
                          TyConFlavour
ClosedTypeFamilyFlavour

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

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

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

------------------------------------------------------------------------
kcLTyClDecl :: LTyClDecl GhcRn -> TcM ()
  -- See Note [Kind checking for type and class decls]
  -- Called only for declarations without a signature (no CUSKs or SAKs here)
kcLTyClDecl :: LTyClDecl GhcRn -> TcRn ()
kcLTyClDecl (L SrcSpan
loc TyClDecl GhcRn
decl)
  = SrcSpan -> TcRn () -> TcRn ()
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan SrcSpan
loc (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
    do { TyCon
tycon <- Name -> TcRn TyCon
kcLookupTcTyCon Name
IdP GhcRn
tc_name
       ; String -> SDoc -> TcRn ()
traceTc String
"kcTyClDecl {" (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
IdP GhcRn
tc_name)
       ; TyCon -> TcRn () -> TcRn ()
forall a. TyCon -> TcM a -> TcM a
addVDQNote TyCon
tycon (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$   -- See Note [Inferring visible dependent quantification]
         SDoc -> TcRn () -> TcRn ()
forall a. SDoc -> TcM a -> TcM a
addErrCtxt (TyClDecl GhcRn -> SDoc
tcMkDeclCtxt TyClDecl GhcRn
decl) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
         TyClDecl GhcRn -> TyCon -> TcRn ()
kcTyClDecl TyClDecl GhcRn
decl TyCon
tycon
       ; String -> SDoc -> TcRn ()
traceTc String
"kcTyClDecl done }" (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
IdP GhcRn
tc_name) }
  where
    tc_name :: IdP GhcRn
tc_name = TyClDecl GhcRn -> IdP GhcRn
forall (p :: Pass). TyClDecl (GhcPass p) -> IdP (GhcPass p)
tcdName TyClDecl GhcRn
decl

kcTyClDecl :: TyClDecl GhcRn -> TcTyCon -> TcM ()
-- This function is used solely for its side effect on kind variables
-- NB kind signatures on the type variables and
--    result kind signature have already been dealt with
--    by inferInitialKind, so we can ignore them here.

kcTyClDecl :: TyClDecl GhcRn -> TyCon -> TcRn ()
kcTyClDecl (DataDecl { tcdLName :: forall pass. TyClDecl pass -> Located (IdP pass)
tcdLName    = (L SrcSpan
_ IdP GhcRn
name)
                     , tcdDataDefn :: forall pass. TyClDecl pass -> HsDataDefn pass
tcdDataDefn = HsDataDefn GhcRn
defn }) TyCon
tyCon
  | HsDataDefn { dd_cons :: forall pass. HsDataDefn pass -> [LConDecl pass]
dd_cons = cons :: [LConDecl GhcRn]
cons@((L SrcSpan
_ (ConDeclGADT {})) : [LConDecl GhcRn]
_)
               , dd_ctxt :: forall pass. HsDataDefn pass -> LHsContext pass
dd_ctxt = (L SrcSpan
_ [])
               , dd_ND :: forall pass. HsDataDefn pass -> NewOrData
dd_ND = NewOrData
new_or_data } <- HsDataDefn GhcRn
defn
  = -- See Note [Implementation of UnliftedNewtypes] STEP 2
    NewOrData -> Kind -> [LConDecl GhcRn] -> TcRn ()
kcConDecls NewOrData
new_or_data (TyCon -> Kind
tyConResKind TyCon
tyCon) [LConDecl GhcRn]
cons

    -- hs_tvs and dd_kindSig already dealt with in inferInitialKind
    -- This must be a GADT-style decl,
    --        (see invariants of DataDefn declaration)
    -- so (a) we don't need to bring the hs_tvs into scope, because the
    --        ConDecls bind all their own variables
    --    (b) dd_ctxt is not allowed for GADT-style decls, so we can ignore it

  | HsDataDefn { dd_ctxt :: forall pass. HsDataDefn pass -> LHsContext pass
dd_ctxt = GenLocated SrcSpan (HsContext GhcRn)
ctxt
               , dd_cons :: forall pass. HsDataDefn pass -> [LConDecl pass]
dd_cons = [LConDecl GhcRn]
cons
               , dd_ND :: forall pass. HsDataDefn pass -> NewOrData
dd_ND = NewOrData
new_or_data } <- HsDataDefn GhcRn
defn
  = Name -> ([TyConBinder] -> Kind -> TcRn ()) -> TcRn ()
forall a. Name -> ([TyConBinder] -> Kind -> TcM a) -> TcM a
bindTyClTyVars Name
IdP GhcRn
name (([TyConBinder] -> Kind -> TcRn ()) -> TcRn ())
-> ([TyConBinder] -> Kind -> TcRn ()) -> TcRn ()
forall a b. (a -> b) -> a -> b
$ \ [TyConBinder]
_ Kind
_ ->
    do { [Kind]
_ <- GenLocated SrcSpan (HsContext GhcRn) -> TcM [Kind]
tcHsContext GenLocated SrcSpan (HsContext GhcRn)
ctxt
       ; NewOrData -> Kind -> [LConDecl GhcRn] -> TcRn ()
kcConDecls NewOrData
new_or_data (TyCon -> Kind
tyConResKind TyCon
tyCon) [LConDecl GhcRn]
cons
       }

kcTyClDecl (SynDecl { tcdLName :: forall pass. TyClDecl pass -> Located (IdP pass)
tcdLName = L SrcSpan
_ IdP GhcRn
name, tcdRhs :: forall pass. TyClDecl pass -> LHsType pass
tcdRhs = LHsKind GhcRn
rhs }) TyCon
_tycon
  = Name -> ([TyConBinder] -> Kind -> TcRn ()) -> TcRn ()
forall a. Name -> ([TyConBinder] -> Kind -> TcM a) -> TcM a
bindTyClTyVars Name
IdP GhcRn
name (([TyConBinder] -> Kind -> TcRn ()) -> TcRn ())
-> ([TyConBinder] -> Kind -> TcRn ()) -> TcRn ()
forall a b. (a -> b) -> a -> b
$ \ [TyConBinder]
_ Kind
res_kind ->
    TcM Kind -> TcRn ()
forall a. TcM a -> TcRn ()
discardResult (TcM Kind -> TcRn ()) -> TcM Kind -> TcRn ()
forall a b. (a -> b) -> a -> b
$ LHsKind GhcRn -> Kind -> TcM Kind
tcCheckLHsType LHsKind GhcRn
rhs Kind
res_kind
        -- NB: check against the result kind that we allocated
        -- in inferInitialKinds.

kcTyClDecl (ClassDecl { tcdLName :: forall pass. TyClDecl pass -> Located (IdP pass)
tcdLName = L SrcSpan
_ IdP GhcRn
name
                      , tcdCtxt :: forall pass. TyClDecl pass -> LHsContext pass
tcdCtxt = GenLocated SrcSpan (HsContext GhcRn)
ctxt, tcdSigs :: forall pass. TyClDecl pass -> [LSig pass]
tcdSigs = [LSig GhcRn]
sigs }) TyCon
_tycon
  = Name -> ([TyConBinder] -> Kind -> TcRn ()) -> TcRn ()
forall a. Name -> ([TyConBinder] -> Kind -> TcM a) -> TcM a
bindTyClTyVars Name
IdP GhcRn
name (([TyConBinder] -> Kind -> TcRn ()) -> TcRn ())
-> ([TyConBinder] -> Kind -> TcRn ()) -> TcRn ()
forall a b. (a -> b) -> a -> b
$ \ [TyConBinder]
_ Kind
_ ->
    do  { [Kind]
_ <- GenLocated SrcSpan (HsContext GhcRn) -> TcM [Kind]
tcHsContext GenLocated SrcSpan (HsContext GhcRn)
ctxt
        ; (LSig GhcRn -> TcRn ()) -> [LSig GhcRn] -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ ((SrcSpanLess (LSig GhcRn) -> TcRn ()) -> LSig GhcRn -> TcRn ()
forall a.
HasSrcSpan a =>
(SrcSpanLess a -> TcRn ()) -> a -> TcRn ()
wrapLocM_ SrcSpanLess (LSig GhcRn) -> TcRn ()
Sig GhcRn -> TcRn ()
kc_sig) [LSig GhcRn]
sigs }
  where
    kc_sig :: Sig GhcRn -> TcRn ()
kc_sig (ClassOpSig XClassOpSig GhcRn
_ Bool
_ [GenLocated SrcSpan (IdP GhcRn)]
nms LHsSigType GhcRn
op_ty) = SkolemInfo
-> [GenLocated SrcSpan Name] -> LHsSigType GhcRn -> TcRn ()
kcClassSigType SkolemInfo
skol_info [GenLocated SrcSpan Name]
[GenLocated SrcSpan (IdP GhcRn)]
nms LHsSigType GhcRn
op_ty
    kc_sig Sig GhcRn
_                          = () -> TcRn ()
forall (m :: * -> *) a. Monad m => a -> m a
return ()

    skol_info :: SkolemInfo
skol_info = TyConFlavour -> Name -> SkolemInfo
TyConSkol TyConFlavour
ClassFlavour Name
IdP GhcRn
name

kcTyClDecl (FamDecl XFamDecl GhcRn
_ (FamilyDecl { fdInfo :: forall pass. FamilyDecl pass -> FamilyInfo pass
fdInfo   = FamilyInfo GhcRn
fd_info })) TyCon
fam_tc
-- closed type families look at their equations, but other families don't
-- do anything here
  = case FamilyInfo GhcRn
fd_info of
      ClosedTypeFamily (Just [LTyFamInstEqn GhcRn]
eqns) -> (LTyFamInstEqn GhcRn -> TcRn ())
-> [LTyFamInstEqn GhcRn] -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ (TyCon -> LTyFamInstEqn GhcRn -> TcRn ()
kcTyFamInstEqn TyCon
fam_tc) [LTyFamInstEqn GhcRn]
eqns
      FamilyInfo GhcRn
_ -> () -> TcRn ()
forall (m :: * -> *) a. Monad m => a -> m a
return ()
kcTyClDecl (FamDecl XFamDecl GhcRn
_ (XFamilyDecl XXFamilyDecl GhcRn
nec))        TyCon
_ = NoExtCon -> TcRn ()
forall a. NoExtCon -> a
noExtCon XXFamilyDecl GhcRn
NoExtCon
nec
kcTyClDecl (DataDecl XDataDecl GhcRn
_ GenLocated SrcSpan (IdP GhcRn)
_ LHsQTyVars GhcRn
_ LexicalFixity
_ (XHsDataDefn XXHsDataDefn GhcRn
nec)) TyCon
_ = NoExtCon -> TcRn ()
forall a. NoExtCon -> a
noExtCon XXHsDataDefn GhcRn
NoExtCon
nec
kcTyClDecl (XTyClDecl XXTyClDecl GhcRn
nec)                      TyCon
_ = NoExtCon -> TcRn ()
forall a. NoExtCon -> a
noExtCon XXTyClDecl GhcRn
NoExtCon
nec

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

-- | Unify the kind of the first type provided with the newtype's kind, if
-- -XUnliftedNewtypes is enabled and the NewOrData indicates Newtype. If there
-- is more than one type provided, do nothing: the newtype is in error, and this
-- will be caught in validity checking (which will give a better error than we can
-- here.)
unifyNewtypeKind :: DynFlags
                 -> NewOrData
                 -> [LHsType GhcRn]   -- user-written argument types, should be just 1
                 -> [TcType]          -- type-checked argument types, should be just 1
                 -> TcKind            -- expected kind of newtype
                 -> TcM [TcType]      -- casted argument types (should be just 1)
                                      --  result = orig_arg |> kind_co
                                      -- where kind_co :: orig_arg_ki ~N expected_ki
unifyNewtypeKind :: DynFlags
-> NewOrData -> HsContext GhcRn -> [Kind] -> Kind -> TcM [Kind]
unifyNewtypeKind DynFlags
dflags NewOrData
NewType [LHsKind GhcRn
hs_ty] [Kind
tc_ty] Kind
ki
  | Extension -> DynFlags -> Bool
xopt Extension
LangExt.UnliftedNewtypes DynFlags
dflags
  = do { String -> SDoc -> TcRn ()
traceTc String
"unifyNewtypeKind" (LHsKind GhcRn -> SDoc
forall a. Outputable a => a -> SDoc
ppr LHsKind GhcRn
hs_ty SDoc -> SDoc -> SDoc
$$ Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr Kind
tc_ty SDoc -> SDoc -> SDoc
$$ Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr Kind
ki)
       ; Coercion
co <- Maybe (HsType GhcRn) -> Kind -> Kind -> TcM Coercion
unifyKind (HsType GhcRn -> Maybe (HsType GhcRn)
forall a. a -> Maybe a
Just (LHsKind GhcRn -> SrcSpanLess (LHsKind GhcRn)
forall a. HasSrcSpan a => a -> SrcSpanLess a
unLoc LHsKind GhcRn
hs_ty)) (HasDebugCallStack => Kind -> Kind
Kind -> Kind
typeKind Kind
tc_ty) Kind
ki
       ; [Kind] -> TcM [Kind]
forall (m :: * -> *) a. Monad m => a -> m a
return [Kind
tc_ty Kind -> Coercion -> Kind
`mkCastTy` Coercion
co] }
  -- See comments above: just do nothing here
unifyNewtypeKind DynFlags
_ NewOrData
_ HsContext GhcRn
_ [Kind]
arg_tys Kind
_ = [Kind] -> TcM [Kind]
forall (m :: * -> *) a. Monad m => a -> m a
return [Kind]
arg_tys

-- Type check the types of the arguments to a data constructor.
-- This includes doing kind unification if the type is a newtype.
-- See Note [Implementation of UnliftedNewtypes] for why we need
-- the first two arguments.
kcConArgTys :: NewOrData -> Kind -> [LHsType GhcRn] -> TcM ()
kcConArgTys :: NewOrData -> Kind -> HsContext GhcRn -> TcRn ()
kcConArgTys NewOrData
new_or_data Kind
res_kind HsContext GhcRn
arg_tys = do
  { [Kind]
arg_tc_tys <- (LHsKind GhcRn -> TcM Kind) -> HsContext GhcRn -> TcM [Kind]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM (LHsKind GhcRn -> TcM Kind
tcHsOpenType (LHsKind GhcRn -> TcM Kind)
-> (LHsKind GhcRn -> LHsKind GhcRn) -> LHsKind GhcRn -> TcM Kind
forall b c a. (b -> c) -> (a -> b) -> a -> c
. LHsKind GhcRn -> LHsKind GhcRn
forall a. LHsType a -> LHsType a
getBangType) HsContext GhcRn
arg_tys
    -- See Note [Implementation of UnliftedNewtypes], STEP 2
  ; DynFlags
dflags <- IOEnv (Env TcGblEnv TcLclEnv) DynFlags
forall (m :: * -> *). HasDynFlags m => m DynFlags
getDynFlags
  ; TcM [Kind] -> TcRn ()
forall a. TcM a -> TcRn ()
discardResult (TcM [Kind] -> TcRn ()) -> TcM [Kind] -> TcRn ()
forall a b. (a -> b) -> a -> b
$
      DynFlags
-> NewOrData -> HsContext GhcRn -> [Kind] -> Kind -> TcM [Kind]
unifyNewtypeKind DynFlags
dflags NewOrData
new_or_data HsContext GhcRn
arg_tys [Kind]
arg_tc_tys Kind
res_kind
  }

kcConDecls :: NewOrData
           -> Kind             -- The result kind signature
           -> [LConDecl GhcRn] -- The data constructors
           -> TcM ()
kcConDecls :: NewOrData -> Kind -> [LConDecl GhcRn] -> TcRn ()
kcConDecls NewOrData
new_or_data Kind
res_kind [LConDecl GhcRn]
cons
  = (LConDecl GhcRn -> TcRn ()) -> [LConDecl GhcRn] -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ ((SrcSpanLess (LConDecl GhcRn) -> TcRn ())
-> LConDecl GhcRn -> TcRn ()
forall a.
HasSrcSpan a =>
(SrcSpanLess a -> TcRn ()) -> a -> TcRn ()
wrapLocM_ (NewOrData -> Kind -> ConDecl GhcRn -> TcRn ()
kcConDecl NewOrData
new_or_data Kind
final_res_kind)) [LConDecl GhcRn]
cons
  where
    ([TyCoBinder]
_, Kind
final_res_kind) = Kind -> ([TyCoBinder], Kind)
splitPiTys Kind
res_kind
        -- See Note [kcConDecls result kind]

-- Kind check a data constructor. In additional to the data constructor,
-- we also need to know about whether or not its corresponding type was
-- declared with data or newtype, and we need to know the result kind of
-- this type. See Note [Implementation of UnliftedNewtypes] for why
-- we need the first two arguments.
kcConDecl :: NewOrData
          -> Kind  -- Result kind of the type constructor
                   -- Usually Type but can be TYPE UnliftedRep
                   -- or even TYPE r, in the case of unlifted newtype
          -> ConDecl GhcRn
          -> TcM ()
kcConDecl :: NewOrData -> Kind -> ConDecl GhcRn -> TcRn ()
kcConDecl NewOrData
new_or_data Kind
res_kind (ConDeclH98
  { con_name :: forall pass. ConDecl pass -> Located (IdP pass)
con_name = GenLocated SrcSpan (IdP GhcRn)
name, con_ex_tvs :: forall pass. ConDecl pass -> [LHsTyVarBndr pass]
con_ex_tvs = [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
ex_tvs
  , con_mb_cxt :: forall pass. ConDecl pass -> Maybe (LHsContext pass)
con_mb_cxt = Maybe (GenLocated SrcSpan (HsContext GhcRn))
ex_ctxt, con_args :: forall pass. ConDecl pass -> HsConDeclDetails pass
con_args = HsConDeclDetails GhcRn
args })
  = SDoc -> TcRn () -> TcRn ()
forall a. SDoc -> TcM a -> TcM a
addErrCtxt ([GenLocated SrcSpan Name] -> SDoc
dataConCtxtName [GenLocated SrcSpan Name
GenLocated SrcSpan (IdP GhcRn)
name]) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
    TcM ([TcTyCoVar], ()) -> TcRn ()
forall a. TcM a -> TcRn ()
discardResult                   (TcM ([TcTyCoVar], ()) -> TcRn ())
-> TcM ([TcTyCoVar], ()) -> TcRn ()
forall a b. (a -> b) -> a -> b
$
    [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
-> TcRn () -> TcM ([TcTyCoVar], ())
forall a.
[GenLocated SrcSpan (HsTyVarBndr GhcRn)]
-> TcM a -> TcM ([TcTyCoVar], a)
bindExplicitTKBndrs_Tv [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
ex_tvs (TcRn () -> TcM ([TcTyCoVar], ()))
-> TcRn () -> TcM ([TcTyCoVar], ())
forall a b. (a -> b) -> a -> b
$
    do { [Kind]
_ <- Maybe (GenLocated SrcSpan (HsContext GhcRn)) -> TcM [Kind]
tcHsMbContext Maybe (GenLocated SrcSpan (HsContext GhcRn))
ex_ctxt
       ; NewOrData -> Kind -> HsContext GhcRn -> TcRn ()
kcConArgTys NewOrData
new_or_data Kind
res_kind (HsConDeclDetails GhcRn -> HsContext GhcRn
forall pass. HsConDeclDetails pass -> [LBangType pass]
hsConDeclArgTys HsConDeclDetails GhcRn
args)
         -- We don't need to check the telescope here,
         -- because that's done in tcConDecl
       }

kcConDecl NewOrData
new_or_data Kind
res_kind (ConDeclGADT
    { con_names :: forall pass. ConDecl pass -> [Located (IdP pass)]
con_names = [GenLocated SrcSpan (IdP GhcRn)]
names, con_qvars :: forall pass. ConDecl pass -> LHsQTyVars pass
con_qvars = LHsQTyVars GhcRn
qtvs, con_mb_cxt :: forall pass. ConDecl pass -> Maybe (LHsContext pass)
con_mb_cxt = Maybe (GenLocated SrcSpan (HsContext GhcRn))
cxt
    , con_args :: forall pass. ConDecl pass -> HsConDeclDetails pass
con_args = HsConDeclDetails GhcRn
args, con_res_ty :: forall pass. ConDecl pass -> LHsType pass
con_res_ty = LHsKind GhcRn
res_ty })
  | HsQTvs { hsq_ext :: forall pass. LHsQTyVars pass -> XHsQTvs pass
hsq_ext = XHsQTvs GhcRn
implicit_tkv_nms
           , hsq_explicit :: forall pass. LHsQTyVars pass -> [LHsTyVarBndr pass]
hsq_explicit = [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
explicit_tkv_nms } <- LHsQTyVars GhcRn
qtvs
  = -- Even though the GADT-style data constructor's type is closed,
    -- we must still kind-check the type, because that may influence
    -- the inferred kind of the /type/ constructor.  Example:
    --    data T f a where
    --      MkT :: f a -> T f a
    -- If we don't look at MkT we won't get the correct kind
    -- for the type constructor T
    SDoc -> TcRn () -> TcRn ()
forall a. SDoc -> TcM a -> TcM a
addErrCtxt ([GenLocated SrcSpan Name] -> SDoc
dataConCtxtName [GenLocated SrcSpan Name]
[GenLocated SrcSpan (IdP GhcRn)]
names) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
    TcM ([TcTyCoVar], ([TcTyCoVar], ())) -> TcRn ()
forall a. TcM a -> TcRn ()
discardResult (TcM ([TcTyCoVar], ([TcTyCoVar], ())) -> TcRn ())
-> TcM ([TcTyCoVar], ([TcTyCoVar], ())) -> TcRn ()
forall a b. (a -> b) -> a -> b
$
    [Name]
-> TcM ([TcTyCoVar], ()) -> TcM ([TcTyCoVar], ([TcTyCoVar], ()))
forall a. [Name] -> TcM a -> TcM ([TcTyCoVar], a)
bindImplicitTKBndrs_Tv [Name]
XHsQTvs GhcRn
implicit_tkv_nms (TcM ([TcTyCoVar], ()) -> TcM ([TcTyCoVar], ([TcTyCoVar], ())))
-> TcM ([TcTyCoVar], ()) -> TcM ([TcTyCoVar], ([TcTyCoVar], ()))
forall a b. (a -> b) -> a -> b
$
    [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
-> TcRn () -> TcM ([TcTyCoVar], ())
forall a.
[GenLocated SrcSpan (HsTyVarBndr GhcRn)]
-> TcM a -> TcM ([TcTyCoVar], a)
bindExplicitTKBndrs_Tv [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
explicit_tkv_nms (TcRn () -> TcM ([TcTyCoVar], ()))
-> TcRn () -> TcM ([TcTyCoVar], ())
forall a b. (a -> b) -> a -> b
$
        -- Why "_Tv"?  See Note [Kind-checking for GADTs]
    do { [Kind]
_ <- Maybe (GenLocated SrcSpan (HsContext GhcRn)) -> TcM [Kind]
tcHsMbContext Maybe (GenLocated SrcSpan (HsContext GhcRn))
cxt
       ; NewOrData -> Kind -> HsContext GhcRn -> TcRn ()
kcConArgTys NewOrData
new_or_data Kind
res_kind (HsConDeclDetails GhcRn -> HsContext GhcRn
forall pass. HsConDeclDetails pass -> [LBangType pass]
hsConDeclArgTys HsConDeclDetails GhcRn
args)
       ; Kind
_ <- LHsKind GhcRn -> TcM Kind
tcHsOpenType LHsKind GhcRn
res_ty
       ; () -> TcRn ()
forall (m :: * -> *) a. Monad m => a -> m a
return () }
kcConDecl NewOrData
_ Kind
_ (ConDeclGADT XConDeclGADT GhcRn
_ [GenLocated SrcSpan (IdP GhcRn)]
_ Located Bool
_ (XLHsQTyVars XXLHsQTyVars GhcRn
nec) Maybe (GenLocated SrcSpan (HsContext GhcRn))
_ HsConDeclDetails GhcRn
_ LHsKind GhcRn
_ Maybe LHsDocString
_) = NoExtCon -> TcRn ()
forall a. NoExtCon -> a
noExtCon XXLHsQTyVars GhcRn
NoExtCon
nec
kcConDecl NewOrData
_ Kind
_ (XConDecl XXConDecl GhcRn
nec) = NoExtCon -> TcRn ()
forall a. NoExtCon -> a
noExtCon XXConDecl GhcRn
NoExtCon
nec

{- Note [kcConDecls result kind]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We might have e.g.
    data T a :: Type -> Type where ...
or
    newtype instance N a :: Type -> Type  where ..
in which case, the 'res_kind' passed to kcConDecls will be
   Type->Type

We must look past those arrows, or even foralls, to the Type in the
corner, to pass to kcConDecl c.f. #16828. Hence the splitPiTys here.

I am a bit concerned about tycons with a declaration like
   data T a :: Type -> forall k. k -> Type  where ...

It does not have a CUSK, so kcInferDeclHeader will make a TcTyCon
with tyConResKind of Type -> forall k. k -> Type.  Even that is fine:
the splitPiTys will look past the forall.  But I'm bothered about
what if the type "in the corner" mentions k?  This is incredibly
obscure but something like this could be bad:
   data T a :: Type -> foral k. k -> TYPE (F k) where ...

I bet we are not quite right here, but my brain suffered a buffer
overflow and I thought it best to nail the common cases right now.

Note [Recursion and promoting data constructors]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We don't want to allow promotion in a strongly connected component
when kind checking.

Consider:
  data T f = K (f (K Any))

When kind checking the `data T' declaration the local env contains the
mappings:
  T -> ATcTyCon <some initial kind>
  K -> APromotionErr

APromotionErr is only used for DataCons, and only used during type checking
in tcTyClGroup.

Note [Kind-checking for GADTs]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider

  data Proxy a where
    MkProxy1 :: forall k (b :: k). Proxy b
    MkProxy2 :: forall j (c :: j). Proxy c

It seems reasonable that this should be accepted. But something very strange
is going on here: when we're kind-checking this declaration, we need to unify
the kind of `a` with k and j -- even though k and j's scopes are local to the type of
MkProxy{1,2}. The best approach we've come up with is to use TyVarTvs during
the kind-checking pass. First off, note that it's OK if the kind-checking pass
is too permissive: we'll snag the problems in the type-checking pass later.
(This extra permissiveness might happen with something like

  data SameKind :: k -> k -> Type
  data Bad a where
    MkBad :: forall k1 k2 (a :: k1) (b :: k2). Bad (SameKind a b)

which would be accepted if k1 and k2 were TyVarTvs. This is correctly rejected
in the second pass, though. Test case: polykinds/TyVarTvKinds3)
Recall that the kind-checking pass exists solely to collect constraints
on the kinds and to power unification.

To achieve the use of TyVarTvs, we must be careful to use specialized functions
that produce TyVarTvs, not ordinary skolems. This is why we need
kcExplicitTKBndrs and kcImplicitTKBndrs in TcHsType, separate from their
tc... variants.

The drawback of this approach is sometimes it will accept a definition that
a (hypothetical) declarative specification would likely reject. As a general
rule, we don't want to allow polymorphic recursion without a CUSK. Indeed,
the whole point of CUSKs is to allow polymorphic recursion. Yet, the TyVarTvs
approach allows a limited form of polymorphic recursion *without* a CUSK.

To wit:
  data T a = forall k (b :: k). MkT (T b) Int
  (test case: dependent/should_compile/T14066a)

Note that this is polymorphically recursive, with the recursive occurrence
of T used at a kind other than a's kind. The approach outlined here accepts
this definition, because this kind is still a kind variable (and so the
TyVarTvs unify). Stepping back, I (Richard) have a hard time envisioning a
way to describe exactly what declarations will be accepted and which will
be rejected (without a CUSK). However, the accepted definitions are indeed
well-kinded and any rejected definitions would be accepted with a CUSK,
and so this wrinkle need not cause anyone to lose sleep.

************************************************************************
*                                                                      *
\subsection{Type checking}
*                                                                      *
************************************************************************

Note [Type checking recursive type and class declarations]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
At this point we have completed *kind-checking* of a mutually
recursive group of type/class decls (done in kcTyClGroup). However,
we discarded the kind-checked types (eg RHSs of data type decls);
note that kcTyClDecl returns ().  There are two reasons:

  * It's convenient, because we don't have to rebuild a
    kinded HsDecl (a fairly elaborate type)

  * It's necessary, because after kind-generalisation, the
    TyCons/Classes may now be kind-polymorphic, and hence need
    to be given kind arguments.

Example:
       data T f a = MkT (f a) (T f a)
During kind-checking, we give T the kind T :: k1 -> k2 -> *
and figure out constraints on k1, k2 etc. Then we generalise
to get   T :: forall k. (k->*) -> k -> *
So now the (T f a) in the RHS must be elaborated to (T k f a).

However, during tcTyClDecl of T (above) we will be in a recursive
"knot". So we aren't allowed to look at the TyCon T itself; we are only
allowed to put it (lazily) in the returned structures.  But when
kind-checking the RHS of T's decl, we *do* need to know T's kind (so
that we can correctly elaboarate (T k f a).  How can we get T's kind
without looking at T?  Delicate answer: during tcTyClDecl, we extend

  *Global* env with T -> ATyCon (the (not yet built) final TyCon for T)
  *Local*  env with T -> ATcTyCon (TcTyCon with the polymorphic kind of T)

Then:

  * During TcHsType.tcTyVar we look in the *local* env, to get the
    fully-known, not knot-tied TcTyCon for T.

  * Then, in TcHsSyn.zonkTcTypeToType (and zonkTcTyCon in particular)
    we look in the *global* env to get the TyCon.

This fancy footwork (with two bindings for T) is only necessary for the
TyCons or Classes of this recursive group.  Earlier, finished groups,
live in the global env only.

See also Note [Kind checking recursive type and class declarations]

Note [Kind checking recursive type and class declarations]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Before we can type-check the decls, we must kind check them. This
is done by establishing an "initial kind", which is a rather uninformed
guess at a tycon's kind (by counting arguments, mainly) and then
using this initial kind for recursive occurrences.

The initial kind is stored in exactly the same way during
kind-checking as it is during type-checking (Note [Type checking
recursive type and class declarations]): in the *local* environment,
with ATcTyCon. But we still must store *something* in the *global*
environment. Even though we discard the result of kind-checking, we
sometimes need to produce error messages. These error messages will
want to refer to the tycons being checked, except that they don't
exist yet, and it would be Terribly Annoying to get the error messages
to refer back to HsSyn. So we create a TcTyCon and put it in the
global env. This tycon can print out its name and knows its kind, but
any other action taken on it will panic. Note that TcTyCons are *not*
knot-tied, unlike the rather valid but knot-tied ones that occur
during type-checking.

Note [Declarations for wired-in things]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
For wired-in things we simply ignore the declaration
and take the wired-in information.  That avoids complications.
e.g. the need to make the data constructor worker name for
     a constraint tuple match the wired-in one

Note [Implementation of UnliftedNewtypes]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Expected behavior of UnliftedNewtypes:

* Proposal: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0013-unlifted-newtypes.rst
* Discussion: https://github.com/ghc-proposals/ghc-proposals/pull/98

What follows is a high-level overview of the implementation of the
proposal.

STEP 1: Getting the initial kind, as done by inferInitialKind. We have
two sub-cases (assuming we have a newtype and -XUnliftedNewtypes is enabled):

* With a CUSK: no change in kind-checking; the tycon is given the kind
  the user writes, whatever it may be.

* Without a CUSK: If there is no kind signature, the tycon is given
  a kind `TYPE r`, for a fresh unification variable `r`.

STEP 2: Kind-checking, as done by kcTyClDecl. This step is skipped for CUSKs.
The key function here is kcConDecl, which looks at an individual constructor
declaration. In the unlifted-newtypes case (i.e., -XUnliftedNewtypes and,
indeed, we are processing a newtype), we call unifyNewtypeKind, which is a
thin wrapper around unifyKind, unifying the kind of the one argument and the
result kind of the newtype tycon.

Examples of newtypes affected by STEP 2, assuming -XUnliftedNewtypes is
enabled (we use r0 to denote a unification variable):

newtype Foo rep = MkFoo (forall (a :: TYPE rep). a)
+ kcConDecl unifies (TYPE r0) with (TYPE rep), where (TYPE r0)
  is the kind that inferInitialKind invented for (Foo rep).

data Color = Red | Blue
type family Interpret (x :: Color) :: RuntimeRep where
  Interpret 'Red = 'IntRep
  Interpret 'Blue = 'WordRep
data family Foo (x :: Color) :: TYPE (Interpret x)
newtype instance Foo 'Red = FooRedC Int#
+ kcConDecl unifies TYPE (Interpret 'Red) with TYPE 'IntRep

Note that, in the GADT case, we might have a kind signature with arrows
(newtype XYZ a b :: Type -> Type where ...). We want only the final
component of the kind for checking in kcConDecl, so we call etaExpandAlgTyCon
in kcTyClDecl.

STEP 3: Type-checking (desugaring), as done by tcTyClDecl. The key function
here is tcConDecl. Once again, we must call unifyNewtypeKind, for two reasons:

  A. It is possible that a GADT has a CUSK. (Note that this is *not*
     possible for H98 types. Recall that CUSK types don't go through
     kcTyClDecl, so we might not have done this kind check.
  B. We need to produce the coercion to put on the argument type
     if the kinds are different (for both H98 and GADT).

Example of (B):

type family F a where
  F Int = LiftedRep

newtype N :: TYPE (F Int) where
  MkN :: Int -> N

We really need to have the argument to MkN be (Int |> TYPE (sym axF)), where
axF :: F Int ~ LiftedRep. That way, the argument kind is the same as the
newtype kind, which is the principal correctness condition for newtypes.
This call to unifyNewtypeKind is what produces that coercion.

Note that this is possible in the H98 case only for a data family, because
the H98 syntax doesn't permit a kind signature on the newtype itself.


1. In tcFamDecl1, we suppress a tcIsLiftedTypeKind check if
   UnliftedNewtypes is on. This allows us to write things like:
     data family Foo :: TYPE 'IntRep

2. In a newtype instance (with -XUnliftedNewtypes), if the user does
   not write a kind signature, we want to allow the possibility that
   the kind is not Type, so we use newOpenTypeKind instead of liftedTypeKind.
   This is done in tcDataFamInstHeader in TcInstDcls. Example:

       data family Bar (a :: RuntimeRep) :: TYPE a
       newtype instance Bar 'IntRep = BarIntC Int#
       newtype instance Bar 'WordRep :: TYPE 'WordRep where
         BarWordC :: Word# -> Bar 'WordRep

   The data instance corresponding to IntRep does not specify a kind signature,
   so tc_kind_sig just returns `TYPE r0` (where `r0` is a fresh metavariable).
   The data instance corresponding to WordRep does have a kind signature, so
   we use that kind signature.

3. A data family and its newtype instance may be declared with slightly
   different kinds. See Note [Unifying data family kinds] in TcInstDcls.

There's also a change in the renamer:

* In GHC.RenameSource.rnTyClDecl, enabling UnliftedNewtypes changes what is means
  for a newtype to have a CUSK. This is necessary since UnliftedNewtypes
  means that, for newtypes without kind signatures, we must use the field
  inside the data constructor to determine the result kind.
  See Note [Unlifted Newtypes and CUSKs] for more detail.

For completeness, it was also necessary to make coerce work on
unlifted types, resolving #13595.

-}

tcTyClDecl :: RolesInfo -> LTyClDecl GhcRn -> TcM (TyCon, [DerivInfo])
tcTyClDecl :: (Name -> [Role])
-> LTyClDecl GhcRn
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
tcTyClDecl Name -> [Role]
roles_info (L SrcSpan
loc TyClDecl GhcRn
decl)
  | Just TyThing
thing <- Name -> Maybe TyThing
wiredInNameTyThing_maybe (TyClDecl GhcRn -> IdP GhcRn
forall (p :: Pass). TyClDecl (GhcPass p) -> IdP (GhcPass p)
tcdName TyClDecl GhcRn
decl)
  = case TyThing
thing of -- See Note [Declarations for wired-in things]
      ATyCon TyCon
tc -> (TyCon, [DerivInfo])
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
forall (m :: * -> *) a. Monad m => a -> m a
return (TyCon
tc, TyCon -> TyClDecl GhcRn -> [DerivInfo]
wiredInDerivInfo TyCon
tc TyClDecl GhcRn
decl)
      TyThing
_ -> String
-> SDoc -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"tcTyClDecl" (TyThing -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyThing
thing)

  | Bool
otherwise
  = SrcSpan
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan SrcSpan
loc (IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
 -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo]))
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
forall a b. (a -> b) -> a -> b
$ TyClDecl GhcRn
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
forall a. TyClDecl GhcRn -> TcM a -> TcM a
tcAddDeclCtxt TyClDecl GhcRn
decl (IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
 -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo]))
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
forall a b. (a -> b) -> a -> b
$
    do { String -> SDoc -> TcRn ()
traceTc String
"---- tcTyClDecl ---- {" (TyClDecl GhcRn -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyClDecl GhcRn
decl)
       ; (TyCon
tc, [DerivInfo]
deriv_infos) <- Maybe Class
-> (Name -> [Role])
-> TyClDecl GhcRn
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
tcTyClDecl1 Maybe Class
forall a. Maybe a
Nothing Name -> [Role]
roles_info TyClDecl GhcRn
decl
       ; String -> SDoc -> TcRn ()
traceTc String
"---- tcTyClDecl end ---- }" (TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tc)
       ; (TyCon, [DerivInfo])
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
forall (m :: * -> *) a. Monad m => a -> m a
return (TyCon
tc, [DerivInfo]
deriv_infos) }

noDerivInfos :: a -> (a, [DerivInfo])
noDerivInfos :: a -> (a, [DerivInfo])
noDerivInfos a
a = (a
a, [])

wiredInDerivInfo :: TyCon -> TyClDecl GhcRn -> [DerivInfo]
wiredInDerivInfo :: TyCon -> TyClDecl GhcRn -> [DerivInfo]
wiredInDerivInfo TyCon
tycon TyClDecl GhcRn
decl
  | DataDecl { tcdDataDefn :: forall pass. TyClDecl pass -> HsDataDefn pass
tcdDataDefn = HsDataDefn GhcRn
dataDefn } <- TyClDecl GhcRn
decl
  , HsDataDefn { dd_derivs :: forall pass. HsDataDefn pass -> HsDeriving pass
dd_derivs = HsDeriving GhcRn
derivs } <- HsDataDefn GhcRn
dataDefn
  = [ DerivInfo :: TyCon
-> ScopedPairs -> [LHsDerivingClause GhcRn] -> SDoc -> DerivInfo
DerivInfo { di_rep_tc :: TyCon
di_rep_tc = TyCon
tycon
                , di_scoped_tvs :: ScopedPairs
di_scoped_tvs =
                    if TyCon -> Bool
isFunTyCon TyCon
tycon Bool -> Bool -> Bool
|| TyCon -> Bool
isPrimTyCon TyCon
tycon
                       then []  -- no tyConTyVars
                       else [TcTyCoVar] -> ScopedPairs
mkTyVarNamePairs (TyCon -> [TcTyCoVar]
tyConTyVars TyCon
tycon)
                , di_clauses :: [LHsDerivingClause GhcRn]
di_clauses = HsDeriving GhcRn -> SrcSpanLess (HsDeriving GhcRn)
forall a. HasSrcSpan a => a -> SrcSpanLess a
unLoc HsDeriving GhcRn
derivs
                , di_ctxt :: SDoc
di_ctxt = TyClDecl GhcRn -> SDoc
tcMkDeclCtxt TyClDecl GhcRn
decl } ]
wiredInDerivInfo TyCon
_ TyClDecl GhcRn
_ = []

  -- "type family" declarations
tcTyClDecl1 :: Maybe Class -> RolesInfo -> TyClDecl GhcRn -> TcM (TyCon, [DerivInfo])
tcTyClDecl1 :: Maybe Class
-> (Name -> [Role])
-> TyClDecl GhcRn
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
tcTyClDecl1 Maybe Class
parent Name -> [Role]
_roles_info (FamDecl { tcdFam :: forall pass. TyClDecl pass -> FamilyDecl pass
tcdFam = FamilyDecl GhcRn
fd })
  = (TyCon -> (TyCon, [DerivInfo]))
-> TcRn TyCon -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap TyCon -> (TyCon, [DerivInfo])
forall a. a -> (a, [DerivInfo])
noDerivInfos (TcRn TyCon -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo]))
-> TcRn TyCon -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
forall a b. (a -> b) -> a -> b
$
    Maybe Class -> FamilyDecl GhcRn -> TcRn TyCon
tcFamDecl1 Maybe Class
parent FamilyDecl GhcRn
fd

  -- "type" synonym declaration
tcTyClDecl1 Maybe Class
_parent Name -> [Role]
roles_info
            (SynDecl { tcdLName :: forall pass. TyClDecl pass -> Located (IdP pass)
tcdLName = L SrcSpan
_ IdP GhcRn
tc_name
                     , tcdRhs :: forall pass. TyClDecl pass -> LHsType pass
tcdRhs   = LHsKind GhcRn
rhs })
  = ASSERT( isNothing _parent )
    (TyCon -> (TyCon, [DerivInfo]))
-> TcRn TyCon -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap TyCon -> (TyCon, [DerivInfo])
forall a. a -> (a, [DerivInfo])
noDerivInfos (TcRn TyCon -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo]))
-> TcRn TyCon -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
forall a b. (a -> b) -> a -> b
$
    (Name -> [Role]) -> Name -> LHsKind GhcRn -> TcRn TyCon
tcTySynRhs Name -> [Role]
roles_info Name
IdP GhcRn
tc_name LHsKind GhcRn
rhs

