{-# LANGUAGE DeriveFunctor #-}
{-# LANGUAGE TypeFamilies #-}

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

{-
(c) The University of Glasgow 2006
(c) The GRASP/AQUA Project, Glasgow University, 1992-1999

-}

-- | Analysis functions over data types. Specifically, detecting recursive types.
--
-- This stuff is only used for source-code decls; it's recorded in interface
-- files for imported data types.
module GHC.Tc.TyCl.Utils(
        RolesInfo,
        inferRoles,
        checkSynCycles,
        checkClassCycles,

        -- * Implicits
        addTyConsToGblEnv, mkDefaultMethodType,

        -- * Record selectors
        tcRecSelBinds, mkRecSelBinds, mkOneRecordSelector
    ) where

import GHC.Prelude

import GHC.Tc.Errors.Types
import GHC.Tc.Utils.Monad
import GHC.Tc.Utils.Env
import GHC.Tc.Gen.Bind( tcValBinds )
import GHC.Tc.Utils.TcType

import GHC.Builtin.Types( unitTy )
import GHC.Builtin.Uniques ( mkBuiltinUnique )

import GHC.Hs

import GHC.Core.TyCo.Rep( Type(..), Coercion(..), MCoercion(..), UnivCoProvenance(..) )
import GHC.Core.Multiplicity
import GHC.Core.Predicate
import GHC.Core.Make( rEC_SEL_ERROR_ID )
import GHC.Core.Class
import GHC.Core.Type
import GHC.Core.TyCon
import GHC.Core.ConLike
import GHC.Core.DataCon
import GHC.Core.TyCon.Set
import GHC.Core.Coercion ( ltRole )

import GHC.Utils.Outputable
import GHC.Utils.Panic
import GHC.Utils.Panic.Plain
import GHC.Utils.Misc
import GHC.Utils.FV as FV

import GHC.Data.Maybe
import GHC.Data.Bag
import GHC.Data.FastString

import GHC.Unit.Module

import GHC.Types.Basic
import GHC.Types.Error
import GHC.Types.FieldLabel
import GHC.Types.SrcLoc
import GHC.Types.SourceFile
import GHC.Types.SourceText
import GHC.Types.Name
import GHC.Types.Name.Env
import GHC.Types.Name.Reader ( mkVarUnqual )
import GHC.Types.Id
import GHC.Types.Id.Info
import GHC.Types.Var.Env
import GHC.Types.Var.Set
import GHC.Types.Unique.Set
import GHC.Types.TyThing
import qualified GHC.LanguageExtensions as LangExt

import Language.Haskell.Syntax.Basic (FieldLabelString(..))

import Control.Monad

{-
************************************************************************
*                                                                      *
        Cycles in type synonym declarations
*                                                                      *
************************************************************************
-}

synonymTyConsOfType :: Type -> [TyCon]
-- Does not look through type synonyms at all.
-- Returns a list of synonym tycons in nondeterministic order.
-- Keep this synchronized with 'expandTypeSynonyms'
synonymTyConsOfType :: PredType -> [TyCon]
synonymTyConsOfType PredType
ty
  = NameEnv TyCon -> [TyCon]
forall a. NameEnv a -> [a]
nonDetNameEnvElts (PredType -> NameEnv TyCon
go PredType
ty)
  where
     go :: Type -> NameEnv TyCon  -- The NameEnv does duplicate elim
     go :: PredType -> NameEnv TyCon
go (TyConApp TyCon
tc [PredType]
tys) = TyCon -> NameEnv TyCon
go_tc TyCon
tc NameEnv TyCon -> NameEnv TyCon -> NameEnv TyCon
forall a. NameEnv a -> NameEnv a -> NameEnv a
`plusNameEnv` [PredType] -> NameEnv TyCon
forall {t :: * -> *}. Foldable t => t PredType -> NameEnv TyCon
go_s [PredType]
tys
     go (LitTy TyLit
_)         = NameEnv TyCon
forall a. NameEnv a
emptyNameEnv
     go (TyVarTy Id
_)       = NameEnv TyCon
forall a. NameEnv a
emptyNameEnv
     go (AppTy PredType
a PredType
b)       = PredType -> NameEnv TyCon
go PredType
a NameEnv TyCon -> NameEnv TyCon -> NameEnv TyCon
forall a. NameEnv a -> NameEnv a -> NameEnv a
`plusNameEnv` PredType -> NameEnv TyCon
go PredType
b
     go (FunTy FunTyFlag
_ PredType
w PredType
a PredType
b)   = PredType -> NameEnv TyCon
go PredType
w NameEnv TyCon -> NameEnv TyCon -> NameEnv TyCon
forall a. NameEnv a -> NameEnv a -> NameEnv a
`plusNameEnv` PredType -> NameEnv TyCon
go PredType
a NameEnv TyCon -> NameEnv TyCon -> NameEnv TyCon
forall a. NameEnv a -> NameEnv a -> NameEnv a
`plusNameEnv` PredType -> NameEnv TyCon
go PredType
b
     go (ForAllTy ForAllTyBinder
_ PredType
ty)   = PredType -> NameEnv TyCon
go PredType
ty
     go (CastTy PredType
ty KindCoercion
co)    = PredType -> NameEnv TyCon
go PredType
ty NameEnv TyCon -> NameEnv TyCon -> NameEnv TyCon
forall a. NameEnv a -> NameEnv a -> NameEnv a
`plusNameEnv` KindCoercion -> NameEnv TyCon
go_co KindCoercion
co
     go (CoercionTy KindCoercion
co)   = KindCoercion -> NameEnv TyCon
go_co KindCoercion
co

     -- Note [TyCon cycles through coercions?!]
     -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     -- Although, in principle, it's possible for a type synonym loop
     -- could go through a coercion (since a coercion can refer to
     -- a TyCon or Type), it doesn't seem possible to actually construct
     -- a Haskell program which tickles this case.  Here is an example
     -- program which causes a coercion:
     --
     --   type family Star where
     --       Star = Type
     --
     --   data T :: Star -> Type
     --   data S :: forall (a :: Type). T a -> Type
     --
     -- Here, the application 'T a' must first coerce a :: Type to a :: Star,
     -- witnessed by the type family.  But if we now try to make Type refer
     -- to a type synonym which in turn refers to Star, we'll run into
     -- trouble: we're trying to define and use the type constructor
     -- in the same recursive group.  Possibly this restriction will be
     -- lifted in the future but for now, this code is "just for completeness
     -- sake".
     go_mco :: MCoercionN -> NameEnv TyCon
go_mco MCoercionN
MRefl    = NameEnv TyCon
forall a. NameEnv a
emptyNameEnv
     go_mco (MCo KindCoercion
co) = KindCoercion -> NameEnv TyCon
go_co KindCoercion
co

     go_co :: KindCoercion -> NameEnv TyCon
go_co (Refl PredType
ty)              = PredType -> NameEnv TyCon
go PredType
ty
     go_co (GRefl Role
_ PredType
ty MCoercionN
mco)       = PredType -> NameEnv TyCon
go PredType
ty NameEnv TyCon -> NameEnv TyCon -> NameEnv TyCon
forall a. NameEnv a -> NameEnv a -> NameEnv a
`plusNameEnv` MCoercionN -> NameEnv TyCon
go_mco MCoercionN
mco
     go_co (TyConAppCo Role
_ TyCon
tc [KindCoercion]
cs)   = TyCon -> NameEnv TyCon
go_tc TyCon
tc NameEnv TyCon -> NameEnv TyCon -> NameEnv TyCon
forall a. NameEnv a -> NameEnv a -> NameEnv a
`plusNameEnv` [KindCoercion] -> NameEnv TyCon
go_co_s [KindCoercion]
cs
     go_co (AppCo KindCoercion
co KindCoercion
co')         = KindCoercion -> NameEnv TyCon
go_co KindCoercion
co NameEnv TyCon -> NameEnv TyCon -> NameEnv TyCon
forall a. NameEnv a -> NameEnv a -> NameEnv a
`plusNameEnv` KindCoercion -> NameEnv TyCon
go_co KindCoercion
co'
     go_co (ForAllCo Id
_ KindCoercion
co KindCoercion
co')    = KindCoercion -> NameEnv TyCon
go_co KindCoercion
co NameEnv TyCon -> NameEnv TyCon -> NameEnv TyCon
forall a. NameEnv a -> NameEnv a -> NameEnv a
`plusNameEnv` KindCoercion -> NameEnv TyCon
go_co KindCoercion
co'
     go_co (FunCo { fco_mult :: KindCoercion -> KindCoercion
fco_mult = KindCoercion
m, fco_arg :: KindCoercion -> KindCoercion
fco_arg = KindCoercion
a, fco_res :: KindCoercion -> KindCoercion
fco_res = KindCoercion
r })
                                  = KindCoercion -> NameEnv TyCon
go_co KindCoercion
m NameEnv TyCon -> NameEnv TyCon -> NameEnv TyCon
forall a. NameEnv a -> NameEnv a -> NameEnv a
`plusNameEnv` KindCoercion -> NameEnv TyCon
go_co KindCoercion
a NameEnv TyCon -> NameEnv TyCon -> NameEnv TyCon
forall a. NameEnv a -> NameEnv a -> NameEnv a
`plusNameEnv` KindCoercion -> NameEnv TyCon
go_co KindCoercion
r
     go_co (CoVarCo Id
_)            = NameEnv TyCon
forall a. NameEnv a
emptyNameEnv
     go_co (HoleCo {})            = NameEnv TyCon
forall a. NameEnv a
emptyNameEnv
     go_co (AxiomInstCo CoAxiom Branched
_ Int
_ [KindCoercion]
cs)   = [KindCoercion] -> NameEnv TyCon
go_co_s [KindCoercion]
cs
     go_co (UnivCo UnivCoProvenance
p Role
_ PredType
ty PredType
ty')    = UnivCoProvenance -> NameEnv TyCon
go_prov UnivCoProvenance
p NameEnv TyCon -> NameEnv TyCon -> NameEnv TyCon
forall a. NameEnv a -> NameEnv a -> NameEnv a
`plusNameEnv` PredType -> NameEnv TyCon
go PredType
ty NameEnv TyCon -> NameEnv TyCon -> NameEnv TyCon
forall a. NameEnv a -> NameEnv a -> NameEnv a
`plusNameEnv` PredType -> NameEnv TyCon
go PredType
ty'
     go_co (SymCo KindCoercion
co)             = KindCoercion -> NameEnv TyCon
go_co KindCoercion
co
     go_co (TransCo KindCoercion
co KindCoercion
co')       = KindCoercion -> NameEnv TyCon
go_co KindCoercion
co NameEnv TyCon -> NameEnv TyCon -> NameEnv TyCon
forall a. NameEnv a -> NameEnv a -> NameEnv a
`plusNameEnv` KindCoercion -> NameEnv TyCon
go_co KindCoercion
co'
     go_co (SelCo CoSel
_ KindCoercion
co)           = KindCoercion -> NameEnv TyCon
go_co KindCoercion
co
     go_co (LRCo LeftOrRight
_ KindCoercion
co)            = KindCoercion -> NameEnv TyCon
go_co KindCoercion
co
     go_co (InstCo KindCoercion
co KindCoercion
co')        = KindCoercion -> NameEnv TyCon
go_co KindCoercion
co NameEnv TyCon -> NameEnv TyCon -> NameEnv TyCon
forall a. NameEnv a -> NameEnv a -> NameEnv a
`plusNameEnv` KindCoercion -> NameEnv TyCon
go_co KindCoercion
co'
     go_co (KindCo KindCoercion
co)            = KindCoercion -> NameEnv TyCon
go_co KindCoercion
co
     go_co (SubCo KindCoercion
co)             = KindCoercion -> NameEnv TyCon
go_co KindCoercion
co
     go_co (AxiomRuleCo CoAxiomRule
_ [KindCoercion]
cs)     = [KindCoercion] -> NameEnv TyCon
go_co_s [KindCoercion]
cs