  -- "data/newtype" declaration
tcTyClDecl1 Maybe Class
_parent Name -> [Role]
roles_info
            decl :: TyClDecl GhcRn
decl@(DataDecl { tcdLName :: forall pass. TyClDecl pass -> Located (IdP pass)
tcdLName = L SrcSpan
_ IdP GhcRn
tc_name
                           , tcdDataDefn :: forall pass. TyClDecl pass -> HsDataDefn pass
tcdDataDefn = HsDataDefn GhcRn
defn })
  = ASSERT( isNothing _parent )
    SDoc
-> (Name -> [Role])
-> Name
-> HsDataDefn GhcRn
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
tcDataDefn (TyClDecl GhcRn -> SDoc
tcMkDeclCtxt TyClDecl GhcRn
decl) Name -> [Role]
roles_info Name
IdP GhcRn
tc_name HsDataDefn GhcRn
defn

tcTyClDecl1 Maybe Class
_parent Name -> [Role]
roles_info
            (ClassDecl { tcdLName :: forall pass. TyClDecl pass -> Located (IdP pass)
tcdLName = L SrcSpan
_ IdP GhcRn
class_name
                       , tcdCtxt :: forall pass. TyClDecl pass -> LHsContext pass
tcdCtxt = GenLocated SrcSpan (HsContext GhcRn)
hs_ctxt
                       , tcdMeths :: forall pass. TyClDecl pass -> LHsBinds pass
tcdMeths = LHsBinds GhcRn
meths
                       , tcdFDs :: forall pass. TyClDecl pass -> [LHsFunDep pass]
tcdFDs = [LHsFunDep GhcRn]
fundeps
                       , tcdSigs :: forall pass. TyClDecl pass -> [LSig pass]
tcdSigs = [LSig GhcRn]
sigs
                       , tcdATs :: forall pass. TyClDecl pass -> [LFamilyDecl pass]
tcdATs = [LFamilyDecl GhcRn]
ats
                       , tcdATDefs :: forall pass. TyClDecl pass -> [LTyFamDefltDecl pass]
tcdATDefs = [LTyFamDefltDecl GhcRn]
at_defs })
  = ASSERT( isNothing _parent )
    do { Class
clas <- (Name -> [Role])
-> Name
-> GenLocated SrcSpan (HsContext GhcRn)
-> LHsBinds GhcRn
-> [LHsFunDep GhcRn]
-> [LSig GhcRn]
-> [LFamilyDecl GhcRn]
-> [LTyFamDefltDecl GhcRn]
-> TcM Class
tcClassDecl1 Name -> [Role]
roles_info Name
IdP GhcRn
class_name GenLocated SrcSpan (HsContext GhcRn)
hs_ctxt
                              LHsBinds GhcRn
meths [LHsFunDep GhcRn]
fundeps [LSig GhcRn]
sigs [LFamilyDecl GhcRn]
ats [LTyFamDefltDecl GhcRn]
at_defs
       ; (TyCon, [DerivInfo])
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
forall (m :: * -> *) a. Monad m => a -> m a
return (TyCon -> (TyCon, [DerivInfo])
forall a. a -> (a, [DerivInfo])
noDerivInfos (Class -> TyCon
classTyCon Class
clas)) }

tcTyClDecl1 Maybe Class
_ Name -> [Role]
_ (XTyClDecl XXTyClDecl GhcRn
nec) = NoExtCon -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
forall a. NoExtCon -> a
noExtCon XXTyClDecl GhcRn
NoExtCon
nec


{- *********************************************************************
*                                                                      *
          Class declarations
*                                                                      *
********************************************************************* -}

tcClassDecl1 :: RolesInfo -> Name -> LHsContext GhcRn
             -> LHsBinds GhcRn -> [LHsFunDep GhcRn] -> [LSig GhcRn]
             -> [LFamilyDecl GhcRn] -> [LTyFamDefltDecl GhcRn]
             -> TcM Class
tcClassDecl1 :: (Name -> [Role])
-> Name
-> GenLocated SrcSpan (HsContext GhcRn)
-> LHsBinds GhcRn
-> [LHsFunDep GhcRn]
-> [LSig GhcRn]
-> [LFamilyDecl GhcRn]
-> [LTyFamDefltDecl GhcRn]
-> TcM Class
tcClassDecl1 Name -> [Role]
roles_info Name
class_name GenLocated SrcSpan (HsContext GhcRn)
hs_ctxt LHsBinds GhcRn
meths [LHsFunDep GhcRn]
fundeps [LSig GhcRn]
sigs [LFamilyDecl GhcRn]
ats [LTyFamDefltDecl GhcRn]
at_defs
  = (Class -> TcM Class) -> TcM Class
forall a env. (a -> IOEnv env a) -> IOEnv env a
fixM ((Class -> TcM Class) -> TcM Class)
-> (Class -> TcM Class) -> TcM Class
forall a b. (a -> b) -> a -> b
$ \ Class
clas ->
    -- We need the knot because 'clas' is passed into tcClassATs
    Name -> ([TyConBinder] -> Kind -> TcM Class) -> TcM Class
forall a. Name -> ([TyConBinder] -> Kind -> TcM a) -> TcM a
bindTyClTyVars Name
class_name (([TyConBinder] -> Kind -> TcM Class) -> TcM Class)
-> ([TyConBinder] -> Kind -> TcM Class) -> TcM Class
forall a b. (a -> b) -> a -> b
$ \ [TyConBinder]
binders Kind
res_kind ->
    do { Kind -> TcRn ()
checkClassKindSig Kind
res_kind
       ; String -> SDoc -> TcRn ()
traceTc String
"tcClassDecl 1" (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
class_name SDoc -> SDoc -> SDoc
$$ [TyConBinder] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TyConBinder]
binders)
       ; let tycon_name :: Name
tycon_name = Name
class_name        -- We use the same name
             roles :: [Role]
roles = Name -> [Role]
roles_info Name
tycon_name  -- for TyCon and Class

       ; ([Kind]
ctxt, [([TcTyCoVar], [TcTyCoVar])]
fds, [TcMethInfo]
sig_stuff, [ClassATItem]
at_stuff)
            <- TcM
  ([Kind], [([TcTyCoVar], [TcTyCoVar])], [TcMethInfo], [ClassATItem])
-> TcM
     ([Kind], [([TcTyCoVar], [TcTyCoVar])], [TcMethInfo], [ClassATItem])
forall r. TcM r -> TcM r
pushTcLevelM_   (TcM
   ([Kind], [([TcTyCoVar], [TcTyCoVar])], [TcMethInfo], [ClassATItem])
 -> TcM
      ([Kind], [([TcTyCoVar], [TcTyCoVar])], [TcMethInfo],
       [ClassATItem]))
-> TcM
     ([Kind], [([TcTyCoVar], [TcTyCoVar])], [TcMethInfo], [ClassATItem])
-> TcM
     ([Kind], [([TcTyCoVar], [TcTyCoVar])], [TcMethInfo], [ClassATItem])
forall a b. (a -> b) -> a -> b
$
               TcM
  ([Kind], [([TcTyCoVar], [TcTyCoVar])], [TcMethInfo], [ClassATItem])
-> TcM
     ([Kind], [([TcTyCoVar], [TcTyCoVar])], [TcMethInfo], [ClassATItem])
forall r. TcM r -> TcM r
solveEqualities (TcM
   ([Kind], [([TcTyCoVar], [TcTyCoVar])], [TcMethInfo], [ClassATItem])
 -> TcM
      ([Kind], [([TcTyCoVar], [TcTyCoVar])], [TcMethInfo],
       [ClassATItem]))
-> TcM
     ([Kind], [([TcTyCoVar], [TcTyCoVar])], [TcMethInfo], [ClassATItem])
-> TcM
     ([Kind], [([TcTyCoVar], [TcTyCoVar])], [TcMethInfo], [ClassATItem])
forall a b. (a -> b) -> a -> b
$
               SkolemInfo
-> [TcTyCoVar]
-> TcM
     ([Kind], [([TcTyCoVar], [TcTyCoVar])], [TcMethInfo], [ClassATItem])
-> TcM
     ([Kind], [([TcTyCoVar], [TcTyCoVar])], [TcMethInfo], [ClassATItem])
forall result.
SkolemInfo -> [TcTyCoVar] -> TcM result -> TcM result
checkTvConstraints SkolemInfo
skol_info ([TyConBinder] -> [TcTyCoVar]
forall tv argf. [VarBndr tv argf] -> [tv]
binderVars [TyConBinder]
binders) (TcM
   ([Kind], [([TcTyCoVar], [TcTyCoVar])], [TcMethInfo], [ClassATItem])
 -> TcM
      ([Kind], [([TcTyCoVar], [TcTyCoVar])], [TcMethInfo],
       [ClassATItem]))
-> TcM
     ([Kind], [([TcTyCoVar], [TcTyCoVar])], [TcMethInfo], [ClassATItem])
-> TcM
     ([Kind], [([TcTyCoVar], [TcTyCoVar])], [TcMethInfo], [ClassATItem])
forall a b. (a -> b) -> a -> b
$
               -- The checkTvConstraints is needed bring into scope the
               -- skolems bound by the class decl header (#17841)
               do { [Kind]
ctxt <- GenLocated SrcSpan (HsContext GhcRn) -> TcM [Kind]
tcHsContext GenLocated SrcSpan (HsContext GhcRn)
hs_ctxt
                  ; [([TcTyCoVar], [TcTyCoVar])]
fds  <- (Located (FunDep (GenLocated SrcSpan Name))
 -> IOEnv (Env TcGblEnv TcLclEnv) ([TcTyCoVar], [TcTyCoVar]))
-> [Located (FunDep (GenLocated SrcSpan Name))]
-> IOEnv (Env TcGblEnv TcLclEnv) [([TcTyCoVar], [TcTyCoVar])]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM ((SrcSpanLess (Located (FunDep (GenLocated SrcSpan Name)))
 -> IOEnv (Env TcGblEnv TcLclEnv) ([TcTyCoVar], [TcTyCoVar]))
-> Located (FunDep (GenLocated SrcSpan Name))
-> IOEnv (Env TcGblEnv TcLclEnv) ([TcTyCoVar], [TcTyCoVar])
forall a b. HasSrcSpan a => (SrcSpanLess a -> TcM b) -> a -> TcM b
addLocM SrcSpanLess (Located (FunDep (GenLocated SrcSpan Name)))
-> IOEnv (Env TcGblEnv TcLclEnv) ([TcTyCoVar], [TcTyCoVar])
forall (t :: * -> *) (t :: * -> *) a a.
(Traversable t, Traversable t, HasSrcSpan a, HasSrcSpan a,
 SrcSpanLess a ~ Name, SrcSpanLess a ~ Name) =>
(t a, t a)
-> IOEnv (Env TcGblEnv TcLclEnv) (t TcTyCoVar, t TcTyCoVar)
tc_fundep) [Located (FunDep (GenLocated SrcSpan Name))]
[LHsFunDep GhcRn]
fundeps
                  ; [TcMethInfo]
sig_stuff <- Name -> [LSig GhcRn] -> LHsBinds GhcRn -> TcM [TcMethInfo]
tcClassSigs Name
class_name [LSig GhcRn]
sigs LHsBinds GhcRn
meths
                  ; [ClassATItem]
at_stuff  <- Name
-> Class
-> [LFamilyDecl GhcRn]
-> [LTyFamDefltDecl GhcRn]
-> TcM [ClassATItem]
tcClassATs Name
class_name Class
clas [LFamilyDecl GhcRn]
ats [LTyFamDefltDecl GhcRn]
at_defs
                  ; ([Kind], [([TcTyCoVar], [TcTyCoVar])], [TcMethInfo], [ClassATItem])
-> TcM
     ([Kind], [([TcTyCoVar], [TcTyCoVar])], [TcMethInfo], [ClassATItem])
forall (m :: * -> *) a. Monad m => a -> m a
return ([Kind]
ctxt, [([TcTyCoVar], [TcTyCoVar])]
fds, [TcMethInfo]
sig_stuff, [ClassATItem]
at_stuff) }

       -- The solveEqualities will report errors for any
       -- unsolved equalities, so these zonks should not encounter
       -- any unfilled coercion variables unless there is such an error
       -- The zonk also squeeze out the TcTyCons, and converts
       -- Skolems to tyvars.
       ; ZonkEnv
ze        <- TcM ZonkEnv
emptyZonkEnv
       ; [Kind]
ctxt      <- ZonkEnv -> [Kind] -> TcM [Kind]
zonkTcTypesToTypesX ZonkEnv
ze [Kind]
ctxt
       ; [TcMethInfo]
sig_stuff <- (TcMethInfo -> IOEnv (Env TcGblEnv TcLclEnv) TcMethInfo)
-> [TcMethInfo] -> TcM [TcMethInfo]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM (ZonkEnv -> TcMethInfo -> IOEnv (Env TcGblEnv TcLclEnv) TcMethInfo
zonkTcMethInfoToMethInfoX ZonkEnv
ze) [TcMethInfo]
sig_stuff
         -- ToDo: do we need to zonk at_stuff?

       -- TODO: Allow us to distinguish between abstract class,
       -- and concrete class with no methods (maybe by
       -- specifying a trailing where or not

       ; ClassMinimalDef
mindef <- Name -> [LSig GhcRn] -> [TcMethInfo] -> TcM ClassMinimalDef
tcClassMinimalDef Name
class_name [LSig GhcRn]
sigs [TcMethInfo]
sig_stuff
       ; Bool
is_boot <- TcRnIf TcGblEnv TcLclEnv Bool
tcIsHsBootOrSig
       ; let body :: Maybe ([Kind], [ClassATItem], [TcMethInfo], ClassMinimalDef)
body | Bool
is_boot, [Kind] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [Kind]
ctxt, [ClassATItem] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [ClassATItem]
at_stuff, [TcMethInfo] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [TcMethInfo]
sig_stuff
                  = Maybe ([Kind], [ClassATItem], [TcMethInfo], ClassMinimalDef)
forall a. Maybe a
Nothing
                  | Bool
otherwise
                  = ([Kind], [ClassATItem], [TcMethInfo], ClassMinimalDef)
-> Maybe ([Kind], [ClassATItem], [TcMethInfo], ClassMinimalDef)
forall a. a -> Maybe a
Just ([Kind]
ctxt, [ClassATItem]
at_stuff, [TcMethInfo]
sig_stuff, ClassMinimalDef
mindef)

       ; Class
clas <- Name
-> [TyConBinder]
-> [Role]
-> [([TcTyCoVar], [TcTyCoVar])]
-> Maybe ([Kind], [ClassATItem], [TcMethInfo], ClassMinimalDef)
-> TcM Class
forall m n.
Name
-> [TyConBinder]
-> [Role]
-> [([TcTyCoVar], [TcTyCoVar])]
-> Maybe ([Kind], [ClassATItem], [TcMethInfo], ClassMinimalDef)
-> TcRnIf m n Class
buildClass Name
class_name [TyConBinder]
binders [Role]
roles [([TcTyCoVar], [TcTyCoVar])]
fds Maybe ([Kind], [ClassATItem], [TcMethInfo], ClassMinimalDef)
body
       ; String -> SDoc -> TcRn ()
traceTc String
"tcClassDecl" ([Located (FunDep (GenLocated SrcSpan Name))] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Located (FunDep (GenLocated SrcSpan Name))]
[LHsFunDep GhcRn]
fundeps SDoc -> SDoc -> SDoc
$$ [TyConBinder] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TyConBinder]
binders SDoc -> SDoc -> SDoc
$$
                                [([TcTyCoVar], [TcTyCoVar])] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [([TcTyCoVar], [TcTyCoVar])]
fds)
       ; Class -> TcM Class
forall (m :: * -> *) a. Monad m => a -> m a
return Class
clas }
  where
    skol_info :: SkolemInfo
skol_info = TyConFlavour -> Name -> SkolemInfo
TyConSkol TyConFlavour
ClassFlavour Name
class_name
    tc_fundep :: (t a, t a)
-> IOEnv (Env TcGblEnv TcLclEnv) (t TcTyCoVar, t TcTyCoVar)
tc_fundep (t a
tvs1, t a
tvs2) = do { t TcTyCoVar
tvs1' <- (a -> IOEnv (Env TcGblEnv TcLclEnv) TcTyCoVar)
-> t a -> IOEnv (Env TcGblEnv TcLclEnv) (t TcTyCoVar)
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM (Name -> IOEnv (Env TcGblEnv TcLclEnv) TcTyCoVar
tcLookupTyVar (Name -> IOEnv (Env TcGblEnv TcLclEnv) TcTyCoVar)
-> (a -> Name) -> a -> IOEnv (Env TcGblEnv TcLclEnv) TcTyCoVar
forall b c a. (b -> c) -> (a -> b) -> a -> c
. a -> Name
forall a. HasSrcSpan a => a -> SrcSpanLess a
unLoc) t a
tvs1 ;
                                ; t TcTyCoVar
tvs2' <- (a -> IOEnv (Env TcGblEnv TcLclEnv) TcTyCoVar)
-> t a -> IOEnv (Env TcGblEnv TcLclEnv) (t TcTyCoVar)
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM (Name -> IOEnv (Env TcGblEnv TcLclEnv) TcTyCoVar
tcLookupTyVar (Name -> IOEnv (Env TcGblEnv TcLclEnv) TcTyCoVar)
-> (a -> Name) -> a -> IOEnv (Env TcGblEnv TcLclEnv) TcTyCoVar
forall b c a. (b -> c) -> (a -> b) -> a -> c
. a -> Name
forall a. HasSrcSpan a => a -> SrcSpanLess a
unLoc) t a
tvs2 ;
                                ; (t TcTyCoVar, t TcTyCoVar)
-> IOEnv (Env TcGblEnv TcLclEnv) (t TcTyCoVar, t TcTyCoVar)
forall (m :: * -> *) a. Monad m => a -> m a
return (t TcTyCoVar
tvs1', t TcTyCoVar
tvs2') }


{- Note [Associated type defaults]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The following is an example of associated type defaults:
             class C a where
               data D a

               type F a b :: *
               type F a b = [a]        -- Default

Note that we can get default definitions only for type families, not data
families.
-}

tcClassATs :: Name                    -- The class name (not knot-tied)
           -> Class                   -- The class parent of this associated type
           -> [LFamilyDecl GhcRn]     -- Associated types.
           -> [LTyFamDefltDecl GhcRn] -- Associated type defaults.
           -> TcM [ClassATItem]
tcClassATs :: Name
-> Class
-> [LFamilyDecl GhcRn]
-> [LTyFamDefltDecl GhcRn]
-> TcM [ClassATItem]
tcClassATs Name
class_name Class
cls [LFamilyDecl GhcRn]
ats [LTyFamDefltDecl GhcRn]
at_defs
  = do {  -- Complain about associated type defaults for non associated-types
         [IOEnv (Env TcGblEnv TcLclEnv) Any] -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a.
(Foldable t, Monad m) =>
t (m a) -> m ()
sequence_ [ SDoc -> IOEnv (Env TcGblEnv TcLclEnv) Any
forall a. SDoc -> TcM a
failWithTc (Name -> Name -> SDoc
badATErr Name
class_name Name
n)
                   | Name
n <- (LTyFamDefltDecl GhcRn -> Name)
-> [LTyFamDefltDecl GhcRn] -> [Name]
forall a b. (a -> b) -> [a] -> [b]
map LTyFamDefltDecl GhcRn -> Name
at_def_tycon [LTyFamDefltDecl GhcRn]
at_defs
                   , Bool -> Bool
not (Name
n Name -> NameSet -> Bool
`elemNameSet` NameSet
at_names) ]
       ; (LFamilyDecl GhcRn -> IOEnv (Env TcGblEnv TcLclEnv) ClassATItem)
-> [LFamilyDecl GhcRn] -> TcM [ClassATItem]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM LFamilyDecl GhcRn -> IOEnv (Env TcGblEnv TcLclEnv) ClassATItem
tc_at [LFamilyDecl GhcRn]
ats }
  where
    at_def_tycon :: LTyFamDefltDecl GhcRn -> Name
    at_def_tycon :: LTyFamDefltDecl GhcRn -> Name
at_def_tycon = TyFamInstDecl GhcRn -> Name
forall (p :: Pass). TyFamInstDecl (GhcPass p) -> IdP (GhcPass p)
tyFamInstDeclName (TyFamInstDecl GhcRn -> Name)
-> (LTyFamDefltDecl GhcRn -> TyFamInstDecl GhcRn)
-> LTyFamDefltDecl GhcRn
-> Name
forall b c a. (b -> c) -> (a -> b) -> a -> c
. LTyFamDefltDecl GhcRn -> TyFamInstDecl GhcRn
forall a. HasSrcSpan a => a -> SrcSpanLess a
unLoc

    at_fam_name :: LFamilyDecl GhcRn -> Name
    at_fam_name :: LFamilyDecl GhcRn -> Name
at_fam_name = FamilyDecl GhcRn -> Name
forall (p :: Pass). FamilyDecl (GhcPass p) -> IdP (GhcPass p)
familyDeclName (FamilyDecl GhcRn -> Name)
-> (LFamilyDecl GhcRn -> FamilyDecl GhcRn)
-> LFamilyDecl GhcRn
-> Name
forall b c a. (b -> c) -> (a -> b) -> a -> c
. LFamilyDecl GhcRn -> FamilyDecl GhcRn
forall a. HasSrcSpan a => a -> SrcSpanLess a
unLoc

    at_names :: NameSet
at_names = [Name] -> NameSet
mkNameSet ((LFamilyDecl GhcRn -> Name) -> [LFamilyDecl GhcRn] -> [Name]
forall a b. (a -> b) -> [a] -> [b]
map LFamilyDecl GhcRn -> Name
at_fam_name [LFamilyDecl GhcRn]
ats)

    at_defs_map :: NameEnv [LTyFamDefltDecl GhcRn]
    -- Maps an AT in 'ats' to a list of all its default defs in 'at_defs'
    at_defs_map :: NameEnv [LTyFamDefltDecl GhcRn]
at_defs_map = (LTyFamDefltDecl GhcRn
 -> NameEnv [LTyFamDefltDecl GhcRn]
 -> NameEnv [LTyFamDefltDecl GhcRn])
-> NameEnv [LTyFamDefltDecl GhcRn]
-> [LTyFamDefltDecl GhcRn]
-> NameEnv [LTyFamDefltDecl GhcRn]
forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr (\LTyFamDefltDecl GhcRn
at_def NameEnv [LTyFamDefltDecl GhcRn]
nenv -> ([LTyFamDefltDecl GhcRn]
 -> [LTyFamDefltDecl GhcRn] -> [LTyFamDefltDecl GhcRn])
-> NameEnv [LTyFamDefltDecl GhcRn]
-> Name
-> [LTyFamDefltDecl GhcRn]
-> NameEnv [LTyFamDefltDecl GhcRn]
forall a. (a -> a -> a) -> NameEnv a -> Name -> a -> NameEnv a
extendNameEnv_C [LTyFamDefltDecl GhcRn]
-> [LTyFamDefltDecl GhcRn] -> [LTyFamDefltDecl GhcRn]
forall a. [a] -> [a] -> [a]
(++) NameEnv [LTyFamDefltDecl GhcRn]
nenv
                                          (LTyFamDefltDecl GhcRn -> Name
at_def_tycon LTyFamDefltDecl GhcRn
at_def) [LTyFamDefltDecl GhcRn
at_def])
                        NameEnv [LTyFamDefltDecl GhcRn]
forall a. NameEnv a
emptyNameEnv [LTyFamDefltDecl GhcRn]
at_defs

    tc_at :: LFamilyDecl GhcRn -> IOEnv (Env TcGblEnv TcLclEnv) ClassATItem
tc_at LFamilyDecl GhcRn
at = do { TyCon
fam_tc <- (SrcSpanLess (LFamilyDecl GhcRn) -> TcRn TyCon)
-> LFamilyDecl GhcRn -> TcRn TyCon
forall a b. HasSrcSpan a => (SrcSpanLess a -> TcM b) -> a -> TcM b
addLocM (Maybe Class -> FamilyDecl GhcRn -> TcRn TyCon
tcFamDecl1 (Class -> Maybe Class
forall a. a -> Maybe a
Just Class
cls)) LFamilyDecl GhcRn
at
                  ; let at_defs :: [LTyFamDefltDecl GhcRn]
at_defs = NameEnv [LTyFamDefltDecl GhcRn]
-> Name -> Maybe [LTyFamDefltDecl GhcRn]
forall a. NameEnv a -> Name -> Maybe a
lookupNameEnv NameEnv [LTyFamDefltDecl GhcRn]
at_defs_map (LFamilyDecl GhcRn -> Name
at_fam_name LFamilyDecl GhcRn
at)
                                  Maybe [LTyFamDefltDecl GhcRn]
-> [LTyFamDefltDecl GhcRn] -> [LTyFamDefltDecl GhcRn]
forall a. Maybe a -> a -> a
`orElse` []
                  ; Maybe (Kind, SrcSpan)
atd <- TyCon -> [LTyFamDefltDecl GhcRn] -> TcM (Maybe (Kind, SrcSpan))
tcDefaultAssocDecl TyCon
fam_tc [LTyFamDefltDecl GhcRn]
at_defs
                  ; ClassATItem -> IOEnv (Env TcGblEnv TcLclEnv) ClassATItem
forall (m :: * -> *) a. Monad m => a -> m a
return (TyCon -> Maybe (Kind, SrcSpan) -> ClassATItem
ATI TyCon
fam_tc Maybe (Kind, SrcSpan)
atd) }

-------------------------
tcDefaultAssocDecl ::
     TyCon                                -- ^ Family TyCon (not knot-tied)
  -> [LTyFamDefltDecl GhcRn]              -- ^ Defaults
  -> TcM (Maybe (KnotTied Type, SrcSpan)) -- ^ Type checked RHS
tcDefaultAssocDecl :: TyCon -> [LTyFamDefltDecl GhcRn] -> TcM (Maybe (Kind, SrcSpan))
tcDefaultAssocDecl TyCon
_ []
  = Maybe (Kind, SrcSpan) -> TcM (Maybe (Kind, SrcSpan))
forall (m :: * -> *) a. Monad m => a -> m a
return Maybe (Kind, SrcSpan)
forall a. Maybe a
Nothing  -- No default declaration

tcDefaultAssocDecl TyCon
_ (LTyFamDefltDecl GhcRn
d1:LTyFamDefltDecl GhcRn
_:[LTyFamDefltDecl GhcRn]
_)
  = SDoc -> TcM (Maybe (Kind, SrcSpan))
forall a. SDoc -> TcM a
failWithTc (String -> SDoc
text String
"More than one default declaration for"
                SDoc -> SDoc -> SDoc
<+> Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyFamInstDecl GhcRn -> IdP GhcRn
forall (p :: Pass). TyFamInstDecl (GhcPass p) -> IdP (GhcPass p)
tyFamInstDeclName (LTyFamDefltDecl GhcRn -> SrcSpanLess (LTyFamDefltDecl GhcRn)
forall a. HasSrcSpan a => a -> SrcSpanLess a
unLoc LTyFamDefltDecl GhcRn
d1)))

tcDefaultAssocDecl TyCon
fam_tc
  [L SrcSpan
loc (TyFamInstDecl { tfid_eqn :: forall pass. TyFamInstDecl pass -> TyFamInstEqn pass
tfid_eqn =
         HsIB { hsib_ext :: forall pass thing. HsImplicitBndrs pass thing -> XHsIB pass thing
hsib_ext  = XHsIB GhcRn (FamEqn GhcRn (LHsKind GhcRn))
imp_vars
              , hsib_body :: forall pass thing. HsImplicitBndrs pass thing -> thing
hsib_body = FamEqn { feqn_tycon :: forall pass rhs. FamEqn pass rhs -> Located (IdP pass)
feqn_tycon = L SrcSpan
_ IdP GhcRn
tc_name
                                   , feqn_bndrs :: forall pass rhs. FamEqn pass rhs -> Maybe [LHsTyVarBndr pass]
feqn_bndrs = Maybe [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
mb_expl_bndrs
                                   , feqn_pats :: forall pass rhs. FamEqn pass rhs -> HsTyPats pass
feqn_pats  = HsTyPats GhcRn
hs_pats
                                   , feqn_rhs :: forall pass rhs. FamEqn pass rhs -> rhs
feqn_rhs   = LHsKind GhcRn
hs_rhs_ty }}})]
  = -- See Note [Type-checking default assoc decls]
    SrcSpan
-> TcM (Maybe (Kind, SrcSpan)) -> TcM (Maybe (Kind, SrcSpan))
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan SrcSpan
loc (TcM (Maybe (Kind, SrcSpan)) -> TcM (Maybe (Kind, SrcSpan)))
-> TcM (Maybe (Kind, SrcSpan)) -> TcM (Maybe (Kind, SrcSpan))
forall a b. (a -> b) -> a -> b
$
    SDoc
-> Name
-> TcM (Maybe (Kind, SrcSpan))
-> TcM (Maybe (Kind, SrcSpan))
forall a. SDoc -> Name -> TcM a -> TcM a
tcAddFamInstCtxt (String -> SDoc
text String
"default type instance") Name
IdP GhcRn
tc_name (TcM (Maybe (Kind, SrcSpan)) -> TcM (Maybe (Kind, SrcSpan)))
-> TcM (Maybe (Kind, SrcSpan)) -> TcM (Maybe (Kind, SrcSpan))
forall a b. (a -> b) -> a -> b
$
    do { String -> SDoc -> TcRn ()
traceTc String
"tcDefaultAssocDecl 1" (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
IdP GhcRn
tc_name)
       ; let fam_tc_name :: Name
fam_tc_name = TyCon -> Name
tyConName TyCon
fam_tc
             vis_arity :: Int
vis_arity = [TcTyCoVar] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length (TyCon -> [TcTyCoVar]
tyConVisibleTyVars TyCon
fam_tc)
             vis_pats :: Int
vis_pats  = HsTyPats GhcRn -> Int
forall tm ty. [HsArg tm ty] -> Int
numVisibleArgs HsTyPats GhcRn
hs_pats

       -- Kind of family check
       ; ASSERT( fam_tc_name == tc_name )
         Bool -> SDoc -> TcRn ()
checkTc (TyCon -> Bool
isTypeFamilyTyCon TyCon
fam_tc) (TyCon -> SDoc
wrongKindOfFamily TyCon
fam_tc)

       -- Arity check
       ; Bool -> SDoc -> TcRn ()
checkTc (Int
vis_pats Int -> Int -> Bool
forall a. Eq a => a -> a -> Bool
== Int
vis_arity)
                 (Int -> SDoc
wrongNumberOfParmsErr Int
vis_arity)

       -- Typecheck RHS
       --
       -- You might think we should pass in some AssocInstInfo, as we're looking
       -- at an associated type. But this would be wrong, because an associated
       -- type default LHS can mention *different* type variables than the
       -- enclosing class. So it's treated more as a freestanding beast.
       ; ([TcTyCoVar]
qtvs, [Kind]
pats, Kind
rhs_ty) <- TyCon
-> AssocInstInfo
-> [Name]
-> [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
-> HsTyPats GhcRn
-> LHsKind GhcRn
-> TcM ([TcTyCoVar], [Kind], Kind)
tcTyFamInstEqnGuts TyCon
fam_tc AssocInstInfo
NotAssociated
                                                    [Name]
XHsIB GhcRn (FamEqn GhcRn (LHsKind GhcRn))
imp_vars (Maybe [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
mb_expl_bndrs Maybe [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
-> [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
-> [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
forall a. Maybe a -> a -> a
`orElse` [])
                                                    HsTyPats GhcRn
hs_pats LHsKind GhcRn
hs_rhs_ty

       ; let fam_tvs :: [TcTyCoVar]
fam_tvs  = TyCon -> [TcTyCoVar]
tyConTyVars TyCon
fam_tc
             ppr_eqn :: SDoc
ppr_eqn  = [Kind] -> Kind -> SDoc
ppr_default_eqn [Kind]
pats Kind
rhs_ty
             pats_vis :: [ArgFlag]
pats_vis = TyCon -> [Kind] -> [ArgFlag]
tyConArgFlags TyCon
fam_tc [Kind]
pats
       ; String -> SDoc -> TcRn ()
traceTc String
"tcDefaultAssocDecl 2" ([SDoc] -> SDoc
vcat
           [ String -> SDoc
text String
"fam_tvs" SDoc -> SDoc -> SDoc
<+> [TcTyCoVar] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TcTyCoVar]
fam_tvs
           , String -> SDoc
text String
"qtvs"    SDoc -> SDoc -> SDoc
<+> [TcTyCoVar] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TcTyCoVar]
qtvs
           , String -> SDoc
text String
"pats"    SDoc -> SDoc -> SDoc
<+> [Kind] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Kind]
pats
           , String -> SDoc
text String
"rhs_ty"  SDoc -> SDoc -> SDoc
<+> Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr Kind
rhs_ty
           ])
       ; [TcTyCoVar]
pat_tvs <- (Kind -> ArgFlag -> IOEnv (Env TcGblEnv TcLclEnv) TcTyCoVar)
-> [Kind] -> [ArgFlag] -> TcM [TcTyCoVar]
forall (m :: * -> *) a b c.
Applicative m =>
(a -> b -> m c) -> [a] -> [b] -> m [c]
zipWithM (SDoc -> Kind -> ArgFlag -> IOEnv (Env TcGblEnv TcLclEnv) TcTyCoVar
extract_tv SDoc
ppr_eqn) [Kind]
pats [ArgFlag]
pats_vis
       ; SDoc -> [(TcTyCoVar, ArgFlag)] -> TcRn ()
check_all_distinct_tvs SDoc
ppr_eqn ([(TcTyCoVar, ArgFlag)] -> TcRn ())
-> [(TcTyCoVar, ArgFlag)] -> TcRn ()
forall a b. (a -> b) -> a -> b
$ [TcTyCoVar] -> [ArgFlag] -> [(TcTyCoVar, ArgFlag)]
forall a b. [a] -> [b] -> [(a, b)]
zip [TcTyCoVar]
pat_tvs [ArgFlag]
pats_vis
       ; let subst :: TCvSubst
subst = [TcTyCoVar] -> [Kind] -> TCvSubst
HasDebugCallStack => [TcTyCoVar] -> [Kind] -> TCvSubst
zipTvSubst [TcTyCoVar]
pat_tvs ([TcTyCoVar] -> [Kind]
mkTyVarTys [TcTyCoVar]
fam_tvs)
       ; Maybe (Kind, SrcSpan) -> TcM (Maybe (Kind, SrcSpan))
forall (f :: * -> *) a. Applicative f => a -> f a
pure (Maybe (Kind, SrcSpan) -> TcM (Maybe (Kind, SrcSpan)))
-> Maybe (Kind, SrcSpan) -> TcM (Maybe (Kind, SrcSpan))
forall a b. (a -> b) -> a -> b
$ (Kind, SrcSpan) -> Maybe (Kind, SrcSpan)
forall a. a -> Maybe a
Just (TCvSubst -> Kind -> Kind
substTyUnchecked TCvSubst
subst Kind
rhs_ty, SrcSpan
loc)
           -- We also perform other checks for well-formedness and validity
           -- later, in checkValidClass
     }
  where
    -- Checks that a pattern on the LHS of a default is a type
    -- variable. If so, return the underlying type variable, and if
    -- not, throw an error.
    -- See Note [Type-checking default assoc decls]
    extract_tv :: SDoc    -- The pretty-printed default equation
                          -- (only used for error message purposes)
               -> Type    -- The particular type pattern from which to extract
                          -- its underlying type variable
               -> ArgFlag -- The visibility of the type pattern
                          -- (only used for error message purposes)
               -> TcM TyVar
    extract_tv :: SDoc -> Kind -> ArgFlag -> IOEnv (Env TcGblEnv TcLclEnv) TcTyCoVar
extract_tv SDoc
ppr_eqn Kind
pat ArgFlag
pat_vis =
      case Kind -> Maybe TcTyCoVar
getTyVar_maybe Kind
pat of
        Just TcTyCoVar
tv -> TcTyCoVar -> IOEnv (Env TcGblEnv TcLclEnv) TcTyCoVar
forall (f :: * -> *) a. Applicative f => a -> f a
pure TcTyCoVar
tv
        Maybe TcTyCoVar
Nothing -> SDoc -> IOEnv (Env TcGblEnv TcLclEnv) TcTyCoVar
forall a. SDoc -> TcM a
failWithTc (SDoc -> IOEnv (Env TcGblEnv TcLclEnv) TcTyCoVar)
-> SDoc -> IOEnv (Env TcGblEnv TcLclEnv) TcTyCoVar
forall a b. (a -> b) -> a -> b
$
          Bool -> SDoc -> SDoc
pprWithExplicitKindsWhen (ArgFlag -> Bool
isInvisibleArgFlag ArgFlag
pat_vis) (SDoc -> SDoc) -> SDoc -> SDoc
forall a b. (a -> b) -> a -> b
$
          SDoc -> Int -> SDoc -> SDoc
hang (String -> SDoc
text String
"Illegal argument" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr Kind
pat) SDoc -> SDoc -> SDoc
<+> String -> SDoc
text String
"in:")
             Int
2 ([SDoc] -> SDoc
vcat [SDoc
ppr_eqn, SDoc
suggestion])


    -- Checks that no type variables in an associated default declaration are
    -- duplicated. If that is the case, throw an error.
    -- See Note [Type-checking default assoc decls]
    check_all_distinct_tvs ::
         SDoc               -- The pretty-printed default equation (only used
                            -- for error message purposes)
      -> [(TyVar, ArgFlag)] -- The type variable arguments in the associated
                            -- default declaration, along with their respective
                            -- visibilities (the latter are only used for error
                            -- message purposes)
      -> TcM ()
    check_all_distinct_tvs :: SDoc -> [(TcTyCoVar, ArgFlag)] -> TcRn ()
check_all_distinct_tvs SDoc
ppr_eqn [(TcTyCoVar, ArgFlag)]
pat_tvs_vis =
      let dups :: [NonEmpty (TcTyCoVar, ArgFlag)]
dups = ((TcTyCoVar, ArgFlag) -> (TcTyCoVar, ArgFlag) -> Bool)
-> [(TcTyCoVar, ArgFlag)] -> [NonEmpty (TcTyCoVar, ArgFlag)]
forall a. (a -> a -> Bool) -> [a] -> [NonEmpty a]
findDupsEq (TcTyCoVar -> TcTyCoVar -> Bool
forall a. Eq a => a -> a -> Bool
(==) (TcTyCoVar -> TcTyCoVar -> Bool)
-> ((TcTyCoVar, ArgFlag) -> TcTyCoVar)
-> (TcTyCoVar, ArgFlag)
-> (TcTyCoVar, ArgFlag)
-> Bool
forall b c a. (b -> b -> c) -> (a -> b) -> a -> a -> c
`on` (TcTyCoVar, ArgFlag) -> TcTyCoVar
forall a b. (a, b) -> a
fst) [(TcTyCoVar, ArgFlag)]
pat_tvs_vis in
      (NonEmpty (TcTyCoVar, ArgFlag)
 -> IOEnv (Env TcGblEnv TcLclEnv) Any)
-> [NonEmpty (TcTyCoVar, ArgFlag)] -> TcRn ()
forall (t :: * -> *) (f :: * -> *) a b.
(Foldable t, Applicative f) =>
(a -> f b) -> t a -> f ()
traverse_
        (\NonEmpty (TcTyCoVar, ArgFlag)
d -> let (TcTyCoVar
pat_tv, ArgFlag
pat_vis) = NonEmpty (TcTyCoVar, ArgFlag) -> (TcTyCoVar, ArgFlag)
forall a. NonEmpty a -> a
NE.head NonEmpty (TcTyCoVar, ArgFlag)
d in SDoc -> IOEnv (Env TcGblEnv TcLclEnv) Any
forall a. SDoc -> TcM a
failWithTc (SDoc -> IOEnv (Env TcGblEnv TcLclEnv) Any)
-> SDoc -> IOEnv (Env TcGblEnv TcLclEnv) Any
forall a b. (a -> b) -> a -> b
$
               Bool -> SDoc -> SDoc
pprWithExplicitKindsWhen (ArgFlag -> Bool
isInvisibleArgFlag ArgFlag
pat_vis) (SDoc -> SDoc) -> SDoc -> SDoc
forall a b. (a -> b) -> a -> b
$
               SDoc -> Int -> SDoc -> SDoc
hang (String -> SDoc
text String
"Illegal duplicate variable"
                       SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (TcTyCoVar -> SDoc
forall a. Outputable a => a -> SDoc
ppr TcTyCoVar
pat_tv) SDoc -> SDoc -> SDoc
<+> String -> SDoc
text String
"in:")
                  Int
2 ([SDoc] -> SDoc
vcat [SDoc
ppr_eqn, SDoc
suggestion]))
        [NonEmpty (TcTyCoVar, ArgFlag)]
dups

    ppr_default_eqn :: [Type] -> Type -> SDoc
    ppr_default_eqn :: [Kind] -> Kind -> SDoc
ppr_default_eqn [Kind]
pats Kind
rhs_ty =
      SDoc -> SDoc
quotes (String -> SDoc
text String
"type" SDoc -> SDoc -> SDoc
<+> Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyCon -> [Kind] -> Kind
mkTyConApp TyCon
fam_tc [Kind]
pats)
                SDoc -> SDoc -> SDoc
<+> SDoc
equals SDoc -> SDoc -> SDoc
<+> Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr Kind
rhs_ty)

    suggestion :: SDoc
    suggestion :: SDoc
suggestion = String -> SDoc
text String
"The arguments to" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
fam_tc)
             SDoc -> SDoc -> SDoc
<+> String -> SDoc
text String
"must all be distinct type variables"

tcDefaultAssocDecl TyCon
_ [L SrcSpan
_ (TyFamInstDecl (HsIB XHsIB GhcRn (FamEqn GhcRn (LHsKind GhcRn))
_ (XFamEqn XXFamEqn GhcRn (LHsKind GhcRn)
x)))] = NoExtCon -> TcM (Maybe (Kind, SrcSpan))
forall a. NoExtCon -> a
noExtCon XXFamEqn GhcRn (LHsKind GhcRn)
NoExtCon
x
tcDefaultAssocDecl TyCon
_ [L SrcSpan
_ (TyFamInstDecl (XHsImplicitBndrs XXHsImplicitBndrs GhcRn (FamEqn GhcRn (LHsKind GhcRn))
x))] = NoExtCon -> TcM (Maybe (Kind, SrcSpan))
forall a. NoExtCon -> a
noExtCon XXHsImplicitBndrs GhcRn (FamEqn GhcRn (LHsKind GhcRn))
NoExtCon
x


{- Note [Type-checking default assoc decls]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider this default declaration for an associated type

   class C a where
      type F (a :: k) b :: Type
      type F (x :: j) y = Proxy x -> y

Note that the class variable 'a' doesn't scope over the default assoc
decl (rather oddly I think), and (less oddly) neither does the second
argument 'b' of the associated type 'F', or the kind variable 'k'.
Instead, the default decl is treated more like a top-level type
instance.