     go_prov :: UnivCoProvenance -> NameEnv TyCon
go_prov (PhantomProv KindCoercion
co)     = KindCoercion -> NameEnv TyCon
go_co KindCoercion
co
     go_prov (ProofIrrelProv KindCoercion
co)  = KindCoercion -> NameEnv TyCon
go_co KindCoercion
co
     go_prov (PluginProv String
_)       = NameEnv TyCon
forall a. NameEnv a
emptyNameEnv
     go_prov (CorePrepProv Bool
_)     = NameEnv TyCon
forall a. NameEnv a
emptyNameEnv

     go_tc :: TyCon -> NameEnv TyCon
go_tc TyCon
tc | TyCon -> Bool
isTypeSynonymTyCon TyCon
tc = Name -> TyCon -> NameEnv TyCon
forall a. Name -> a -> NameEnv a
unitNameEnv (TyCon -> Name
tyConName TyCon
tc) TyCon
tc
              | Bool
otherwise             = NameEnv TyCon
forall a. NameEnv a
emptyNameEnv
     go_s :: t PredType -> NameEnv TyCon
go_s t PredType
tys = (PredType -> NameEnv TyCon -> NameEnv TyCon)
-> NameEnv TyCon -> t PredType -> NameEnv TyCon
forall a b. (a -> b -> b) -> b -> t a -> b
forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr (NameEnv TyCon -> NameEnv TyCon -> NameEnv TyCon
forall a. NameEnv a -> NameEnv a -> NameEnv a
plusNameEnv (NameEnv TyCon -> NameEnv TyCon -> NameEnv TyCon)
-> (PredType -> NameEnv TyCon)
-> PredType
-> NameEnv TyCon
-> NameEnv TyCon
forall b c a. (b -> c) -> (a -> b) -> a -> c
. PredType -> NameEnv TyCon
go) NameEnv TyCon
forall a. NameEnv a
emptyNameEnv t PredType
tys
     go_co_s :: [KindCoercion] -> NameEnv TyCon
go_co_s [KindCoercion]
cos = (KindCoercion -> NameEnv TyCon -> NameEnv TyCon)
-> NameEnv TyCon -> [KindCoercion] -> NameEnv TyCon
forall a b. (a -> b -> b) -> b -> [a] -> b
forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr (NameEnv TyCon -> NameEnv TyCon -> NameEnv TyCon
forall a. NameEnv a -> NameEnv a -> NameEnv a
plusNameEnv (NameEnv TyCon -> NameEnv TyCon -> NameEnv TyCon)
-> (KindCoercion -> NameEnv TyCon)
-> KindCoercion
-> NameEnv TyCon
-> NameEnv TyCon
forall b c a. (b -> c) -> (a -> b) -> a -> c
. KindCoercion -> NameEnv TyCon
go_co) NameEnv TyCon
forall a. NameEnv a
emptyNameEnv [KindCoercion]
cos

-- | A monad for type synonym cycle checking, which keeps
-- track of the TyCons which are known to be acyclic, or
-- a failure message reporting that a cycle was found.
newtype SynCycleM a = SynCycleM {
    forall a.
SynCycleM a
-> SynCycleState -> Either (SrcSpan, SDoc) (a, SynCycleState)
runSynCycleM :: SynCycleState -> Either (SrcSpan, SDoc) (a, SynCycleState) }
    deriving ((forall a b. (a -> b) -> SynCycleM a -> SynCycleM b)
-> (forall a b. a -> SynCycleM b -> SynCycleM a)
-> Functor SynCycleM
forall a b. a -> SynCycleM b -> SynCycleM a
forall a b. (a -> b) -> SynCycleM a -> SynCycleM b
forall (f :: * -> *).
(forall a b. (a -> b) -> f a -> f b)
-> (forall a b. a -> f b -> f a) -> Functor f
$cfmap :: forall a b. (a -> b) -> SynCycleM a -> SynCycleM b
fmap :: forall a b. (a -> b) -> SynCycleM a -> SynCycleM b
$c<$ :: forall a b. a -> SynCycleM b -> SynCycleM a
<$ :: forall a b. a -> SynCycleM b -> SynCycleM a
Functor)

-- TODO: TyConSet is implemented as IntMap over uniques.
-- But we could get away with something based on IntSet
-- since we only check membership, but never extract the
-- elements.
type SynCycleState = TyConSet

instance Applicative SynCycleM where
    pure :: forall a. a -> SynCycleM a
pure a
x = (SynCycleState -> Either (SrcSpan, SDoc) (a, SynCycleState))
-> SynCycleM a
forall a.
(SynCycleState -> Either (SrcSpan, SDoc) (a, SynCycleState))
-> SynCycleM a
SynCycleM ((SynCycleState -> Either (SrcSpan, SDoc) (a, SynCycleState))
 -> SynCycleM a)
-> (SynCycleState -> Either (SrcSpan, SDoc) (a, SynCycleState))
-> SynCycleM a
forall a b. (a -> b) -> a -> b
$ \SynCycleState
state -> (a, SynCycleState) -> Either (SrcSpan, SDoc) (a, SynCycleState)
forall a b. b -> Either a b
Right (a
x, SynCycleState
state)
    <*> :: forall a b. SynCycleM (a -> b) -> SynCycleM a -> SynCycleM b
(<*>) = SynCycleM (a -> b) -> SynCycleM a -> SynCycleM b
forall (m :: * -> *) a b. Monad m => m (a -> b) -> m a -> m b
ap

instance Monad SynCycleM where
    SynCycleM a
m >>= :: forall a b. SynCycleM a -> (a -> SynCycleM b) -> SynCycleM b
>>= a -> SynCycleM b
f = (SynCycleState -> Either (SrcSpan, SDoc) (b, SynCycleState))
-> SynCycleM b
forall a.
(SynCycleState -> Either (SrcSpan, SDoc) (a, SynCycleState))
-> SynCycleM a
SynCycleM ((SynCycleState -> Either (SrcSpan, SDoc) (b, SynCycleState))
 -> SynCycleM b)
-> (SynCycleState -> Either (SrcSpan, SDoc) (b, SynCycleState))
-> SynCycleM b
forall a b. (a -> b) -> a -> b
$ \SynCycleState
state ->
        case SynCycleM a
-> SynCycleState -> Either (SrcSpan, SDoc) (a, SynCycleState)
forall a.
SynCycleM a
-> SynCycleState -> Either (SrcSpan, SDoc) (a, SynCycleState)
runSynCycleM SynCycleM a
m SynCycleState
state of
            Right (a
x, SynCycleState
state') ->
                SynCycleM b
-> SynCycleState -> Either (SrcSpan, SDoc) (b, SynCycleState)
forall a.
SynCycleM a
-> SynCycleState -> Either (SrcSpan, SDoc) (a, SynCycleState)
runSynCycleM (a -> SynCycleM b
f a
x) SynCycleState
state'
            Left (SrcSpan, SDoc)
err -> (SrcSpan, SDoc) -> Either (SrcSpan, SDoc) (b, SynCycleState)
forall a b. a -> Either a b
Left (SrcSpan, SDoc)
err

failSynCycleM :: SrcSpan -> SDoc -> SynCycleM ()
failSynCycleM :: SrcSpan -> SDoc -> SynCycleM ()
failSynCycleM SrcSpan
loc SDoc
err = (SynCycleState -> Either (SrcSpan, SDoc) ((), SynCycleState))
-> SynCycleM ()
forall a.
(SynCycleState -> Either (SrcSpan, SDoc) (a, SynCycleState))
-> SynCycleM a
SynCycleM ((SynCycleState -> Either (SrcSpan, SDoc) ((), SynCycleState))
 -> SynCycleM ())
-> (SynCycleState -> Either (SrcSpan, SDoc) ((), SynCycleState))
-> SynCycleM ()
forall a b. (a -> b) -> a -> b
$ \SynCycleState
_ -> (SrcSpan, SDoc) -> Either (SrcSpan, SDoc) ((), SynCycleState)
forall a b. a -> Either a b
Left (SrcSpan
loc, SDoc
err)

-- | Test if a 'Name' is acyclic, short-circuiting if we've
-- seen it already.
checkTyConIsAcyclic :: TyCon -> SynCycleM () -> SynCycleM ()
checkTyConIsAcyclic :: TyCon -> SynCycleM () -> SynCycleM ()
checkTyConIsAcyclic TyCon
tc SynCycleM ()
m = (SynCycleState -> Either (SrcSpan, SDoc) ((), SynCycleState))
-> SynCycleM ()
forall a.
(SynCycleState -> Either (SrcSpan, SDoc) (a, SynCycleState))
-> SynCycleM a
SynCycleM ((SynCycleState -> Either (SrcSpan, SDoc) ((), SynCycleState))
 -> SynCycleM ())
-> (SynCycleState -> Either (SrcSpan, SDoc) ((), SynCycleState))
-> SynCycleM ()
forall a b. (a -> b) -> a -> b
$ \SynCycleState
s ->
    if TyCon
tc TyCon -> SynCycleState -> Bool
`elemTyConSet` SynCycleState
s
        then ((), SynCycleState) -> Either (SrcSpan, SDoc) ((), SynCycleState)
forall a b. b -> Either a b
Right ((), SynCycleState
s) -- short circuit
        else case SynCycleM ()
-> SynCycleState -> Either (SrcSpan, SDoc) ((), SynCycleState)
forall a.
SynCycleM a
-> SynCycleState -> Either (SrcSpan, SDoc) (a, SynCycleState)
runSynCycleM SynCycleM ()
m SynCycleState
s of
                Right ((), SynCycleState
s') -> ((), SynCycleState) -> Either (SrcSpan, SDoc) ((), SynCycleState)
forall a b. b -> Either a b
Right ((), SynCycleState -> TyCon -> SynCycleState
extendTyConSet SynCycleState
s' TyCon
tc)
                Left (SrcSpan, SDoc)
err -> (SrcSpan, SDoc) -> Either (SrcSpan, SDoc) ((), SynCycleState)
forall a b. a -> Either a b
Left (SrcSpan, SDoc)
err

-- | Checks if any of the passed in 'TyCon's have cycles.
-- Takes the 'Unit' of the home package (as we can avoid
-- checking those TyCons: cycles never go through foreign packages) and
-- the corresponding @LTyClDecl Name@ for each 'TyCon', so we
-- can give better error messages.
checkSynCycles :: Unit -> [TyCon] -> [LTyClDecl GhcRn] -> TcM ()
checkSynCycles :: Unit -> [TyCon] -> [LTyClDecl (GhcPass 'Renamed)] -> TcM ()
checkSynCycles Unit
this_uid [TyCon]
tcs [LTyClDecl (GhcPass 'Renamed)]
tyclds =
    case SynCycleM ()
-> SynCycleState -> Either (SrcSpan, SDoc) ((), SynCycleState)
forall a.
SynCycleM a
-> SynCycleState -> Either (SrcSpan, SDoc) (a, SynCycleState)
runSynCycleM ((TyCon -> SynCycleM ()) -> [TyCon] -> SynCycleM ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ (SynCycleState -> [TyCon] -> TyCon -> SynCycleM ()
go SynCycleState
emptyTyConSet []) [TyCon]
tcs) SynCycleState
emptyTyConSet of
        Left (SrcSpan
loc, SDoc
err) -> SrcSpan -> TcM () -> TcM ()
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan SrcSpan
loc (TcM () -> TcM ()) -> TcM () -> TcM ()
forall a b. (a -> b) -> a -> b
$ TcRnMessage -> TcM ()
forall a. TcRnMessage -> TcM a
failWithTc (DiagnosticMessage -> TcRnMessage
forall a.
(Diagnostic a, Typeable a, DiagnosticOpts a ~ NoDiagnosticOpts) =>
a -> TcRnMessage
mkTcRnUnknownMessage (DiagnosticMessage -> TcRnMessage)
-> DiagnosticMessage -> TcRnMessage
forall a b. (a -> b) -> a -> b
$ [GhcHint] -> SDoc -> DiagnosticMessage
mkPlainError [GhcHint]
noHints SDoc
err)
        Right ((), SynCycleState)
_  -> () -> TcM ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ()
  where
    -- Try our best to print the LTyClDecl for locally defined things
    lcl_decls :: NameEnv (GenLocated SrcSpanAnnA (TyClDecl (GhcPass 'Renamed)))
lcl_decls = [(Name, GenLocated SrcSpanAnnA (TyClDecl (GhcPass 'Renamed)))]
-> NameEnv (GenLocated SrcSpanAnnA (TyClDecl (GhcPass 'Renamed)))
forall a. [(Name, a)] -> NameEnv a
mkNameEnv ([Name]
-> [GenLocated SrcSpanAnnA (TyClDecl (GhcPass 'Renamed))]
-> [(Name, GenLocated SrcSpanAnnA (TyClDecl (GhcPass 'Renamed)))]
forall a b. [a] -> [b] -> [(a, b)]
zip ((TyCon -> Name) -> [TyCon] -> [Name]
forall a b. (a -> b) -> [a] -> [b]
map TyCon -> Name
tyConName [TyCon]
tcs) [LTyClDecl (GhcPass 'Renamed)]
[GenLocated SrcSpanAnnA (TyClDecl (GhcPass 'Renamed))]
tyclds)