However we store the default rhs (Proxy x -> y) in F's TyCon, using
F's own type variables, so we need to convert it to (Proxy a -> b).
We do this by creating a substitution [j |-> k, x |-> a, b |-> y] and
applying this substitution to the RHS.

In order to create this substitution, we must first ensure that all of
the arguments in the default instance consist of distinct type variables.
One might think that this is a simple task that could be implemented earlier
in the compiler, perhaps in the parser or the renamer. However, there are some
tricky corner cases that really do require the full power of typechecking to
weed out, as the examples below should illustrate.

First, we must check that all arguments are type variables. As a motivating
example, consider this erroneous program (inspired by #11361):

   class C a where
      type F (a :: k) b :: Type
      type F x        b = x

If you squint, you'll notice that the kind of `x` is actually Type. However,
we cannot substitute from [Type |-> k], so we reject this default.

Next, we must check that all arguments are distinct. Here is another offending
example, this time taken from #13971:

   class C2 (a :: j) where
      type F2 (a :: j) (b :: k)
      type F2 (x :: z) y = SameKind x y
   data SameKind :: k -> k -> Type

All of the arguments in the default equation for `F2` are type variables, so
that passes the first check. However, if we were to build this substitution,
then both `j` and `k` map to `z`! In terms of visible kind application, it's as
if we had written `type F2 @z @z x y = SameKind @z x y`, which makes it clear
that we have duplicated a use of `z` on the LHS. Therefore, `F2`'s default is
also rejected.

Since the LHS of an associated type family default is always just variables,
it won't contain any tycons. Accordingly, the patterns used in the substitution
won't actually be knot-tied, even though we're in the knot. This is too
delicate for my taste, but it works.
-}

{- *********************************************************************
*                                                                      *
          Type family declarations
*                                                                      *
********************************************************************* -}

tcFamDecl1 :: Maybe Class -> FamilyDecl GhcRn -> TcM TyCon
tcFamDecl1 :: Maybe Class -> FamilyDecl GhcRn -> TcRn TyCon
tcFamDecl1 Maybe Class
parent (FamilyDecl { fdInfo :: forall pass. FamilyDecl pass -> FamilyInfo pass
fdInfo = FamilyInfo GhcRn
fam_info
                              , fdLName :: forall pass. FamilyDecl pass -> Located (IdP pass)
fdLName = tc_lname :: GenLocated SrcSpan (IdP GhcRn)
tc_lname@(L SrcSpan
_ IdP GhcRn
tc_name)
                              , fdResultSig :: forall pass. FamilyDecl pass -> LFamilyResultSig pass
fdResultSig = L SrcSpan
_ FamilyResultSig GhcRn
sig
                              , fdInjectivityAnn :: forall pass. FamilyDecl pass -> Maybe (LInjectivityAnn pass)
fdInjectivityAnn = Maybe (LInjectivityAnn GhcRn)
inj })
  | FamilyInfo GhcRn
DataFamily <- FamilyInfo GhcRn
fam_info
  = Name -> ([TyConBinder] -> Kind -> TcRn TyCon) -> TcRn TyCon
forall a. Name -> ([TyConBinder] -> Kind -> TcM a) -> TcM a
bindTyClTyVars Name
IdP GhcRn
tc_name (([TyConBinder] -> Kind -> TcRn TyCon) -> TcRn TyCon)
-> ([TyConBinder] -> Kind -> TcRn TyCon) -> TcRn TyCon
forall a b. (a -> b) -> a -> b
$ \ [TyConBinder]
binders Kind
res_kind -> do
  { String -> SDoc -> TcRn ()
traceTc String
"data family:" (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
IdP GhcRn
tc_name)
  ; Name -> TcRn ()
checkFamFlag Name
IdP GhcRn
tc_name

  -- Check that the result kind is OK
  -- We allow things like
  --   data family T (a :: Type) :: forall k. k -> Type
  -- We treat T as having arity 1, but result kind forall k. k -> Type
  -- But we want to check that the result kind finishes in
  --   Type or a kind-variable
  -- For the latter, consider
  --   data family D a :: forall k. Type -> k
  -- When UnliftedNewtypes is enabled, we loosen this restriction
  -- on the return kind. See Note [Implementation of UnliftedNewtypes], wrinkle (1).
  ; let ([TyCoBinder]
_, Kind
final_res_kind) = Kind -> ([TyCoBinder], Kind)
splitPiTys Kind
res_kind
  ; DataSort -> Kind -> TcRn ()
checkDataKindSig DataSort
DataFamilySort Kind
final_res_kind
  ; Name
tc_rep_name <- Name -> TcRnIf TcGblEnv TcLclEnv Name
forall gbl lcl. Name -> TcRnIf gbl lcl Name
newTyConRepName Name
IdP GhcRn
tc_name
  ; let inj :: Injectivity
inj   = [Bool] -> Injectivity
Injective ([Bool] -> Injectivity) -> [Bool] -> Injectivity
forall a b. (a -> b) -> a -> b
$ Int -> Bool -> [Bool]
forall a. Int -> a -> [a]
replicate ([TyConBinder] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length [TyConBinder]
binders) Bool
True
        tycon :: TyCon
tycon = Name
-> [TyConBinder]
-> Kind
-> Maybe Name
-> FamTyConFlav
-> Maybe Class
-> Injectivity
-> TyCon
mkFamilyTyCon Name
IdP GhcRn
tc_name [TyConBinder]
binders
                              Kind
res_kind
                              (FamilyResultSig GhcRn -> Maybe (IdP GhcRn)
forall (a :: Pass).
FamilyResultSig (GhcPass a) -> Maybe (IdP (GhcPass a))
resultVariableName FamilyResultSig GhcRn
sig)
                              (Name -> FamTyConFlav
DataFamilyTyCon Name
tc_rep_name)
                              Maybe Class
parent Injectivity
inj
  ; TyCon -> TcRn TyCon
forall (m :: * -> *) a. Monad m => a -> m a
return TyCon
tycon }

  | FamilyInfo GhcRn
OpenTypeFamily <- FamilyInfo GhcRn
fam_info
  = Name -> ([TyConBinder] -> Kind -> TcRn TyCon) -> TcRn TyCon
forall a. Name -> ([TyConBinder] -> Kind -> TcM a) -> TcM a
bindTyClTyVars Name
IdP GhcRn
tc_name (([TyConBinder] -> Kind -> TcRn TyCon) -> TcRn TyCon)
-> ([TyConBinder] -> Kind -> TcRn TyCon) -> TcRn TyCon
forall a b. (a -> b) -> a -> b
$ \ [TyConBinder]
binders Kind
res_kind -> do
  { String -> SDoc -> TcRn ()
traceTc String
"open type family:" (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
IdP GhcRn
tc_name)
  ; Name -> TcRn ()
checkFamFlag Name
IdP GhcRn
tc_name
  ; Injectivity
inj' <- [TyConBinder] -> Maybe (LInjectivityAnn GhcRn) -> TcM Injectivity
tcInjectivity [TyConBinder]
binders Maybe (LInjectivityAnn GhcRn)
inj
  ; Name -> FamilyResultSig GhcRn -> TcRn ()
checkResultSigFlag Name
IdP GhcRn
tc_name FamilyResultSig GhcRn
sig  -- check after injectivity for better errors
  ; let tycon :: TyCon
tycon = Name
-> [TyConBinder]
-> Kind
-> Maybe Name
-> FamTyConFlav
-> Maybe Class
-> Injectivity
-> TyCon
mkFamilyTyCon Name
IdP GhcRn
tc_name [TyConBinder]
binders Kind
res_kind
                               (FamilyResultSig GhcRn -> Maybe (IdP GhcRn)
forall (a :: Pass).
FamilyResultSig (GhcPass a) -> Maybe (IdP (GhcPass a))
resultVariableName FamilyResultSig GhcRn
sig) FamTyConFlav
OpenSynFamilyTyCon
                               Maybe Class
parent Injectivity
inj'
  ; TyCon -> TcRn TyCon
forall (m :: * -> *) a. Monad m => a -> m a
return TyCon
tycon }

  | ClosedTypeFamily Maybe [LTyFamInstEqn GhcRn]
mb_eqns <- FamilyInfo GhcRn
fam_info
  = -- Closed type families are a little tricky, because they contain the definition
    -- of both the type family and the equations for a CoAxiom.
    do { String -> SDoc -> TcRn ()
traceTc String
"Closed type family:" (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
IdP GhcRn
tc_name)
         -- the variables in the header scope only over the injectivity
         -- declaration but this is not involved here
       ; (Injectivity
inj', [TyConBinder]
binders, Kind
res_kind)
            <- Name
-> ([TyConBinder]
    -> Kind -> TcM (Injectivity, [TyConBinder], Kind))
-> TcM (Injectivity, [TyConBinder], Kind)
forall a. Name -> ([TyConBinder] -> Kind -> TcM a) -> TcM a
bindTyClTyVars Name
IdP GhcRn
tc_name (([TyConBinder] -> Kind -> TcM (Injectivity, [TyConBinder], Kind))
 -> TcM (Injectivity, [TyConBinder], Kind))
-> ([TyConBinder]
    -> Kind -> TcM (Injectivity, [TyConBinder], Kind))
-> TcM (Injectivity, [TyConBinder], Kind)
forall a b. (a -> b) -> a -> b
$ \ [TyConBinder]
binders Kind
res_kind ->
               do { Injectivity
inj' <- [TyConBinder] -> Maybe (LInjectivityAnn GhcRn) -> TcM Injectivity
tcInjectivity [TyConBinder]
binders Maybe (LInjectivityAnn GhcRn)
inj
                  ; (Injectivity, [TyConBinder], Kind)
-> TcM (Injectivity, [TyConBinder], Kind)
forall (m :: * -> *) a. Monad m => a -> m a
return (Injectivity
inj', [TyConBinder]
binders, Kind
res_kind) }

       ; Name -> TcRn ()
checkFamFlag Name
IdP GhcRn
tc_name -- make sure we have -XTypeFamilies
       ; Name -> FamilyResultSig GhcRn -> TcRn ()
checkResultSigFlag Name
IdP GhcRn
tc_name FamilyResultSig GhcRn
sig

         -- If Nothing, this is an abstract family in a hs-boot file;
         -- but eqns might be empty in the Just case as well
       ; case Maybe [LTyFamInstEqn GhcRn]
mb_eqns of
           Maybe [LTyFamInstEqn GhcRn]
Nothing   ->
               TyCon -> TcRn TyCon
forall (m :: * -> *) a. Monad m => a -> m a
return (TyCon -> TcRn TyCon) -> TyCon -> TcRn TyCon
forall a b. (a -> b) -> a -> b
$ Name
-> [TyConBinder]
-> Kind
-> Maybe Name
-> FamTyConFlav
-> Maybe Class
-> Injectivity
-> TyCon
mkFamilyTyCon Name
IdP GhcRn
tc_name [TyConBinder]
binders Kind
res_kind
                                      (FamilyResultSig GhcRn -> Maybe (IdP GhcRn)
forall (a :: Pass).
FamilyResultSig (GhcPass a) -> Maybe (IdP (GhcPass a))
resultVariableName FamilyResultSig GhcRn
sig)
                                      FamTyConFlav
AbstractClosedSynFamilyTyCon Maybe Class
parent
                                      Injectivity
inj'
           Just [LTyFamInstEqn GhcRn]
eqns -> do {

         -- Process the equations, creating CoAxBranches
       ; let tc_fam_tc :: TyCon
tc_fam_tc = Name
-> [TyConBinder]
-> Kind
-> ScopedPairs
-> Bool
-> TyConFlavour
-> TyCon
mkTcTyCon Name
IdP GhcRn
tc_name [TyConBinder]
binders Kind
res_kind
                                   ScopedPairs
noTcTyConScopedTyVars
                                   Bool
False {- this doesn't matter here -}
                                   TyConFlavour
ClosedTypeFamilyFlavour

       ; [KnotTied CoAxBranch]
branches <- (LTyFamInstEqn GhcRn -> TcRn (KnotTied CoAxBranch))
-> [LTyFamInstEqn GhcRn] -> TcRn [KnotTied CoAxBranch]
forall a b. (a -> TcRn b) -> [a] -> TcRn [b]
mapAndReportM (TyCon
-> AssocInstInfo
-> LTyFamInstEqn GhcRn
-> TcRn (KnotTied CoAxBranch)
tcTyFamInstEqn TyCon
tc_fam_tc AssocInstInfo
NotAssociated) [LTyFamInstEqn GhcRn]
eqns
         -- Do not attempt to drop equations dominated by earlier
         -- ones here; in the case of mutual recursion with a data
         -- type, we get a knot-tying failure.  Instead we check
         -- for this afterwards, in TcValidity.checkValidCoAxiom
         -- Example: tc265

         -- Create a CoAxiom, with the correct src location.
       ; Name
co_ax_name <- GenLocated SrcSpan Name
-> [[Kind]] -> TcRnIf TcGblEnv TcLclEnv Name
newFamInstAxiomName GenLocated SrcSpan Name
GenLocated SrcSpan (IdP GhcRn)
tc_lname []

       ; let mb_co_ax :: Maybe (CoAxiom Branched)
mb_co_ax
              | [LTyFamInstEqn GhcRn] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [LTyFamInstEqn GhcRn]
eqns = Maybe (CoAxiom Branched)
forall a. Maybe a
Nothing   -- mkBranchedCoAxiom fails on empty list
              | Bool
otherwise = CoAxiom Branched -> Maybe (CoAxiom Branched)
forall a. a -> Maybe a
Just (Name -> TyCon -> [KnotTied CoAxBranch] -> CoAxiom Branched
mkBranchedCoAxiom Name
co_ax_name TyCon
fam_tc [KnotTied CoAxBranch]
branches)

             fam_tc :: TyCon
fam_tc = Name
-> [TyConBinder]
-> Kind
-> Maybe Name
-> FamTyConFlav
-> Maybe Class
-> Injectivity
-> TyCon
mkFamilyTyCon Name
IdP GhcRn
tc_name [TyConBinder]
binders Kind
res_kind (FamilyResultSig GhcRn -> Maybe (IdP GhcRn)
forall (a :: Pass).
FamilyResultSig (GhcPass a) -> Maybe (IdP (GhcPass a))
resultVariableName FamilyResultSig GhcRn
sig)
                      (Maybe (CoAxiom Branched) -> FamTyConFlav
ClosedSynFamilyTyCon Maybe (CoAxiom Branched)
mb_co_ax) Maybe Class
parent Injectivity
inj'

         -- We check for instance validity later, when doing validity
         -- checking for the tycon. Exception: checking equations
         -- overlap done by dropDominatedAxioms
       ; TyCon -> TcRn TyCon
forall (m :: * -> *) a. Monad m => a -> m a
return TyCon
fam_tc } }

#if __GLASGOW_HASKELL__ <= 810
  | Bool
otherwise = String -> TcRn TyCon
forall a. String -> a
panic String
"tcFamInst1"  -- Silence pattern-exhaustiveness checker
#endif
tcFamDecl1 Maybe Class
_ (XFamilyDecl XXFamilyDecl GhcRn
nec) = NoExtCon -> TcRn TyCon
forall a. NoExtCon -> a
noExtCon XXFamilyDecl GhcRn
NoExtCon
nec

-- | Maybe return a list of Bools that say whether a type family was declared
-- injective in the corresponding type arguments. Length of the list is equal to
-- the number of arguments (including implicit kind/coercion arguments).
-- True on position
-- N means that a function is injective in its Nth argument. False means it is
-- not.
tcInjectivity :: [TyConBinder] -> Maybe (LInjectivityAnn GhcRn)
              -> TcM Injectivity
tcInjectivity :: [TyConBinder] -> Maybe (LInjectivityAnn GhcRn) -> TcM Injectivity
tcInjectivity [TyConBinder]
_ Maybe (LInjectivityAnn GhcRn)
Nothing
  = Injectivity -> TcM Injectivity
forall (m :: * -> *) a. Monad m => a -> m a
return Injectivity
NotInjective

  -- User provided an injectivity annotation, so for each tyvar argument we
  -- check whether a type family was declared injective in that argument. We
  -- return a list of Bools, where True means that corresponding type variable
  -- was mentioned in lInjNames (type family is injective in that argument) and
  -- False means that it was not mentioned in lInjNames (type family is not
  -- injective in that type variable). We also extend injectivity information to
  -- kind variables, so if a user declares:
  --
  --   type family F (a :: k1) (b :: k2) = (r :: k3) | r -> a
  --
  -- then we mark both `a` and `k1` as injective.
  -- NB: the return kind is considered to be *input* argument to a type family.
  -- Since injectivity allows to infer input arguments from the result in theory
  -- we should always mark the result kind variable (`k3` in this example) as
  -- injective.  The reason is that result type has always an assigned kind and
  -- therefore we can always infer the result kind if we know the result type.
  -- But this does not seem to be useful in any way so we don't do it.  (Another
  -- reason is that the implementation would not be straightforward.)
tcInjectivity [TyConBinder]
tcbs (Just (L SrcSpan
loc (InjectivityAnn GenLocated SrcSpan (IdP GhcRn)
_ [GenLocated SrcSpan (IdP GhcRn)]
lInjNames)))
  = SrcSpan -> TcM Injectivity -> TcM Injectivity
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan SrcSpan
loc (TcM Injectivity -> TcM Injectivity)
-> TcM Injectivity -> TcM Injectivity
forall a b. (a -> b) -> a -> b
$
    do { let tvs :: [TcTyCoVar]
tvs = [TyConBinder] -> [TcTyCoVar]
forall tv argf. [VarBndr tv argf] -> [tv]
binderVars [TyConBinder]
tcbs
       ; DynFlags
dflags <- IOEnv (Env TcGblEnv TcLclEnv) DynFlags
forall (m :: * -> *). HasDynFlags m => m DynFlags
getDynFlags
       ; Bool -> SDoc -> TcRn ()
checkTc (Extension -> DynFlags -> Bool
xopt Extension
LangExt.TypeFamilyDependencies DynFlags
dflags)
                 (String -> SDoc
text String
"Illegal injectivity annotation" SDoc -> SDoc -> SDoc
$$
                  String -> SDoc
text String
"Use TypeFamilyDependencies to allow this")
       ; [TcTyCoVar]
inj_tvs <- (GenLocated SrcSpan Name
 -> IOEnv (Env TcGblEnv TcLclEnv) TcTyCoVar)
-> [GenLocated SrcSpan Name] -> TcM [TcTyCoVar]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM (Name -> IOEnv (Env TcGblEnv TcLclEnv) TcTyCoVar
tcLookupTyVar (Name -> IOEnv (Env TcGblEnv TcLclEnv) TcTyCoVar)
-> (GenLocated SrcSpan Name -> Name)
-> GenLocated SrcSpan Name
-> IOEnv (Env TcGblEnv TcLclEnv) TcTyCoVar
forall b c a. (b -> c) -> (a -> b) -> a -> c
. GenLocated SrcSpan Name -> Name
forall a. HasSrcSpan a => a -> SrcSpanLess a
unLoc) [GenLocated SrcSpan Name]
[GenLocated SrcSpan (IdP GhcRn)]
lInjNames
       ; [TcTyCoVar]
inj_tvs <- (TcTyCoVar -> IOEnv (Env TcGblEnv TcLclEnv) TcTyCoVar)
-> [TcTyCoVar] -> TcM [TcTyCoVar]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM HasDebugCallStack =>
TcTyCoVar -> IOEnv (Env TcGblEnv TcLclEnv) TcTyCoVar
TcTyCoVar -> IOEnv (Env TcGblEnv TcLclEnv) TcTyCoVar
zonkTcTyVarToTyVar [TcTyCoVar]
inj_tvs -- zonk the kinds
       ; let inj_ktvs :: TyVarSet
inj_ktvs = (TcTyCoVar -> Bool) -> TyVarSet -> TyVarSet
filterVarSet TcTyCoVar -> Bool
isTyVar (TyVarSet -> TyVarSet) -> TyVarSet -> TyVarSet
forall a b. (a -> b) -> a -> b
$  -- no injective coercion vars
                        TyVarSet -> TyVarSet
closeOverKinds ([TcTyCoVar] -> TyVarSet
mkVarSet [TcTyCoVar]
inj_tvs)
       ; let inj_bools :: [Bool]
inj_bools = (TcTyCoVar -> Bool) -> [TcTyCoVar] -> [Bool]
forall a b. (a -> b) -> [a] -> [b]
map (TcTyCoVar -> TyVarSet -> Bool
`elemVarSet` TyVarSet
inj_ktvs) [TcTyCoVar]
tvs
       ; String -> SDoc -> TcRn ()
traceTc String
"tcInjectivity" ([SDoc] -> SDoc
vcat [ [TcTyCoVar] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TcTyCoVar]
tvs, [GenLocated SrcSpan Name] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [GenLocated SrcSpan Name]
[GenLocated SrcSpan (IdP GhcRn)]
lInjNames, [TcTyCoVar] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TcTyCoVar]
inj_tvs
                                       , TyVarSet -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyVarSet
inj_ktvs, [Bool] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Bool]
inj_bools ])
       ; Injectivity -> TcM Injectivity
forall (m :: * -> *) a. Monad m => a -> m a
return (Injectivity -> TcM Injectivity) -> Injectivity -> TcM Injectivity
forall a b. (a -> b) -> a -> b
$ [Bool] -> Injectivity
Injective [Bool]
inj_bools }

tcTySynRhs :: RolesInfo -> Name
           -> LHsType GhcRn -> TcM TyCon
tcTySynRhs :: (Name -> [Role]) -> Name -> LHsKind GhcRn -> TcRn TyCon
tcTySynRhs Name -> [Role]
roles_info Name
tc_name LHsKind GhcRn
hs_ty
  = Name -> ([TyConBinder] -> Kind -> TcRn TyCon) -> TcRn TyCon
forall a. Name -> ([TyConBinder] -> Kind -> TcM a) -> TcM a
bindTyClTyVars Name
tc_name (([TyConBinder] -> Kind -> TcRn TyCon) -> TcRn TyCon)
-> ([TyConBinder] -> Kind -> TcRn TyCon) -> TcRn TyCon
forall a b. (a -> b) -> a -> b
$ \ [TyConBinder]
binders Kind
res_kind ->
    do { TcLclEnv
env <- TcRnIf TcGblEnv TcLclEnv TcLclEnv
forall gbl lcl. TcRnIf gbl lcl lcl
getLclEnv
       ; String -> SDoc -> TcRn ()
traceTc String
"tc-syn" (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
tc_name SDoc -> SDoc -> SDoc
$$ NameEnv TcTyThing -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TcLclEnv -> NameEnv TcTyThing
tcl_env TcLclEnv
env))
       ; Kind
rhs_ty <- TcM Kind -> TcM Kind
forall r. TcM r -> TcM r
pushTcLevelM_   (TcM Kind -> TcM Kind) -> TcM Kind -> TcM Kind
forall a b. (a -> b) -> a -> b
$
                   TcM Kind -> TcM Kind
forall r. TcM r -> TcM r
solveEqualities (TcM Kind -> TcM Kind) -> TcM Kind -> TcM Kind
forall a b. (a -> b) -> a -> b
$
                   LHsKind GhcRn -> Kind -> TcM Kind
tcCheckLHsType LHsKind GhcRn
hs_ty Kind
res_kind
       ; Kind
rhs_ty <- Kind -> TcM Kind
zonkTcTypeToType Kind
rhs_ty
       ; let roles :: [Role]
roles = Name -> [Role]
roles_info Name
tc_name
             tycon :: TyCon
tycon = Name -> [TyConBinder] -> Kind -> [Role] -> Kind -> TyCon
buildSynTyCon Name
tc_name [TyConBinder]
binders Kind
res_kind [Role]
roles Kind
rhs_ty
       ; TyCon -> TcRn TyCon
forall (m :: * -> *) a. Monad m => a -> m a
return TyCon
tycon }

tcDataDefn :: SDoc -> RolesInfo -> Name
           -> HsDataDefn GhcRn -> TcM (TyCon, [DerivInfo])
  -- NB: not used for newtype/data instances (whether associated or not)
tcDataDefn :: SDoc
-> (Name -> [Role])
-> Name
-> HsDataDefn GhcRn
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
tcDataDefn SDoc
err_ctxt Name -> [Role]
roles_info Name
tc_name
           (HsDataDefn { dd_ND :: forall pass. HsDataDefn pass -> NewOrData
dd_ND = NewOrData
new_or_data, dd_cType :: forall pass. HsDataDefn pass -> Maybe (Located CType)
dd_cType = Maybe (Located CType)
cType
                       , dd_ctxt :: forall pass. HsDataDefn pass -> LHsContext pass
dd_ctxt = GenLocated SrcSpan (HsContext GhcRn)
ctxt
                       , dd_kindSig :: forall pass. HsDataDefn pass -> Maybe (LHsKind pass)
dd_kindSig = Maybe (LHsKind GhcRn)
mb_ksig  -- Already in tc's kind
                                               -- via inferInitialKinds
                       , dd_cons :: forall pass. HsDataDefn pass -> [LConDecl pass]
dd_cons = [LConDecl GhcRn]
cons
                       , dd_derivs :: forall pass. HsDataDefn pass -> HsDeriving pass
dd_derivs = HsDeriving GhcRn
derivs })
  = Name
-> ([TyConBinder]
    -> Kind -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo]))
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
forall a. Name -> ([TyConBinder] -> Kind -> TcM a) -> TcM a
bindTyClTyVars Name
tc_name (([TyConBinder]
  -> Kind -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo]))
 -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo]))
-> ([TyConBinder]
    -> Kind -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo]))
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
forall a b. (a -> b) -> a -> b
$ \ [TyConBinder]
tycon_binders Kind
res_kind ->
       -- The TyCon tyvars must scope over
       --    - the stupid theta (dd_ctxt)
       --    - for H98 constructors only, the ConDecl
       -- But it does no harm to bring them into scope
       -- over GADT ConDecls as well; and it's awkward not to
    do { Bool
gadt_syntax <- Name
-> NewOrData
-> GenLocated SrcSpan (HsContext GhcRn)
-> [LConDecl GhcRn]
-> TcRnIf TcGblEnv TcLclEnv Bool
dataDeclChecks Name
tc_name NewOrData
new_or_data GenLocated SrcSpan (HsContext GhcRn)
ctxt [LConDecl GhcRn]
cons
       ; ([TyConBinder]
extra_bndrs, Kind
final_res_kind) <- [TyConBinder] -> Kind -> TcM ([TyConBinder], Kind)
etaExpandAlgTyCon [TyConBinder]
tycon_binders Kind
res_kind

       ; TcGblEnv
tcg_env <- TcRnIf TcGblEnv TcLclEnv TcGblEnv
forall gbl lcl. TcRnIf gbl lcl gbl
getGblEnv
       ; let hsc_src :: HscSource
hsc_src = TcGblEnv -> HscSource
tcg_src TcGblEnv
tcg_env
       ; Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
unless (HscSource -> [LConDecl GhcRn] -> Bool
forall a. HscSource -> [a] -> Bool
mk_permissive_kind HscSource
hsc_src [LConDecl GhcRn]
cons) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
         DataSort -> Kind -> TcRn ()
checkDataKindSig (NewOrData -> DataSort
DataDeclSort NewOrData
new_or_data) Kind
final_res_kind

       ; [Kind]
stupid_tc_theta <- TcM [Kind] -> TcM [Kind]
forall r. TcM r -> TcM r
pushTcLevelM_ (TcM [Kind] -> TcM [Kind]) -> TcM [Kind] -> TcM [Kind]
forall a b. (a -> b) -> a -> b
$ TcM [Kind] -> TcM [Kind]
forall r. TcM r -> TcM r
solveEqualities (TcM [Kind] -> TcM [Kind]) -> TcM [Kind] -> TcM [Kind]
forall a b. (a -> b) -> a -> b
$ GenLocated SrcSpan (HsContext GhcRn) -> TcM [Kind]
tcHsContext GenLocated SrcSpan (HsContext GhcRn)
ctxt
       ; [Kind]
stupid_theta    <- [Kind] -> TcM [Kind]
zonkTcTypesToTypes [Kind]
stupid_tc_theta
       ; Bool
kind_signatures <- Extension -> TcRnIf TcGblEnv TcLclEnv Bool
forall gbl lcl. Extension -> TcRnIf gbl lcl Bool
xoptM Extension
LangExt.KindSignatures

             -- Check that we don't use kind signatures without Glasgow extensions
       ; Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
when (Maybe (LHsKind GhcRn) -> Bool
forall a. Maybe a -> Bool
isJust Maybe (LHsKind GhcRn)
mb_ksig) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
         Bool -> SDoc -> TcRn ()
checkTc (Bool
kind_signatures) (Name -> SDoc
badSigTyDecl Name
tc_name)

       ; TyCon
tycon <- (TyCon -> TcRn TyCon) -> TcRn TyCon
forall a env. (a -> IOEnv env a) -> IOEnv env a
fixM ((TyCon -> TcRn TyCon) -> TcRn TyCon)
-> (TyCon -> TcRn TyCon) -> TcRn TyCon
forall a b. (a -> b) -> a -> b
$ \ TyCon
tycon -> do
             { let final_bndrs :: [TyConBinder]
final_bndrs = [TyConBinder]
tycon_binders [TyConBinder] -> [TyConBinder] -> [TyConBinder]
forall a. [a] -> [a] -> [a]
`chkAppend` [TyConBinder]
extra_bndrs
                   res_ty :: Kind
res_ty      = TyCon -> [Kind] -> Kind
mkTyConApp TyCon
tycon ([TcTyCoVar] -> [Kind]
mkTyVarTys ([TyConBinder] -> [TcTyCoVar]
forall tv argf. [VarBndr tv argf] -> [tv]
binderVars [TyConBinder]
final_bndrs))
                   roles :: [Role]
roles       = Name -> [Role]
roles_info Name
tc_name
             ; [DataCon]
data_cons <- TyCon
-> NewOrData
-> [TyConBinder]
-> Kind
-> Kind
-> [LConDecl GhcRn]
-> TcM [DataCon]
tcConDecls
                              TyCon
tycon
                              NewOrData
new_or_data
                              [TyConBinder]
final_bndrs
                              Kind
final_res_kind
                              Kind
res_ty
                              [LConDecl GhcRn]
cons
             ; AlgTyConRhs
tc_rhs    <- HscSource
-> TyCon -> [DataCon] -> IOEnv (Env TcGblEnv TcLclEnv) AlgTyConRhs
mk_tc_rhs HscSource
hsc_src TyCon
tycon [DataCon]
data_cons
             ; Name
tc_rep_nm <- Name -> TcRnIf TcGblEnv TcLclEnv Name
forall gbl lcl. Name -> TcRnIf gbl lcl Name
newTyConRepName Name
tc_name
             ; TyCon -> TcRn TyCon
forall (m :: * -> *) a. Monad m => a -> m a
return (Name
-> [TyConBinder]
-> Kind
-> [Role]
-> Maybe CType
-> [Kind]
-> AlgTyConRhs
-> AlgTyConFlav
-> Bool
-> TyCon
mkAlgTyCon Name
tc_name
                                  [TyConBinder]
final_bndrs
                                  Kind
final_res_kind
                                  [Role]
roles
                                  ((Located CType -> CType) -> Maybe (Located CType) -> Maybe CType
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap Located CType -> CType
forall a. HasSrcSpan a => a -> SrcSpanLess a
unLoc Maybe (Located CType)
cType)
                                  [Kind]
stupid_theta AlgTyConRhs
tc_rhs
                                  (Name -> AlgTyConFlav
VanillaAlgTyCon Name
tc_rep_nm)
                                  Bool
gadt_syntax) }
       ; TyCon
tctc <- HasDebugCallStack => Name -> TcRn TyCon
Name -> TcRn TyCon
tcLookupTcTyCon Name
tc_name
            -- 'tctc' is a 'TcTyCon' and has the 'tcTyConScopedTyVars' that we need
            -- unlike the finalized 'tycon' defined above which is an 'AlgTyCon'
       ; let deriv_info :: DerivInfo
deriv_info = DerivInfo :: TyCon
-> ScopedPairs -> [LHsDerivingClause GhcRn] -> SDoc -> DerivInfo
DerivInfo { di_rep_tc :: TyCon
di_rep_tc = TyCon
tycon
                                    , di_scoped_tvs :: ScopedPairs
di_scoped_tvs = TyCon -> ScopedPairs
tcTyConScopedTyVars TyCon
tctc
                                    , di_clauses :: [LHsDerivingClause GhcRn]
di_clauses = HsDeriving GhcRn -> SrcSpanLess (HsDeriving GhcRn)
forall a. HasSrcSpan a => a -> SrcSpanLess a
unLoc HsDeriving GhcRn
derivs
                                    , di_ctxt :: SDoc
di_ctxt = SDoc
err_ctxt }
       ; String -> SDoc -> TcRn ()
traceTc String
"tcDataDefn" (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
tc_name SDoc -> SDoc -> SDoc
$$ [TyConBinder] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TyConBinder]
tycon_binders SDoc -> SDoc -> SDoc
$$ [TyConBinder] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TyConBinder]
extra_bndrs)
       ; (TyCon, [DerivInfo])
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
forall (m :: * -> *) a. Monad m => a -> m a
return (TyCon
tycon, [DerivInfo
deriv_info]) }
  where
    -- Abstract data types in hsig files can have arbitrary kinds,
    -- because they may be implemented by type synonyms
    -- (which themselves can have arbitrary kinds, not just *). See #13955.
    --
    -- Note that this is only a property that data type declarations possess,
    -- so one could not have, say, a data family instance in an hsig file that
    -- has kind `Bool`. Therefore, this check need only occur in the code that
    -- typechecks data type declarations.
    mk_permissive_kind :: HscSource -> [a] -> Bool
mk_permissive_kind HscSource
HsigFile [] = Bool
True
    mk_permissive_kind HscSource
_ [a]
_ = Bool
False

    -- In hs-boot, a 'data' declaration with no constructors
    -- indicates a nominally distinct abstract data type.
    mk_tc_rhs :: HscSource
-> TyCon -> [DataCon] -> IOEnv (Env TcGblEnv TcLclEnv) AlgTyConRhs
mk_tc_rhs HscSource
HsBootFile TyCon
_ []
      = AlgTyConRhs -> IOEnv (Env TcGblEnv TcLclEnv) AlgTyConRhs
forall (m :: * -> *) a. Monad m => a -> m a
return AlgTyConRhs
AbstractTyCon

    mk_tc_rhs HscSource
HsigFile TyCon
_ [] -- ditto
      = AlgTyConRhs -> IOEnv (Env TcGblEnv TcLclEnv) AlgTyConRhs
forall (m :: * -> *) a. Monad m => a -> m a
return AlgTyConRhs
AbstractTyCon

    mk_tc_rhs HscSource
_ TyCon
tycon [DataCon]
data_cons
      = case NewOrData
new_or_data of
          NewOrData
DataType -> AlgTyConRhs -> IOEnv (Env TcGblEnv TcLclEnv) AlgTyConRhs
forall (m :: * -> *) a. Monad m => a -> m a
return ([DataCon] -> AlgTyConRhs
mkDataTyConRhs [DataCon]
data_cons)
          NewOrData
NewType  -> ASSERT( not (null data_cons) )
                      Name
-> TyCon -> DataCon -> IOEnv (Env TcGblEnv TcLclEnv) AlgTyConRhs
forall m n. Name -> TyCon -> DataCon -> TcRnIf m n AlgTyConRhs
mkNewTyConRhs Name
tc_name TyCon
tycon ([DataCon] -> DataCon
forall a. [a] -> a
head [DataCon]
data_cons)
tcDataDefn SDoc
_ Name -> [Role]
_ Name
_ (XHsDataDefn XXHsDataDefn GhcRn
nec) = NoExtCon -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
forall a. NoExtCon -> a
noExtCon XXHsDataDefn GhcRn
NoExtCon
nec


-------------------------
kcTyFamInstEqn :: TcTyCon -> LTyFamInstEqn GhcRn -> TcM ()
-- Used for the equations of a closed type family only
-- Not used for data/type instances
kcTyFamInstEqn :: TyCon -> LTyFamInstEqn GhcRn -> TcRn ()
kcTyFamInstEqn TyCon
tc_fam_tc
    (L SrcSpan
loc (HsIB { hsib_ext :: forall pass thing. HsImplicitBndrs pass thing -> XHsIB pass thing
hsib_ext = XHsIB GhcRn (FamEqn GhcRn (LHsKind GhcRn))
imp_vars
                 , hsib_body :: forall pass thing. HsImplicitBndrs pass thing -> thing
hsib_body = FamEqn { feqn_tycon :: forall pass rhs. FamEqn pass rhs -> Located (IdP pass)
feqn_tycon = L SrcSpan
_ IdP GhcRn
eqn_tc_name
                                      , feqn_bndrs :: forall pass rhs. FamEqn pass rhs -> Maybe [LHsTyVarBndr pass]
feqn_bndrs = Maybe [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
mb_expl_bndrs
                                      , feqn_pats :: forall pass rhs. FamEqn pass rhs -> HsTyPats pass
feqn_pats  = HsTyPats GhcRn
hs_pats
                                      , feqn_rhs :: forall pass rhs. FamEqn pass rhs -> rhs
feqn_rhs   = LHsKind GhcRn
hs_rhs_ty }}))
  = SrcSpan -> TcRn () -> TcRn ()
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan SrcSpan
loc (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
    do { String -> SDoc -> TcRn ()
traceTc String
"kcTyFamInstEqn" ([SDoc] -> SDoc
vcat
           [ String -> SDoc
text String
"tc_name ="    SDoc -> SDoc -> SDoc
<+> Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
IdP GhcRn
eqn_tc_name
           , String -> SDoc
text String
"fam_tc ="     SDoc -> SDoc -> SDoc
<+> TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tc_fam_tc SDoc -> SDoc -> SDoc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
<+> Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyCon -> Kind
tyConKind TyCon
tc_fam_tc)
           , String -> SDoc
text String
"hsib_vars ="  SDoc -> SDoc -> SDoc
<+> [Name] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Name]
XHsIB GhcRn (FamEqn GhcRn (LHsKind GhcRn))
imp_vars
           , String -> SDoc
text String
"feqn_bndrs =" SDoc -> SDoc -> SDoc
<+> Maybe [GenLocated SrcSpan (HsTyVarBndr GhcRn)] -> SDoc
forall a. Outputable a => a -> SDoc
ppr Maybe [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
mb_expl_bndrs
           , String -> SDoc
text String
"feqn_pats ="  SDoc -> SDoc -> SDoc
<+> HsTyPats GhcRn -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsTyPats GhcRn
hs_pats ])
          -- this check reports an arity error instead of a kind error; easier for user
       ; let vis_pats :: Int
vis_pats = HsTyPats GhcRn -> Int
forall tm ty. [HsArg tm ty] -> Int
numVisibleArgs HsTyPats GhcRn
hs_pats
       ; Bool -> SDoc -> TcRn ()
checkTc (Int
vis_pats Int -> Int -> Bool
forall a. Eq a => a -> a -> Bool
== Int
vis_arity) (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$
                  Int -> SDoc
wrongNumberOfParmsErr Int
vis_arity
       ; TcM ([TcTyCoVar], ([TcTyCoVar], Kind)) -> TcRn ()
forall a. TcM a -> TcRn ()
discardResult (TcM ([TcTyCoVar], ([TcTyCoVar], Kind)) -> TcRn ())
-> TcM ([TcTyCoVar], ([TcTyCoVar], Kind)) -> TcRn ()
forall a b. (a -> b) -> a -> b
$
         [Name]
-> TcM ([TcTyCoVar], Kind)
-> TcM ([TcTyCoVar], ([TcTyCoVar], Kind))
forall a. [Name] -> TcM a -> TcM ([TcTyCoVar], a)
bindImplicitTKBndrs_Q_Tv [Name]
XHsIB GhcRn (FamEqn GhcRn (LHsKind GhcRn))
imp_vars (TcM ([TcTyCoVar], Kind) -> TcM ([TcTyCoVar], ([TcTyCoVar], Kind)))
-> TcM ([TcTyCoVar], Kind)
-> TcM ([TcTyCoVar], ([TcTyCoVar], Kind))
forall a b. (a -> b) -> a -> b
$
         ContextKind
-> [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
-> TcM Kind
-> TcM ([TcTyCoVar], Kind)
forall a.
ContextKind
-> [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
-> TcM a
-> TcM ([TcTyCoVar], a)
bindExplicitTKBndrs_Q_Tv ContextKind
AnyKind (Maybe [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
mb_expl_bndrs Maybe [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
-> [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
-> [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
forall a. Maybe a -> a -> a
`orElse` []) (TcM Kind -> TcM ([TcTyCoVar], Kind))
-> TcM Kind -> TcM ([TcTyCoVar], Kind)
forall a b. (a -> b) -> a -> b
$
         do { (Kind
_fam_app, Kind
res_kind) <- TyCon -> HsTyPats GhcRn -> TcM (Kind, Kind)
tcFamTyPats TyCon
tc_fam_tc HsTyPats GhcRn
hs_pats
            ; LHsKind GhcRn -> Kind -> TcM Kind
tcCheckLHsType LHsKind GhcRn
hs_rhs_ty Kind
res_kind }
             -- Why "_Tv" here?  Consider (#14066
             --  type family Bar x y where
             --      Bar (x :: a) (y :: b) = Int
             --      Bar (x :: c) (y :: d) = Bool
             -- During kind-checking, a,b,c,d should be TyVarTvs and unify appropriately
    }
  where
    vis_arity :: Int
vis_arity = [TcTyCoVar] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length (TyCon -> [TcTyCoVar]
tyConVisibleTyVars TyCon
tc_fam_tc)

kcTyFamInstEqn TyCon
_ (L SrcSpan
_ (XHsImplicitBndrs XXHsImplicitBndrs GhcRn (FamEqn GhcRn (LHsKind GhcRn))
nec)) = NoExtCon -> TcRn ()
forall a. NoExtCon -> a
noExtCon XXHsImplicitBndrs GhcRn (FamEqn GhcRn (LHsKind GhcRn))
NoExtCon
nec
kcTyFamInstEqn TyCon
_ (L SrcSpan
_ (HsIB XHsIB GhcRn (FamEqn GhcRn (LHsKind GhcRn))
_ (XFamEqn XXFamEqn GhcRn (LHsKind GhcRn)
nec))) = NoExtCon -> TcRn ()
forall a. NoExtCon -> a
noExtCon XXFamEqn GhcRn (LHsKind GhcRn)
NoExtCon
nec