    -- Short circuit if we've already seen this Name and concluded
    -- it was acyclic.
    go :: TyConSet -> [TyCon] -> TyCon -> SynCycleM ()
    go :: SynCycleState -> [TyCon] -> TyCon -> SynCycleM ()
go SynCycleState
so_far [TyCon]
seen_tcs TyCon
tc =
        TyCon -> SynCycleM () -> SynCycleM ()
checkTyConIsAcyclic TyCon
tc (SynCycleM () -> SynCycleM ()) -> SynCycleM () -> SynCycleM ()
forall a b. (a -> b) -> a -> b
$ SynCycleState -> [TyCon] -> TyCon -> SynCycleM ()
go' SynCycleState
so_far [TyCon]
seen_tcs TyCon
tc

    -- Expand type synonyms, complaining if you find the same
    -- type synonym a second time.
    go' :: TyConSet -> [TyCon] -> TyCon -> SynCycleM ()
    go' :: SynCycleState -> [TyCon] -> TyCon -> SynCycleM ()
go' SynCycleState
so_far [TyCon]
seen_tcs TyCon
tc
        | TyCon
tc TyCon -> SynCycleState -> Bool
`elemTyConSet` SynCycleState
so_far
            = SrcSpan -> SDoc -> SynCycleM ()
failSynCycleM (TyCon -> SrcSpan
forall a. NamedThing a => a -> SrcSpan
getSrcSpan ([TyCon] -> TyCon
forall a. HasCallStack => [a] -> a
head [TyCon]
seen_tcs)) (SDoc -> SynCycleM ()) -> SDoc -> SynCycleM ()
forall a b. (a -> b) -> a -> b
$
                  [SDoc] -> SDoc
forall doc. IsLine doc => [doc] -> doc
sep [ String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"Cycle in type synonym declarations:"
                      , Int -> SDoc -> SDoc
nest Int
2 ([SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat ((TyCon -> SDoc) -> [TyCon] -> [SDoc]
forall a b. (a -> b) -> [a] -> [b]
map TyCon -> SDoc
ppr_decl [TyCon]
seen_tcs)) ]
        -- Optimization: we don't allow cycles through external packages,
        -- so once we find a non-local name we are guaranteed to not
        -- have a cycle.
        --
        -- This won't hold once we get recursive packages with Backpack,
        -- but for now it's fine.
        | Bool -> Bool
not (GenModule Unit -> Bool
forall u. GenModule (GenUnit u) -> Bool
isHoleModule GenModule Unit
mod Bool -> Bool -> Bool
||
               GenModule Unit -> Unit
forall unit. GenModule unit -> unit
moduleUnit GenModule Unit
mod Unit -> Unit -> Bool
forall a. Eq a => a -> a -> Bool
== Unit
this_uid Bool -> Bool -> Bool
||
               GenModule Unit -> Bool
isInteractiveModule GenModule Unit
mod)
            = () -> SynCycleM ()
forall a. a -> SynCycleM a
forall (m :: * -> *) a. Monad m => a -> m a
return ()
        | Just PredType
ty <- TyCon -> Maybe PredType
synTyConRhs_maybe TyCon
tc =
            SynCycleState -> [TyCon] -> PredType -> SynCycleM ()
go_ty (SynCycleState -> TyCon -> SynCycleState
extendTyConSet SynCycleState
so_far TyCon
tc) (TyCon
tcTyCon -> [TyCon] -> [TyCon]
forall a. a -> [a] -> [a]
:[TyCon]
seen_tcs) PredType
ty
        | Bool
otherwise = () -> SynCycleM ()
forall a. a -> SynCycleM a
forall (m :: * -> *) a. Monad m => a -> m a
return ()
      where
        n :: Name
n = TyCon -> Name
tyConName TyCon
tc
        mod :: GenModule Unit
mod = (() :: Constraint) => Name -> GenModule Unit
Name -> GenModule Unit
nameModule Name
n
        ppr_decl :: TyCon -> SDoc
ppr_decl TyCon
tc =
          case NameEnv (GenLocated SrcSpanAnnA (TyClDecl (GhcPass 'Renamed)))
-> Name
-> Maybe (GenLocated SrcSpanAnnA (TyClDecl (GhcPass 'Renamed)))
forall a. NameEnv a -> Name -> Maybe a
lookupNameEnv NameEnv (GenLocated SrcSpanAnnA (TyClDecl (GhcPass 'Renamed)))
lcl_decls Name
n of
            Just (L SrcSpanAnnA
loc TyClDecl (GhcPass 'Renamed)
decl) -> SrcSpan -> SDoc
forall a. Outputable a => a -> SDoc
ppr (SrcSpanAnnA -> SrcSpan
forall a. SrcSpanAnn' a -> SrcSpan
locA SrcSpanAnnA
loc) SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<> SDoc
forall doc. IsLine doc => doc
colon SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> TyClDecl (GhcPass 'Renamed) -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyClDecl (GhcPass 'Renamed)
decl
            Maybe (GenLocated SrcSpanAnnA (TyClDecl (GhcPass 'Renamed)))
Nothing -> SrcSpan -> SDoc
forall a. Outputable a => a -> SDoc
ppr (Name -> SrcSpan
forall a. NamedThing a => a -> SrcSpan
getSrcSpan Name
n) SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<> SDoc
forall doc. IsLine doc => doc
colon SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
n
                       SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"from external module"
         where
          n :: Name
n = TyCon -> Name
tyConName TyCon
tc

    go_ty :: TyConSet -> [TyCon] -> Type -> SynCycleM ()
    go_ty :: SynCycleState -> [TyCon] -> PredType -> SynCycleM ()
go_ty SynCycleState
so_far [TyCon]
seen_tcs PredType
ty =
        (TyCon -> SynCycleM ()) -> [TyCon] -> SynCycleM ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ (SynCycleState -> [TyCon] -> TyCon -> SynCycleM ()
go SynCycleState
so_far [TyCon]
seen_tcs) (PredType -> [TyCon]
synonymTyConsOfType PredType
ty)

{- Note [Superclass cycle check]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The superclass cycle check for C decides if we can statically
guarantee that expanding C's superclass cycles transitively is
guaranteed to terminate.  This is a Haskell98 requirement,
but one that we lift with -XUndecidableSuperClasses.

The worry is that a superclass cycle could make the type checker loop.
More precisely, with a constraint (Given or Wanted)
    C ty1 .. tyn
one approach is to instantiate all of C's superclasses, transitively.
We can only do so if that set is finite.

This potential loop occurs only through superclasses.  This, for
example, is fine
  class C a where
    op :: C b => a -> b -> b
even though C's full definition uses C.

Making the check static also makes it conservative.  Eg
  type family F a
  class F a => C a
Here an instance of (F a) might mention C:
  type instance F [a] = C a
and now we'd have a loop.

The static check works like this, starting with C
  * Look at C's superclass predicates
  * If any is a type-function application,
    or is headed by a type variable, fail
  * If any has C at the head, fail
  * If any has a type class D at the head,
    make the same test with D

A tricky point is: what if there is a type variable at the head?
Consider this:
   class f (C f) => C f
   class c       => Id c
and now expand superclasses for constraint (C Id):
     C Id
 --> Id (C Id)
 --> C Id
 --> ....
Each step expands superclasses one layer, and clearly does not terminate.
-}

type ClassSet = UniqSet Class

checkClassCycles :: Class -> Maybe SDoc
-- Nothing  <=> ok
-- Just err <=> possible cycle error
checkClassCycles :: Class -> Maybe SDoc
checkClassCycles Class
cls
  = do { (Bool
definite_cycle, SDoc
err) <- ClassSet -> Class -> [PredType] -> Maybe (Bool, SDoc)
go (Class -> ClassSet
forall a. Uniquable a => a -> UniqSet a
unitUniqSet Class
cls)
                                     Class
cls ([Id] -> [PredType]
mkTyVarTys (Class -> [Id]
classTyVars Class
cls))
       ; let herald :: SDoc
herald | Bool
definite_cycle = String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"Superclass cycle for"
                    | Bool
otherwise      = String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"Potential superclass cycle for"
       ; SDoc -> Maybe SDoc
forall a. a -> Maybe a
forall (m :: * -> *) a. Monad m => a -> m a
return ([SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat [ SDoc
herald SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> SDoc -> SDoc
quotes (Class -> SDoc
forall a. Outputable a => a -> SDoc
ppr Class
cls)
                      , Int -> SDoc -> SDoc
nest Int
2 SDoc
err, SDoc
hint]) }
  where
    hint :: SDoc
hint = String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"Use UndecidableSuperClasses to accept this"

    -- Expand superclasses starting with (C a b), complaining
    -- if you find the same class a second time, or a type function
    -- or predicate headed by a type variable
    --
    -- NB: this code duplicates TcType.transSuperClasses, but
    --     with more error message generation clobber
    -- Make sure the two stay in sync.
    go :: ClassSet -> Class -> [Type] -> Maybe (Bool, SDoc)
    go :: ClassSet -> Class -> [PredType] -> Maybe (Bool, SDoc)
go ClassSet
so_far Class
cls [PredType]
tys = [Maybe (Bool, SDoc)] -> Maybe (Bool, SDoc)
forall (f :: * -> *) a. Foldable f => f (Maybe a) -> Maybe a
firstJusts ([Maybe (Bool, SDoc)] -> Maybe (Bool, SDoc))
-> [Maybe (Bool, SDoc)] -> Maybe (Bool, SDoc)
forall a b. (a -> b) -> a -> b
$
                        (PredType -> Maybe (Bool, SDoc))
-> [PredType] -> [Maybe (Bool, SDoc)]
forall a b. (a -> b) -> [a] -> [b]
map (ClassSet -> PredType -> Maybe (Bool, SDoc)
go_pred ClassSet
so_far) ([PredType] -> [Maybe (Bool, SDoc)])
-> [PredType] -> [Maybe (Bool, SDoc)]
forall a b. (a -> b) -> a -> b
$
                        Class -> [PredType] -> [PredType]
immSuperClasses Class
cls [PredType]
tys

    go_pred :: ClassSet -> PredType -> Maybe (Bool, SDoc)
       -- Nothing <=> ok
       -- Just (True, err)  <=> definite cycle
       -- Just (False, err) <=> possible cycle
    go_pred :: ClassSet -> PredType -> Maybe (Bool, SDoc)
go_pred ClassSet
so_far PredType
pred  -- NB: tcSplitTyConApp looks through synonyms
       | Just (TyCon
tc, [PredType]
tys) <- HasCallStack => PredType -> Maybe (TyCon, [PredType])
PredType -> Maybe (TyCon, [PredType])
tcSplitTyConApp_maybe PredType
pred
       = ClassSet -> PredType -> TyCon -> [PredType] -> Maybe (Bool, SDoc)
go_tc ClassSet
so_far PredType
pred TyCon
tc [PredType]
tys
       | PredType -> Bool
hasTyVarHead PredType
pred
       = (Bool, SDoc) -> Maybe (Bool, SDoc)
forall a. a -> Maybe a
Just (Bool
False, SDoc -> Int -> SDoc -> SDoc
hang (String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"one of whose superclass constraints is headed by a type variable:")
                         Int
2 (SDoc -> SDoc
quotes (PredType -> SDoc
forall a. Outputable a => a -> SDoc
ppr PredType
pred)))
       | Bool
otherwise
       = Maybe (Bool, SDoc)
forall a. Maybe a
Nothing