--------------------------
tcTyFamInstEqn :: TcTyCon -> AssocInstInfo -> LTyFamInstEqn GhcRn
               -> TcM (KnotTied CoAxBranch)
-- Needs to be here, not in TcInstDcls, because closed families
-- (typechecked here) have TyFamInstEqns

tcTyFamInstEqn :: TyCon
-> AssocInstInfo
-> LTyFamInstEqn GhcRn
-> TcRn (KnotTied CoAxBranch)
tcTyFamInstEqn TyCon
fam_tc AssocInstInfo
mb_clsinfo
    (L SrcSpan
loc (HsIB { hsib_ext :: forall pass thing. HsImplicitBndrs pass thing -> XHsIB pass thing
hsib_ext = XHsIB GhcRn (FamEqn GhcRn (LHsKind GhcRn))
imp_vars
                 , hsib_body :: forall pass thing. HsImplicitBndrs pass thing -> thing
hsib_body = FamEqn { feqn_tycon :: forall pass rhs. FamEqn pass rhs -> Located (IdP pass)
feqn_tycon  = L SrcSpan
_ IdP GhcRn
eqn_tc_name
                                      , feqn_bndrs :: forall pass rhs. FamEqn pass rhs -> Maybe [LHsTyVarBndr pass]
feqn_bndrs  = Maybe [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
mb_expl_bndrs
                                      , feqn_pats :: forall pass rhs. FamEqn pass rhs -> HsTyPats pass
feqn_pats   = HsTyPats GhcRn
hs_pats
                                      , feqn_rhs :: forall pass rhs. FamEqn pass rhs -> rhs
feqn_rhs    = LHsKind GhcRn
hs_rhs_ty }}))
  = ASSERT( getName fam_tc == eqn_tc_name )
    SrcSpan -> TcRn (KnotTied CoAxBranch) -> TcRn (KnotTied CoAxBranch)
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan SrcSpan
loc (TcRn (KnotTied CoAxBranch) -> TcRn (KnotTied CoAxBranch))
-> TcRn (KnotTied CoAxBranch) -> TcRn (KnotTied CoAxBranch)
forall a b. (a -> b) -> a -> b
$
    do { String -> SDoc -> TcRn ()
traceTc String
"tcTyFamInstEqn" (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$
         [SDoc] -> SDoc
vcat [ TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
fam_tc SDoc -> SDoc -> SDoc
<+> HsTyPats GhcRn -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsTyPats GhcRn
hs_pats
              , String -> SDoc
text String
"fam tc bndrs" SDoc -> SDoc -> SDoc
<+> [TcTyCoVar] -> SDoc
pprTyVars (TyCon -> [TcTyCoVar]
tyConTyVars TyCon
fam_tc)
              , case AssocInstInfo
mb_clsinfo of
                  AssocInstInfo
NotAssociated -> SDoc
empty
                  InClsInst { ai_class :: AssocInstInfo -> Class
ai_class = Class
cls } -> String -> SDoc
text String
"class" SDoc -> SDoc -> SDoc
<+> Class -> SDoc
forall a. Outputable a => a -> SDoc
ppr Class
cls SDoc -> SDoc -> SDoc
<+> [TcTyCoVar] -> SDoc
pprTyVars (Class -> [TcTyCoVar]
classTyVars Class
cls) ]

       -- First, check the arity of visible arguments
       -- If we wait until validity checking, we'll get kind errors
       -- below when an arity error will be much easier to understand.
       ; let vis_arity :: Int
vis_arity = [TcTyCoVar] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length (TyCon -> [TcTyCoVar]
tyConVisibleTyVars TyCon
fam_tc)
             vis_pats :: Int
vis_pats  = HsTyPats GhcRn -> Int
forall tm ty. [HsArg tm ty] -> Int
numVisibleArgs HsTyPats GhcRn
hs_pats
       ; Bool -> SDoc -> TcRn ()
checkTc (Int
vis_pats Int -> Int -> Bool
forall a. Eq a => a -> a -> Bool
== Int
vis_arity) (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$
         Int -> SDoc
wrongNumberOfParmsErr Int
vis_arity
       ; ([TcTyCoVar]
qtvs, [Kind]
pats, Kind
rhs_ty) <- TyCon
-> AssocInstInfo
-> [Name]
-> [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
-> HsTyPats GhcRn
-> LHsKind GhcRn
-> TcM ([TcTyCoVar], [Kind], Kind)
tcTyFamInstEqnGuts TyCon
fam_tc AssocInstInfo
mb_clsinfo
                                      [Name]
XHsIB GhcRn (FamEqn GhcRn (LHsKind GhcRn))
imp_vars (Maybe [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
mb_expl_bndrs Maybe [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
-> [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
-> [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
forall a. Maybe a -> a -> a
`orElse` [])
                                      HsTyPats GhcRn
hs_pats LHsKind GhcRn
hs_rhs_ty
       -- Don't print results they may be knot-tied
       -- (tcFamInstEqnGuts zonks to Type)
       ; KnotTied CoAxBranch -> TcRn (KnotTied CoAxBranch)
forall (m :: * -> *) a. Monad m => a -> m a
return ([TcTyCoVar]
-> [TcTyCoVar]
-> [TcTyCoVar]
-> [Kind]
-> Kind
-> [Role]
-> SrcSpan
-> KnotTied CoAxBranch
mkCoAxBranch [TcTyCoVar]
qtvs [] [] [Kind]
pats Kind
rhs_ty
                              ((TcTyCoVar -> Role) -> [TcTyCoVar] -> [Role]
forall a b. (a -> b) -> [a] -> [b]
map (Role -> TcTyCoVar -> Role
forall a b. a -> b -> a
const Role
Nominal) [TcTyCoVar]
qtvs)
                              SrcSpan
loc) }

tcTyFamInstEqn TyCon
_ AssocInstInfo
_ LTyFamInstEqn GhcRn
_ = String -> TcRn (KnotTied CoAxBranch)
forall a. String -> a
panic String
"tcTyFamInstEqn"

{-
Kind check type patterns and kind annotate the embedded type variables.
     type instance F [a] = rhs

 * Here we check that a type instance matches its kind signature, but we do
   not check whether there is a pattern for each type index; the latter
   check is only required for type synonym instances.

Note [Instantiating a family tycon]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
It's possible that kind-checking the result of a family tycon applied to
its patterns will instantiate the tycon further. For example, we might
have

  type family F :: k where
    F = Int
    F = Maybe

After checking (F :: forall k. k) (with no visible patterns), we still need
to instantiate the k. With data family instances, this problem can be even
more intricate, due to Note [Arity of data families] in FamInstEnv. See
indexed-types/should_compile/T12369 for an example.

So, the kind-checker must return the new skolems and args (that is, Type
or (Type -> Type) for the equations above) and the instantiated kind.

Note [Generalising in tcTyFamInstEqnGuts]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Suppose we have something like
  type instance forall (a::k) b. F t1 t2 = rhs

Then  imp_vars = [k], exp_bndrs = [a::k, b]

We want to quantify over
  * k, a, and b  (all user-specified)
  * and any inferred free kind vars from
      - the kinds of k, a, b
      - the types t1, t2

However, unlike a type signature like
  f :: forall (a::k). blah

we do /not/ care about the Inferred/Specified designation
or order for the final quantified tyvars.  Type-family
instances are not invoked directly in Haskell source code,
so visible type application etc plays no role.

So, the simple thing is
   - gather candidates from [k, a, b] and pats
   - quantify over them

Hence the slightly mysterious call:
    candidateQTyVarsOfTypes (pats ++ mkTyVarTys scoped_tvs)

Simple, neat, but a little non-obvious!
-}

--------------------------
tcTyFamInstEqnGuts :: TyCon -> AssocInstInfo
                   -> [Name] -> [LHsTyVarBndr GhcRn]  -- Implicit and explicicit binder
                   -> HsTyPats GhcRn                  -- Patterns
                   -> LHsType GhcRn                   -- RHS
                   -> TcM ([TyVar], [TcType], TcType)      -- (tyvars, pats, rhs)
-- Used only for type families, not data families
tcTyFamInstEqnGuts :: TyCon
-> AssocInstInfo
-> [Name]
-> [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
-> HsTyPats GhcRn
-> LHsKind GhcRn
-> TcM ([TcTyCoVar], [Kind], Kind)
tcTyFamInstEqnGuts TyCon
fam_tc AssocInstInfo
mb_clsinfo [Name]
imp_vars [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
exp_bndrs HsTyPats GhcRn
hs_pats LHsKind GhcRn
hs_rhs_ty
  = do { String -> SDoc -> TcRn ()
traceTc String
"tcTyFamInstEqnGuts {" (TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
fam_tc)

       -- By now, for type families (but not data families) we should
       -- have checked that the number of patterns matches tyConArity

       -- This code is closely related to the code
       -- in TcHsType.kcCheckDeclHeader_cusk
       ; ([TcTyCoVar]
imp_tvs, ([TcTyCoVar]
exp_tvs, (Kind
lhs_ty, Kind
rhs_ty)))
               <- TcM ([TcTyCoVar], ([TcTyCoVar], (Kind, Kind)))
-> TcM ([TcTyCoVar], ([TcTyCoVar], (Kind, Kind)))
forall r. TcM r -> TcM r
pushTcLevelM_                                (TcM ([TcTyCoVar], ([TcTyCoVar], (Kind, Kind)))
 -> TcM ([TcTyCoVar], ([TcTyCoVar], (Kind, Kind))))
-> TcM ([TcTyCoVar], ([TcTyCoVar], (Kind, Kind)))
-> TcM ([TcTyCoVar], ([TcTyCoVar], (Kind, Kind)))
forall a b. (a -> b) -> a -> b
$
                  TcM ([TcTyCoVar], ([TcTyCoVar], (Kind, Kind)))
-> TcM ([TcTyCoVar], ([TcTyCoVar], (Kind, Kind)))
forall r. TcM r -> TcM r
solveEqualities                              (TcM ([TcTyCoVar], ([TcTyCoVar], (Kind, Kind)))
 -> TcM ([TcTyCoVar], ([TcTyCoVar], (Kind, Kind))))
-> TcM ([TcTyCoVar], ([TcTyCoVar], (Kind, Kind)))
-> TcM ([TcTyCoVar], ([TcTyCoVar], (Kind, Kind)))
forall a b. (a -> b) -> a -> b
$
                  [Name]
-> TcM ([TcTyCoVar], (Kind, Kind))
-> TcM ([TcTyCoVar], ([TcTyCoVar], (Kind, Kind)))
forall a. [Name] -> TcM a -> TcM ([TcTyCoVar], a)
bindImplicitTKBndrs_Q_Skol [Name]
imp_vars          (TcM ([TcTyCoVar], (Kind, Kind))
 -> TcM ([TcTyCoVar], ([TcTyCoVar], (Kind, Kind))))
-> TcM ([TcTyCoVar], (Kind, Kind))
-> TcM ([TcTyCoVar], ([TcTyCoVar], (Kind, Kind)))
forall a b. (a -> b) -> a -> b
$
                  ContextKind
-> [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
-> TcM (Kind, Kind)
-> TcM ([TcTyCoVar], (Kind, Kind))
forall a.
ContextKind
-> [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
-> TcM a
-> TcM ([TcTyCoVar], a)
bindExplicitTKBndrs_Q_Skol ContextKind
AnyKind [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
exp_bndrs (TcM (Kind, Kind) -> TcM ([TcTyCoVar], (Kind, Kind)))
-> TcM (Kind, Kind) -> TcM ([TcTyCoVar], (Kind, Kind))
forall a b. (a -> b) -> a -> b
$
                  do { (Kind
lhs_ty, Kind
rhs_kind) <- TyCon -> HsTyPats GhcRn -> TcM (Kind, Kind)
tcFamTyPats TyCon
fam_tc HsTyPats GhcRn
hs_pats
                       -- Ensure that the instance is consistent with its
                       -- parent class (#16008)
                     ; AssocInstInfo -> Kind -> TcRn ()
addConsistencyConstraints AssocInstInfo
mb_clsinfo Kind
lhs_ty
                     ; Kind
rhs_ty <- LHsKind GhcRn -> Kind -> TcM Kind
tcCheckLHsType LHsKind GhcRn
hs_rhs_ty Kind
rhs_kind
                     ; (Kind, Kind) -> TcM (Kind, Kind)
forall (m :: * -> *) a. Monad m => a -> m a
return (Kind
lhs_ty, Kind
rhs_ty) }

       -- See Note [Generalising in tcTyFamInstEqnGuts]
       -- This code (and the stuff immediately above) is very similar
       -- to that in tcDataFamInstHeader.  Maybe we should abstract the
       -- common code; but for the moment I concluded that it's
       -- clearer to duplicate it.  Still, if you fix a bug here,
       -- check there too!
       ; let scoped_tvs :: [TcTyCoVar]
scoped_tvs = [TcTyCoVar]
imp_tvs [TcTyCoVar] -> [TcTyCoVar] -> [TcTyCoVar]
forall a. [a] -> [a] -> [a]
++ [TcTyCoVar]
exp_tvs
       ; CandidatesQTvs
dvs  <- [Kind] -> TcM CandidatesQTvs
candidateQTyVarsOfTypes (Kind
lhs_ty Kind -> [Kind] -> [Kind]
forall a. a -> [a] -> [a]
: [TcTyCoVar] -> [Kind]
mkTyVarTys [TcTyCoVar]
scoped_tvs)
       ; [TcTyCoVar]
qtvs <- CandidatesQTvs -> TcM [TcTyCoVar]
quantifyTyVars CandidatesQTvs
dvs

       ; String -> SDoc -> TcRn ()
traceTc String
"tcTyFamInstEqnGuts 2" (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$
         [SDoc] -> SDoc
vcat [ TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
fam_tc
              , String -> SDoc
text String
"scoped_tvs" SDoc -> SDoc -> SDoc
<+> [TcTyCoVar] -> SDoc
pprTyVars [TcTyCoVar]
scoped_tvs
              , String -> SDoc
text String
"lhs_ty"     SDoc -> SDoc -> SDoc
<+> Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr Kind
lhs_ty
              , String -> SDoc
text String
"dvs"        SDoc -> SDoc -> SDoc
<+> CandidatesQTvs -> SDoc
forall a. Outputable a => a -> SDoc
ppr CandidatesQTvs
dvs
              , String -> SDoc
text String
"qtvs"       SDoc -> SDoc -> SDoc
<+> [TcTyCoVar] -> SDoc
pprTyVars [TcTyCoVar]
qtvs ]

       ; (ZonkEnv
ze, [TcTyCoVar]
qtvs) <- [TcTyCoVar] -> TcM (ZonkEnv, [TcTyCoVar])
zonkTyBndrs [TcTyCoVar]
qtvs
       ; Kind
lhs_ty     <- ZonkEnv -> Kind -> TcM Kind
zonkTcTypeToTypeX ZonkEnv
ze Kind
lhs_ty
       ; Kind
rhs_ty     <- ZonkEnv -> Kind -> TcM Kind
zonkTcTypeToTypeX ZonkEnv
ze Kind
rhs_ty

       ; let pats :: [Kind]
pats = Kind -> [Kind]
unravelFamInstPats Kind
lhs_ty
             -- Note that we do this after solveEqualities
             -- so that any strange coercions inside lhs_ty
             -- have been solved before we attempt to unravel it
       ; String -> SDoc -> TcRn ()
traceTc String
"tcTyFamInstEqnGuts }" (TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
fam_tc SDoc -> SDoc -> SDoc
<+> [TcTyCoVar] -> SDoc
pprTyVars [TcTyCoVar]
qtvs)
       ; ([TcTyCoVar], [Kind], Kind) -> TcM ([TcTyCoVar], [Kind], Kind)
forall (m :: * -> *) a. Monad m => a -> m a
return ([TcTyCoVar]
qtvs, [Kind]
pats, Kind
rhs_ty) }

-----------------
tcFamTyPats :: TyCon
            -> HsTyPats GhcRn                -- Patterns
            -> TcM (TcType, TcKind)          -- (lhs_type, lhs_kind)
-- Used for both type and data families
tcFamTyPats :: TyCon -> HsTyPats GhcRn -> TcM (Kind, Kind)
tcFamTyPats TyCon
fam_tc HsTyPats GhcRn
hs_pats
  = do { String -> SDoc -> TcRn ()
traceTc String
"tcFamTyPats {" (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$
         [SDoc] -> SDoc
vcat [ TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
fam_tc, String -> SDoc
text String
"arity:" SDoc -> SDoc -> SDoc
<+> Int -> SDoc
forall a. Outputable a => a -> SDoc
ppr Int
fam_arity ]

       ; let fun_ty :: Kind
fun_ty = TyCon -> [Kind] -> Kind
mkTyConApp TyCon
fam_tc []

       ; (Kind
fam_app, Kind
res_kind) <- WarningFlag -> TcM (Kind, Kind) -> TcM (Kind, Kind)
forall gbl lcl a.
WarningFlag -> TcRnIf gbl lcl a -> TcRnIf gbl lcl a
unsetWOptM WarningFlag
Opt_WarnPartialTypeSignatures (TcM (Kind, Kind) -> TcM (Kind, Kind))
-> TcM (Kind, Kind) -> TcM (Kind, Kind)
forall a b. (a -> b) -> a -> b
$
                                Extension -> TcM (Kind, Kind) -> TcM (Kind, Kind)
forall gbl lcl a. Extension -> TcRnIf gbl lcl a -> TcRnIf gbl lcl a
setXOptM Extension
LangExt.PartialTypeSignatures (TcM (Kind, Kind) -> TcM (Kind, Kind))
-> TcM (Kind, Kind) -> TcM (Kind, Kind)
forall a b. (a -> b) -> a -> b
$
                                -- See Note [Wildcards in family instances] in
                                -- GHC.Rename.Source
                                TcTyMode
-> LHsKind GhcRn -> Kind -> HsTyPats GhcRn -> TcM (Kind, Kind)
tcInferApps TcTyMode
typeLevelMode LHsKind GhcRn
lhs_fun Kind
fun_ty HsTyPats GhcRn
hs_pats

       ; String -> SDoc -> TcRn ()
traceTc String
"End tcFamTyPats }" (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$
         [SDoc] -> SDoc
vcat [ TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
fam_tc, String -> SDoc
text String
"res_kind:" SDoc -> SDoc -> SDoc
<+> Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr Kind
res_kind ]

       ; (Kind, Kind) -> TcM (Kind, Kind)
forall (m :: * -> *) a. Monad m => a -> m a
return (Kind
fam_app, Kind
res_kind) }
  where
    fam_name :: Name
fam_name  = TyCon -> Name
tyConName TyCon
fam_tc
    fam_arity :: Int
fam_arity = TyCon -> Int
tyConArity TyCon
fam_tc
    lhs_fun :: LHsKind GhcRn
lhs_fun   = SrcSpanLess (LHsKind GhcRn) -> LHsKind GhcRn
forall a. HasSrcSpan a => SrcSpanLess a -> a
noLoc (XTyVar GhcRn
-> PromotionFlag -> GenLocated SrcSpan (IdP GhcRn) -> HsType GhcRn
forall pass.
XTyVar pass -> PromotionFlag -> Located (IdP pass) -> HsType pass
HsTyVar XTyVar GhcRn
NoExtField
noExtField PromotionFlag
NotPromoted (SrcSpanLess (GenLocated SrcSpan Name) -> GenLocated SrcSpan Name
forall a. HasSrcSpan a => SrcSpanLess a -> a
noLoc Name
SrcSpanLess (GenLocated SrcSpan Name)
fam_name))

unravelFamInstPats :: TcType -> [TcType]
-- Decompose fam_app to get the argument patterns
--
-- We expect fam_app to look like (F t1 .. tn)
-- tcInferApps is capable of returning ((F ty1 |> co) ty2),
-- but that can't happen here because we already checked the
-- arity of F matches the number of pattern
unravelFamInstPats :: Kind -> [Kind]
unravelFamInstPats Kind
fam_app
  = case HasDebugCallStack => Kind -> Maybe (TyCon, [Kind])
Kind -> Maybe (TyCon, [Kind])
splitTyConApp_maybe Kind
fam_app of
      Just (TyCon
_, [Kind]
pats) -> [Kind]
pats
      Maybe (TyCon, [Kind])
Nothing -> String -> [Kind]
forall a. String -> a
panic String
"unravelFamInstPats: Ill-typed LHS of family instance"
        -- The Nothing case cannot happen for type families, because
        -- we don't call unravelFamInstPats until we've solved the
        -- equalities. For data families, it shouldn't happen either,
        -- we need to fail hard and early if it does. See trac issue #15905
        -- for an example of this happening.

addConsistencyConstraints :: AssocInstInfo -> TcType -> TcM ()
-- In the corresponding positions of the class and type-family,
-- ensure the the family argument is the same as the class argument
--   E.g    class C a b c d where
--             F c x y a :: Type
-- Here the first  arg of F should be the same as the third of C
--  and the fourth arg of F should be the same as the first of C
--
-- We emit /Derived/ constraints (a bit like fundeps) to encourage
-- unification to happen, but without actually reporting errors.
-- If, despite the efforts, corresponding positions do not match,
-- checkConsistentFamInst will complain
addConsistencyConstraints :: AssocInstInfo -> Kind -> TcRn ()
addConsistencyConstraints AssocInstInfo
mb_clsinfo Kind
fam_app
  | InClsInst { ai_inst_env :: AssocInstInfo -> NameEnv Kind
ai_inst_env = NameEnv Kind
inst_env } <- AssocInstInfo
mb_clsinfo
  , Just (TyCon
fam_tc, [Kind]
pats) <- HasCallStack => Kind -> Maybe (TyCon, [Kind])
Kind -> Maybe (TyCon, [Kind])
tcSplitTyConApp_maybe Kind
fam_app
  = do { let eqs :: [(Kind, Kind)]
eqs = [ (Kind
cls_ty, Kind
pat)
                   | (TcTyCoVar
fam_tc_tv, Kind
pat) <- TyCon -> [TcTyCoVar]
tyConTyVars TyCon
fam_tc [TcTyCoVar] -> [Kind] -> [(TcTyCoVar, Kind)]
forall a b. [a] -> [b] -> [(a, b)]
`zip` [Kind]
pats
                   , Just Kind
cls_ty <- [NameEnv Kind -> TcTyCoVar -> Maybe Kind
forall a. VarEnv a -> TcTyCoVar -> Maybe a
lookupVarEnv NameEnv Kind
inst_env TcTyCoVar
fam_tc_tv] ]
       ; String -> SDoc -> TcRn ()
traceTc String
"addConsistencyConstraints" ([(Kind, Kind)] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [(Kind, Kind)]
eqs)
       ; CtOrigin -> [(Kind, Kind)] -> TcRn ()
emitDerivedEqs CtOrigin
AssocFamPatOrigin [(Kind, Kind)]
eqs }
    -- Improve inference
    -- Any mis-match is reports by checkConsistentFamInst
  | Bool
otherwise
  = () -> TcRn ()
forall (m :: * -> *) a. Monad m => a -> m a
return ()

{- Note [Constraints in patterns]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NB: This isn't the whole story. See comment in tcFamTyPats.

At first glance, it seems there is a complicated story to tell in tcFamTyPats
around constraint solving. After all, type family patterns can now do
GADT pattern-matching, which is jolly complicated. But, there's a key fact
which makes this all simple: everything is at top level! There cannot
be untouchable type variables. There can't be weird interaction between
case branches. There can't be global skolems.

This means that the semantics of type-level GADT matching is a little
different than term level. If we have

  data G a where
    MkGBool :: G Bool

And then

  type family F (a :: G k) :: k
  type instance F MkGBool = True

we get

  axF : F Bool (MkGBool <Bool>) ~ True

Simple! No casting on the RHS, because we can affect the kind parameter
to F.

If we ever introduce local type families, this all gets a lot more
complicated, and will end up looking awfully like term-level GADT
pattern-matching.


** The new story **

Here is really what we want:

The matcher really can't deal with covars in arbitrary spots in coercions.
But it can deal with covars that are arguments to GADT data constructors.
So we somehow want to allow covars only in precisely those spots, then use
them as givens when checking the RHS. TODO (RAE): Implement plan.

Note [Quantified kind variables of a family pattern]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider   type family KindFam (p :: k1) (q :: k1)
           data T :: Maybe k1 -> k2 -> *
           type instance KindFam (a :: Maybe k) b = T a b -> Int
The HsBSig for the family patterns will be ([k], [a])

Then in the family instance we want to
  * Bring into scope [ "k" -> k:*, "a" -> a:k ]
  * Kind-check the RHS
  * Quantify the type instance over k and k', as well as a,b, thus
       type instance [k, k', a:Maybe k, b:k']
                     KindFam (Maybe k) k' a b = T k k' a b -> Int

Notice that in the third step we quantify over all the visibly-mentioned
type variables (a,b), but also over the implicitly mentioned kind variables
(k, k').  In this case one is bound explicitly but often there will be
none. The role of the kind signature (a :: Maybe k) is to add a constraint
that 'a' must have that kind, and to bring 'k' into scope.



************************************************************************
*                                                                      *
               Data types
*                                                                      *
************************************************************************
-}

dataDeclChecks :: Name -> NewOrData
               -> LHsContext GhcRn -> [LConDecl GhcRn]
               -> TcM Bool
dataDeclChecks :: Name
-> NewOrData
-> GenLocated SrcSpan (HsContext GhcRn)
-> [LConDecl GhcRn]
-> TcRnIf TcGblEnv TcLclEnv Bool
dataDeclChecks Name
tc_name NewOrData
new_or_data (L SrcSpan
_ HsContext GhcRn
stupid_theta) [LConDecl GhcRn]
cons
  = do {   -- Check that we don't use GADT syntax in H98 world
         Bool
gadtSyntax_ok <- Extension -> TcRnIf TcGblEnv TcLclEnv Bool
forall gbl lcl. Extension -> TcRnIf gbl lcl Bool
xoptM Extension
LangExt.GADTSyntax
       ; let gadt_syntax :: Bool
gadt_syntax = [LConDecl GhcRn] -> Bool
forall a. [LConDecl a] -> Bool
consUseGadtSyntax [LConDecl GhcRn]
cons
       ; Bool -> SDoc -> TcRn ()
checkTc (Bool
gadtSyntax_ok Bool -> Bool -> Bool
|| Bool -> Bool
not Bool
gadt_syntax) (Name -> SDoc
badGadtDecl Name
tc_name)

           -- Check that the stupid theta is empty for a GADT-style declaration
       ; Bool -> SDoc -> TcRn ()
checkTc (HsContext GhcRn -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null HsContext GhcRn
stupid_theta Bool -> Bool -> Bool
|| Bool -> Bool
not Bool
gadt_syntax) (Name -> SDoc
badStupidTheta Name
tc_name)

         -- Check that a newtype has exactly one constructor
         -- Do this before checking for empty data decls, so that
         -- we don't suggest -XEmptyDataDecls for newtypes
       ; Bool -> SDoc -> TcRn ()
checkTc (NewOrData
new_or_data NewOrData -> NewOrData -> Bool
forall a. Eq a => a -> a -> Bool
== NewOrData
DataType Bool -> Bool -> Bool
|| [LConDecl GhcRn] -> Bool
forall a. [a] -> Bool
isSingleton [LConDecl GhcRn]
cons)
                (Name -> Int -> SDoc
newtypeConError Name
tc_name ([LConDecl GhcRn] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length [LConDecl GhcRn]
cons))

         -- Check that there's at least one condecl,
         -- or else we're reading an hs-boot file, or -XEmptyDataDecls
       ; Bool
empty_data_decls <- Extension -> TcRnIf TcGblEnv TcLclEnv Bool
forall gbl lcl. Extension -> TcRnIf gbl lcl Bool
xoptM Extension
LangExt.EmptyDataDecls
       ; Bool
is_boot <- TcRnIf TcGblEnv TcLclEnv Bool
tcIsHsBootOrSig  -- Are we compiling an hs-boot file?
       ; Bool -> SDoc -> TcRn ()
checkTc (Bool -> Bool
not ([LConDecl GhcRn] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [LConDecl GhcRn]
cons) Bool -> Bool -> Bool
|| Bool
empty_data_decls Bool -> Bool -> Bool
|| Bool
is_boot)
                 (Name -> SDoc
emptyConDeclsErr Name
tc_name)
       ; Bool -> TcRnIf TcGblEnv TcLclEnv Bool
forall (m :: * -> *) a. Monad m => a -> m a
return Bool
gadt_syntax }


-----------------------------------
consUseGadtSyntax :: [LConDecl a] -> Bool
consUseGadtSyntax :: [LConDecl a] -> Bool
consUseGadtSyntax (L SrcSpan
_ (ConDeclGADT {}) : [LConDecl a]
_) = Bool
True
consUseGadtSyntax [LConDecl a]
_                          = Bool
False
                 -- All constructors have same shape

-----------------------------------
tcConDecls :: KnotTied TyCon -> NewOrData
           -> [TyConBinder] -> TcKind   -- binders and result kind of tycon
           -> KnotTied Type -> [LConDecl GhcRn] -> TcM [DataCon]
tcConDecls :: TyCon
-> NewOrData
-> [TyConBinder]
-> Kind
-> Kind
-> [LConDecl GhcRn]
-> TcM [DataCon]
tcConDecls TyCon
rep_tycon NewOrData
new_or_data [TyConBinder]
tmpl_bndrs Kind
res_kind Kind
res_tmpl
  = (LConDecl GhcRn -> TcM [DataCon])
-> [LConDecl GhcRn] -> TcM [DataCon]
forall (m :: * -> *) a b. Monad m => (a -> m [b]) -> [a] -> m [b]
concatMapM ((LConDecl GhcRn -> TcM [DataCon])
 -> [LConDecl GhcRn] -> TcM [DataCon])
-> (LConDecl GhcRn -> TcM [DataCon])
-> [LConDecl GhcRn]
-> TcM [DataCon]
forall a b. (a -> b) -> a -> b
$ (SrcSpanLess (LConDecl GhcRn) -> TcM [DataCon])
-> LConDecl GhcRn -> TcM [DataCon]
forall a b. HasSrcSpan a => (SrcSpanLess a -> TcM b) -> a -> TcM b
addLocM ((SrcSpanLess (LConDecl GhcRn) -> TcM [DataCon])
 -> LConDecl GhcRn -> TcM [DataCon])
-> (SrcSpanLess (LConDecl GhcRn) -> TcM [DataCon])
-> LConDecl GhcRn
-> TcM [DataCon]
forall a b. (a -> b) -> a -> b
$
    TyCon
-> NameEnv Int
-> [TyConBinder]
-> Kind
-> Kind
-> NewOrData
-> ConDecl GhcRn
-> TcM [DataCon]
tcConDecl TyCon
rep_tycon (TyCon -> NameEnv Int
mkTyConTagMap TyCon
rep_tycon)
              [TyConBinder]
tmpl_bndrs Kind
res_kind Kind
res_tmpl NewOrData
new_or_data
    -- It's important that we pay for tag allocation here, once per TyCon,
    -- See Note [Constructor tag allocation], fixes #14657

tcConDecl :: KnotTied TyCon          -- Representation tycon. Knot-tied!
          -> NameEnv ConTag
          -> [TyConBinder] -> TcKind   -- tycon binders and result kind
          -> KnotTied Type
                 -- Return type template (T tys), where T is the family TyCon
          -> NewOrData
          -> ConDecl GhcRn
          -> TcM [DataCon]

tcConDecl :: TyCon
-> NameEnv Int
-> [TyConBinder]
-> Kind
-> Kind
-> NewOrData
-> ConDecl GhcRn
-> TcM [DataCon]
tcConDecl TyCon
rep_tycon NameEnv Int
tag_map [TyConBinder]
tmpl_bndrs Kind
res_kind Kind
res_tmpl NewOrData
new_or_data
          (ConDeclH98 { con_name :: forall pass. ConDecl pass -> Located (IdP pass)
con_name = GenLocated SrcSpan (IdP GhcRn)
name
                      , con_ex_tvs :: forall pass. ConDecl pass -> [LHsTyVarBndr pass]
con_ex_tvs = [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
explicit_tkv_nms
                      , con_mb_cxt :: forall pass. ConDecl pass -> Maybe (LHsContext pass)
con_mb_cxt = Maybe (GenLocated SrcSpan (HsContext GhcRn))
hs_ctxt
                      , con_args :: forall pass. ConDecl pass -> HsConDeclDetails pass
con_args = HsConDeclDetails GhcRn
hs_args })
  = SDoc -> TcM [DataCon] -> TcM [DataCon]
forall a. SDoc -> TcM a -> TcM a
addErrCtxt ([GenLocated SrcSpan Name] -> SDoc
dataConCtxtName [GenLocated SrcSpan Name
GenLocated SrcSpan (IdP GhcRn)
name]) (TcM [DataCon] -> TcM [DataCon]) -> TcM [DataCon] -> TcM [DataCon]
forall a b. (a -> b) -> a -> b
$
    do { -- NB: the tyvars from the declaration header are in scope

         -- Get hold of the existential type variables
         -- e.g. data T a = forall k (b::k) f. MkT a (f b)
         -- Here tmpl_bndrs = {a}
         --      hs_qvars = HsQTvs { hsq_implicit = {k}
         --                        , hsq_explicit = {f,b} }

       ; String -> SDoc -> TcRn ()
traceTc String
"tcConDecl 1" ([SDoc] -> SDoc
vcat [ GenLocated SrcSpan Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr GenLocated SrcSpan Name
GenLocated SrcSpan (IdP GhcRn)
name, [GenLocated SrcSpan (HsTyVarBndr GhcRn)] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
explicit_tkv_nms ])

       ; ([TcTyCoVar]
exp_tvs, ([Kind]
ctxt, [Kind]
arg_tys, [FieldLabel]
field_lbls, [HsSrcBang]
stricts))
           <- TcM ([TcTyCoVar], ([Kind], [Kind], [FieldLabel], [HsSrcBang]))
-> TcM ([TcTyCoVar], ([Kind], [Kind], [FieldLabel], [HsSrcBang]))
forall r. TcM r -> TcM r
pushTcLevelM_                             (TcM ([TcTyCoVar], ([Kind], [Kind], [FieldLabel], [HsSrcBang]))
 -> TcM ([TcTyCoVar], ([Kind], [Kind], [FieldLabel], [HsSrcBang])))
-> TcM ([TcTyCoVar], ([Kind], [Kind], [FieldLabel], [HsSrcBang]))
-> TcM ([TcTyCoVar], ([Kind], [Kind], [FieldLabel], [HsSrcBang]))
forall a b. (a -> b) -> a -> b
$
              TcM ([TcTyCoVar], ([Kind], [Kind], [FieldLabel], [HsSrcBang]))
-> TcM ([TcTyCoVar], ([Kind], [Kind], [FieldLabel], [HsSrcBang]))
forall r. TcM r -> TcM r
solveEqualities                           (TcM ([TcTyCoVar], ([Kind], [Kind], [FieldLabel], [HsSrcBang]))
 -> TcM ([TcTyCoVar], ([Kind], [Kind], [FieldLabel], [HsSrcBang])))
-> TcM ([TcTyCoVar], ([Kind], [Kind], [FieldLabel], [HsSrcBang]))
-> TcM ([TcTyCoVar], ([Kind], [Kind], [FieldLabel], [HsSrcBang]))
forall a b. (a -> b) -> a -> b
$
              [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
-> TcM ([Kind], [Kind], [FieldLabel], [HsSrcBang])
-> TcM ([TcTyCoVar], ([Kind], [Kind], [FieldLabel], [HsSrcBang]))
forall a.
[GenLocated SrcSpan (HsTyVarBndr GhcRn)]
-> TcM a -> TcM ([TcTyCoVar], a)
bindExplicitTKBndrs_Skol [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
explicit_tkv_nms (TcM ([Kind], [Kind], [FieldLabel], [HsSrcBang])
 -> TcM ([TcTyCoVar], ([Kind], [Kind], [FieldLabel], [HsSrcBang])))
-> TcM ([Kind], [Kind], [FieldLabel], [HsSrcBang])
-> TcM ([TcTyCoVar], ([Kind], [Kind], [FieldLabel], [HsSrcBang]))
forall a b. (a -> b) -> a -> b
$
              do { [Kind]
ctxt <- Maybe (GenLocated SrcSpan (HsContext GhcRn)) -> TcM [Kind]
tcHsMbContext Maybe (GenLocated SrcSpan (HsContext GhcRn))
hs_ctxt
                 ; [(Kind, HsSrcBang)]
btys <- HsConDeclDetails GhcRn -> TcM [(Kind, HsSrcBang)]
tcConArgs HsConDeclDetails GhcRn
hs_args
                 ; [FieldLabel]
field_lbls <- Name -> RnM [FieldLabel]
lookupConstructorFields (GenLocated SrcSpan Name -> SrcSpanLess (GenLocated SrcSpan Name)
forall a. HasSrcSpan a => a -> SrcSpanLess a
unLoc GenLocated SrcSpan Name
GenLocated SrcSpan (IdP GhcRn)
name)
                 ; let ([Kind]
arg_tys, [HsSrcBang]
stricts) = [(Kind, HsSrcBang)] -> ([Kind], [HsSrcBang])
forall a b. [(a, b)] -> ([a], [b])
unzip [(Kind, HsSrcBang)]
btys
                 ; DynFlags
dflags <- IOEnv (Env TcGblEnv TcLclEnv) DynFlags
forall (m :: * -> *). HasDynFlags m => m DynFlags
getDynFlags
                 ; [Kind]
final_arg_tys <-
                     DynFlags
-> NewOrData -> HsContext GhcRn -> [Kind] -> Kind -> TcM [Kind]
unifyNewtypeKind DynFlags
dflags NewOrData
new_or_data
                                      (HsConDeclDetails GhcRn -> HsContext GhcRn
forall pass. HsConDeclDetails pass -> [LBangType pass]
hsConDeclArgTys HsConDeclDetails GhcRn
hs_args)
                                      [Kind]
arg_tys Kind
res_kind
                 ; ([Kind], [Kind], [FieldLabel], [HsSrcBang])
-> TcM ([Kind], [Kind], [FieldLabel], [HsSrcBang])
forall (m :: * -> *) a. Monad m => a -> m a
return ([Kind]
ctxt, [Kind]
final_arg_tys, [FieldLabel]
field_lbls, [HsSrcBang]
stricts)
                 }

         -- exp_tvs have explicit, user-written binding sites
         -- the kvs below are those kind variables entirely unmentioned by the user
         --   and discovered only by generalization

       ; [TcTyCoVar]
kvs <- Kind -> TcM [TcTyCoVar]
kindGeneralizeAll ([TcTyCoVar] -> Kind -> Kind
mkSpecForAllTys ([TyConBinder] -> [TcTyCoVar]
forall tv argf. [VarBndr tv argf] -> [tv]
binderVars [TyConBinder]
tmpl_bndrs) (Kind -> Kind) -> Kind -> Kind
forall a b. (a -> b) -> a -> b
$
                                   [TcTyCoVar] -> Kind -> Kind
mkSpecForAllTys [TcTyCoVar]
exp_tvs (Kind -> Kind) -> Kind -> Kind
forall a b. (a -> b) -> a -> b
$
                                   [Kind] -> Kind -> Kind
mkPhiTy [Kind]
ctxt (Kind -> Kind) -> Kind -> Kind
forall a b. (a -> b) -> a -> b
$
                                   [Kind] -> Kind -> Kind
mkVisFunTys [Kind]
arg_tys (Kind -> Kind) -> Kind -> Kind
forall a b. (a -> b) -> a -> b
$
                                   Kind
unitTy)
                 -- That type is a lie, of course. (It shouldn't end in ()!)
                 -- And we could construct a proper result type from the info
                 -- at hand. But the result would mention only the tmpl_tvs,
                 -- and so it just creates more work to do it right. Really,
                 -- we're only doing this to find the right kind variables to
                 -- quantify over, and this type is fine for that purpose.