    go_tc :: ClassSet -> PredType -> TyCon -> [Type] -> Maybe (Bool, SDoc)
    go_tc :: ClassSet -> PredType -> TyCon -> [PredType] -> Maybe (Bool, SDoc)
go_tc ClassSet
so_far PredType
pred TyCon
tc [PredType]
tys
      | TyCon -> Bool
isFamilyTyCon TyCon
tc
      = (Bool, SDoc) -> Maybe (Bool, SDoc)
forall a. a -> Maybe a
Just (Bool
False, SDoc -> Int -> SDoc -> SDoc
hang (String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"one of whose superclass constraints is headed by a type family:")
                        Int
2 (SDoc -> SDoc
quotes (PredType -> SDoc
forall a. Outputable a => a -> SDoc
ppr PredType
pred)))
      | Just Class
cls <- TyCon -> Maybe Class
tyConClass_maybe TyCon
tc
      = ClassSet -> Class -> [PredType] -> Maybe (Bool, SDoc)
go_cls ClassSet
so_far Class
cls [PredType]
tys
      | Bool
otherwise   -- Equality predicate, for example
      = Maybe (Bool, SDoc)
forall a. Maybe a
Nothing

    go_cls :: ClassSet -> Class -> [Type] -> Maybe (Bool, SDoc)
    go_cls :: ClassSet -> Class -> [PredType] -> Maybe (Bool, SDoc)
go_cls ClassSet
so_far Class
cls [PredType]
tys
       | Class
cls Class -> ClassSet -> Bool
forall a. Uniquable a => a -> UniqSet a -> Bool
`elementOfUniqSet` ClassSet
so_far
       = (Bool, SDoc) -> Maybe (Bool, SDoc)
forall a. a -> Maybe a
Just (Bool
True, String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"one of whose superclasses is" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> SDoc -> SDoc
quotes (Class -> SDoc
forall a. Outputable a => a -> SDoc
ppr Class
cls))
       | Class -> Bool
isCTupleClass Class
cls
       = ClassSet -> Class -> [PredType] -> Maybe (Bool, SDoc)
go ClassSet
so_far Class
cls [PredType]
tys
       | Bool
otherwise
       = do { (Bool
b,SDoc
err) <- ClassSet -> Class -> [PredType] -> Maybe (Bool, SDoc)
go  (ClassSet
so_far ClassSet -> Class -> ClassSet
forall a. Uniquable a => UniqSet a -> a -> UniqSet a
`addOneToUniqSet` Class
cls) Class
cls [PredType]
tys
          ; (Bool, SDoc) -> Maybe (Bool, SDoc)
forall a. a -> Maybe a
forall (m :: * -> *) a. Monad m => a -> m a
return (Bool
b, String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"one of whose superclasses is" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> SDoc -> SDoc
quotes (Class -> SDoc
forall a. Outputable a => a -> SDoc
ppr Class
cls)
                       SDoc -> SDoc -> SDoc
forall doc. IsDoc doc => doc -> doc -> doc
$$ SDoc
err) }

{-
************************************************************************
*                                                                      *
        Role inference
*                                                                      *
************************************************************************