             -- Zonk to Types
       ; (ZonkEnv
ze, [TcTyCoVar]
qkvs)      <- [TcTyCoVar] -> TcM (ZonkEnv, [TcTyCoVar])
zonkTyBndrs [TcTyCoVar]
kvs
       ; (ZonkEnv
ze, [TcTyCoVar]
user_qtvs) <- ZonkEnv -> [TcTyCoVar] -> TcM (ZonkEnv, [TcTyCoVar])
zonkTyBndrsX ZonkEnv
ze [TcTyCoVar]
exp_tvs
       ; [Kind]
arg_tys         <- ZonkEnv -> [Kind] -> TcM [Kind]
zonkTcTypesToTypesX ZonkEnv
ze [Kind]
arg_tys
       ; [Kind]
ctxt            <- ZonkEnv -> [Kind] -> TcM [Kind]
zonkTcTypesToTypesX ZonkEnv
ze [Kind]
ctxt

       ; FamInstEnvs
fam_envs <- TcM FamInstEnvs
tcGetFamInstEnvs

       -- Can't print univ_tvs, arg_tys etc, because we are inside the knot here
       ; String -> SDoc -> TcRn ()
traceTc String
"tcConDecl 2" (GenLocated SrcSpan Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr GenLocated SrcSpan Name
GenLocated SrcSpan (IdP GhcRn)
name SDoc -> SDoc -> SDoc
$$ [FieldLabel] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [FieldLabel]
field_lbls)
       ; let
           univ_tvbs :: [TyVarBinder]
univ_tvbs = [TyConBinder] -> [TyVarBinder]
tyConTyVarBinders [TyConBinder]
tmpl_bndrs
           univ_tvs :: [TcTyCoVar]
univ_tvs  = [TyVarBinder] -> [TcTyCoVar]
forall tv argf. [VarBndr tv argf] -> [tv]
binderVars [TyVarBinder]
univ_tvbs
           ex_tvbs :: [TyVarBinder]
ex_tvbs   = ArgFlag -> [TcTyCoVar] -> [TyVarBinder]
mkTyVarBinders ArgFlag
Inferred [TcTyCoVar]
qkvs [TyVarBinder] -> [TyVarBinder] -> [TyVarBinder]
forall a. [a] -> [a] -> [a]
++
                       ArgFlag -> [TcTyCoVar] -> [TyVarBinder]
mkTyVarBinders ArgFlag
Specified [TcTyCoVar]
user_qtvs
           ex_tvs :: [TcTyCoVar]
ex_tvs    = [TcTyCoVar]
qkvs [TcTyCoVar] -> [TcTyCoVar] -> [TcTyCoVar]
forall a. [a] -> [a] -> [a]
++ [TcTyCoVar]
user_qtvs
           -- For H98 datatypes, the user-written tyvar binders are precisely
           -- the universals followed by the existentials.
           -- See Note [DataCon user type variable binders] in DataCon.
           user_tvbs :: [TyVarBinder]
user_tvbs = [TyVarBinder]
univ_tvbs [TyVarBinder] -> [TyVarBinder] -> [TyVarBinder]
forall a. [a] -> [a] -> [a]
++ [TyVarBinder]
ex_tvbs
           buildOneDataCon :: GenLocated SrcSpan Name -> IOEnv (Env TcGblEnv TcLclEnv) DataCon
buildOneDataCon (L SrcSpan
_ Name
name) = do
             { Bool
is_infix <- Name -> HsConDeclDetails GhcRn -> TcRnIf TcGblEnv TcLclEnv Bool
tcConIsInfixH98 Name
name HsConDeclDetails GhcRn
hs_args
             ; Name
rep_nm   <- Name -> TcRnIf TcGblEnv TcLclEnv Name
forall gbl lcl. Name -> TcRnIf gbl lcl Name
newTyConRepName Name
name

             ; FamInstEnvs
-> Name
-> Bool
-> Name
-> [HsSrcBang]
-> Maybe [HsImplBang]
-> [FieldLabel]
-> [TcTyCoVar]
-> [TcTyCoVar]
-> [TyVarBinder]
-> [EqSpec]
-> [Kind]
-> [Kind]
-> Kind
-> TyCon
-> NameEnv Int
-> IOEnv (Env TcGblEnv TcLclEnv) DataCon
forall m n.
FamInstEnvs
-> Name
-> Bool
-> Name
-> [HsSrcBang]
-> Maybe [HsImplBang]
-> [FieldLabel]
-> [TcTyCoVar]
-> [TcTyCoVar]
-> [TyVarBinder]
-> [EqSpec]
-> [Kind]
-> [Kind]
-> Kind
-> TyCon
-> NameEnv Int
-> TcRnIf m n DataCon
buildDataCon FamInstEnvs
fam_envs Name
name Bool
is_infix Name
rep_nm
                            [HsSrcBang]
stricts Maybe [HsImplBang]
forall a. Maybe a
Nothing [FieldLabel]
field_lbls
                            [TcTyCoVar]
univ_tvs [TcTyCoVar]
ex_tvs [TyVarBinder]
user_tvbs
                            [{- no eq_preds -}] [Kind]
ctxt [Kind]
arg_tys
                            Kind
res_tmpl TyCon
rep_tycon NameEnv Int
tag_map
                  -- NB:  we put data_tc, the type constructor gotten from the
                  --      constructor type signature into the data constructor;
                  --      that way checkValidDataCon can complain if it's wrong.
             }
       ; String -> SDoc -> TcRn ()
traceTc String
"tcConDecl 2" (GenLocated SrcSpan Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr GenLocated SrcSpan Name
GenLocated SrcSpan (IdP GhcRn)
name)
       ; (GenLocated SrcSpan Name -> IOEnv (Env TcGblEnv TcLclEnv) DataCon)
-> [GenLocated SrcSpan Name] -> TcM [DataCon]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM GenLocated SrcSpan Name -> IOEnv (Env TcGblEnv TcLclEnv) DataCon
buildOneDataCon [GenLocated SrcSpan Name
GenLocated SrcSpan (IdP GhcRn)
name]
       }

tcConDecl TyCon
rep_tycon NameEnv Int
tag_map [TyConBinder]
tmpl_bndrs Kind
_res_kind Kind
res_tmpl NewOrData
new_or_data
  -- NB: don't use res_kind here, as it's ill-scoped. Instead, we get
  -- the res_kind by typechecking the result type.
          (ConDeclGADT { con_names :: forall pass. ConDecl pass -> [Located (IdP pass)]
con_names = [GenLocated SrcSpan (IdP GhcRn)]
names
                       , con_qvars :: forall pass. ConDecl pass -> LHsQTyVars pass
con_qvars = LHsQTyVars GhcRn
qtvs
                       , con_mb_cxt :: forall pass. ConDecl pass -> Maybe (LHsContext pass)
con_mb_cxt = Maybe (GenLocated SrcSpan (HsContext GhcRn))
cxt, con_args :: forall pass. ConDecl pass -> HsConDeclDetails pass
con_args = HsConDeclDetails GhcRn
hs_args
                       , con_res_ty :: forall pass. ConDecl pass -> LHsType pass
con_res_ty = LHsKind GhcRn
hs_res_ty })
  | HsQTvs { hsq_ext :: forall pass. LHsQTyVars pass -> XHsQTvs pass
hsq_ext = XHsQTvs GhcRn
implicit_tkv_nms
           , hsq_explicit :: forall pass. LHsQTyVars pass -> [LHsTyVarBndr pass]
hsq_explicit = [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
explicit_tkv_nms } <- LHsQTyVars GhcRn
qtvs
  = SDoc -> TcM [DataCon] -> TcM [DataCon]
forall a. SDoc -> TcM a -> TcM a
addErrCtxt ([GenLocated SrcSpan Name] -> SDoc
dataConCtxtName [GenLocated SrcSpan Name]
[GenLocated SrcSpan (IdP GhcRn)]
names) (TcM [DataCon] -> TcM [DataCon]) -> TcM [DataCon] -> TcM [DataCon]
forall a b. (a -> b) -> a -> b
$
    do { String -> SDoc -> TcRn ()
traceTc String
"tcConDecl 1 gadt" ([GenLocated SrcSpan Name] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [GenLocated SrcSpan Name]
[GenLocated SrcSpan (IdP GhcRn)]
names)
       ; let (L SrcSpan
_ Name
name : [GenLocated SrcSpan Name]
_) = [GenLocated SrcSpan Name]
[GenLocated SrcSpan (IdP GhcRn)]
names

       ; ([TcTyCoVar]
imp_tvs, ([TcTyCoVar]
exp_tvs, ([Kind]
ctxt, [Kind]
arg_tys, Kind
res_ty, [FieldLabel]
field_lbls, [HsSrcBang]
stricts)))
           <- TcM
  ([TcTyCoVar],
   ([TcTyCoVar], ([Kind], [Kind], Kind, [FieldLabel], [HsSrcBang])))
-> TcM
     ([TcTyCoVar],
      ([TcTyCoVar], ([Kind], [Kind], Kind, [FieldLabel], [HsSrcBang])))
forall r. TcM r -> TcM r
pushTcLevelM_    (TcM
   ([TcTyCoVar],
    ([TcTyCoVar], ([Kind], [Kind], Kind, [FieldLabel], [HsSrcBang])))
 -> TcM
      ([TcTyCoVar],
       ([TcTyCoVar], ([Kind], [Kind], Kind, [FieldLabel], [HsSrcBang]))))
-> TcM
     ([TcTyCoVar],
      ([TcTyCoVar], ([Kind], [Kind], Kind, [FieldLabel], [HsSrcBang])))
-> TcM
     ([TcTyCoVar],
      ([TcTyCoVar], ([Kind], [Kind], Kind, [FieldLabel], [HsSrcBang])))
forall a b. (a -> b) -> a -> b
$  -- We are going to generalise
              TcM
  ([TcTyCoVar],
   ([TcTyCoVar], ([Kind], [Kind], Kind, [FieldLabel], [HsSrcBang])))
-> TcM
     ([TcTyCoVar],
      ([TcTyCoVar], ([Kind], [Kind], Kind, [FieldLabel], [HsSrcBang])))
forall r. TcM r -> TcM r
solveEqualities  (TcM
   ([TcTyCoVar],
    ([TcTyCoVar], ([Kind], [Kind], Kind, [FieldLabel], [HsSrcBang])))
 -> TcM
      ([TcTyCoVar],
       ([TcTyCoVar], ([Kind], [Kind], Kind, [FieldLabel], [HsSrcBang]))))
-> TcM
     ([TcTyCoVar],
      ([TcTyCoVar], ([Kind], [Kind], Kind, [FieldLabel], [HsSrcBang])))
-> TcM
     ([TcTyCoVar],
      ([TcTyCoVar], ([Kind], [Kind], Kind, [FieldLabel], [HsSrcBang])))
forall a b. (a -> b) -> a -> b
$  -- We won't get another crack, and we don't
                                  -- want an error cascade
              [Name]
-> TcM
     ([TcTyCoVar], ([Kind], [Kind], Kind, [FieldLabel], [HsSrcBang]))
-> TcM
     ([TcTyCoVar],
      ([TcTyCoVar], ([Kind], [Kind], Kind, [FieldLabel], [HsSrcBang])))
forall a. [Name] -> TcM a -> TcM ([TcTyCoVar], a)
bindImplicitTKBndrs_Skol [Name]
XHsQTvs GhcRn
implicit_tkv_nms (TcM
   ([TcTyCoVar], ([Kind], [Kind], Kind, [FieldLabel], [HsSrcBang]))
 -> TcM
      ([TcTyCoVar],
       ([TcTyCoVar], ([Kind], [Kind], Kind, [FieldLabel], [HsSrcBang]))))
-> TcM
     ([TcTyCoVar], ([Kind], [Kind], Kind, [FieldLabel], [HsSrcBang]))
-> TcM
     ([TcTyCoVar],
      ([TcTyCoVar], ([Kind], [Kind], Kind, [FieldLabel], [HsSrcBang])))
forall a b. (a -> b) -> a -> b
$
              [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
-> TcM ([Kind], [Kind], Kind, [FieldLabel], [HsSrcBang])
-> TcM
     ([TcTyCoVar], ([Kind], [Kind], Kind, [FieldLabel], [HsSrcBang]))
forall a.
[GenLocated SrcSpan (HsTyVarBndr GhcRn)]
-> TcM a -> TcM ([TcTyCoVar], a)
bindExplicitTKBndrs_Skol [GenLocated SrcSpan (HsTyVarBndr GhcRn)]
explicit_tkv_nms (TcM ([Kind], [Kind], Kind, [FieldLabel], [HsSrcBang])
 -> TcM
      ([TcTyCoVar], ([Kind], [Kind], Kind, [FieldLabel], [HsSrcBang])))
-> TcM ([Kind], [Kind], Kind, [FieldLabel], [HsSrcBang])
-> TcM
     ([TcTyCoVar], ([Kind], [Kind], Kind, [FieldLabel], [HsSrcBang]))
forall a b. (a -> b) -> a -> b
$
              do { [Kind]
ctxt <- Maybe (GenLocated SrcSpan (HsContext GhcRn)) -> TcM [Kind]
tcHsMbContext Maybe (GenLocated SrcSpan (HsContext GhcRn))
cxt
                 ; [(Kind, HsSrcBang)]
btys <- HsConDeclDetails GhcRn -> TcM [(Kind, HsSrcBang)]
tcConArgs HsConDeclDetails GhcRn
hs_args
                 ; let ([Kind]
arg_tys, [HsSrcBang]
stricts) = [(Kind, HsSrcBang)] -> ([Kind], [HsSrcBang])
forall a b. [(a, b)] -> ([a], [b])
unzip [(Kind, HsSrcBang)]
btys
                 ; Kind
res_ty <- LHsKind GhcRn -> TcM Kind
tcHsOpenType LHsKind GhcRn
hs_res_ty
                   -- See Note [Implementation of UnliftedNewtypes]
                 ; DynFlags
dflags <- IOEnv (Env TcGblEnv TcLclEnv) DynFlags
forall (m :: * -> *). HasDynFlags m => m DynFlags
getDynFlags
                 ; [Kind]
final_arg_tys <-
                     DynFlags
-> NewOrData -> HsContext GhcRn -> [Kind] -> Kind -> TcM [Kind]
unifyNewtypeKind DynFlags
dflags NewOrData
new_or_data
                                      (HsConDeclDetails GhcRn -> HsContext GhcRn
forall pass. HsConDeclDetails pass -> [LBangType pass]
hsConDeclArgTys HsConDeclDetails GhcRn
hs_args)
                                      [Kind]
arg_tys (HasDebugCallStack => Kind -> Kind
Kind -> Kind
typeKind Kind
res_ty)
                 ; [FieldLabel]
field_lbls <- Name -> RnM [FieldLabel]
lookupConstructorFields Name
name
                 ; ([Kind], [Kind], Kind, [FieldLabel], [HsSrcBang])
-> TcM ([Kind], [Kind], Kind, [FieldLabel], [HsSrcBang])
forall (m :: * -> *) a. Monad m => a -> m a
return ([Kind]
ctxt, [Kind]
final_arg_tys, Kind
res_ty, [FieldLabel]
field_lbls, [HsSrcBang]
stricts)
                 }
       ; [TcTyCoVar]
imp_tvs <- [TcTyCoVar] -> TcM [TcTyCoVar]
zonkAndScopedSort [TcTyCoVar]
imp_tvs
       ; let user_tvs :: [TcTyCoVar]
user_tvs = [TcTyCoVar]
imp_tvs [TcTyCoVar] -> [TcTyCoVar] -> [TcTyCoVar]
forall a. [a] -> [a] -> [a]
++ [TcTyCoVar]
exp_tvs

       ; [TcTyCoVar]
tkvs <- Kind -> TcM [TcTyCoVar]
kindGeneralizeAll ([TcTyCoVar] -> Kind -> Kind
mkSpecForAllTys [TcTyCoVar]
user_tvs (Kind -> Kind) -> Kind -> Kind
forall a b. (a -> b) -> a -> b
$
                                    [Kind] -> Kind -> Kind
mkPhiTy [Kind]
ctxt (Kind -> Kind) -> Kind -> Kind
forall a b. (a -> b) -> a -> b
$
                                    [Kind] -> Kind -> Kind
mkVisFunTys [Kind]
arg_tys (Kind -> Kind) -> Kind -> Kind
forall a b. (a -> b) -> a -> b
$
                                    Kind
res_ty)

             -- Zonk to Types
       ; (ZonkEnv
ze, [TcTyCoVar]
tkvs)     <- [TcTyCoVar] -> TcM (ZonkEnv, [TcTyCoVar])
zonkTyBndrs [TcTyCoVar]
tkvs
       ; (ZonkEnv
ze, [TcTyCoVar]
user_tvs) <- ZonkEnv -> [TcTyCoVar] -> TcM (ZonkEnv, [TcTyCoVar])
zonkTyBndrsX ZonkEnv
ze [TcTyCoVar]
user_tvs
       ; [Kind]
arg_tys <- ZonkEnv -> [Kind] -> TcM [Kind]
zonkTcTypesToTypesX ZonkEnv
ze [Kind]
arg_tys
       ; [Kind]
ctxt    <- ZonkEnv -> [Kind] -> TcM [Kind]
zonkTcTypesToTypesX ZonkEnv
ze [Kind]
ctxt
       ; Kind
res_ty  <- ZonkEnv -> Kind -> TcM Kind
zonkTcTypeToTypeX   ZonkEnv
ze Kind
res_ty

       ; let ([TcTyCoVar]
univ_tvs, [TcTyCoVar]
ex_tvs, [TcTyCoVar]
tkvs', [TcTyCoVar]
user_tvs', [EqSpec]
eq_preds, TCvSubst
arg_subst)
               = [TyConBinder]
-> Kind
-> [TcTyCoVar]
-> [TcTyCoVar]
-> Kind
-> ([TcTyCoVar], [TcTyCoVar], [TcTyCoVar], [TcTyCoVar], [EqSpec],
    TCvSubst)
rejigConRes [TyConBinder]
tmpl_bndrs Kind
res_tmpl [TcTyCoVar]
tkvs [TcTyCoVar]
user_tvs Kind
res_ty
             -- NB: this is a /lazy/ binding, so we pass six thunks to
             --     buildDataCon without yet forcing the guards in rejigConRes
             -- See Note [Checking GADT return types]

             -- Compute the user-written tyvar binders. These have the same
             -- tyvars as univ_tvs/ex_tvs, but perhaps in a different order.
             -- See Note [DataCon user type variable binders] in DataCon.
             tkv_bndrs :: [TyVarBinder]
tkv_bndrs      = ArgFlag -> [TcTyCoVar] -> [TyVarBinder]
mkTyVarBinders ArgFlag
Inferred  [TcTyCoVar]
tkvs'
             user_tv_bndrs :: [TyVarBinder]
user_tv_bndrs  = ArgFlag -> [TcTyCoVar] -> [TyVarBinder]
mkTyVarBinders ArgFlag
Specified [TcTyCoVar]
user_tvs'
             all_user_bndrs :: [TyVarBinder]
all_user_bndrs = [TyVarBinder]
tkv_bndrs [TyVarBinder] -> [TyVarBinder] -> [TyVarBinder]
forall a. [a] -> [a] -> [a]
++ [TyVarBinder]
user_tv_bndrs

             ctxt' :: [Kind]
ctxt'      = HasCallStack => TCvSubst -> [Kind] -> [Kind]
TCvSubst -> [Kind] -> [Kind]
substTys TCvSubst
arg_subst [Kind]
ctxt
             arg_tys' :: [Kind]
arg_tys'   = HasCallStack => TCvSubst -> [Kind] -> [Kind]
TCvSubst -> [Kind] -> [Kind]
substTys TCvSubst
arg_subst [Kind]
arg_tys
             res_ty' :: Kind
res_ty'    = HasCallStack => TCvSubst -> Kind -> Kind
TCvSubst -> Kind -> Kind
substTy  TCvSubst
arg_subst Kind
res_ty


       ; FamInstEnvs
fam_envs <- TcM FamInstEnvs
tcGetFamInstEnvs

       -- Can't print univ_tvs, arg_tys etc, because we are inside the knot here
       ; String -> SDoc -> TcRn ()
traceTc String
"tcConDecl 2" ([GenLocated SrcSpan Name] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [GenLocated SrcSpan Name]
[GenLocated SrcSpan (IdP GhcRn)]
names SDoc -> SDoc -> SDoc
$$ [FieldLabel] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [FieldLabel]
field_lbls)
       ; let
           buildOneDataCon :: GenLocated SrcSpan Name -> IOEnv (Env TcGblEnv TcLclEnv) DataCon
buildOneDataCon (L SrcSpan
_ Name
name) = do
             { Bool
is_infix <- Name -> HsConDeclDetails GhcRn -> TcRnIf TcGblEnv TcLclEnv Bool
tcConIsInfixGADT Name
name HsConDeclDetails GhcRn
hs_args
             ; Name
rep_nm   <- Name -> TcRnIf TcGblEnv TcLclEnv Name
forall gbl lcl. Name -> TcRnIf gbl lcl Name
newTyConRepName Name
name

             ; FamInstEnvs
-> Name
-> Bool
-> Name
-> [HsSrcBang]
-> Maybe [HsImplBang]
-> [FieldLabel]
-> [TcTyCoVar]
-> [TcTyCoVar]
-> [TyVarBinder]
-> [EqSpec]
-> [Kind]
-> [Kind]
-> Kind
-> TyCon
-> NameEnv Int
-> IOEnv (Env TcGblEnv TcLclEnv) DataCon
forall m n.
FamInstEnvs
-> Name
-> Bool
-> Name
-> [HsSrcBang]
-> Maybe [HsImplBang]
-> [FieldLabel]
-> [TcTyCoVar]
-> [TcTyCoVar]
-> [TyVarBinder]
-> [EqSpec]
-> [Kind]
-> [Kind]
-> Kind
-> TyCon
-> NameEnv Int
-> TcRnIf m n DataCon
buildDataCon FamInstEnvs
fam_envs Name
name Bool
is_infix
                            Name
rep_nm
                            [HsSrcBang]
stricts Maybe [HsImplBang]
forall a. Maybe a
Nothing [FieldLabel]
field_lbls
                            [TcTyCoVar]
univ_tvs [TcTyCoVar]
ex_tvs [TyVarBinder]
all_user_bndrs [EqSpec]
eq_preds
                            [Kind]
ctxt' [Kind]
arg_tys' Kind
res_ty' TyCon
rep_tycon NameEnv Int
tag_map
                  -- NB:  we put data_tc, the type constructor gotten from the
                  --      constructor type signature into the data constructor;
                  --      that way checkValidDataCon can complain if it's wrong.
             }
       ; String -> SDoc -> TcRn ()
traceTc String
"tcConDecl 2" ([GenLocated SrcSpan Name] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [GenLocated SrcSpan Name]
[GenLocated SrcSpan (IdP GhcRn)]
names)
       ; (GenLocated SrcSpan Name -> IOEnv (Env TcGblEnv TcLclEnv) DataCon)
-> [GenLocated SrcSpan Name] -> TcM [DataCon]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM GenLocated SrcSpan Name -> IOEnv (Env TcGblEnv TcLclEnv) DataCon
buildOneDataCon [GenLocated SrcSpan Name]
[GenLocated SrcSpan (IdP GhcRn)]
names
       }
tcConDecl TyCon
_ NameEnv Int
_ [TyConBinder]
_ Kind
_ Kind
_ NewOrData
_ (ConDeclGADT XConDeclGADT GhcRn
_ [GenLocated SrcSpan (IdP GhcRn)]
_ Located Bool
_ (XLHsQTyVars XXLHsQTyVars GhcRn
nec) Maybe (GenLocated SrcSpan (HsContext GhcRn))
_ HsConDeclDetails GhcRn
_ LHsKind GhcRn
_ Maybe LHsDocString
_)
  = NoExtCon -> TcM [DataCon]
forall a. NoExtCon -> a
noExtCon XXLHsQTyVars GhcRn
NoExtCon
nec
tcConDecl TyCon
_ NameEnv Int
_ [TyConBinder]
_ Kind
_ Kind
_ NewOrData
_ (XConDecl XXConDecl GhcRn
nec) = NoExtCon -> TcM [DataCon]
forall a. NoExtCon -> a
noExtCon XXConDecl GhcRn
NoExtCon
nec

tcConIsInfixH98 :: Name
             -> HsConDetails (LHsType GhcRn) (Located [LConDeclField GhcRn])
             -> TcM Bool
tcConIsInfixH98 :: Name -> HsConDeclDetails GhcRn -> TcRnIf TcGblEnv TcLclEnv Bool
tcConIsInfixH98 Name
_   HsConDeclDetails GhcRn
details
  = case HsConDeclDetails GhcRn
details of
           InfixCon {}  -> Bool -> TcRnIf TcGblEnv TcLclEnv Bool
forall (m :: * -> *) a. Monad m => a -> m a
return Bool
True
           HsConDeclDetails GhcRn
_            -> Bool -> TcRnIf TcGblEnv TcLclEnv Bool
forall (m :: * -> *) a. Monad m => a -> m a
return Bool
False

tcConIsInfixGADT :: Name
             -> HsConDetails (LHsType GhcRn) (Located [LConDeclField GhcRn])
             -> TcM Bool
tcConIsInfixGADT :: Name -> HsConDeclDetails GhcRn -> TcRnIf TcGblEnv TcLclEnv Bool
tcConIsInfixGADT Name
con HsConDeclDetails GhcRn
details
  = case HsConDeclDetails GhcRn
details of
           InfixCon {}  -> Bool -> TcRnIf TcGblEnv TcLclEnv Bool
forall (m :: * -> *) a. Monad m => a -> m a
return Bool
True
           RecCon {}    -> Bool -> TcRnIf TcGblEnv TcLclEnv Bool
forall (m :: * -> *) a. Monad m => a -> m a
return Bool
False
           PrefixCon HsContext GhcRn
arg_tys           -- See Note [Infix GADT constructors]
               | OccName -> Bool
isSymOcc (Name -> OccName
forall a. NamedThing a => a -> OccName
getOccName Name
con)
               , [LHsKind GhcRn
_ty1,LHsKind GhcRn
_ty2] <- HsContext GhcRn
arg_tys
                  -> do { FixityEnv
fix_env <- TcRn FixityEnv
getFixityEnv
                        ; Bool -> TcRnIf TcGblEnv TcLclEnv Bool
forall (m :: * -> *) a. Monad m => a -> m a
return (Name
con Name -> FixityEnv -> Bool
forall a. Name -> NameEnv a -> Bool
`elemNameEnv` FixityEnv
fix_env) }
               | Bool
otherwise -> Bool -> TcRnIf TcGblEnv TcLclEnv Bool
forall (m :: * -> *) a. Monad m => a -> m a
return Bool
False

tcConArgs :: HsConDeclDetails GhcRn
          -> TcM [(TcType, HsSrcBang)]
tcConArgs :: HsConDeclDetails GhcRn -> TcM [(Kind, HsSrcBang)]
tcConArgs (PrefixCon HsContext GhcRn
btys)
  = (LHsKind GhcRn -> IOEnv (Env TcGblEnv TcLclEnv) (Kind, HsSrcBang))
-> HsContext GhcRn -> TcM [(Kind, HsSrcBang)]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM LHsKind GhcRn -> IOEnv (Env TcGblEnv TcLclEnv) (Kind, HsSrcBang)
tcConArg HsContext GhcRn
btys
tcConArgs (InfixCon LHsKind GhcRn
bty1 LHsKind GhcRn
bty2)
  = do { (Kind, HsSrcBang)
bty1' <- LHsKind GhcRn -> IOEnv (Env TcGblEnv TcLclEnv) (Kind, HsSrcBang)
tcConArg LHsKind GhcRn
bty1
       ; (Kind, HsSrcBang)
bty2' <- LHsKind GhcRn -> IOEnv (Env TcGblEnv TcLclEnv) (Kind, HsSrcBang)
tcConArg LHsKind GhcRn
bty2
       ; [(Kind, HsSrcBang)] -> TcM [(Kind, HsSrcBang)]
forall (m :: * -> *) a. Monad m => a -> m a
return [(Kind, HsSrcBang)
bty1', (Kind, HsSrcBang)
bty2'] }
tcConArgs (RecCon Located [LConDeclField GhcRn]
fields)
  = (LHsKind GhcRn -> IOEnv (Env TcGblEnv TcLclEnv) (Kind, HsSrcBang))
-> HsContext GhcRn -> TcM [(Kind, HsSrcBang)]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM LHsKind GhcRn -> IOEnv (Env TcGblEnv TcLclEnv) (Kind, HsSrcBang)
tcConArg HsContext GhcRn
btys
  where
    -- We need a one-to-one mapping from field_names to btys
    combined :: [([LFieldOcc GhcRn], LHsKind GhcRn)]
combined = (LConDeclField GhcRn -> ([LFieldOcc GhcRn], LHsKind GhcRn))
-> [LConDeclField GhcRn] -> [([LFieldOcc GhcRn], LHsKind GhcRn)]
forall a b. (a -> b) -> [a] -> [b]
map (\(L SrcSpan
_ ConDeclField GhcRn
f) -> (ConDeclField GhcRn -> [LFieldOcc GhcRn]
forall pass. ConDeclField pass -> [LFieldOcc pass]
cd_fld_names ConDeclField GhcRn
f,ConDeclField GhcRn -> LHsKind GhcRn
forall pass. ConDeclField pass -> LBangType pass
cd_fld_type ConDeclField GhcRn
f))
                   (Located [LConDeclField GhcRn]
-> SrcSpanLess (Located [LConDeclField GhcRn])
forall a. HasSrcSpan a => a -> SrcSpanLess a
unLoc Located [LConDeclField GhcRn]
fields)
    explode :: ([a], b) -> [(a, b)]
explode ([a]
ns,b
ty) = [a] -> [b] -> [(a, b)]
forall a b. [a] -> [b] -> [(a, b)]
zip [a]
ns (b -> [b]
forall a. a -> [a]
repeat b
ty)
    exploded :: [(LFieldOcc GhcRn, LHsKind GhcRn)]
exploded = (([LFieldOcc GhcRn], LHsKind GhcRn)
 -> [(LFieldOcc GhcRn, LHsKind GhcRn)])
-> [([LFieldOcc GhcRn], LHsKind GhcRn)]
-> [(LFieldOcc GhcRn, LHsKind GhcRn)]
forall (t :: * -> *) a b. Foldable t => (a -> [b]) -> t a -> [b]
concatMap ([LFieldOcc GhcRn], LHsKind GhcRn)
-> [(LFieldOcc GhcRn, LHsKind GhcRn)]
forall a b. ([a], b) -> [(a, b)]
explode [([LFieldOcc GhcRn], LHsKind GhcRn)]
combined
    ([LFieldOcc GhcRn]
_,HsContext GhcRn
btys) = [(LFieldOcc GhcRn, LHsKind GhcRn)]
-> ([LFieldOcc GhcRn], HsContext GhcRn)
forall a b. [(a, b)] -> ([a], [b])
unzip [(LFieldOcc GhcRn, LHsKind GhcRn)]
exploded


tcConArg :: LHsType GhcRn -> TcM (TcType, HsSrcBang)
tcConArg :: LHsKind GhcRn -> IOEnv (Env TcGblEnv TcLclEnv) (Kind, HsSrcBang)
tcConArg LHsKind GhcRn
bty
  = do  { String -> SDoc -> TcRn ()
traceTc String
"tcConArg 1" (LHsKind GhcRn -> SDoc
forall a. Outputable a => a -> SDoc
ppr LHsKind GhcRn
bty)
        ; Kind
arg_ty <- LHsKind GhcRn -> TcM Kind
tcHsOpenType (LHsKind GhcRn -> LHsKind GhcRn
forall a. LHsType a -> LHsType a
getBangType LHsKind GhcRn
bty)
             -- Newtypes can't have unboxed types, but we check
             -- that in checkValidDataCon; this tcConArg stuff
             -- doesn't happen for GADT-style declarations
        ; String -> SDoc -> TcRn ()
traceTc String
"tcConArg 2" (LHsKind GhcRn -> SDoc
forall a. Outputable a => a -> SDoc
ppr LHsKind GhcRn
bty)
        ; (Kind, HsSrcBang)
-> IOEnv (Env TcGblEnv TcLclEnv) (Kind, HsSrcBang)
forall (m :: * -> *) a. Monad m => a -> m a
return (Kind
arg_ty, LHsKind GhcRn -> HsSrcBang
forall a. LHsType a -> HsSrcBang
getBangStrictness LHsKind GhcRn
bty) }

{-
Note [Infix GADT constructors]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We do not currently have syntax to declare an infix constructor in GADT syntax,
but it makes a (small) difference to the Show instance.  So as a slightly
ad-hoc solution, we regard a GADT data constructor as infix if
  a) it is an operator symbol
  b) it has two arguments
  c) there is a fixity declaration for it
For example:
   infix 6 (:--:)
   data T a where
     (:--:) :: t1 -> t2 -> T Int


Note [Checking GADT return types]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
There is a delicacy around checking the return types of a datacon. The
central problem is dealing with a declaration like

  data T a where
    MkT :: T a -> Q a

Note that the return type of MkT is totally bogus. When creating the T
tycon, we also need to create the MkT datacon, which must have a "rejigged"
return type. That is, the MkT datacon's type must be transformed to have
a uniform return type with explicit coercions for GADT-like type parameters.
This rejigging is what rejigConRes does. The problem is, though, that checking
that the return type is appropriate is much easier when done over *Type*,
not *HsType*, and doing a call to tcMatchTy will loop because T isn't fully
defined yet.

So, we want to make rejigConRes lazy and then check the validity of
the return type in checkValidDataCon.  To do this we /always/ return a
6-tuple from rejigConRes (so that we can compute the return type from it, which
checkValidDataCon needs), but the first three fields may be bogus if
the return type isn't valid (the last equation for rejigConRes).

This is better than an earlier solution which reduced the number of
errors reported in one pass.  See #7175, and #10836.
-}

-- Example
--   data instance T (b,c) where
--      TI :: forall e. e -> T (e,e)
--
-- The representation tycon looks like this:
--   data :R7T b c where
--      TI :: forall b1 c1. (b1 ~ c1) => b1 -> :R7T b1 c1
-- In this case orig_res_ty = T (e,e)

rejigConRes :: [KnotTied TyConBinder] -> KnotTied Type    -- Template for result type; e.g.
                                  -- data instance T [a] b c ...
                                  --      gives template ([a,b,c], T [a] b c)
            -> [TyVar]            -- The constructor's inferred type variables
            -> [TyVar]            -- The constructor's user-written, specified
                                  -- type variables
            -> KnotTied Type      -- res_ty
            -> ([TyVar],          -- Universal
                [TyVar],          -- Existential (distinct OccNames from univs)
                [TyVar],          -- The constructor's rejigged, user-written,
                                  -- inferred type variables
                [TyVar],          -- The constructor's rejigged, user-written,
                                  -- specified type variables
                [EqSpec],      -- Equality predicates
                TCvSubst)      -- Substitution to apply to argument types
        -- We don't check that the TyCon given in the ResTy is
        -- the same as the parent tycon, because checkValidDataCon will do it
-- NB: All arguments may potentially be knot-tied
rejigConRes :: [TyConBinder]
-> Kind
-> [TcTyCoVar]
-> [TcTyCoVar]
-> Kind
-> ([TcTyCoVar], [TcTyCoVar], [TcTyCoVar], [TcTyCoVar], [EqSpec],
    TCvSubst)
rejigConRes [TyConBinder]
tmpl_bndrs Kind
res_tmpl [TcTyCoVar]
dc_inferred_tvs [TcTyCoVar]
dc_specified_tvs Kind
res_ty
        -- E.g.  data T [a] b c where
        --         MkT :: forall x y z. T [(x,y)] z z
        -- The {a,b,c} are the tmpl_tvs, and the {x,y,z} are the dc_tvs
        --     (NB: unlike the H98 case, the dc_tvs are not all existential)
        -- Then we generate
        --      Univ tyvars     Eq-spec
        --          a              a~(x,y)
        --          b              b~z
        --          z
        -- Existentials are the leftover type vars: [x,y]
        -- The user-written type variables are what is listed in the forall:
        --   [x, y, z] (all specified). We must rejig these as well.
        --   See Note [DataCon user type variable binders] in DataCon.
        -- So we return ( [a,b,z], [x,y]
        --              , [], [x,y,z]
        --              , [a~(x,y),b~z], <arg-subst> )
  | Just TCvSubst
subst <- Kind -> Kind -> Maybe TCvSubst
tcMatchTy Kind
res_tmpl Kind
res_ty
  = let ([TcTyCoVar]
univ_tvs, [EqSpec]
raw_eqs, TCvSubst
kind_subst) = [TcTyCoVar]
-> [TcTyCoVar] -> TCvSubst -> ([TcTyCoVar], [EqSpec], TCvSubst)
mkGADTVars [TcTyCoVar]
tmpl_tvs [TcTyCoVar]
dc_tvs TCvSubst
subst
        raw_ex_tvs :: [TcTyCoVar]
raw_ex_tvs = [TcTyCoVar]
dc_tvs [TcTyCoVar] -> [TcTyCoVar] -> [TcTyCoVar]
forall a. Ord a => [a] -> [a] -> [a]
`minusList` [TcTyCoVar]
univ_tvs
        (TCvSubst
arg_subst, [TcTyCoVar]
substed_ex_tvs) = HasCallStack => TCvSubst -> [TcTyCoVar] -> (TCvSubst, [TcTyCoVar])
TCvSubst -> [TcTyCoVar] -> (TCvSubst, [TcTyCoVar])
substTyVarBndrs TCvSubst
kind_subst [TcTyCoVar]
raw_ex_tvs

        -- After rejigging the existential tyvars, the resulting substitution
        -- gives us exactly what we need to rejig the user-written tyvars,
        -- since the dcUserTyVarBinders invariant guarantees that the
        -- substitution has *all* the tyvars in its domain.
        -- See Note [DataCon user type variable binders] in DataCon.
        subst_user_tvs :: [TcTyCoVar] -> [TcTyCoVar]
subst_user_tvs = (TcTyCoVar -> TcTyCoVar) -> [TcTyCoVar] -> [TcTyCoVar]
forall a b. (a -> b) -> [a] -> [b]
map (String -> Kind -> TcTyCoVar
getTyVar String
"rejigConRes" (Kind -> TcTyCoVar)
-> (TcTyCoVar -> Kind) -> TcTyCoVar -> TcTyCoVar
forall b c a. (b -> c) -> (a -> b) -> a -> c
. TCvSubst -> TcTyCoVar -> Kind
substTyVar TCvSubst
arg_subst)
        substed_inferred_tvs :: [TcTyCoVar]
substed_inferred_tvs  = [TcTyCoVar] -> [TcTyCoVar]
subst_user_tvs [TcTyCoVar]
dc_inferred_tvs
        substed_specified_tvs :: [TcTyCoVar]
substed_specified_tvs = [TcTyCoVar] -> [TcTyCoVar]
subst_user_tvs [TcTyCoVar]
dc_specified_tvs

        substed_eqs :: [EqSpec]
substed_eqs = (EqSpec -> EqSpec) -> [EqSpec] -> [EqSpec]
forall a b. (a -> b) -> [a] -> [b]
map (TCvSubst -> EqSpec -> EqSpec
substEqSpec TCvSubst
arg_subst) [EqSpec]
raw_eqs
    in
    ([TcTyCoVar]
univ_tvs, [TcTyCoVar]
substed_ex_tvs, [TcTyCoVar]
substed_inferred_tvs, [TcTyCoVar]
substed_specified_tvs,
     [EqSpec]
substed_eqs, TCvSubst
arg_subst)

  | Bool
otherwise
        -- If the return type of the data constructor doesn't match the parent
        -- type constructor, or the arity is wrong, the tcMatchTy will fail
        --    e.g   data T a b where
        --            T1 :: Maybe a   -- Wrong tycon
        --            T2 :: T [a]     -- Wrong arity
        -- We are detect that later, in checkValidDataCon, but meanwhile
        -- we must do *something*, not just crash.  So we do something simple
        -- albeit bogus, relying on checkValidDataCon to check the
        --  bad-result-type error before seeing that the other fields look odd
        -- See Note [Checking GADT return types]
  = ([TcTyCoVar]
tmpl_tvs, [TcTyCoVar]
dc_tvs [TcTyCoVar] -> [TcTyCoVar] -> [TcTyCoVar]
forall a. Ord a => [a] -> [a] -> [a]
`minusList` [TcTyCoVar]
tmpl_tvs, [TcTyCoVar]
dc_inferred_tvs, [TcTyCoVar]
dc_specified_tvs,
     [], TCvSubst
emptyTCvSubst)
  where
    dc_tvs :: [TcTyCoVar]
dc_tvs   = [TcTyCoVar]
dc_inferred_tvs [TcTyCoVar] -> [TcTyCoVar] -> [TcTyCoVar]
forall a. [a] -> [a] -> [a]
++ [TcTyCoVar]
dc_specified_tvs
    tmpl_tvs :: [TcTyCoVar]
tmpl_tvs = [TyConBinder] -> [TcTyCoVar]
forall tv argf. [VarBndr tv argf] -> [tv]
binderVars [TyConBinder]
tmpl_bndrs

{- Note [mkGADTVars]
~~~~~~~~~~~~~~~~~~~~
Running example:

data T (k1 :: *) (k2 :: *) (a :: k2) (b :: k2) where
  MkT :: forall (x1 : *) (y :: x1) (z :: *).
         T x1 * (Proxy (y :: x1), z) z

We need the rejigged type to be

  MkT :: forall (x1 :: *) (k2 :: *) (a :: k2) (b :: k2).
         forall (y :: x1) (z :: *).
         (k2 ~ *, a ~ (Proxy x1 y, z), b ~ z)
      => T x1 k2 a b

You might naively expect that z should become a universal tyvar,
not an existential. (After all, x1 becomes a universal tyvar.)
But z has kind * while b has kind k2, so the return type
   T x1 k2 a z
is ill-kinded.  Another way to say it is this: the universal
tyvars must have exactly the same kinds as the tyConTyVars.

So we need an existential tyvar and a heterogeneous equality
constraint. (The b ~ z is a bit redundant with the k2 ~ * that
comes before in that b ~ z implies k2 ~ *. I'm sure we could do
some analysis that could eliminate k2 ~ *. But we don't do this
yet.)

The data con signature has already been fully kind-checked.
The return type

  T x1 * (Proxy (y :: x1), z) z
becomes
  qtkvs    = [x1 :: *, y :: x1, z :: *]
  res_tmpl = T x1 * (Proxy x1 y, z) z

We start off by matching (T k1 k2 a b) with (T x1 * (Proxy x1 y, z) z). We
know this match will succeed because of the validity check (actually done
later, but laziness saves us -- see Note [Checking GADT return types]).
Thus, we get

  subst := { k1 |-> x1, k2 |-> *, a |-> (Proxy x1 y, z), b |-> z }

Now, we need to figure out what the GADT equalities should be. In this case,
we *don't* want (k1 ~ x1) to be a GADT equality: it should just be a
renaming. The others should be GADT equalities. We also need to make
sure that the universally-quantified variables of the datacon match up
with the tyvars of the tycon, as required for Core context well-formedness.
(This last bit is why we have to rejig at all!)

`choose` walks down the tycon tyvars, figuring out what to do with each one.
It carries two substitutions:
  - t_sub's domain is *template* or *tycon* tyvars, mapping them to variables
    mentioned in the datacon signature.
  - r_sub's domain is *result* tyvars, names written by the programmer in
    the datacon signature. The final rejigged type will use these names, but
    the subst is still needed because sometimes the printed name of these variables
    is different. (See choose_tv_name, below.)

Before explaining the details of `choose`, let's just look at its operation
on our example:

  choose [] [] {} {} [k1, k2, a, b]
  -->          -- first branch of `case` statement
  choose
    univs:    [x1 :: *]
    eq_spec:  []
    t_sub:    {k1 |-> x1}
    r_sub:    {x1 |-> x1}
    t_tvs:    [k2, a, b]
  -->          -- second branch of `case` statement
  choose
    univs:    [k2 :: *, x1 :: *]
    eq_spec:  [k2 ~ *]
    t_sub:    {k1 |-> x1, k2 |-> k2}
    r_sub:    {x1 |-> x1}
    t_tvs:    [a, b]
  -->          -- second branch of `case` statement
  choose
    univs:    [a :: k2, k2 :: *, x1 :: *]
    eq_spec:  [ a ~ (Proxy x1 y, z)
              , k2 ~ * ]
    t_sub:    {k1 |-> x1, k2 |-> k2, a |-> a}
    r_sub:    {x1 |-> x1}
    t_tvs:    [b]
  -->          -- second branch of `case` statement
  choose
    univs:    [b :: k2, a :: k2, k2 :: *, x1 :: *]
    eq_spec:  [ b ~ z
              , a ~ (Proxy x1 y, z)
              , k2 ~ * ]
    t_sub:    {k1 |-> x1, k2 |-> k2, a |-> a, b |-> z}
    r_sub:    {x1 |-> x1}
    t_tvs:    []
  -->          -- end of recursion
  ( [x1 :: *, k2 :: *, a :: k2, b :: k2]
  , [k2 ~ *, a ~ (Proxy x1 y, z), b ~ z]
  , {x1 |-> x1} )

`choose` looks up each tycon tyvar in the matching (it *must* be matched!).

* If it finds a bare result tyvar (the first branch of the `case`
  statement), it checks to make sure that the result tyvar isn't yet
  in the list of univ_tvs.  If it is in that list, then we have a
  repeated variable in the return type, and we in fact need a GADT
  equality.

* It then checks to make sure that the kind of the result tyvar
  matches the kind of the template tyvar. This check is what forces
  `z` to be existential, as it should be, explained above.

* Assuming no repeated variables or kind-changing, we wish to use the
  variable name given in the datacon signature (that is, `x1` not
  `k1`), not the tycon signature (which may have been made up by
  GHC). So, we add a mapping from the tycon tyvar to the result tyvar
  to t_sub.

* If we discover that a mapping in `subst` gives us a non-tyvar (the
  second branch of the `case` statement), then we have a GADT equality
  to create.  We create a fresh equality, but we don't extend any
  substitutions. The template variable substitution is meant for use
  in universal tyvar kinds, and these shouldn't be affected by any
  GADT equalities.

This whole algorithm is quite delicate, indeed. I (Richard E.) see two ways
of simplifying it:

1) The first branch of the `case` statement is really an optimization, used
in order to get fewer GADT equalities. It might be possible to make a GADT
equality for *every* univ. tyvar, even if the equality is trivial, and then
either deal with the bigger type or somehow reduce it later.

2) This algorithm strives to use the names for type variables as specified
by the user in the datacon signature. If we always used the tycon tyvar
names, for example, this would be simplified. This change would almost
certainly degrade error messages a bit, though.
-}

-- ^ From information about a source datacon definition, extract out
-- what the universal variables and the GADT equalities should be.
-- See Note [mkGADTVars].
mkGADTVars :: [TyVar]    -- ^ The tycon vars
           -> [TyVar]    -- ^ The datacon vars
           -> TCvSubst   -- ^ The matching between the template result type
                         -- and the actual result type
           -> ( [TyVar]
              , [EqSpec]
              , TCvSubst ) -- ^ The univ. variables, the GADT equalities,
                           -- and a subst to apply to the GADT equalities
                           -- and existentials.
mkGADTVars :: [TcTyCoVar]
-> [TcTyCoVar] -> TCvSubst -> ([TcTyCoVar], [EqSpec], TCvSubst)
mkGADTVars [TcTyCoVar]
tmpl_tvs [TcTyCoVar]
dc_tvs TCvSubst
subst
  = [TcTyCoVar]
-> [EqSpec]
-> TCvSubst
-> TCvSubst
-> [TcTyCoVar]
-> ([TcTyCoVar], [EqSpec], TCvSubst)
choose [] [] TCvSubst
empty_subst TCvSubst
empty_subst [TcTyCoVar]
tmpl_tvs
  where
    in_scope :: InScopeSet
in_scope = TyVarSet -> InScopeSet
mkInScopeSet ([TcTyCoVar] -> TyVarSet
mkVarSet [TcTyCoVar]
tmpl_tvs TyVarSet -> TyVarSet -> TyVarSet
`unionVarSet` [TcTyCoVar] -> TyVarSet
mkVarSet [TcTyCoVar]
dc_tvs)
               InScopeSet -> InScopeSet -> InScopeSet
`unionInScope` TCvSubst -> InScopeSet
getTCvInScope TCvSubst
subst
    empty_subst :: TCvSubst
empty_subst = InScopeSet -> TCvSubst
mkEmptyTCvSubst InScopeSet
in_scope

    choose :: [TyVar]           -- accumulator of univ tvs, reversed
           -> [EqSpec]          -- accumulator of GADT equalities, reversed
           -> TCvSubst          -- template substitution
           -> TCvSubst          -- res. substitution
           -> [TyVar]           -- template tvs (the univ tvs passed in)
           -> ( [TyVar]         -- the univ_tvs
              , [EqSpec]        -- GADT equalities
              , TCvSubst )       -- a substitution to fix kinds in ex_tvs

    choose :: [TcTyCoVar]
-> [EqSpec]
-> TCvSubst
-> TCvSubst
-> [TcTyCoVar]
-> ([TcTyCoVar], [EqSpec], TCvSubst)
choose [TcTyCoVar]
univs [EqSpec]
eqs TCvSubst
_t_sub TCvSubst
r_sub []
      = ([TcTyCoVar] -> [TcTyCoVar]
forall a. [a] -> [a]
reverse [TcTyCoVar]
univs, [EqSpec] -> [EqSpec]
forall a. [a] -> [a]
reverse [EqSpec]
eqs, TCvSubst
r_sub)
    choose [TcTyCoVar]
univs [EqSpec]
eqs TCvSubst
t_sub TCvSubst
r_sub (TcTyCoVar
t_tv:[TcTyCoVar]
t_tvs)
      | Just Kind
r_ty <- TCvSubst -> TcTyCoVar -> Maybe Kind
lookupTyVar TCvSubst
subst TcTyCoVar
t_tv
      = case Kind -> Maybe TcTyCoVar
getTyVar_maybe Kind
r_ty of
          Just TcTyCoVar
r_tv
            |  Bool -> Bool
not (TcTyCoVar
r_tv TcTyCoVar -> [TcTyCoVar] -> Bool
forall (t :: * -> *) a. (Foldable t, Eq a) => a -> t a -> Bool
`elem` [TcTyCoVar]
univs)
            ,  TcTyCoVar -> Kind
tyVarKind TcTyCoVar
r_tv Kind -> Kind -> Bool
`eqType` (HasCallStack => TCvSubst -> Kind -> Kind
TCvSubst -> Kind -> Kind
substTy TCvSubst
t_sub (TcTyCoVar -> Kind
tyVarKind TcTyCoVar
t_tv))
            -> -- simple, well-kinded variable substitution.
               [TcTyCoVar]
-> [EqSpec]
-> TCvSubst
-> TCvSubst
-> [TcTyCoVar]
-> ([TcTyCoVar], [EqSpec], TCvSubst)
choose (TcTyCoVar
r_tvTcTyCoVar -> [TcTyCoVar] -> [TcTyCoVar]
forall a. a -> [a] -> [a]
:[TcTyCoVar]
univs) [EqSpec]
eqs
                      (TCvSubst -> TcTyCoVar -> Kind -> TCvSubst
extendTvSubst TCvSubst
t_sub TcTyCoVar
t_tv Kind
r_ty')
                      (TCvSubst -> TcTyCoVar -> Kind -> TCvSubst
extendTvSubst TCvSubst
r_sub TcTyCoVar
r_tv Kind
r_ty')
                      [TcTyCoVar]
t_tvs
            where
              r_tv1 :: TcTyCoVar
r_tv1  = TcTyCoVar -> Name -> TcTyCoVar
setTyVarName TcTyCoVar
r_tv (TcTyCoVar -> TcTyCoVar -> Name
choose_tv_name TcTyCoVar
r_tv TcTyCoVar
t_tv)
              r_ty' :: Kind
r_ty'  = TcTyCoVar -> Kind
mkTyVarTy TcTyCoVar
r_tv1

               -- Not a simple substitution: make an equality predicate
          Maybe TcTyCoVar
_ -> [TcTyCoVar]
-> [EqSpec]
-> TCvSubst
-> TCvSubst
-> [TcTyCoVar]
-> ([TcTyCoVar], [EqSpec], TCvSubst)
choose (TcTyCoVar
t_tv'TcTyCoVar -> [TcTyCoVar] -> [TcTyCoVar]
forall a. a -> [a] -> [a]
:[TcTyCoVar]
univs) (TcTyCoVar -> Kind -> EqSpec
mkEqSpec TcTyCoVar
t_tv' Kind
r_ty EqSpec -> [EqSpec] -> [EqSpec]
forall a. a -> [a] -> [a]
: [EqSpec]
eqs)
                      (TCvSubst -> TcTyCoVar -> Kind -> TCvSubst
extendTvSubst TCvSubst
t_sub TcTyCoVar
t_tv (TcTyCoVar -> Kind
mkTyVarTy TcTyCoVar
t_tv'))
                         -- We've updated the kind of t_tv,
                         -- so add it to t_sub (#14162)
                      TCvSubst
r_sub [TcTyCoVar]
t_tvs
            where
              t_tv' :: TcTyCoVar
t_tv' = (Kind -> Kind) -> TcTyCoVar -> TcTyCoVar
updateTyVarKind (HasCallStack => TCvSubst -> Kind -> Kind
TCvSubst -> Kind -> Kind
substTy TCvSubst
t_sub) TcTyCoVar
t_tv

      | Bool
otherwise
      = String -> SDoc -> ([TcTyCoVar], [EqSpec], TCvSubst)
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"mkGADTVars" ([TcTyCoVar] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TcTyCoVar]
tmpl_tvs SDoc -> SDoc -> SDoc
$$ TCvSubst -> SDoc
forall a. Outputable a => a -> SDoc
ppr TCvSubst
subst)

      -- choose an appropriate name for a univ tyvar.
      -- This *must* preserve the Unique of the result tv, so that we
      -- can detect repeated variables. It prefers user-specified names
      -- over system names. A result variable with a system name can
      -- happen with GHC-generated implicit kind variables.
    choose_tv_name :: TyVar -> TyVar -> Name
    choose_tv_name :: TcTyCoVar -> TcTyCoVar -> Name
choose_tv_name TcTyCoVar
r_tv TcTyCoVar
t_tv
      | Name -> Bool
isSystemName Name
r_tv_name
      = Name -> Unique -> Name
setNameUnique Name
t_tv_name (Name -> Unique
forall a. Uniquable a => a -> Unique
getUnique Name
r_tv_name)

      | Bool
otherwise
      = Name
r_tv_name

      where
        r_tv_name :: Name
r_tv_name = TcTyCoVar -> Name
forall a. NamedThing a => a -> Name
getName TcTyCoVar
r_tv
        t_tv_name :: Name
t_tv_name = TcTyCoVar -> Name
forall a. NamedThing a => a -> Name
getName TcTyCoVar
t_tv

{-
Note [Substitution in template variables kinds]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

data G (a :: Maybe k) where
  MkG :: G Nothing

With explicit kind variables

data G k (a :: Maybe k) where
  MkG :: G k1 (Nothing k1)

Note how k1 is distinct from k. So, when we match the template
`G k a` against `G k1 (Nothing k1)`, we get a subst
[ k |-> k1, a |-> Nothing k1 ]. Even though this subst has two
mappings, we surely don't want to add (k, k1) to the list of
GADT equalities -- that would be overly complex and would create
more untouchable variables than we need. So, when figuring out
which tyvars are GADT-like and which aren't (the fundamental
job of `choose`), we want to treat `k` as *not* GADT-like.
Instead, we wish to substitute in `a`'s kind, to get (a :: Maybe k1)
instead of (a :: Maybe k). This is the reason for dealing
with a substitution in here.

However, we do not *always* want to substitute. Consider

data H (a :: k) where
  MkH :: H Int

With explicit kind variables:

data H k (a :: k) where
  MkH :: H * Int

Here, we have a kind-indexed GADT. The subst in question is
[ k |-> *, a |-> Int ]. Now, we *don't* want to substitute in `a`'s
kind, because that would give a constructor with the type

MkH :: forall (k :: *) (a :: *). (k ~ *) -> (a ~ Int) -> H k a

The problem here is that a's kind is wrong -- it needs to be k, not *!
So, if the matching for a variable is anything but another bare variable,
we drop the mapping from the substitution before proceeding. This
was not an issue before kind-indexed GADTs because this case could
never happen.

************************************************************************
*                                                                      *
                Validity checking
*                                                                      *
************************************************************************

Validity checking is done once the mutually-recursive knot has been
tied, so we can look at things freely.
-}

checkValidTyCl :: TyCon -> TcM [TyCon]
-- The returned list is either a singleton (if valid)
-- or a list of "fake tycons" (if not); the fake tycons
-- include any implicits, like promoted data constructors
-- See Note [Recover from validity error]
checkValidTyCl :: TyCon -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
checkValidTyCl TyCon
tc
  = SrcSpan
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan (TyCon -> SrcSpan
forall a. NamedThing a => a -> SrcSpan
getSrcSpan TyCon
tc) (IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
 -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon])
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall a b. (a -> b) -> a -> b
$
    TyCon
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall a. TyCon -> TcM a -> TcM a
addTyConCtxt TyCon
tc            (IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
 -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon])
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall a b. (a -> b) -> a -> b
$
    IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall r. TcRn r -> TcRn r -> TcRn r
recoverM IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
recovery_code     (IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
 -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon])
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
-> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall a b. (a -> b) -> a -> b
$
    do { String -> SDoc -> TcRn ()
traceTc String
"Starting validity for tycon" (TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tc)
       ; TyCon -> TcRn ()
checkValidTyCon TyCon
tc
       ; String -> SDoc -> TcRn ()
traceTc String
"Done validity for tycon" (TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tc)
       ; [TyCon] -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall (m :: * -> *) a. Monad m => a -> m a
return [TyCon
tc] }
  where
    recovery_code :: IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
recovery_code -- See Note [Recover from validity error]
      = do { String -> SDoc -> TcRn ()
traceTc String
"Aborted validity for tycon" (TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tc)
           ; [TyCon] -> IOEnv (Env TcGblEnv TcLclEnv) [TyCon]
forall (m :: * -> *) a. Monad m => a -> m a
return ((TyThing -> [TyCon]) -> [TyThing] -> [TyCon]
forall (t :: * -> *) a b. Foldable t => (a -> [b]) -> t a -> [b]
concatMap TyThing -> [TyCon]
mk_fake_tc ([TyThing] -> [TyCon]) -> [TyThing] -> [TyCon]
forall a b. (a -> b) -> a -> b
$
                     TyCon -> TyThing
ATyCon TyCon
tc TyThing -> [TyThing] -> [TyThing]
forall a. a -> [a] -> [a]
: TyCon -> [TyThing]
implicitTyConThings TyCon
tc) }

    mk_fake_tc :: TyThing -> [TyCon]
mk_fake_tc (ATyCon TyCon
tc)
      | TyCon -> Bool
isClassTyCon TyCon
tc = [TyCon
tc]   -- Ugh! Note [Recover from validity error]
      | Bool
otherwise       = [TyCon -> TyCon
makeRecoveryTyCon TyCon
tc]
    mk_fake_tc (AConLike (RealDataCon DataCon
dc))
                        = [TyCon -> TyCon
makeRecoveryTyCon (DataCon -> TyCon
promoteDataCon DataCon
dc)]
    mk_fake_tc TyThing
_        = []

{- Note [Recover from validity error]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We recover from a validity error in a type or class, which allows us
to report multiple validity errors. In the failure case we return a
TyCon of the right kind, but with no interesting behaviour
(makeRecoveryTyCon). Why?  Suppose we have
   type T a = Fun
where Fun is a type family of arity 1.  The RHS is invalid, but we
want to go on checking validity of subsequent type declarations.
So we replace T with an abstract TyCon which will do no harm.
See indexed-types/should_fail/BadSock and #10896

Some notes:

* We must make fakes for promoted DataCons too. Consider (#15215)
      data T a = MkT ...
      data S a = ...T...MkT....
  If there is an error in the definition of 'T' we add a "fake type
  constructor" to the type environment, so that we can continue to
  typecheck 'S'.  But we /were not/ adding a fake anything for 'MkT'
  and so there was an internal error when we met 'MkT' in the body of
  'S'.

* Painfully, we *don't* want to do this for classes.
  Consider tcfail041:
     class (?x::Int) => C a where ...
     instance C Int
  The class is invalid because of the superclass constraint.  But
  we still want it to look like a /class/, else the instance bleats
  that the instance is mal-formed because it hasn't got a class in
  the head.

  This is really bogus; now we have in scope a Class that is invalid
  in some way, with unknown downstream consequences.  A better
  alternative might be to make a fake class TyCon.  A job for another day.
-}

-------------------------
-- For data types declared with record syntax, we require
-- that each constructor that has a field 'f'
--      (a) has the same result type
--      (b) has the same type for 'f'
-- module alpha conversion of the quantified type variables
-- of the constructor.
--
-- Note that we allow existentials to match because the
-- fields can never meet. E.g
--      data T where
--        T1 { f1 :: b, f2 :: a, f3 ::Int } :: T
--        T2 { f1 :: c, f2 :: c, f3 ::Int } :: T
-- Here we do not complain about f1,f2 because they are existential

checkValidTyCon :: TyCon -> TcM ()
checkValidTyCon :: TyCon -> TcRn ()
checkValidTyCon TyCon
tc
  | TyCon -> Bool
isPrimTyCon TyCon
tc   -- Happens when Haddock'ing GHC.Prim
  = () -> TcRn ()
forall (m :: * -> *) a. Monad m => a -> m a
return ()

  | Name -> Bool
isWiredInName (TyCon -> Name
forall a. NamedThing a => a -> Name
getName TyCon
tc)
                     -- validity-checking wired-in tycons is a waste of
                     -- time. More importantly, a wired-in tycon might
                     -- violate assumptions. Example: (~) has a superclass
                     -- mentioning (~#), which is ill-kinded in source Haskell
  = String -> SDoc -> TcRn ()
traceTc String
"Skipping validity check for wired-in" (TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tc)

  | Bool
otherwise
  = do { String -> SDoc -> TcRn ()
traceTc String
"checkValidTyCon" (TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tc SDoc -> SDoc -> SDoc
$$ Maybe Class -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyCon -> Maybe Class
tyConClass_maybe TyCon
tc))
       ; if | Just Class
cl <- TyCon -> Maybe Class
tyConClass_maybe TyCon
tc
              -> Class -> TcRn ()
checkValidClass Class
cl

            | Just Kind
syn_rhs <- TyCon -> Maybe Kind
synTyConRhs_maybe TyCon
tc
              -> do { UserTypeCtxt -> Kind -> TcRn ()
checkValidType UserTypeCtxt
syn_ctxt Kind
syn_rhs
                    ; UserTypeCtxt -> Kind -> TcRn ()
checkTySynRhs UserTypeCtxt
syn_ctxt Kind
syn_rhs }

            | Just FamTyConFlav
fam_flav <- TyCon -> Maybe FamTyConFlav
famTyConFlav_maybe TyCon
tc
              -> case FamTyConFlav
fam_flav of
               { ClosedSynFamilyTyCon (Just CoAxiom Branched
ax)
                   -> TyCon -> TcRn () -> TcRn ()
forall a. TyCon -> TcM a -> TcM a
tcAddClosedTypeFamilyDeclCtxt TyCon
tc (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
                      CoAxiom Branched -> TcRn ()
checkValidCoAxiom CoAxiom Branched
ax
               ; ClosedSynFamilyTyCon Maybe (CoAxiom Branched)
Nothing   -> () -> TcRn ()
forall (m :: * -> *) a. Monad m => a -> m a
return ()
               ; FamTyConFlav
AbstractClosedSynFamilyTyCon ->
                 do { Bool
hsBoot <- TcRnIf TcGblEnv TcLclEnv Bool
tcIsHsBootOrSig
                    ; Bool -> SDoc -> TcRn ()
checkTc Bool
hsBoot (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$
                      String -> SDoc
text String
"You may define an abstract closed type family" SDoc -> SDoc -> SDoc
$$
                      String -> SDoc
text String
"only in a .hs-boot file" }
               ; DataFamilyTyCon {}           -> () -> TcRn ()
forall (m :: * -> *) a. Monad m => a -> m a
return ()
               ; FamTyConFlav
OpenSynFamilyTyCon           -> () -> TcRn ()
forall (m :: * -> *) a. Monad m => a -> m a
return ()
               ; BuiltInSynFamTyCon BuiltInSynFamily
_         -> () -> TcRn ()
forall (m :: * -> *) a. Monad m => a -> m a
return () }

             | Bool
otherwise -> do
               { -- Check the context on the data decl
                 String -> SDoc -> TcRn ()
traceTc String
"cvtc1" (TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tc)
               ; UserTypeCtxt -> [Kind] -> TcRn ()
checkValidTheta (Name -> UserTypeCtxt
DataTyCtxt Name
name) (TyCon -> [Kind]
tyConStupidTheta TyCon
tc)

               ; String -> SDoc -> TcRn ()
traceTc String
"cvtc2" (TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tc)

               ; DynFlags
dflags          <- IOEnv (Env TcGblEnv TcLclEnv) DynFlags
forall (m :: * -> *). HasDynFlags m => m DynFlags
getDynFlags
               ; Bool
existential_ok  <- Extension -> TcRnIf TcGblEnv TcLclEnv Bool
forall gbl lcl. Extension -> TcRnIf gbl lcl Bool
xoptM Extension
LangExt.ExistentialQuantification
               ; Bool
gadt_ok         <- Extension -> TcRnIf TcGblEnv TcLclEnv Bool
forall gbl lcl. Extension -> TcRnIf gbl lcl Bool
xoptM Extension
LangExt.GADTs
               ; let ex_ok :: Bool
ex_ok = Bool
existential_ok Bool -> Bool -> Bool
|| Bool
gadt_ok
                     -- Data cons can have existential context
               ; (DataCon -> TcRn ()) -> [DataCon] -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ (DynFlags -> Bool -> TyCon -> DataCon -> TcRn ()
checkValidDataCon DynFlags
dflags Bool
ex_ok TyCon
tc) [DataCon]
data_cons
               ; (FieldLabel -> TcRn ()) -> [FieldLabel] -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ ([DataCon] -> FieldLabel -> TcRn ()
checkPartialRecordField [DataCon]
data_cons) (TyCon -> [FieldLabel]
tyConFieldLabels TyCon
tc)

                -- Check that fields with the same name share a type
               ; (NonEmpty (FieldLabel, DataCon) -> TcRn ())
-> [NonEmpty (FieldLabel, DataCon)] -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ NonEmpty (FieldLabel, DataCon) -> TcRn ()
forall a. NonEmpty (FieldLbl a, DataCon) -> TcRn ()
check_fields [NonEmpty (FieldLabel, DataCon)]
groups }}
  where
    syn_ctxt :: UserTypeCtxt
syn_ctxt  = Name -> UserTypeCtxt
TySynCtxt Name
name
    name :: Name
name      = TyCon -> Name
tyConName TyCon
tc
    data_cons :: [DataCon]
data_cons = TyCon -> [DataCon]
tyConDataCons TyCon
tc

    groups :: [NonEmpty (FieldLabel, DataCon)]
groups = ((FieldLabel, DataCon) -> (FieldLabel, DataCon) -> Ordering)
-> [(FieldLabel, DataCon)] -> [NonEmpty (FieldLabel, DataCon)]
forall a. (a -> a -> Ordering) -> [a] -> [NonEmpty a]
equivClasses (FieldLabel, DataCon) -> (FieldLabel, DataCon) -> Ordering
forall a b a b. (FieldLbl a, b) -> (FieldLbl a, b) -> Ordering
cmp_fld ((DataCon -> [(FieldLabel, DataCon)])
-> [DataCon] -> [(FieldLabel, DataCon)]
forall (t :: * -> *) a b. Foldable t => (a -> [b]) -> t a -> [b]
concatMap DataCon -> [(FieldLabel, DataCon)]
get_fields [DataCon]
data_cons)
    cmp_fld :: (FieldLbl a, b) -> (FieldLbl a, b) -> Ordering
cmp_fld (FieldLbl a
f1,b
_) (FieldLbl a
f2,b
_) = FieldLbl a -> FieldLabelString
forall a. FieldLbl a -> FieldLabelString
flLabel FieldLbl a
f1 FieldLabelString -> FieldLabelString -> Ordering
forall a. Ord a => a -> a -> Ordering
`compare` FieldLbl a -> FieldLabelString
forall a. FieldLbl a -> FieldLabelString
flLabel FieldLbl a
f2
    get_fields :: DataCon -> [(FieldLabel, DataCon)]
get_fields DataCon
con = DataCon -> [FieldLabel]
dataConFieldLabels DataCon
con [FieldLabel] -> [DataCon] -> [(FieldLabel, DataCon)]
forall a b. [a] -> [b] -> [(a, b)]
`zip` DataCon -> [DataCon]
forall a. a -> [a]
repeat DataCon
con
        -- dataConFieldLabels may return the empty list, which is fine

    -- See Note [GADT record selectors] in TcTyDecls
    -- We must check (a) that the named field has the same
    --                   type in each constructor
    --               (b) that those constructors have the same result type
    --
    -- However, the constructors may have differently named type variable
    -- and (worse) we don't know how the correspond to each other.  E.g.
    --     C1 :: forall a b. { f :: a, g :: b } -> T a b
    --     C2 :: forall d c. { f :: c, g :: c } -> T c d
    --
    -- So what we do is to ust Unify.tcMatchTys to compare the first candidate's
    -- result type against other candidates' types BOTH WAYS ROUND.
    -- If they magically agrees, take the substitution and
    -- apply them to the latter ones, and see if they match perfectly.
    check_fields :: NonEmpty (FieldLbl a, DataCon) -> TcRn ()
check_fields ((FieldLbl a
label, DataCon
con1) :| [(FieldLbl a, DataCon)]
other_fields)
        -- These fields all have the same name, but are from
        -- different constructors in the data type
        = TcRn () -> TcRn () -> TcRn ()
forall r. TcRn r -> TcRn r -> TcRn r
recoverM (() -> TcRn ()
forall (m :: * -> *) a. Monad m => a -> m a
return ()) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$ ((FieldLbl a, DataCon) -> TcRn ())
-> [(FieldLbl a, DataCon)] -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ (FieldLbl a, DataCon) -> TcRn ()
checkOne [(FieldLbl a, DataCon)]
other_fields
                -- Check that all the fields in the group have the same type
                -- NB: this check assumes that all the constructors of a given
                -- data type use the same type variables
        where
        res1 :: Kind
res1 = DataCon -> Kind
dataConOrigResTy DataCon
con1
        fty1 :: Kind
fty1 = DataCon -> FieldLabelString -> Kind
dataConFieldType DataCon
con1 FieldLabelString
lbl
        lbl :: FieldLabelString
lbl = FieldLbl a -> FieldLabelString
forall a. FieldLbl a -> FieldLabelString
flLabel FieldLbl a
label

        checkOne :: (FieldLbl a, DataCon) -> TcRn ()
checkOne (FieldLbl a
_, DataCon
con2)    -- Do it both ways to ensure they are structurally identical
            = do { FieldLabelString
-> DataCon -> DataCon -> Kind -> Kind -> Kind -> Kind -> TcRn ()
checkFieldCompat FieldLabelString
lbl DataCon
con1 DataCon
con2 Kind
res1 Kind
res2 Kind
fty1 Kind
fty2
                 ; FieldLabelString
-> DataCon -> DataCon -> Kind -> Kind -> Kind -> Kind -> TcRn ()
checkFieldCompat FieldLabelString
lbl DataCon
con2 DataCon
con1 Kind
res2 Kind
res1 Kind
fty2 Kind
fty1 }
            where
                res2 :: Kind
res2 = DataCon -> Kind
dataConOrigResTy DataCon
con2
                fty2 :: Kind
fty2 = DataCon -> FieldLabelString -> Kind
dataConFieldType DataCon
con2 FieldLabelString
lbl

checkPartialRecordField :: [DataCon] -> FieldLabel -> TcM ()
-- Checks the partial record field selector, and warns.
-- See Note [Checking partial record field]
checkPartialRecordField :: [DataCon] -> FieldLabel -> TcRn ()
checkPartialRecordField [DataCon]
all_cons FieldLabel
fld
  = SrcSpan -> TcRn () -> TcRn ()
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan SrcSpan
loc (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
      WarningFlag -> Bool -> SDoc -> TcRn ()
warnIfFlag WarningFlag
Opt_WarnPartialFields
        (Bool -> Bool
not Bool
is_exhaustive Bool -> Bool -> Bool
&& Bool -> Bool
not (OccName -> Bool
startsWithUnderscore OccName
occ_name))
        ([SDoc] -> SDoc
sep [String -> SDoc
text String
"Use of partial record field selector" SDoc -> SDoc -> SDoc
<> SDoc
colon,
              Int -> SDoc -> SDoc
nest Int
2 (SDoc -> SDoc) -> SDoc -> SDoc
forall a b. (a -> b) -> a -> b
$ SDoc -> SDoc
quotes (OccName -> SDoc
forall a. Outputable a => a -> SDoc
ppr OccName
occ_name)])
  where
    sel_name :: Name
sel_name = FieldLabel -> Name
forall a. FieldLbl a -> a
flSelector FieldLabel
fld
    loc :: SrcSpan
loc    = Name -> SrcSpan
forall a. NamedThing a => a -> SrcSpan
getSrcSpan Name
sel_name
    occ_name :: OccName
occ_name = Name -> OccName
forall a. NamedThing a => a -> OccName
getOccName Name
sel_name

    ([DataCon]
cons_with_field, [DataCon]
cons_without_field) = (DataCon -> Bool) -> [DataCon] -> ([DataCon], [DataCon])
forall a. (a -> Bool) -> [a] -> ([a], [a])
partition DataCon -> Bool
has_field [DataCon]
all_cons
    has_field :: DataCon -> Bool
has_field DataCon
con = FieldLabel
fld FieldLabel -> [FieldLabel] -> Bool
forall (t :: * -> *) a. (Foldable t, Eq a) => a -> t a -> Bool
`elem` (DataCon -> [FieldLabel]
dataConFieldLabels DataCon
con)
    is_exhaustive :: Bool
is_exhaustive = (DataCon -> Bool) -> [DataCon] -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
all ([Kind] -> DataCon -> Bool
dataConCannotMatch [Kind]
inst_tys) [DataCon]
cons_without_field

    con1 :: DataCon
con1 = ASSERT( not (null cons_with_field) ) head cons_with_field
    ([TcTyCoVar]
univ_tvs, [TcTyCoVar]
_, [EqSpec]
eq_spec, [Kind]
_, [Kind]
_, Kind
_) = DataCon
-> ([TcTyCoVar], [TcTyCoVar], [EqSpec], [Kind], [Kind], Kind)
dataConFullSig DataCon
con1
    eq_subst :: TCvSubst
eq_subst = [(TcTyCoVar, Kind)] -> TCvSubst
mkTvSubstPrs ((EqSpec -> (TcTyCoVar, Kind)) -> [EqSpec] -> [(TcTyCoVar, Kind)]
forall a b. (a -> b) -> [a] -> [b]
map EqSpec -> (TcTyCoVar, Kind)
eqSpecPair [EqSpec]
eq_spec)
    inst_tys :: [Kind]
inst_tys = TCvSubst -> [TcTyCoVar] -> [Kind]
substTyVars TCvSubst
eq_subst [TcTyCoVar]
univ_tvs

checkFieldCompat :: FieldLabelString -> DataCon -> DataCon
                 -> Type -> Type -> Type -> Type -> TcM ()
checkFieldCompat :: FieldLabelString
-> DataCon -> DataCon -> Kind -> Kind -> Kind -> Kind -> TcRn ()
checkFieldCompat FieldLabelString
fld DataCon
con1 DataCon
con2 Kind
res1 Kind
res2 Kind
fty1 Kind
fty2
  = do  { Bool -> SDoc -> TcRn ()
checkTc (Maybe TCvSubst -> Bool
forall a. Maybe a -> Bool
isJust Maybe TCvSubst
mb_subst1) (FieldLabelString -> DataCon -> DataCon -> SDoc
resultTypeMisMatch FieldLabelString
fld DataCon
con1 DataCon
con2)
        ; Bool -> SDoc -> TcRn ()
checkTc (Maybe TCvSubst -> Bool
forall a. Maybe a -> Bool
isJust Maybe TCvSubst
mb_subst2) (FieldLabelString -> DataCon -> DataCon -> SDoc
fieldTypeMisMatch FieldLabelString
fld DataCon
con1 DataCon
con2) }
  where
    mb_subst1 :: Maybe TCvSubst
mb_subst1 = Kind -> Kind -> Maybe TCvSubst
tcMatchTy Kind
res1 Kind
res2
    mb_subst2 :: Maybe TCvSubst
mb_subst2 = TCvSubst -> Kind -> Kind -> Maybe TCvSubst
tcMatchTyX (String -> Maybe TCvSubst -> TCvSubst
forall a. HasCallStack => String -> Maybe a -> a
expectJust String
"checkFieldCompat" Maybe TCvSubst
mb_subst1) Kind
fty1 Kind
fty2

-------------------------------
checkValidDataCon :: DynFlags -> Bool -> TyCon -> DataCon -> TcM ()
checkValidDataCon :: DynFlags -> Bool -> TyCon -> DataCon -> TcRn ()
checkValidDataCon DynFlags
dflags Bool
existential_ok TyCon
tc DataCon
con
  = SrcSpan -> TcRn () -> TcRn ()
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan (DataCon -> SrcSpan
forall a. NamedThing a => a -> SrcSpan
getSrcSpan DataCon
con)  (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
    SDoc -> TcRn () -> TcRn ()
forall a. SDoc -> TcM a -> TcM a
addErrCtxt (DataCon -> SDoc
forall a. Outputable a => a -> SDoc
dataConCtxt DataCon
con) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
    do  { -- Check that the return type of the data constructor
          -- matches the type constructor; eg reject this:
          --   data T a where { MkT :: Bogus a }
          -- It's important to do this first:
          --  see Note [Checking GADT return types]
          --  and c.f. Note [Check role annotations in a second pass]
          let tc_tvs :: [TcTyCoVar]
tc_tvs      = TyCon -> [TcTyCoVar]
tyConTyVars TyCon
tc
              res_ty_tmpl :: Kind
res_ty_tmpl = TyCon -> [Kind] -> Kind
mkFamilyTyConApp TyCon
tc ([TcTyCoVar] -> [Kind]
mkTyVarTys [TcTyCoVar]
tc_tvs)
              orig_res_ty :: Kind
orig_res_ty = DataCon -> Kind
dataConOrigResTy DataCon
con
        ; String -> SDoc -> TcRn ()
traceTc String
"checkValidDataCon" ([SDoc] -> SDoc
vcat
              [ DataCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr DataCon
con, TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tc, [TcTyCoVar] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TcTyCoVar]
tc_tvs
              , Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr Kind
res_ty_tmpl SDoc -> SDoc -> SDoc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
<+> Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr (HasDebugCallStack => Kind -> Kind
Kind -> Kind
tcTypeKind Kind
res_ty_tmpl)
              , Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr Kind
orig_res_ty SDoc -> SDoc -> SDoc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
<+> Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr (HasDebugCallStack => Kind -> Kind
Kind -> Kind
tcTypeKind Kind
orig_res_ty)])


        ; Bool -> SDoc -> TcRn ()
checkTc (Maybe TCvSubst -> Bool
forall a. Maybe a -> Bool
isJust (Kind -> Kind -> Maybe TCvSubst
tcMatchTy Kind
res_ty_tmpl Kind
orig_res_ty))
                  (DataCon -> Kind -> SDoc
badDataConTyCon DataCon
con Kind
res_ty_tmpl)
            -- Note that checkTc aborts if it finds an error. This is
            -- critical to avoid panicking when we call dataConUserType
            -- on an un-rejiggable datacon!

        ; String -> SDoc -> TcRn ()
traceTc String
"checkValidDataCon 2" (Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr (DataCon -> Kind
dataConUserType DataCon
con))

          -- Check that the result type is a *monotype*
          --  e.g. reject this:   MkT :: T (forall a. a->a)
          -- Reason: it's really the argument of an equality constraint
        ; Kind -> TcRn ()
checkValidMonoType Kind
orig_res_ty

          -- Check all argument types for validity
        ; UserTypeCtxt -> Kind -> TcRn ()
checkValidType UserTypeCtxt
ctxt (DataCon -> Kind
dataConUserType DataCon
con)

          -- If we are dealing with a newtype, we allow levity polymorphism
          -- regardless of whether or not UnliftedNewtypes is enabled. A
          -- later check in checkNewDataCon handles this, producing a
          -- better error message than checkForLevPoly would.
        ; Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
unless (TyCon -> Bool
isNewTyCon TyCon
tc)
            ((Kind -> TcRn ()) -> [Kind] -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ (SDoc -> Kind -> TcRn ()
checkForLevPoly SDoc
empty) (DataCon -> [Kind]
dataConOrigArgTys DataCon
con))

          -- Extra checks for newtype data constructors
        ; Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
when (TyCon -> Bool
isNewTyCon TyCon
tc) (DataCon -> TcRn ()
checkNewDataCon DataCon
con)

          -- Check that existentials are allowed if they are used
        ; Bool -> SDoc -> TcRn ()
checkTc (Bool
existential_ok Bool -> Bool -> Bool
|| DataCon -> Bool
isVanillaDataCon DataCon
con)
                  (DataCon -> SDoc
badExistential DataCon
con)

          -- Check that UNPACK pragmas and bangs work out
          -- E.g.  reject   data T = MkT {-# UNPACK #-} Int     -- No "!"
          --                data T = MkT {-# UNPACK #-} !a      -- Can't unpack
        ; (HsSrcBang -> HsImplBang -> Int -> TcRn ())
-> [HsSrcBang] -> [HsImplBang] -> [Int] -> TcRn ()
forall (m :: * -> *) a b c d.
Monad m =>
(a -> b -> c -> m d) -> [a] -> [b] -> [c] -> m ()
zipWith3M_ HsSrcBang -> HsImplBang -> Int -> TcRn ()
check_bang (DataCon -> [HsSrcBang]
dataConSrcBangs DataCon
con) (DataCon -> [HsImplBang]
dataConImplBangs DataCon
con) [Int
1..]

          -- Check the dcUserTyVarBinders invariant
          -- See Note [DataCon user type variable binders] in DataCon
          -- checked here because we sometimes build invalid DataCons before
          -- erroring above here
        ; Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
when Bool
debugIsOn (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
          do { let ([TcTyCoVar]
univs, [TcTyCoVar]
exs, [EqSpec]
eq_spec, [Kind]
_, [Kind]
_, Kind
_) = DataCon
-> ([TcTyCoVar], [TcTyCoVar], [EqSpec], [Kind], [Kind], Kind)
dataConFullSig DataCon
con
                   user_tvs :: [TcTyCoVar]
user_tvs                       = DataCon -> [TcTyCoVar]
dataConUserTyVars DataCon
con
                   user_tvbs_invariant :: Bool
user_tvbs_invariant
                     =    [TcTyCoVar] -> Set TcTyCoVar
forall a. Ord a => [a] -> Set a
Set.fromList ([EqSpec] -> [TcTyCoVar] -> [TcTyCoVar]
filterEqSpec [EqSpec]
eq_spec [TcTyCoVar]
univs [TcTyCoVar] -> [TcTyCoVar] -> [TcTyCoVar]
forall a. [a] -> [a] -> [a]
++ [TcTyCoVar]
exs)
                       Set TcTyCoVar -> Set TcTyCoVar -> Bool
forall a. Eq a => a -> a -> Bool
== [TcTyCoVar] -> Set TcTyCoVar
forall a. Ord a => [a] -> Set a
Set.fromList [TcTyCoVar]
user_tvs
             ; MASSERT2( user_tvbs_invariant
                       , vcat ([ ppr con
                               , ppr univs
                               , ppr exs
                               , ppr eq_spec
                               , ppr user_tvs ])) }

        ; String -> SDoc -> TcRn ()
traceTc String
"Done validity of data con" (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$
          [SDoc] -> SDoc
vcat [ DataCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr DataCon
con
               , String -> SDoc
text String
"Datacon user type:" SDoc -> SDoc -> SDoc
<+> Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr (DataCon -> Kind
dataConUserType DataCon
con)
               , String -> SDoc
text String
"Datacon rep type:" SDoc -> SDoc -> SDoc
<+> Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr (DataCon -> Kind
dataConRepType DataCon
con)
               , String -> SDoc
text String
"Rep typcon binders:" SDoc -> SDoc -> SDoc
<+> [TyConBinder] -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyCon -> [TyConBinder]
tyConBinders (DataCon -> TyCon
dataConTyCon DataCon
con))
               , case TyCon -> Maybe (TyCon, [Kind])
tyConFamInst_maybe (DataCon -> TyCon
dataConTyCon DataCon
con) of
                   Maybe (TyCon, [Kind])
Nothing -> String -> SDoc
text String
"not family"
                   Just (TyCon
f, [Kind]
_) -> [TyConBinder] -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyCon -> [TyConBinder]
tyConBinders TyCon
f) ]
    }
  where
    ctxt :: UserTypeCtxt
ctxt = Name -> UserTypeCtxt
ConArgCtxt (DataCon -> Name
dataConName DataCon
con)

    check_bang :: HsSrcBang -> HsImplBang -> Int -> TcM ()
    check_bang :: HsSrcBang -> HsImplBang -> Int -> TcRn ()
check_bang (HsSrcBang SourceText
_ SrcUnpackedness
_ SrcStrictness
SrcLazy) HsImplBang
_ Int
n
      | Bool -> Bool
not (Extension -> DynFlags -> Bool
xopt Extension
LangExt.StrictData DynFlags
dflags)
      = SDoc -> TcRn ()
addErrTc
          (Int -> SDoc -> SDoc
bad_bang Int
n (String -> SDoc
text String
"Lazy annotation (~) without StrictData"))
    check_bang (HsSrcBang SourceText
_ SrcUnpackedness
want_unpack SrcStrictness
strict_mark) HsImplBang
rep_bang Int
n
      | SrcUnpackedness -> Bool
isSrcUnpacked SrcUnpackedness
want_unpack, Bool -> Bool
not Bool
is_strict
      = WarnReason -> SDoc -> TcRn ()
addWarnTc WarnReason
NoReason (Int -> SDoc -> SDoc
bad_bang Int
n (String -> SDoc
text String
"UNPACK pragma lacks '!'"))
      | SrcUnpackedness -> Bool
isSrcUnpacked SrcUnpackedness
want_unpack
      , case HsImplBang
rep_bang of { HsUnpack {} -> Bool
False; HsImplBang
_ -> Bool
True }
      -- If not optimising, we don't unpack (rep_bang is never
      -- HsUnpack), so don't complain!  This happens, e.g., in Haddock.
      -- See dataConSrcToImplBang.
      , Bool -> Bool
not (GeneralFlag -> DynFlags -> Bool
gopt GeneralFlag
Opt_OmitInterfacePragmas DynFlags
dflags)
      -- When typechecking an indefinite package in Backpack, we
      -- may attempt to UNPACK an abstract type.  The test here will
      -- conclude that this is unusable, but it might become usable
      -- when we actually fill in the abstract type.  As such, don't
      -- warn in this case (it gives users the wrong idea about whether
      -- or not UNPACK on abstract types is supported; it is!)
      , UnitId -> Bool
unitIdIsDefinite (DynFlags -> UnitId
thisPackage DynFlags
dflags)
      = WarnReason -> SDoc -> TcRn ()
addWarnTc WarnReason
NoReason (Int -> SDoc -> SDoc
bad_bang Int
n (String -> SDoc
text String
"Ignoring unusable UNPACK pragma"))
      where
        is_strict :: Bool
is_strict = case SrcStrictness
strict_mark of
                      SrcStrictness
NoSrcStrict -> Extension -> DynFlags -> Bool
xopt Extension
LangExt.StrictData DynFlags
dflags
                      SrcStrictness
bang        -> SrcStrictness -> Bool
isSrcStrict SrcStrictness
bang

    check_bang HsSrcBang
_ HsImplBang
_ Int
_
      = () -> TcRn ()
forall (m :: * -> *) a. Monad m => a -> m a
return ()

    bad_bang :: Int -> SDoc -> SDoc
bad_bang Int
n SDoc
herald
      = SDoc -> Int -> SDoc -> SDoc
hang SDoc
herald Int
2 (String -> SDoc
text String
"on the" SDoc -> SDoc -> SDoc
<+> Int -> SDoc
speakNth Int
n
                       SDoc -> SDoc -> SDoc
<+> String -> SDoc
text String
"argument of" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (DataCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr DataCon
con))
-------------------------------
checkNewDataCon :: DataCon -> TcM ()
-- Further checks for the data constructor of a newtype
checkNewDataCon :: DataCon -> TcRn ()
checkNewDataCon DataCon
con
  = do  { Bool -> SDoc -> TcRn ()
checkTc ([Kind] -> Bool
forall a. [a] -> Bool
isSingleton [Kind]
arg_tys) (DataCon -> Int -> SDoc
newtypeFieldErr DataCon
con ([Kind] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length [Kind]
arg_tys))
              -- One argument

        ; Bool
unlifted_newtypes <- Extension -> TcRnIf TcGblEnv TcLclEnv Bool
forall gbl lcl. Extension -> TcRnIf gbl lcl Bool
xoptM Extension
LangExt.UnliftedNewtypes
        ; let allowedArgType :: Bool
allowedArgType =
                Bool
unlifted_newtypes Bool -> Bool -> Bool
|| HasDebugCallStack => Kind -> Maybe Bool
Kind -> Maybe Bool
isLiftedType_maybe Kind
arg_ty1 Maybe Bool -> Maybe Bool -> Bool
forall a. Eq a => a -> a -> Bool
== Bool -> Maybe Bool
forall a. a -> Maybe a
Just Bool
True
        ; Bool -> SDoc -> TcRn ()
checkTc Bool
allowedArgType (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$ [SDoc] -> SDoc
vcat
          [ String -> SDoc
text String
"A newtype cannot have an unlifted argument type"
          , String -> SDoc
text String
"Perhaps you intended to use UnliftedNewtypes"
          ]

        ; Bool -> SDoc -> TcRn ()
check_con ([EqSpec] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [EqSpec]
eq_spec) (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$
          String -> SDoc
text String
"A newtype constructor must have a return type of form T a1 ... an"
                -- Return type is (T a b c)

        ; Bool -> SDoc -> TcRn ()
check_con ([Kind] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [Kind]
theta) (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$
          String -> SDoc
text String
"A newtype constructor cannot have a context in its type"

        ; Bool -> SDoc -> TcRn ()
check_con ([TcTyCoVar] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [TcTyCoVar]
ex_tvs) (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$
          String -> SDoc
text String
"A newtype constructor cannot have existential type variables"
                -- No existentials

        ; Bool -> SDoc -> TcRn ()
checkTc ((HsSrcBang -> Bool) -> [HsSrcBang] -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
all HsSrcBang -> Bool
ok_bang (DataCon -> [HsSrcBang]
dataConSrcBangs DataCon
con))
                  (DataCon -> SDoc
newtypeStrictError DataCon
con)
                -- No strictness annotations
    }
  where
    ([TcTyCoVar]
_univ_tvs, [TcTyCoVar]
ex_tvs, [EqSpec]
eq_spec, [Kind]
theta, [Kind]
arg_tys, Kind
_res_ty)
      = DataCon
-> ([TcTyCoVar], [TcTyCoVar], [EqSpec], [Kind], [Kind], Kind)
dataConFullSig DataCon
con
    check_con :: Bool -> SDoc -> TcRn ()
check_con Bool
what SDoc
msg
       = Bool -> SDoc -> TcRn ()
checkTc Bool
what (SDoc
msg SDoc -> SDoc -> SDoc
$$ DataCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr DataCon
con SDoc -> SDoc -> SDoc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
<+> Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr (DataCon -> Kind
dataConUserType DataCon
con))

    (Kind
arg_ty1 : [Kind]
_) = [Kind]
arg_tys

    ok_bang :: HsSrcBang -> Bool
ok_bang (HsSrcBang SourceText
_ SrcUnpackedness
_ SrcStrictness
SrcStrict) = Bool
False
    ok_bang (HsSrcBang SourceText
_ SrcUnpackedness
_ SrcStrictness
SrcLazy)   = Bool
False
    ok_bang HsSrcBang
_                         = Bool
True

-------------------------------
checkValidClass :: Class -> TcM ()
checkValidClass :: Class -> TcRn ()
checkValidClass Class
cls
  = do  { Bool
constrained_class_methods <- Extension -> TcRnIf TcGblEnv TcLclEnv Bool
forall gbl lcl. Extension -> TcRnIf gbl lcl Bool
xoptM Extension
LangExt.ConstrainedClassMethods
        ; Bool
multi_param_type_classes  <- Extension -> TcRnIf TcGblEnv TcLclEnv Bool
forall gbl lcl. Extension -> TcRnIf gbl lcl Bool
xoptM Extension
LangExt.MultiParamTypeClasses
        ; Bool
nullary_type_classes      <- Extension -> TcRnIf TcGblEnv TcLclEnv Bool
forall gbl lcl. Extension -> TcRnIf gbl lcl Bool
xoptM Extension
LangExt.NullaryTypeClasses
        ; Bool
fundep_classes            <- Extension -> TcRnIf TcGblEnv TcLclEnv Bool
forall gbl lcl. Extension -> TcRnIf gbl lcl Bool
xoptM Extension
LangExt.FunctionalDependencies
        ; Bool
undecidable_super_classes <- Extension -> TcRnIf TcGblEnv TcLclEnv Bool
forall gbl lcl. Extension -> TcRnIf gbl lcl Bool
xoptM Extension
LangExt.UndecidableSuperClasses

        -- Check that the class is unary, unless multiparameter type classes
        -- are enabled; also recognize deprecated nullary type classes
        -- extension (subsumed by multiparameter type classes, #8993)
        ; Bool -> SDoc -> TcRn ()
checkTc (Bool
multi_param_type_classes Bool -> Bool -> Bool
|| Int
cls_arity Int -> Int -> Bool
forall a. Eq a => a -> a -> Bool
== Int
1 Bool -> Bool -> Bool
||
                    (Bool
nullary_type_classes Bool -> Bool -> Bool
&& Int
cls_arity Int -> Int -> Bool
forall a. Eq a => a -> a -> Bool
== Int
0))
                  (Int -> Class -> SDoc
classArityErr Int
cls_arity Class
cls)
        ; Bool -> SDoc -> TcRn ()
checkTc (Bool
fundep_classes Bool -> Bool -> Bool
|| [([TcTyCoVar], [TcTyCoVar])] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [([TcTyCoVar], [TcTyCoVar])]
fundeps) (Class -> SDoc
classFunDepsErr Class
cls)

        -- Check the super-classes
        ; UserTypeCtxt -> [Kind] -> TcRn ()
checkValidTheta (Name -> UserTypeCtxt
ClassSCCtxt (Class -> Name
className Class
cls)) [Kind]
theta

          -- Now check for cyclic superclasses
          -- If there are superclass cycles, checkClassCycleErrs bails.
        ; Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
unless Bool
undecidable_super_classes (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
          case Class -> Maybe SDoc
checkClassCycles Class
cls of
             Just SDoc
err -> SrcSpan -> TcRn () -> TcRn ()
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan (Class -> SrcSpan
forall a. NamedThing a => a -> SrcSpan
getSrcSpan Class
cls) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
                         SDoc -> TcRn ()
addErrTc SDoc
err
             Maybe SDoc
Nothing  -> () -> TcRn ()
forall (m :: * -> *) a. Monad m => a -> m a
return ()

        -- Check the class operations.
        -- But only if there have been no earlier errors
        -- See Note [Abort when superclass cycle is detected]
        ; TcRn () -> TcRn ()
whenNoErrs (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
          ((TcTyCoVar, DefMethInfo) -> TcRn ())
-> [(TcTyCoVar, DefMethInfo)] -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ (Bool -> (TcTyCoVar, DefMethInfo) -> TcRn ()
check_op Bool
constrained_class_methods) [(TcTyCoVar, DefMethInfo)]
op_stuff

        -- Check the associated type defaults are well-formed and instantiated
        ; (ClassATItem -> TcRn ()) -> [ClassATItem] -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ ClassATItem -> TcRn ()
check_at [ClassATItem]
at_stuff  }
  where
    ([TcTyCoVar]
tyvars, [([TcTyCoVar], [TcTyCoVar])]
fundeps, [Kind]
theta, [TcTyCoVar]
_, [ClassATItem]
at_stuff, [(TcTyCoVar, DefMethInfo)]
op_stuff) = Class
-> ([TcTyCoVar], [([TcTyCoVar], [TcTyCoVar])], [Kind], [TcTyCoVar],
    [ClassATItem], [(TcTyCoVar, DefMethInfo)])
classExtraBigSig Class
cls
    cls_arity :: Int
cls_arity = [TcTyCoVar] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length (TyCon -> [TcTyCoVar]
tyConVisibleTyVars (Class -> TyCon
classTyCon Class
cls))
       -- Ignore invisible variables
    cls_tv_set :: TyVarSet
cls_tv_set = [TcTyCoVar] -> TyVarSet
mkVarSet [TcTyCoVar]
tyvars

    check_op :: Bool -> (TcTyCoVar, DefMethInfo) -> TcRn ()
check_op Bool
constrained_class_methods (TcTyCoVar
sel_id, DefMethInfo
dm)
      = SrcSpan -> TcRn () -> TcRn ()
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan (TcTyCoVar -> SrcSpan
forall a. NamedThing a => a -> SrcSpan
getSrcSpan TcTyCoVar
sel_id) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
        SDoc -> TcRn () -> TcRn ()
forall a. SDoc -> TcM a -> TcM a
addErrCtxt (TcTyCoVar -> Kind -> SDoc
classOpCtxt TcTyCoVar
sel_id Kind
op_ty) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$ do
        { String -> SDoc -> TcRn ()
traceTc String
"class op type" (Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr Kind
op_ty)
        ; UserTypeCtxt -> Kind -> TcRn ()
checkValidType UserTypeCtxt
ctxt Kind
op_ty
                -- This implements the ambiguity check, among other things
                -- Example: tc223
                --   class Error e => Game b mv e | b -> mv e where
                --      newBoard :: MonadState b m => m ()
                -- Here, MonadState has a fundep m->b, so newBoard is fine

           -- a method cannot be levity polymorphic, as we have to store the
           -- method in a dictionary
           -- example of what this prevents:
           --   class BoundedX (a :: TYPE r) where minBound :: a
           -- See Note [Levity polymorphism checking] in DsMonad
        ; SDoc -> Kind -> TcRn ()
checkForLevPoly SDoc
empty Kind
tau1

        ; Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
unless Bool
constrained_class_methods (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
          (Kind -> TcRn ()) -> [Kind] -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ Kind -> TcRn ()
check_constraint ([Kind] -> [Kind]
forall a. [a] -> [a]
tail (Kind
cls_predKind -> [Kind] -> [Kind]
forall a. a -> [a] -> [a]
:[Kind]
op_theta))

        ; UserTypeCtxt -> TcTyCoVar -> Kind -> Kind -> DefMethInfo -> TcRn ()
check_dm UserTypeCtxt
ctxt TcTyCoVar
sel_id Kind
cls_pred Kind
tau2 DefMethInfo
dm
        }
        where
          ctxt :: UserTypeCtxt
ctxt    = Name -> Bool -> UserTypeCtxt
FunSigCtxt Name
op_name Bool
True -- Report redundant class constraints
          op_name :: Name
op_name = TcTyCoVar -> Name
idName TcTyCoVar
sel_id
          op_ty :: Kind
op_ty   = TcTyCoVar -> Kind
idType TcTyCoVar
sel_id
          ([TcTyCoVar]
_,Kind
cls_pred,Kind
tau1) = Kind -> ([TcTyCoVar], Kind, Kind)
tcSplitMethodTy Kind
op_ty
          -- See Note [Splitting nested sigma types in class type signatures]
          ([TcTyCoVar]
_,[Kind]
op_theta,Kind
tau2) = Kind -> ([TcTyCoVar], [Kind], Kind)
tcSplitNestedSigmaTys Kind
tau1

          check_constraint :: TcPredType -> TcM ()
          check_constraint :: Kind -> TcRn ()
check_constraint Kind
pred -- See Note [Class method constraints]
            = Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
when (Bool -> Bool
not (TyVarSet -> Bool
isEmptyVarSet TyVarSet
pred_tvs) Bool -> Bool -> Bool
&&
                    TyVarSet
pred_tvs TyVarSet -> TyVarSet -> Bool
`subVarSet` TyVarSet
cls_tv_set)
                   (SDoc -> TcRn ()
addErrTc (TcTyCoVar -> Kind -> SDoc
badMethPred TcTyCoVar
sel_id Kind
pred))
            where
              pred_tvs :: TyVarSet
pred_tvs = Kind -> TyVarSet
tyCoVarsOfType Kind
pred

    check_at :: ClassATItem -> TcRn ()
check_at (ATI TyCon
fam_tc Maybe (Kind, SrcSpan)
m_dflt_rhs)
      = do { Bool -> SDoc -> TcRn ()
checkTc (Int
cls_arity Int -> Int -> Bool
forall a. Eq a => a -> a -> Bool
== Int
0 Bool -> Bool -> Bool
|| (TcTyCoVar -> Bool) -> [TcTyCoVar] -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
any (TcTyCoVar -> TyVarSet -> Bool
`elemVarSet` TyVarSet
cls_tv_set) [TcTyCoVar]
fam_tvs)
                     (Class -> TyCon -> SDoc
noClassTyVarErr Class
cls TyCon
fam_tc)
                        -- Check that the associated type mentions at least
                        -- one of the class type variables
                        -- The check is disabled for nullary type classes,
                        -- since there is no possible ambiguity (#10020)

             -- Check that any default declarations for associated types are valid
           ; Maybe (Kind, SrcSpan) -> ((Kind, SrcSpan) -> TcRn ()) -> TcRn ()
forall (m :: * -> *) a. Monad m => Maybe a -> (a -> m ()) -> m ()
whenIsJust Maybe (Kind, SrcSpan)
m_dflt_rhs (((Kind, SrcSpan) -> TcRn ()) -> TcRn ())
-> ((Kind, SrcSpan) -> TcRn ()) -> TcRn ()
forall a b. (a -> b) -> a -> b
$ \ (Kind
rhs, SrcSpan
loc) ->
             SrcSpan -> TcRn () -> TcRn ()
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan SrcSpan
loc (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
             SDoc -> Name -> TcRn () -> TcRn ()
forall a. SDoc -> Name -> TcM a -> TcM a
tcAddFamInstCtxt (String -> SDoc
text String
"default type instance") (TyCon -> Name
forall a. NamedThing a => a -> Name
getName TyCon
fam_tc) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
             TyCon -> [TcTyCoVar] -> [Kind] -> Kind -> TcRn ()
checkValidTyFamEqn TyCon
fam_tc [TcTyCoVar]
fam_tvs ([TcTyCoVar] -> [Kind]
mkTyVarTys [TcTyCoVar]
fam_tvs) Kind
rhs }
        where
          fam_tvs :: [TcTyCoVar]
fam_tvs = TyCon -> [TcTyCoVar]
tyConTyVars TyCon
fam_tc

    check_dm :: UserTypeCtxt -> Id -> PredType -> Type -> DefMethInfo -> TcM ()
    -- Check validity of the /top-level/ generic-default type
    -- E.g for   class C a where
    --             default op :: forall b. (a~b) => blah
    -- we do not want to do an ambiguity check on a type with
    -- a free TyVar 'a' (#11608).  See TcType
    -- Note [TyVars and TcTyVars during type checking] in TcType
    -- Hence the mkDefaultMethodType to close the type.
    check_dm :: UserTypeCtxt -> TcTyCoVar -> Kind -> Kind -> DefMethInfo -> TcRn ()
check_dm UserTypeCtxt
ctxt TcTyCoVar
sel_id Kind
vanilla_cls_pred Kind
vanilla_tau
             (Just (Name
dm_name, dm_spec :: DefMethSpec Kind
dm_spec@(GenericDM Kind
dm_ty)))
      = SrcSpan -> TcRn () -> TcRn ()
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan (Name -> SrcSpan
forall a. NamedThing a => a -> SrcSpan
getSrcSpan Name
dm_name) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$ do
            -- We have carefully set the SrcSpan on the generic
            -- default-method Name to be that of the generic
            -- default type signature

          -- First, we check that that the method's default type signature
          -- aligns with the non-default type signature.
          -- See Note [Default method type signatures must align]
          let cls_pred :: Kind
cls_pred = Class -> [Kind] -> Kind
mkClassPred Class
cls ([Kind] -> Kind) -> [Kind] -> Kind
forall a b. (a -> b) -> a -> b
$ [TcTyCoVar] -> [Kind]
mkTyVarTys ([TcTyCoVar] -> [Kind]) -> [TcTyCoVar] -> [Kind]
forall a b. (a -> b) -> a -> b
$ Class -> [TcTyCoVar]
classTyVars Class
cls
              -- Note that the second field of this tuple contains the context
              -- of the default type signature, making it apparent that we
              -- ignore method contexts completely when validity-checking
              -- default type signatures. See the end of
              -- Note [Default method type signatures must align]
              -- to learn why this is OK.
              --
              -- See also
              -- Note [Splitting nested sigma types in class type signatures]
              -- for an explanation of why we don't use tcSplitSigmaTy here.
              ([TcTyCoVar]
_, [Kind]
_, Kind
dm_tau) = Kind -> ([TcTyCoVar], [Kind], Kind)
tcSplitNestedSigmaTys Kind
dm_ty

              -- Given this class definition:
              --
              --  class C a b where
              --    op         :: forall p q. (Ord a, D p q)
              --               => a -> b -> p -> (a, b)
              --    default op :: forall r s. E r
              --               => a -> b -> s -> (a, b)
              --
              -- We want to match up two types of the form:
              --
              --   Vanilla type sig: C aa bb => aa -> bb -> p -> (aa, bb)
              --   Default type sig: C a  b  => a  -> b  -> s -> (a,  b)
              --
              -- Notice that the two type signatures can be quantified over
              -- different class type variables! Therefore, it's important that
              -- we include the class predicate parts to match up a with aa and
              -- b with bb.
              vanilla_phi_ty :: Kind
vanilla_phi_ty = [Kind] -> Kind -> Kind
mkPhiTy [Kind
vanilla_cls_pred] Kind
vanilla_tau
              dm_phi_ty :: Kind
dm_phi_ty      = [Kind] -> Kind -> Kind
mkPhiTy [Kind
cls_pred] Kind
dm_tau

          String -> SDoc -> TcRn ()
traceTc String
"check_dm" (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$ [SDoc] -> SDoc
vcat
              [ String -> SDoc
text String
"vanilla_phi_ty" SDoc -> SDoc -> SDoc
<+> Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr Kind
vanilla_phi_ty
              , String -> SDoc
text String
"dm_phi_ty"      SDoc -> SDoc -> SDoc
<+> Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr Kind
dm_phi_ty ]

          -- Actually checking that the types align is done with a call to
          -- tcMatchTys. We need to get a match in both directions to rule
          -- out degenerate cases like these:
          --
          --  class Foo a where
          --    foo1         :: a -> b
          --    default foo1 :: a -> Int
          --
          --    foo2         :: a -> Int
          --    default foo2 :: a -> b
          Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
unless (Maybe TCvSubst -> Bool
forall a. Maybe a -> Bool
isJust (Maybe TCvSubst -> Bool) -> Maybe TCvSubst -> Bool
forall a b. (a -> b) -> a -> b
$ [Kind] -> [Kind] -> Maybe TCvSubst
tcMatchTys [Kind
dm_phi_ty, Kind
vanilla_phi_ty]
                                      [Kind
vanilla_phi_ty, Kind
dm_phi_ty]) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$ SDoc -> TcRn ()
addErrTc (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$
               SDoc -> Int -> SDoc -> SDoc
hang (String -> SDoc
text String
"The default type signature for"
                     SDoc -> SDoc -> SDoc
<+> TcTyCoVar -> SDoc
forall a. Outputable a => a -> SDoc
ppr TcTyCoVar
sel_id SDoc -> SDoc -> SDoc
<> SDoc
colon)
                 Int
2 (Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr Kind
dm_ty)
            SDoc -> SDoc -> SDoc
$$ (String -> SDoc
text String
"does not match its corresponding"
                SDoc -> SDoc -> SDoc
<+> String -> SDoc
text String
"non-default type signature")

          -- Now do an ambiguity check on the default type signature.
          UserTypeCtxt -> Kind -> TcRn ()
checkValidType UserTypeCtxt
ctxt (Class -> TcTyCoVar -> DefMethSpec Kind -> Kind
mkDefaultMethodType Class
cls TcTyCoVar
sel_id DefMethSpec Kind
dm_spec)
    check_dm UserTypeCtxt
_ TcTyCoVar
_ Kind
_ Kind
_ DefMethInfo
_ = () -> TcRn ()
forall (m :: * -> *) a. Monad m => a -> m a
return ()

checkFamFlag :: Name -> TcM ()
-- Check that we don't use families without -XTypeFamilies
-- The parser won't even parse them, but I suppose a GHC API
-- client might have a go!
checkFamFlag :: Name -> TcRn ()
checkFamFlag Name
tc_name
  = do { Bool
idx_tys <- Extension -> TcRnIf TcGblEnv TcLclEnv Bool
forall gbl lcl. Extension -> TcRnIf gbl lcl Bool
xoptM Extension
LangExt.TypeFamilies
       ; Bool -> SDoc -> TcRn ()
checkTc Bool
idx_tys SDoc
err_msg }
  where
    err_msg :: SDoc
err_msg = SDoc -> Int -> SDoc -> SDoc
hang (String -> SDoc
text String
"Illegal family declaration for" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
tc_name))
                 Int
2 (String -> SDoc
text String
"Enable TypeFamilies to allow indexed type families")

checkResultSigFlag :: Name -> FamilyResultSig GhcRn -> TcM ()
checkResultSigFlag :: Name -> FamilyResultSig GhcRn -> TcRn ()
checkResultSigFlag Name
tc_name (TyVarSig XTyVarSig GhcRn
_ GenLocated SrcSpan (HsTyVarBndr GhcRn)
tvb)
  = do { Bool
ty_fam_deps <- Extension -> TcRnIf TcGblEnv TcLclEnv Bool
forall gbl lcl. Extension -> TcRnIf gbl lcl Bool
xoptM Extension
LangExt.TypeFamilyDependencies
       ; Bool -> SDoc -> TcRn ()
checkTc Bool
ty_fam_deps (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$
         SDoc -> Int -> SDoc -> SDoc
hang (String -> SDoc
text String
"Illegal result type variable" SDoc -> SDoc -> SDoc
<+> GenLocated SrcSpan (HsTyVarBndr GhcRn) -> SDoc
forall a. Outputable a => a -> SDoc
ppr GenLocated SrcSpan (HsTyVarBndr GhcRn)
tvb SDoc -> SDoc -> SDoc
<+> String -> SDoc
text String
"for" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
tc_name))
            Int
2 (String -> SDoc
text String
"Enable TypeFamilyDependencies to allow result variable names") }
checkResultSigFlag Name
_ FamilyResultSig GhcRn
_ = () -> TcRn ()
forall (m :: * -> *) a. Monad m => a -> m a
return ()  -- other cases OK

{- Note [Class method constraints]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Haskell 2010 is supposed to reject
  class C a where
    op :: Eq a => a -> a
where the method type constrains only the class variable(s).  (The extension
-XConstrainedClassMethods switches off this check.)  But regardless
we should not reject
  class C a where
    op :: (?x::Int) => a -> a
as pointed out in #11793. So the test here rejects the program if
  * -XConstrainedClassMethods is off
  * the tyvars of the constraint are non-empty
  * all the tyvars are class tyvars, none are locally quantified

Note [Abort when superclass cycle is detected]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We must avoid doing the ambiguity check for the methods (in
checkValidClass.check_op) when there are already errors accumulated.
This is because one of the errors may be a superclass cycle, and
superclass cycles cause canonicalization to loop. Here is a
representative example:

  class D a => C a where
    meth :: D a => ()
  class C a => D a

This fixes #9415, #9739

Note [Default method type signatures must align]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
GHC enforces the invariant that a class method's default type signature
must "align" with that of the method's non-default type signature, as per
GHC #12918. For instance, if you have:

  class Foo a where
    bar :: forall b. Context => a -> b

Then a default type signature for bar must be alpha equivalent to
(forall b. a -> b). That is, the types must be the same modulo differences in
contexts. So the following would be acceptable default type signatures:

    default bar :: forall b. Context1 => a -> b
    default bar :: forall x. Context2 => a -> x

But the following are NOT acceptable default type signatures:

    default bar :: forall b. b -> a
    default bar :: forall x. x
    default bar :: a -> Int

Note that a is bound by the class declaration for Foo itself, so it is
not allowed to differ in the default type signature.

The default type signature (default bar :: a -> Int) deserves special mention,
since (a -> Int) is a straightforward instantiation of (forall b. a -> b). To
write this, you need to declare the default type signature like so:

    default bar :: forall b. (b ~ Int). a -> b

As noted in #12918, there are several reasons to do this:

1. It would make no sense to have a type that was flat-out incompatible with
   the non-default type signature. For instance, if you had:

     class Foo a where
       bar :: a -> Int
       default bar :: a -> Bool

   Then that would always fail in an instance declaration. So this check
   nips such cases in the bud before they have the chance to produce
   confusing error messages.

2. Internally, GHC uses TypeApplications to instantiate the default method in
   an instance. See Note [Default methods in instances] in TcInstDcls.
   Thus, GHC needs to know exactly what the universally quantified type
   variables are, and when instantiated that way, the default method's type
   must match the expected type.

3. Aesthetically, by only allowing the default type signature to differ in its
   context, we are making it more explicit the ways in which the default type
   signature is less polymorphic than the non-default type signature.

You might be wondering: why are the contexts allowed to be different, but not
the rest of the type signature? That's because default implementations often
rely on assumptions that the more general, non-default type signatures do not.
For instance, in the Enum class declaration:

    class Enum a where
      enum :: [a]
      default enum :: (Generic a, GEnum (Rep a)) => [a]
      enum = map to genum

    class GEnum f where
      genum :: [f a]

The default implementation for enum only works for types that are instances of
Generic, and for which their generic Rep type is an instance of GEnum. But
clearly enum doesn't _have_ to use this implementation, so naturally, the
context for enum is allowed to be different to accommodate this. As a result,
when we validity-check default type signatures, we ignore contexts completely.

Note that when checking whether two type signatures match, we must take care to
split as many foralls as it takes to retrieve the tau types we which to check.
See Note [Splitting nested sigma types in class type signatures].

Note [Splitting nested sigma types in class type signatures]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider this type synonym and class definition:

  type Traversal s t a b = forall f. Applicative f => (a -> f b) -> s -> f t

  class Each s t a b where
    each         ::                                      Traversal s t a b
    default each :: (Traversable g, s ~ g a, t ~ g b) => Traversal s t a b

It might seem obvious that the tau types in both type signatures for `each`
are the same, but actually getting GHC to conclude this is surprisingly tricky.
That is because in general, the form of a class method's non-default type
signature is:

  forall a. C a => forall d. D d => E a b

And the general form of a default type signature is:

  forall f. F f => E a f -- The variable `a` comes from the class

So it you want to get the tau types in each type signature, you might find it
reasonable to call tcSplitSigmaTy twice on the non-default type signature, and
call it once on the default type signature. For most classes and methods, this
will work, but Each is a bit of an exceptional case. The way `each` is written,
it doesn't quantify any additional type variables besides those of the Each
class itself, so the non-default type signature for `each` is actually this:

  forall s t a b. Each s t a b => Traversal s t a b

Notice that there _appears_ to only be one forall. But there's actually another
forall lurking in the Traversal type synonym, so if you call tcSplitSigmaTy
twice, you'll also go under the forall in Traversal! That is, you'll end up
with:

  (a -> f b) -> s -> f t

A problem arises because you only call tcSplitSigmaTy once on the default type
signature for `each`, which gives you

  Traversal s t a b

Or, equivalently:

  forall f. Applicative f => (a -> f b) -> s -> f t

This is _not_ the same thing as (a -> f b) -> s -> f t! So now tcMatchTy will
say that the tau types for `each` are not equal.

A solution to this problem is to use tcSplitNestedSigmaTys instead of
tcSplitSigmaTy. tcSplitNestedSigmaTys will always split any foralls that it
sees until it can't go any further, so if you called it on the default type
signature for `each`, it would return (a -> f b) -> s -> f t like we desired.

Note [Checking partial record field]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This check checks the partial record field selector, and warns (#7169).

For example:

  data T a = A { m1 :: a, m2 :: a } | B { m1 :: a }

The function 'm2' is partial record field, and will fail when it is applied to
'B'. The warning identifies such partial fields. The check is performed at the
declaration of T, not at the call-sites of m2.

The warning can be suppressed by prefixing the field-name with an underscore.
For example:

  data T a = A { m1 :: a, _m2 :: a } | B { m1 :: a }

************************************************************************
*                                                                      *
                Checking role validity
*                                                                      *
************************************************************************
-}

checkValidRoleAnnots :: RoleAnnotEnv -> TyCon -> TcM ()
checkValidRoleAnnots :: RoleAnnotEnv -> TyCon -> TcRn ()
checkValidRoleAnnots RoleAnnotEnv
role_annots TyCon
tc
  | TyCon -> Bool
isTypeSynonymTyCon TyCon
tc = TcRn ()
check_no_roles
  | TyCon -> Bool
isFamilyTyCon TyCon
tc      = TcRn ()
check_no_roles
  | TyCon -> Bool
isAlgTyCon TyCon
tc         = TcRn ()
check_roles
  | Bool
otherwise             = () -> TcRn ()
forall (m :: * -> *) a. Monad m => a -> m a
return ()
  where
    -- Role annotations are given only on *explicit* variables,
    -- but a tycon stores roles for all variables.
    -- So, we drop the implicit roles (which are all Nominal, anyway).
    name :: Name
name                   = TyCon -> Name
tyConName TyCon
tc
    roles :: [Role]
roles                  = TyCon -> [Role]
tyConRoles TyCon
tc
    ([Role]
vis_roles, [TcTyCoVar]
vis_vars)  = [(Role, TcTyCoVar)] -> ([Role], [TcTyCoVar])
forall a b. [(a, b)] -> ([a], [b])
unzip ([(Role, TcTyCoVar)] -> ([Role], [TcTyCoVar]))
-> [(Role, TcTyCoVar)] -> ([Role], [TcTyCoVar])
forall a b. (a -> b) -> a -> b
$ ((Role, TyConBinder) -> Maybe (Role, TcTyCoVar))
-> [(Role, TyConBinder)] -> [(Role, TcTyCoVar)]
forall a b. (a -> Maybe b) -> [a] -> [b]
mapMaybe (Role, TyConBinder) -> Maybe (Role, TcTyCoVar)
pick_vis ([(Role, TyConBinder)] -> [(Role, TcTyCoVar)])
-> [(Role, TyConBinder)] -> [(Role, TcTyCoVar)]
forall a b. (a -> b) -> a -> b
$
                             [Role] -> [TyConBinder] -> [(Role, TyConBinder)]
forall a b. [a] -> [b] -> [(a, b)]
zip [Role]
roles (TyCon -> [TyConBinder]
tyConBinders TyCon
tc)
    role_annot_decl_maybe :: Maybe (LRoleAnnotDecl GhcRn)
role_annot_decl_maybe  = RoleAnnotEnv -> Name -> Maybe (LRoleAnnotDecl GhcRn)
lookupRoleAnnot RoleAnnotEnv
role_annots Name
name

    pick_vis :: (Role, TyConBinder) -> Maybe (Role, TyVar)
    pick_vis :: (Role, TyConBinder) -> Maybe (Role, TcTyCoVar)
pick_vis (Role
role, TyConBinder
tvb)
      | TyConBinder -> Bool
forall tv. VarBndr tv TyConBndrVis -> Bool
isVisibleTyConBinder TyConBinder
tvb = (Role, TcTyCoVar) -> Maybe (Role, TcTyCoVar)
forall a. a -> Maybe a
Just (Role
role, TyConBinder -> TcTyCoVar
forall tv argf. VarBndr tv argf -> tv
binderVar TyConBinder
tvb)
      | Bool
otherwise                = Maybe (Role, TcTyCoVar)
forall a. Maybe a
Nothing

    check_roles :: TcRn ()
check_roles
      = Maybe (LRoleAnnotDecl GhcRn)
-> (LRoleAnnotDecl GhcRn -> TcRn ()) -> TcRn ()
forall (m :: * -> *) a. Monad m => Maybe a -> (a -> m ()) -> m ()
whenIsJust Maybe (LRoleAnnotDecl GhcRn)
role_annot_decl_maybe ((LRoleAnnotDecl GhcRn -> TcRn ()) -> TcRn ())
-> (LRoleAnnotDecl GhcRn -> TcRn ()) -> TcRn ()
forall a b. (a -> b) -> a -> b
$
          \decl :: LRoleAnnotDecl GhcRn
decl@(L SrcSpan
loc (RoleAnnotDecl XCRoleAnnotDecl GhcRn
_ GenLocated SrcSpan (IdP GhcRn)
_ [Located (Maybe Role)]
the_role_annots)) ->
          Name -> TcRn () -> TcRn ()
forall a. Name -> TcM a -> TcM a
addRoleAnnotCtxt Name
name (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
          SrcSpan -> TcRn () -> TcRn ()
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan SrcSpan
loc (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$ do
          { Bool
role_annots_ok <- Extension -> TcRnIf TcGblEnv TcLclEnv Bool
forall gbl lcl. Extension -> TcRnIf gbl lcl Bool
xoptM Extension
LangExt.RoleAnnotations
          ; Bool -> SDoc -> TcRn ()
checkTc Bool
role_annots_ok (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$ TyCon -> SDoc
needXRoleAnnotations TyCon
tc
          ; Bool -> SDoc -> TcRn ()
checkTc ([TcTyCoVar]
vis_vars [TcTyCoVar] -> [Located (Maybe Role)] -> Bool
forall a b. [a] -> [b] -> Bool
`equalLength` [Located (Maybe Role)]
the_role_annots)
                    ([TcTyCoVar] -> LRoleAnnotDecl GhcRn -> SDoc
forall a. [a] -> LRoleAnnotDecl GhcRn -> SDoc
wrongNumberOfRoles [TcTyCoVar]
vis_vars LRoleAnnotDecl GhcRn
decl)
          ; [()]
_ <- (TcTyCoVar -> Located (Maybe Role) -> Role -> TcRn ())
-> [TcTyCoVar]
-> [Located (Maybe Role)]
-> [Role]
-> IOEnv (Env TcGblEnv TcLclEnv) [()]
forall (m :: * -> *) a b c d.
Monad m =>
(a -> b -> c -> m d) -> [a] -> [b] -> [c] -> m [d]
zipWith3M TcTyCoVar -> Located (Maybe Role) -> Role -> TcRn ()
checkRoleAnnot [TcTyCoVar]
vis_vars [Located (Maybe Role)]
the_role_annots [Role]
vis_roles
          -- Representational or phantom roles for class parameters
          -- quickly lead to incoherence. So, we require
          -- IncoherentInstances to have them. See #8773, #14292
          ; Bool
incoherent_roles_ok <- Extension -> TcRnIf TcGblEnv TcLclEnv Bool
forall gbl lcl. Extension -> TcRnIf gbl lcl Bool
xoptM Extension
LangExt.IncoherentInstances
          ; Bool -> SDoc -> TcRn ()
checkTc (  Bool
incoherent_roles_ok
                    Bool -> Bool -> Bool
|| (Bool -> Bool
not (Bool -> Bool) -> Bool -> Bool
forall a b. (a -> b) -> a -> b
$ TyCon -> Bool
isClassTyCon TyCon
tc)
                    Bool -> Bool -> Bool
|| ((Role -> Bool) -> [Role] -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
all (Role -> Role -> Bool
forall a. Eq a => a -> a -> Bool
== Role
Nominal) [Role]
vis_roles))
                    SDoc
incoherentRoles

          ; Bool
lint <- GeneralFlag -> TcRnIf TcGblEnv TcLclEnv Bool
forall gbl lcl. GeneralFlag -> TcRnIf gbl lcl Bool
goptM GeneralFlag
Opt_DoCoreLinting
          ; Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
when Bool
lint (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$ TyCon -> TcRn ()
checkValidRoles TyCon
tc }

    check_no_roles :: TcRn ()
check_no_roles
      = Maybe (LRoleAnnotDecl GhcRn)
-> (LRoleAnnotDecl GhcRn -> TcRn ()) -> TcRn ()
forall (m :: * -> *) a. Monad m => Maybe a -> (a -> m ()) -> m ()
whenIsJust Maybe (LRoleAnnotDecl GhcRn)
role_annot_decl_maybe LRoleAnnotDecl GhcRn -> TcRn ()
illegalRoleAnnotDecl

checkRoleAnnot :: TyVar -> Located (Maybe Role) -> Role -> TcM ()
checkRoleAnnot :: TcTyCoVar -> Located (Maybe Role) -> Role -> TcRn ()
checkRoleAnnot TcTyCoVar
_  (L SrcSpan
_ Maybe Role
Nothing)   Role
_  = () -> TcRn ()
forall (m :: * -> *) a. Monad m => a -> m a
return ()
checkRoleAnnot TcTyCoVar
tv (L SrcSpan
_ (Just Role
r1)) Role
r2
  = Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
when (Role
r1 Role -> Role -> Bool
forall a. Eq a => a -> a -> Bool
/= Role
r2) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
    SDoc -> TcRn ()
addErrTc (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$ Name -> Role -> Role -> SDoc
badRoleAnnot (TcTyCoVar -> Name
tyVarName TcTyCoVar
tv) Role
r1 Role
r2

-- This is a double-check on the role inference algorithm. It is only run when
-- -dcore-lint is enabled. See Note [Role inference] in TcTyDecls
checkValidRoles :: TyCon -> TcM ()
-- If you edit this function, you may need to update the GHC formalism
-- See Note [GHC Formalism] in CoreLint
checkValidRoles :: TyCon -> TcRn ()
checkValidRoles TyCon
tc
  | TyCon -> Bool
isAlgTyCon TyCon
tc
    -- tyConDataCons returns an empty list for data families
  = (DataCon -> TcRn ()) -> [DataCon] -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ DataCon -> TcRn ()
check_dc_roles (TyCon -> [DataCon]
tyConDataCons TyCon
tc)
  | Just Kind
rhs <- TyCon -> Maybe Kind
synTyConRhs_maybe TyCon
tc
  = UniqFM Role -> Role -> Kind -> TcRn ()
check_ty_roles ([TcTyCoVar] -> [Role] -> UniqFM Role
forall a. [TcTyCoVar] -> [a] -> VarEnv a
zipVarEnv (TyCon -> [TcTyCoVar]
tyConTyVars TyCon
tc) (TyCon -> [Role]
tyConRoles TyCon
tc)) Role
Representational Kind
rhs
  | Bool
otherwise
  = () -> TcRn ()
forall (m :: * -> *) a. Monad m => a -> m a
return ()
  where
    check_dc_roles :: DataCon -> TcRn ()
check_dc_roles DataCon
datacon
      = do { String -> SDoc -> TcRn ()
traceTc String
"check_dc_roles" (DataCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr DataCon
datacon SDoc -> SDoc -> SDoc
<+> [Role] -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyCon -> [Role]
tyConRoles TyCon
tc))
           ; (Kind -> TcRn ()) -> [Kind] -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ (UniqFM Role -> Role -> Kind -> TcRn ()
check_ty_roles UniqFM Role
role_env Role
Representational) ([Kind] -> TcRn ()) -> [Kind] -> TcRn ()
forall a b. (a -> b) -> a -> b
$
                    [EqSpec] -> [Kind]
eqSpecPreds [EqSpec]
eq_spec [Kind] -> [Kind] -> [Kind]
forall a. [a] -> [a] -> [a]
++ [Kind]
theta [Kind] -> [Kind] -> [Kind]
forall a. [a] -> [a] -> [a]
++ [Kind]
arg_tys }
                    -- See Note [Role-checking data constructor arguments] in TcTyDecls
      where
        ([TcTyCoVar]
univ_tvs, [TcTyCoVar]
ex_tvs, [EqSpec]
eq_spec, [Kind]
theta, [Kind]
arg_tys, Kind
_res_ty)
          = DataCon
-> ([TcTyCoVar], [TcTyCoVar], [EqSpec], [Kind], [Kind], Kind)
dataConFullSig DataCon
datacon
        univ_roles :: UniqFM Role
univ_roles = [TcTyCoVar] -> [Role] -> UniqFM Role
forall a. [TcTyCoVar] -> [a] -> VarEnv a
zipVarEnv [TcTyCoVar]
univ_tvs (TyCon -> [Role]
tyConRoles TyCon
tc)
              -- zipVarEnv uses zipEqual, but we don't want that for ex_tvs
        ex_roles :: UniqFM Role
ex_roles   = [(TcTyCoVar, Role)] -> UniqFM Role
forall a. [(TcTyCoVar, a)] -> VarEnv a
mkVarEnv ((TcTyCoVar -> (TcTyCoVar, Role))
-> [TcTyCoVar] -> [(TcTyCoVar, Role)]
forall a b. (a -> b) -> [a] -> [b]
map (, Role
Nominal) [TcTyCoVar]
ex_tvs)
        role_env :: UniqFM Role
role_env   = UniqFM Role
univ_roles UniqFM Role -> UniqFM Role -> UniqFM Role
forall a. NameEnv a -> NameEnv a -> NameEnv a
`plusVarEnv` UniqFM Role
ex_roles

    check_ty_roles :: UniqFM Role -> Role -> Kind -> TcRn ()
check_ty_roles UniqFM Role
env Role
role Kind
ty
      | Just Kind
ty' <- Kind -> Maybe Kind
coreView Kind
ty -- #14101
      = UniqFM Role -> Role -> Kind -> TcRn ()
check_ty_roles UniqFM Role
env Role
role Kind
ty'

    check_ty_roles UniqFM Role
env Role
role (TyVarTy TcTyCoVar
tv)
      = case UniqFM Role -> TcTyCoVar -> Maybe Role
forall a. VarEnv a -> TcTyCoVar -> Maybe a
lookupVarEnv UniqFM Role
env TcTyCoVar
tv of
          Just Role
role' -> Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
unless (Role
role' Role -> Role -> Bool
`ltRole` Role
role Bool -> Bool -> Bool
|| Role
role' Role -> Role -> Bool
forall a. Eq a => a -> a -> Bool
== Role
role) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
                        SDoc -> TcRn ()
report_error (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$ String -> SDoc
text String
"type variable" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (TcTyCoVar -> SDoc
forall a. Outputable a => a -> SDoc
ppr TcTyCoVar
tv) SDoc -> SDoc -> SDoc
<+>
                                       String -> SDoc
text String
"cannot have role" SDoc -> SDoc -> SDoc
<+> Role -> SDoc
forall a. Outputable a => a -> SDoc
ppr Role
role SDoc -> SDoc -> SDoc
<+>
                                       String -> SDoc
text String
"because it was assigned role" SDoc -> SDoc -> SDoc
<+> Role -> SDoc
forall a. Outputable a => a -> SDoc
ppr Role
role'
          Maybe Role
Nothing    -> SDoc -> TcRn ()
report_error (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$ String -> SDoc
text String
"type variable" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (TcTyCoVar -> SDoc
forall a. Outputable a => a -> SDoc
ppr TcTyCoVar
tv) SDoc -> SDoc -> SDoc
<+>
                                       String -> SDoc
text String
"missing in environment"

    check_ty_roles UniqFM Role
env Role
Representational (TyConApp TyCon
tc [Kind]
tys)
      = let roles' :: [Role]
roles' = TyCon -> [Role]
tyConRoles TyCon
tc in
        (Role -> Kind -> TcRn ()) -> [Role] -> [Kind] -> TcRn ()
forall (m :: * -> *) a b c.
Applicative m =>
(a -> b -> m c) -> [a] -> [b] -> m ()
zipWithM_ (UniqFM Role -> Role -> Kind -> TcRn ()
maybe_check_ty_roles UniqFM Role
env) [Role]
roles' [Kind]
tys

    check_ty_roles UniqFM Role
env Role
Nominal (TyConApp TyCon
_ [Kind]
tys)
      = (Kind -> TcRn ()) -> [Kind] -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ (UniqFM Role -> Role -> Kind -> TcRn ()
check_ty_roles UniqFM Role
env Role
Nominal) [Kind]
tys

    check_ty_roles UniqFM Role
_   Role
Phantom ty :: Kind
ty@(TyConApp {})
      = String -> SDoc -> TcRn ()
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"check_ty_roles" (Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr Kind
ty)

    check_ty_roles UniqFM Role
env Role
role (AppTy Kind
ty1 Kind
ty2)
      =  UniqFM Role -> Role -> Kind -> TcRn ()
check_ty_roles UniqFM Role
env Role
role    Kind
ty1
      TcRn () -> TcRn () -> TcRn ()
forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> UniqFM Role -> Role -> Kind -> TcRn ()
check_ty_roles UniqFM Role
env Role
Nominal Kind
ty2

    check_ty_roles UniqFM Role
env Role
role (FunTy AnonArgFlag
_ Kind
ty1 Kind
ty2)
      =  UniqFM Role -> Role -> Kind -> TcRn ()
check_ty_roles UniqFM Role
env Role
role Kind
ty1
      TcRn () -> TcRn () -> TcRn ()
forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> UniqFM Role -> Role -> Kind -> TcRn ()
check_ty_roles UniqFM Role
env Role
role Kind
ty2

    check_ty_roles UniqFM Role
env Role
role (ForAllTy (Bndr TcTyCoVar
tv ArgFlag
_) Kind
ty)
      =  UniqFM Role -> Role -> Kind -> TcRn ()
check_ty_roles UniqFM Role
env Role
Nominal (TcTyCoVar -> Kind
tyVarKind TcTyCoVar
tv)
      TcRn () -> TcRn () -> TcRn ()
forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> UniqFM Role -> Role -> Kind -> TcRn ()
check_ty_roles (UniqFM Role -> TcTyCoVar -> Role -> UniqFM Role
forall a. VarEnv a -> TcTyCoVar -> a -> VarEnv a
extendVarEnv UniqFM Role
env TcTyCoVar
tv Role
Nominal) Role
role Kind
ty

    check_ty_roles UniqFM Role
_   Role
_    (LitTy {}) = () -> TcRn ()
forall (m :: * -> *) a. Monad m => a -> m a
return ()

    check_ty_roles UniqFM Role
env Role
role (CastTy Kind
t Coercion
_)
      = UniqFM Role -> Role -> Kind -> TcRn ()
check_ty_roles UniqFM Role
env Role
role Kind
t

    check_ty_roles UniqFM Role
_   Role
role (CoercionTy Coercion
co)
      = Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
unless (Role
role Role -> Role -> Bool
forall a. Eq a => a -> a -> Bool
== Role
Phantom) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
        SDoc -> TcRn ()
report_error (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$ String -> SDoc
text String
"coercion" SDoc -> SDoc -> SDoc
<+> Coercion -> SDoc
forall a. Outputable a => a -> SDoc
ppr Coercion
co SDoc -> SDoc -> SDoc
<+> String -> SDoc
text String
"has bad role" SDoc -> SDoc -> SDoc
<+> Role -> SDoc
forall a. Outputable a => a -> SDoc
ppr Role
role

    maybe_check_ty_roles :: UniqFM Role -> Role -> Kind -> TcRn ()
maybe_check_ty_roles UniqFM Role
env Role
role Kind
ty
      = Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
when (Role
role Role -> Role -> Bool
forall a. Eq a => a -> a -> Bool
== Role
Nominal Bool -> Bool -> Bool
|| Role
role Role -> Role -> Bool
forall a. Eq a => a -> a -> Bool
== Role
Representational) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
        UniqFM Role -> Role -> Kind -> TcRn ()
check_ty_roles UniqFM Role
env Role
role Kind
ty

    report_error :: SDoc -> TcRn ()
report_error SDoc
doc
      = SDoc -> TcRn ()
addErrTc (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$ [SDoc] -> SDoc
vcat [String -> SDoc
text String
"Internal error in role inference:",
                         SDoc
doc,
                         String -> SDoc
text String
"Please report this as a GHC bug:  https://www.haskell.org/ghc/reportabug"]

{-
************************************************************************
*                                                                      *
                Error messages
*                                                                      *
************************************************************************
-}

addVDQNote :: TcTyCon -> TcM a -> TcM a
-- See Note [Inferring visible dependent quantification]
-- Only types without a signature (CUSK or SAK) here
addVDQNote :: TyCon -> TcM a -> TcM a
addVDQNote TyCon
tycon TcM a
thing_inside
  | ASSERT2( isTcTyCon tycon, ppr tycon )
    ASSERT2( not (tcTyConIsPoly tycon), ppr tycon $$ ppr tc_kind )
    Bool
has_vdq
  = SDoc -> TcM a -> TcM a
forall a. SDoc -> TcM a -> TcM a
addLandmarkErrCtxt SDoc
vdq_warning TcM a
thing_inside
  | Bool
otherwise
  = TcM a
thing_inside
  where
      -- Check whether a tycon has visible dependent quantification.
      -- This will *always* be a TcTyCon. Furthermore, it will *always*
      -- be an ungeneralised TcTyCon, straight out of kcInferDeclHeader.
      -- Thus, all the TyConBinders will be anonymous. Thus, the
      -- free variables of the tycon's kind will be the same as the free
      -- variables from all the binders.
    has_vdq :: Bool
has_vdq  = (TyConBinder -> Bool) -> [TyConBinder] -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
any TyConBinder -> Bool
is_vdq_tcb (TyCon -> [TyConBinder]
tyConBinders TyCon
tycon)
    tc_kind :: Kind
tc_kind  = TyCon -> Kind
tyConKind TyCon
tycon
    kind_fvs :: TyVarSet
kind_fvs = Kind -> TyVarSet
tyCoVarsOfType Kind
tc_kind

    is_vdq_tcb :: TyConBinder -> Bool
is_vdq_tcb TyConBinder
tcb = (TyConBinder -> TcTyCoVar
forall tv argf. VarBndr tv argf -> tv
binderVar TyConBinder
tcb TcTyCoVar -> TyVarSet -> Bool
`elemVarSet` TyVarSet
kind_fvs) Bool -> Bool -> Bool
&&
                     TyConBinder -> Bool
forall tv. VarBndr tv TyConBndrVis -> Bool
isVisibleTyConBinder TyConBinder
tcb

    vdq_warning :: SDoc
vdq_warning = [SDoc] -> SDoc
vcat
      [ String -> SDoc
text String
"NB: Type" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tycon) SDoc -> SDoc -> SDoc
<+>
        String -> SDoc
text String
"was inferred to use visible dependent quantification."
      , String -> SDoc
text String
"Most types with visible dependent quantification are"
      , String -> SDoc
text String
"polymorphically recursive and need a standalone kind"
      , String -> SDoc
text String
"signature. Perhaps supply one, with StandaloneKindSignatures."
      ]

tcAddTyFamInstCtxt :: TyFamInstDecl GhcRn -> TcM a -> TcM a
tcAddTyFamInstCtxt :: TyFamInstDecl GhcRn -> TcM a -> TcM a
tcAddTyFamInstCtxt TyFamInstDecl GhcRn
decl
  = SDoc -> Name -> TcM a -> TcM a
forall a. SDoc -> Name -> TcM a -> TcM a
tcAddFamInstCtxt (String -> SDoc
text String
"type instance") (TyFamInstDecl GhcRn -> IdP GhcRn
forall (p :: Pass). TyFamInstDecl (GhcPass p) -> IdP (GhcPass p)
tyFamInstDeclName TyFamInstDecl GhcRn
decl)

tcMkDataFamInstCtxt :: DataFamInstDecl GhcRn -> SDoc
tcMkDataFamInstCtxt :: DataFamInstDecl GhcRn -> SDoc
tcMkDataFamInstCtxt decl :: DataFamInstDecl GhcRn
decl@(DataFamInstDecl { dfid_eqn :: forall pass.
DataFamInstDecl pass -> FamInstEqn pass (HsDataDefn pass)
dfid_eqn =
                            HsIB { hsib_body :: forall pass thing. HsImplicitBndrs pass thing -> thing
hsib_body = FamEqn GhcRn (HsDataDefn GhcRn)
eqn }})
  = SDoc -> Name -> SDoc
tcMkFamInstCtxt (DataFamInstDecl GhcRn -> SDoc
forall (p :: Pass). DataFamInstDecl (GhcPass p) -> SDoc
pprDataFamInstFlavour DataFamInstDecl GhcRn
decl SDoc -> SDoc -> SDoc
<+> String -> SDoc
text String
"instance")
                    (GenLocated SrcSpan Name -> SrcSpanLess (GenLocated SrcSpan Name)
forall a. HasSrcSpan a => a -> SrcSpanLess a
unLoc (FamEqn GhcRn (HsDataDefn GhcRn) -> GenLocated SrcSpan (IdP GhcRn)
forall pass rhs. FamEqn pass rhs -> Located (IdP pass)
feqn_tycon FamEqn GhcRn (HsDataDefn GhcRn)
eqn))
tcMkDataFamInstCtxt (DataFamInstDecl (XHsImplicitBndrs XXHsImplicitBndrs GhcRn (FamEqn GhcRn (HsDataDefn GhcRn))
nec))
  = NoExtCon -> SDoc
forall a. NoExtCon -> a
noExtCon XXHsImplicitBndrs GhcRn (FamEqn GhcRn (HsDataDefn GhcRn))
NoExtCon
nec

tcAddDataFamInstCtxt :: DataFamInstDecl GhcRn -> TcM a -> TcM a
tcAddDataFamInstCtxt :: DataFamInstDecl GhcRn -> TcM a -> TcM a
tcAddDataFamInstCtxt DataFamInstDecl GhcRn
decl
  = SDoc -> TcM a -> TcM a
forall a. SDoc -> TcM a -> TcM a
addErrCtxt (DataFamInstDecl GhcRn -> SDoc
tcMkDataFamInstCtxt DataFamInstDecl GhcRn
decl)

tcMkFamInstCtxt :: SDoc -> Name -> SDoc
tcMkFamInstCtxt :: SDoc -> Name -> SDoc
tcMkFamInstCtxt SDoc
flavour Name
tycon
  = [SDoc] -> SDoc
hsep [ String -> SDoc
text String
"In the" SDoc -> SDoc -> SDoc
<+> SDoc
flavour SDoc -> SDoc -> SDoc
<+> String -> SDoc
text String
"declaration for"
         , SDoc -> SDoc
quotes (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
tycon) ]

tcAddFamInstCtxt :: SDoc -> Name -> TcM a -> TcM a
tcAddFamInstCtxt :: SDoc -> Name -> TcM a -> TcM a
tcAddFamInstCtxt SDoc
flavour Name
tycon TcM a
thing_inside
  = SDoc -> TcM a -> TcM a
forall a. SDoc -> TcM a -> TcM a
addErrCtxt (SDoc -> Name -> SDoc
tcMkFamInstCtxt SDoc
flavour Name
tycon) TcM a
thing_inside

tcAddClosedTypeFamilyDeclCtxt :: TyCon -> TcM a -> TcM a
tcAddClosedTypeFamilyDeclCtxt :: TyCon -> TcM a -> TcM a
tcAddClosedTypeFamilyDeclCtxt TyCon
tc
  = SDoc -> TcM a -> TcM a
forall a. SDoc -> TcM a -> TcM a
addErrCtxt SDoc
ctxt
  where
    ctxt :: SDoc
ctxt = String -> SDoc
text String
"In the equations for closed type family" SDoc -> SDoc -> SDoc
<+>
           SDoc -> SDoc
quotes (TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tc)

resultTypeMisMatch :: FieldLabelString -> DataCon -> DataCon -> SDoc
resultTypeMisMatch :: FieldLabelString -> DataCon -> DataCon -> SDoc
resultTypeMisMatch FieldLabelString
field_name DataCon
con1 DataCon
con2
  = [SDoc] -> SDoc
vcat [[SDoc] -> SDoc
sep [String -> SDoc
text String
"Constructors" SDoc -> SDoc -> SDoc
<+> DataCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr DataCon
con1 SDoc -> SDoc -> SDoc
<+> String -> SDoc
text String
"and" SDoc -> SDoc -> SDoc
<+> DataCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr DataCon
con2,
                String -> SDoc
text String
"have a common field" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (FieldLabelString -> SDoc
forall a. Outputable a => a -> SDoc
ppr FieldLabelString
field_name) SDoc -> SDoc -> SDoc
<> SDoc
comma],
          Int -> SDoc -> SDoc
nest Int
2 (SDoc -> SDoc) -> SDoc -> SDoc
forall a b. (a -> b) -> a -> b
$ String -> SDoc
text String
"but have different result types"]

fieldTypeMisMatch :: FieldLabelString -> DataCon -> DataCon -> SDoc
fieldTypeMisMatch :: FieldLabelString -> DataCon -> DataCon -> SDoc
fieldTypeMisMatch FieldLabelString
field_name DataCon
con1 DataCon
con2
  = [SDoc] -> SDoc
sep [String -> SDoc
text String
"Constructors" SDoc -> SDoc -> SDoc
<+> DataCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr DataCon
con1 SDoc -> SDoc -> SDoc
<+> String -> SDoc
text String
"and" SDoc -> SDoc -> SDoc
<+> DataCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr DataCon
con2,
         String -> SDoc
text String
"give different types for field", SDoc -> SDoc
quotes (FieldLabelString -> SDoc
forall a. Outputable a => a -> SDoc
ppr FieldLabelString
field_name)]

dataConCtxtName :: [Located Name] -> SDoc
dataConCtxtName :: [GenLocated SrcSpan Name] -> SDoc
dataConCtxtName [GenLocated SrcSpan Name
con]
   = String -> SDoc
text String
"In the definition of data constructor" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (GenLocated SrcSpan Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr GenLocated SrcSpan Name
con)
dataConCtxtName [GenLocated SrcSpan Name]
con
   = String -> SDoc
text String
"In the definition of data constructors" SDoc -> SDoc -> SDoc
<+> [GenLocated SrcSpan Name] -> SDoc
forall a. Outputable a => [a] -> SDoc
interpp'SP [GenLocated SrcSpan Name]
con

dataConCtxt :: Outputable a => a -> SDoc
dataConCtxt :: a -> SDoc
dataConCtxt a
con = String -> SDoc
text String
"In the definition of data constructor" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (a -> SDoc
forall a. Outputable a => a -> SDoc
ppr a
con)

classOpCtxt :: Var -> Type -> SDoc
classOpCtxt :: TcTyCoVar -> Kind -> SDoc
classOpCtxt TcTyCoVar
sel_id Kind
tau = [SDoc] -> SDoc
sep [String -> SDoc
text String
"When checking the class method:",
                              Int -> SDoc -> SDoc
nest Int
2 (TcTyCoVar -> SDoc
forall a. OutputableBndr a => a -> SDoc
pprPrefixOcc TcTyCoVar
sel_id SDoc -> SDoc -> SDoc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
<+> Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr Kind
tau)]

classArityErr :: Int -> Class -> SDoc
classArityErr :: Int -> Class -> SDoc
classArityErr Int
n Class
cls
    | Int
n Int -> Int -> Bool
forall a. Eq a => a -> a -> Bool
== Int
0 = String -> String -> SDoc
mkErr String
"No" String
"no-parameter"
    | Bool
otherwise = String -> String -> SDoc
mkErr String
"Too many" String
"multi-parameter"
  where
    mkErr :: String -> String -> SDoc
mkErr String
howMany String
allowWhat =
        [SDoc] -> SDoc
vcat [String -> SDoc
text (String
howMany String -> String -> String
forall a. [a] -> [a] -> [a]
++ String
" parameters for class") SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (Class -> SDoc
forall a. Outputable a => a -> SDoc
ppr Class
cls),
              SDoc -> SDoc
parens (String -> SDoc
text (String
"Enable MultiParamTypeClasses to allow "
                                    String -> String -> String
forall a. [a] -> [a] -> [a]
++ String
allowWhat String -> String -> String
forall a. [a] -> [a] -> [a]
++ String
" classes"))]

classFunDepsErr :: Class -> SDoc
classFunDepsErr :: Class -> SDoc
classFunDepsErr Class
cls
  = [SDoc] -> SDoc
vcat [String -> SDoc
text String
"Fundeps in class" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (Class -> SDoc
forall a. Outputable a => a -> SDoc
ppr Class
cls),
          SDoc -> SDoc
parens (String -> SDoc
text String
"Enable FunctionalDependencies to allow fundeps")]

badMethPred :: Id -> TcPredType -> SDoc
badMethPred :: TcTyCoVar -> Kind -> SDoc
badMethPred TcTyCoVar
sel_id Kind
pred
  = [SDoc] -> SDoc
vcat [ SDoc -> Int -> SDoc -> SDoc
hang (String -> SDoc
text String
"Constraint" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr Kind
pred)
                 SDoc -> SDoc -> SDoc
<+> String -> SDoc
text String
"in the type of" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (TcTyCoVar -> SDoc
forall a. Outputable a => a -> SDoc
ppr TcTyCoVar
sel_id))
              Int
2 (String -> SDoc
text String
"constrains only the class type variables")
         , String -> SDoc
text String
"Enable ConstrainedClassMethods to allow it" ]

noClassTyVarErr :: Class -> TyCon -> SDoc
noClassTyVarErr :: Class -> TyCon -> SDoc
noClassTyVarErr Class
clas TyCon
fam_tc
  = [SDoc] -> SDoc
sep [ String -> SDoc
text String
"The associated type" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
fam_tc SDoc -> SDoc -> SDoc
<+> [SDoc] -> SDoc
hsep ((TcTyCoVar -> SDoc) -> [TcTyCoVar] -> [SDoc]
forall a b. (a -> b) -> [a] -> [b]
map TcTyCoVar -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyCon -> [TcTyCoVar]
tyConTyVars TyCon
fam_tc)))
        , String -> SDoc
text String
"mentions none of the type or kind variables of the class" SDoc -> SDoc -> SDoc
<+>
                SDoc -> SDoc
quotes (Class -> SDoc
forall a. Outputable a => a -> SDoc
ppr Class
clas SDoc -> SDoc -> SDoc
<+> [SDoc] -> SDoc
hsep ((TcTyCoVar -> SDoc) -> [TcTyCoVar] -> [SDoc]
forall a b. (a -> b) -> [a] -> [b]
map TcTyCoVar -> SDoc
forall a. Outputable a => a -> SDoc
ppr (Class -> [TcTyCoVar]
classTyVars Class
clas)))]

badDataConTyCon :: DataCon -> Type -> SDoc
badDataConTyCon :: DataCon -> Kind -> SDoc
badDataConTyCon DataCon
data_con Kind
res_ty_tmpl
  | ASSERT( all isTyVar tvs )
    Kind -> Bool
tcIsForAllTy Kind
actual_res_ty
  = SDoc
nested_foralls_contexts_suggestion
  | Maybe (Kind, Kind) -> Bool
forall a. Maybe a -> Bool
isJust (Kind -> Maybe (Kind, Kind)
tcSplitPredFunTy_maybe Kind
actual_res_ty)
  = SDoc
nested_foralls_contexts_suggestion
  | Bool
otherwise
  = SDoc -> Int -> SDoc -> SDoc
hang (String -> SDoc
text String
"Data constructor" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (DataCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr DataCon
data_con) SDoc -> SDoc -> SDoc
<+>
                String -> SDoc
text String
"returns type" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr Kind
actual_res_ty))
       Int
2 (String -> SDoc
text String
"instead of an instance of its parent type" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr Kind
res_ty_tmpl))
  where
    actual_res_ty :: Kind
actual_res_ty = DataCon -> Kind
dataConOrigResTy DataCon
data_con

    -- This suggestion is useful for suggesting how to correct code like what
    -- was reported in #12087:
    --
    --   data F a where
    --     MkF :: Ord a => Eq a => a -> F a
    --
    -- Although nested foralls or contexts are allowed in function type
    -- signatures, it is much more difficult to engineer GADT constructor type
    -- signatures to allow something similar, so we error in the latter case.
    -- Nevertheless, we can at least suggest how a user might reshuffle their
    -- exotic GADT constructor type signature so that GHC will accept.
    nested_foralls_contexts_suggestion :: SDoc
nested_foralls_contexts_suggestion =
      String -> SDoc
text String
"GADT constructor type signature cannot contain nested"
      SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes SDoc
forAllLit SDoc -> SDoc -> SDoc
<> String -> SDoc
text String
"s or contexts"
      SDoc -> SDoc -> SDoc
$+$ SDoc -> Int -> SDoc -> SDoc
hang (String -> SDoc
text String
"Suggestion: instead use this type signature:")
             Int
2 (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr (DataCon -> Name
dataConName DataCon
data_con) SDoc -> SDoc -> SDoc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
<+> Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr Kind
suggested_ty)

    -- To construct a type that GHC would accept (suggested_ty), we:
    --
    -- 1) Find the existentially quantified type variables and the class
    --    predicates from the datacon. (NB: We don't need the universally
    --    quantified type variables, since rejigConRes won't substitute them in
    --    the result type if it fails, as in this scenario.)
    -- 2) Split apart the return type (which is headed by a forall or a
    --    context) using tcSplitNestedSigmaTys, collecting the type variables
    --    and class predicates we find, as well as the rho type lurking
    --    underneath the nested foralls and contexts.
    -- 3) Smash together the type variables and class predicates from 1) and
    --    2), and prepend them to the rho type from 2).
    ([TcTyCoVar]
tvs, [Kind]
theta, Kind
rho) = Kind -> ([TcTyCoVar], [Kind], Kind)
tcSplitNestedSigmaTys (DataCon -> Kind
dataConUserType DataCon
data_con)
    suggested_ty :: Kind
suggested_ty = [TcTyCoVar] -> [Kind] -> Kind -> Kind
mkSpecSigmaTy [TcTyCoVar]
tvs [Kind]
theta Kind
rho

badGadtDecl :: Name -> SDoc
badGadtDecl :: Name -> SDoc
badGadtDecl Name
tc_name
  = [SDoc] -> SDoc
vcat [ String -> SDoc
text String
"Illegal generalised algebraic data declaration for" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
tc_name)
         , Int -> SDoc -> SDoc
nest Int
2 (SDoc -> SDoc
parens (SDoc -> SDoc) -> SDoc -> SDoc
forall a b. (a -> b) -> a -> b
$ String -> SDoc
text String
"Enable the GADTs extension to allow this") ]

badExistential :: DataCon -> SDoc
badExistential :: DataCon -> SDoc
badExistential DataCon
con
  = SDoc -> Int -> SDoc -> SDoc
hang (String -> SDoc
text String
"Data constructor" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (DataCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr DataCon
con) SDoc -> SDoc -> SDoc
<+>
                String -> SDoc
text String
"has existential type variables, a context, or a specialised result type")
       Int
2 ([SDoc] -> SDoc
vcat [ DataCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr DataCon
con SDoc -> SDoc -> SDoc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
<+> Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr (DataCon -> Kind
dataConUserType DataCon
con)
               , SDoc -> SDoc
parens (SDoc -> SDoc) -> SDoc -> SDoc
forall a b. (a -> b) -> a -> b
$ String -> SDoc
text String
"Enable ExistentialQuantification or GADTs to allow this" ])

badStupidTheta :: Name -> SDoc
badStupidTheta :: Name -> SDoc
badStupidTheta Name
tc_name
  = String -> SDoc
text String
"A data type declared in GADT style cannot have a context:" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
tc_name)

newtypeConError :: Name -> Int -> SDoc
newtypeConError :: Name -> Int -> SDoc
newtypeConError Name
tycon Int
n
  = [SDoc] -> SDoc
sep [String -> SDoc
text String
"A newtype must have exactly one constructor,",
         Int -> SDoc -> SDoc
nest Int
2 (SDoc -> SDoc) -> SDoc -> SDoc
forall a b. (a -> b) -> a -> b
$ String -> SDoc
text String
"but" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
tycon) SDoc -> SDoc -> SDoc
<+> String -> SDoc
text String
"has" SDoc -> SDoc -> SDoc
<+> Int -> SDoc
speakN Int
n ]

newtypeStrictError :: DataCon -> SDoc
newtypeStrictError :: DataCon -> SDoc
newtypeStrictError DataCon
con
  = [SDoc] -> SDoc
sep [String -> SDoc
text String
"A newtype constructor cannot have a strictness annotation,",
         Int -> SDoc -> SDoc
nest Int
2 (SDoc -> SDoc) -> SDoc -> SDoc
forall a b. (a -> b) -> a -> b
$ String -> SDoc
text String
"but" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (DataCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr DataCon
con) SDoc -> SDoc -> SDoc
<+> String -> SDoc
text String
"does"]

newtypeFieldErr :: DataCon -> Int -> SDoc
newtypeFieldErr :: DataCon -> Int -> SDoc
newtypeFieldErr DataCon
con_name Int
n_flds
  = [SDoc] -> SDoc
sep [String -> SDoc
text String
"The constructor of a newtype must have exactly one field",
         Int -> SDoc -> SDoc
nest Int
2 (SDoc -> SDoc) -> SDoc -> SDoc
forall a b. (a -> b) -> a -> b
$ String -> SDoc
text String
"but" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (DataCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr DataCon
con_name) SDoc -> SDoc -> SDoc
<+> String -> SDoc
text String
"has" SDoc -> SDoc -> SDoc
<+> Int -> SDoc
speakN Int
n_flds]

badSigTyDecl :: Name -> SDoc
badSigTyDecl :: Name -> SDoc
badSigTyDecl Name
tc_name
  = [SDoc] -> SDoc
vcat [ String -> SDoc
text String
"Illegal kind signature" SDoc -> SDoc -> SDoc
<+>
           SDoc -> SDoc
quotes (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
tc_name)
         , Int -> SDoc -> SDoc
nest Int
2 (SDoc -> SDoc
parens (SDoc -> SDoc) -> SDoc -> SDoc
forall a b. (a -> b) -> a -> b
$ String -> SDoc
text String
"Use KindSignatures to allow kind signatures") ]

emptyConDeclsErr :: Name -> SDoc
emptyConDeclsErr :: Name -> SDoc
emptyConDeclsErr Name
tycon
  = [SDoc] -> SDoc
sep [SDoc -> SDoc
quotes (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
tycon) SDoc -> SDoc -> SDoc
<+> String -> SDoc
text String
"has no constructors",
         Int -> SDoc -> SDoc
nest Int
2 (SDoc -> SDoc) -> SDoc -> SDoc
forall a b. (a -> b) -> a -> b
$ String -> SDoc
text String
"(EmptyDataDecls permits this)"]

wrongKindOfFamily :: TyCon -> SDoc
wrongKindOfFamily :: TyCon -> SDoc
wrongKindOfFamily TyCon
family
  = String -> SDoc
text String
"Wrong category of family instance; declaration was for a"
    SDoc -> SDoc -> SDoc
<+> SDoc
kindOfFamily
  where
    kindOfFamily :: SDoc
kindOfFamily | TyCon -> Bool
isTypeFamilyTyCon TyCon
family = String -> SDoc
text String
"type family"
                 | TyCon -> Bool
isDataFamilyTyCon TyCon
family = String -> SDoc
text String
"data family"
                 | Bool
otherwise = String -> SDoc -> SDoc
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"wrongKindOfFamily" (TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
family)

-- | Produce an error for oversaturated type family equations with too many
-- required arguments.
-- See Note [Oversaturated type family equations] in TcValidity.
wrongNumberOfParmsErr :: Arity -> SDoc
wrongNumberOfParmsErr :: Int -> SDoc
wrongNumberOfParmsErr Int
max_args
  = String -> SDoc
text String
"Number of parameters must match family declaration; expected"
    SDoc -> SDoc -> SDoc
<+> Int -> SDoc
forall a. Outputable a => a -> SDoc
ppr Int
max_args

badRoleAnnot :: Name -> Role -> Role -> SDoc
badRoleAnnot :: Name -> Role -> Role -> SDoc
badRoleAnnot Name
var Role
annot Role
inferred
  = SDoc -> Int -> SDoc -> SDoc
hang (String -> SDoc
text String
"Role mismatch on variable" SDoc -> SDoc -> SDoc
<+> Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
var SDoc -> SDoc -> SDoc
<> SDoc
colon)
       Int
2 ([SDoc] -> SDoc
sep [ String -> SDoc
text String
"Annotation says", Role -> SDoc
forall a. Outputable a => a -> SDoc
ppr Role
annot
              , String -> SDoc
text String
"but role", Role -> SDoc
forall a. Outputable a => a -> SDoc
ppr Role
inferred
              , String -> SDoc
text String
"is required" ])

wrongNumberOfRoles :: [a] -> LRoleAnnotDecl GhcRn -> SDoc
wrongNumberOfRoles :: [a] -> LRoleAnnotDecl GhcRn -> SDoc
wrongNumberOfRoles [a]
tyvars d :: LRoleAnnotDecl GhcRn
d@(L SrcSpan
_ (RoleAnnotDecl XCRoleAnnotDecl GhcRn
_ GenLocated SrcSpan (IdP GhcRn)
_ [Located (Maybe Role)]
annots))
  = SDoc -> Int -> SDoc -> SDoc
hang (String -> SDoc
text String
"Wrong number of roles listed in role annotation;" SDoc -> SDoc -> SDoc
$$
          String -> SDoc
text String
"Expected" SDoc -> SDoc -> SDoc
<+> (Int -> SDoc
forall a. Outputable a => a -> SDoc
ppr (Int -> SDoc) -> Int -> SDoc
forall a b. (a -> b) -> a -> b
$ [a] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length [a]
tyvars) SDoc -> SDoc -> SDoc
<> SDoc
comma SDoc -> SDoc -> SDoc
<+>
          String -> SDoc
text String
"got" SDoc -> SDoc -> SDoc
<+> (Int -> SDoc
forall a. Outputable a => a -> SDoc
ppr (Int -> SDoc) -> Int -> SDoc
forall a b. (a -> b) -> a -> b
$ [Located (Maybe Role)] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length [Located (Maybe Role)]
annots) SDoc -> SDoc -> SDoc
<> SDoc
colon)
       Int
2 (LRoleAnnotDecl GhcRn -> SDoc
forall a. Outputable a => a -> SDoc
ppr LRoleAnnotDecl GhcRn
d)
wrongNumberOfRoles [a]
_ (L SrcSpan
_ (XRoleAnnotDecl XXRoleAnnotDecl GhcRn
nec)) = NoExtCon -> SDoc
forall a. NoExtCon -> a
noExtCon XXRoleAnnotDecl GhcRn
NoExtCon
nec


illegalRoleAnnotDecl :: LRoleAnnotDecl GhcRn -> TcM ()
illegalRoleAnnotDecl :: LRoleAnnotDecl GhcRn -> TcRn ()
illegalRoleAnnotDecl (L SrcSpan
loc (RoleAnnotDecl XCRoleAnnotDecl GhcRn
_ GenLocated SrcSpan (IdP GhcRn)
tycon [Located (Maybe Role)]
_))
  = [ErrCtxt] -> TcRn () -> TcRn ()
forall a. [ErrCtxt] -> TcM a -> TcM a
setErrCtxt [] (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
    SrcSpan -> TcRn () -> TcRn ()
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan SrcSpan
loc (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
    SDoc -> TcRn ()
addErrTc (String -> SDoc
text String
"Illegal role annotation for" SDoc -> SDoc -> SDoc
<+> GenLocated SrcSpan Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr GenLocated SrcSpan Name
GenLocated SrcSpan (IdP GhcRn)
tycon SDoc -> SDoc -> SDoc
<> Char -> SDoc
char Char
';' SDoc -> SDoc -> SDoc
$$
              String -> SDoc
text String
"they are allowed only for datatypes and classes.")
illegalRoleAnnotDecl (L SrcSpan
_ (XRoleAnnotDecl XXRoleAnnotDecl GhcRn
nec)) = NoExtCon -> TcRn ()
forall a. NoExtCon -> a
noExtCon XXRoleAnnotDecl GhcRn
NoExtCon
nec

needXRoleAnnotations :: TyCon -> SDoc
needXRoleAnnotations :: TyCon -> SDoc
needXRoleAnnotations TyCon
tc
  = String -> SDoc
text String
"Illegal role annotation for" SDoc -> SDoc -> SDoc
<+> TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tc SDoc -> SDoc -> SDoc
<> Char -> SDoc
char Char
';' SDoc -> SDoc -> SDoc
$$
    String -> SDoc
text String
"did you intend to use RoleAnnotations?"

incoherentRoles :: SDoc
incoherentRoles :: SDoc
incoherentRoles = (String -> SDoc
text String
"Roles other than" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (String -> SDoc
text String
"nominal") SDoc -> SDoc -> SDoc
<+>
                   String -> SDoc
text String
"for class parameters can lead to incoherence.") SDoc -> SDoc -> SDoc
$$
                  (String -> SDoc
text String
"Use IncoherentInstances to allow this; bad role found")

addTyConCtxt :: TyCon -> TcM a -> TcM a
addTyConCtxt :: TyCon -> TcM a -> TcM a
addTyConCtxt TyCon
tc = Name -> TyConFlavour -> TcM a -> TcM a
forall a. Name -> TyConFlavour -> TcM a -> TcM a
addTyConFlavCtxt Name
name TyConFlavour
flav
  where
    name :: Name
name = TyCon -> Name
forall a. NamedThing a => a -> Name
getName TyCon
tc
    flav :: TyConFlavour
flav = TyCon -> TyConFlavour
tyConFlavour TyCon
tc

addRoleAnnotCtxt :: Name -> TcM a -> TcM a
addRoleAnnotCtxt :: Name -> TcM a -> TcM a
addRoleAnnotCtxt Name
name
  = SDoc -> TcM a -> TcM a
forall a. SDoc -> TcM a -> TcM a
addErrCtxt (SDoc -> TcM a -> TcM a) -> SDoc -> TcM a -> TcM a
forall a b. (a -> b) -> a -> b
$
    String -> SDoc
text String
"while checking a role annotation for" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
name)