Note [Role inference]
~~~~~~~~~~~~~~~~~~~~~
The role inference algorithm datatype definitions to infer the roles on the
parameters. Although these roles are stored in the tycons, we can perform this
algorithm on the built tycons, as long as we don't peek at an as-yet-unknown
roles field! Ah, the magic of laziness.

First, we choose appropriate initial roles. For families and classes, roles
(including initial roles) are N. For datatypes, we start with the role in the
role annotation (if any), or otherwise use Phantom. This is done in
initialRoleEnv1.

The function irGroup then propagates role information until it reaches a
fixpoint, preferring N over (R or P) and R over P. To aid in this, we have a
monad RoleM, which is a combination reader and state monad. In its state are
the current RoleEnv, which gets updated by role propagation, and an update
bit, which we use to know whether or not we've reached the fixpoint. The
environment of RoleM contains the tycon whose parameters we are inferring, and
a VarEnv from parameters to their positions, so we can update the RoleEnv.
Between tycons, this reader information is missing; it is added by
addRoleInferenceInfo.

There are two kinds of tycons to consider: algebraic ones (excluding classes)
and type synonyms. (Remember, families don't participate -- all their parameters
are N.) An algebraic tycon processes each of its datacons, in turn. Note that
a datacon's universally quantified parameters might be different from the parent
tycon's parameters, so we use the datacon's univ parameters in the mapping from
vars to positions. Note also that we don't want to infer roles for existentials
(they're all at N, too), so we put them in the set of local variables. As an
optimisation, we skip any tycons whose roles are already all Nominal, as there
nowhere else for them to go. For synonyms, we just analyse their right-hand sides.

irType walks through a type, looking for uses of a variable of interest and
propagating role information. Because anything used under a phantom position
is at phantom and anything used under a nominal position is at nominal, the
irType function can assume that anything it sees is at representational. (The
other possibilities are pruned when they're encountered.)

The rest of the code is just plumbing.

How do we know that this algorithm is correct? It should meet the following
specification:

Let Z be a role context -- a mapping from variables to roles. The following
rules define the property (Z |- t : r), where t is a type and r is a role:

Z(a) = r'        r' <= r
------------------------- RCVar
Z |- a : r

---------- RCConst
Z |- T : r               -- T is a type constructor

Z |- t1 : r
Z |- t2 : N
-------------- RCApp
Z |- t1 t2 : r

forall i<=n. (r_i is R or N) implies Z |- t_i : r_i
roles(T) = r_1 .. r_n
---------------------------------------------------- RCDApp
Z |- T t_1 .. t_n : R

Z, a:N |- t : r
---------------------- RCAll
Z |- forall a:k.t : r


We also have the following rules:

For all datacon_i in type T, where a_1 .. a_n are universally quantified
and b_1 .. b_m are existentially quantified, and the arguments are t_1 .. t_p,
then if forall j<=p, a_1 : r_1 .. a_n : r_n, b_1 : N .. b_m : N |- t_j : R,
then roles(T) = r_1 .. r_n

roles(->) = R, R
roles(~#) = N, N

With -dcore-lint on, the output of this algorithm is checked in checkValidRoles,
called from checkValidTycon.

Note [Role-checking data constructor arguments]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider
  data T a where
    MkT :: Eq b => F a -> (a->a) -> T (G a)

Then we want to check the roles at which 'a' is used
in MkT's type.  We want to work on the user-written type,
so we need to take into account
  * the arguments:   (F a) and (a->a)
  * the context:     C a b
  * the result type: (G a)   -- this is in the eq_spec


Note [Coercions in role inference]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Is (t |> co1) representationally equal to (t |> co2)? Of course they are! Changing
the kind of a type is totally irrelevant to the representation of that type. So,
we want to totally ignore coercions when doing role inference. This includes omitting
any type variables that appear in nominal positions but only within coercions.
-}

type RolesInfo = Name -> [Role]

type RoleEnv = NameEnv [Role]        -- from tycon names to roles

-- This, and any of the functions it calls, must *not* look at the roles
-- field of a tycon we are inferring roles about!
-- See Note [Role inference]
inferRoles :: HscSource -> RoleAnnotEnv -> [TyCon] -> Name -> [Role]
inferRoles :: HscSource -> RoleAnnotEnv -> [TyCon] -> Name -> [Role]
inferRoles HscSource
hsc_src RoleAnnotEnv
annots [TyCon]
tycons
  = let role_env :: RoleEnv
role_env  = HscSource -> RoleAnnotEnv -> [TyCon] -> RoleEnv
initialRoleEnv HscSource
hsc_src RoleAnnotEnv
annots [TyCon]
tycons
        role_env' :: RoleEnv
role_env' = RoleEnv -> [TyCon] -> RoleEnv
irGroup RoleEnv
role_env [TyCon]
tycons in
    \Name
name -> case RoleEnv -> Name -> Maybe [Role]
forall a. NameEnv a -> Name -> Maybe a
lookupNameEnv RoleEnv
role_env' Name
name of
      Just [Role]
roles -> [Role]
roles
      Maybe [Role]
Nothing    -> String -> SDoc -> [Role]
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"inferRoles" (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
name)

initialRoleEnv :: HscSource -> RoleAnnotEnv -> [TyCon] -> RoleEnv
initialRoleEnv :: HscSource -> RoleAnnotEnv -> [TyCon] -> RoleEnv
initialRoleEnv HscSource
hsc_src RoleAnnotEnv
annots = RoleEnv -> [(Name, [Role])] -> RoleEnv
forall a. NameEnv a -> [(Name, a)] -> NameEnv a
extendNameEnvList RoleEnv
forall a. NameEnv a
emptyNameEnv ([(Name, [Role])] -> RoleEnv)
-> ([TyCon] -> [(Name, [Role])]) -> [TyCon] -> RoleEnv
forall b c a. (b -> c) -> (a -> b) -> a -> c
.
                                (TyCon -> (Name, [Role])) -> [TyCon] -> [(Name, [Role])]
forall a b. (a -> b) -> [a] -> [b]
map (HscSource -> RoleAnnotEnv -> TyCon -> (Name, [Role])
initialRoleEnv1 HscSource
hsc_src RoleAnnotEnv
annots)

initialRoleEnv1 :: HscSource -> RoleAnnotEnv -> TyCon -> (Name, [Role])
initialRoleEnv1 :: HscSource -> RoleAnnotEnv -> TyCon -> (Name, [Role])
initialRoleEnv1 HscSource
hsc_src RoleAnnotEnv
annots_env TyCon
tc
  | TyCon -> Bool
isFamilyTyCon TyCon
tc      = (Name
name, (TyConBinder -> Role) -> [TyConBinder] -> [Role]
forall a b. (a -> b) -> [a] -> [b]
map (Role -> TyConBinder -> Role
forall a b. a -> b -> a
const Role
Nominal) [TyConBinder]
bndrs)
  | TyCon -> Bool
isAlgTyCon TyCon
tc         = (Name
name, [Role]
default_roles)
  | TyCon -> Bool
isTypeSynonymTyCon TyCon
tc = (Name
name, [Role]
default_roles)
  | Bool
otherwise             = String -> SDoc -> (Name, [Role])
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"initialRoleEnv1" (TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tc)
  where name :: Name
name         = TyCon -> Name
tyConName TyCon
tc
        bndrs :: [TyConBinder]
bndrs        = TyCon -> [TyConBinder]
tyConBinders TyCon
tc
        argflags :: [ForAllTyFlag]
argflags     = (TyConBinder -> ForAllTyFlag) -> [TyConBinder] -> [ForAllTyFlag]
forall a b. (a -> b) -> [a] -> [b]
map TyConBinder -> ForAllTyFlag
tyConBinderForAllTyFlag [TyConBinder]
bndrs
        num_exps :: Int
num_exps     = (ForAllTyFlag -> Bool) -> [ForAllTyFlag] -> Int
forall a. (a -> Bool) -> [a] -> Int
count ForAllTyFlag -> Bool
isVisibleForAllTyFlag [ForAllTyFlag]
argflags

          -- if the number of annotations in the role annotation decl
          -- is wrong, just ignore it. We check this in the validity check.
        role_annots :: [Maybe Role]
role_annots
          = case RoleAnnotEnv -> Name -> Maybe (LRoleAnnotDecl (GhcPass 'Renamed))
lookupRoleAnnot RoleAnnotEnv
annots_env Name
name of
              Just (L SrcSpanAnnA
_ (RoleAnnotDecl XCRoleAnnotDecl (GhcPass 'Renamed)
_ LIdP (GhcPass 'Renamed)
_ [XRec (GhcPass 'Renamed) (Maybe Role)]
annots))
                | [XRec (GhcPass 'Renamed) (Maybe Role)]
[GenLocated (SrcAnn NoEpAnns) (Maybe Role)]
annots [GenLocated (SrcAnn NoEpAnns) (Maybe Role)] -> Int -> Bool
forall a. [a] -> Int -> Bool
`lengthIs` Int
num_exps -> (GenLocated (SrcAnn NoEpAnns) (Maybe Role) -> Maybe Role)
-> [GenLocated (SrcAnn NoEpAnns) (Maybe Role)] -> [Maybe Role]
forall a b. (a -> b) -> [a] -> [b]
map GenLocated (SrcAnn NoEpAnns) (Maybe Role) -> Maybe Role
forall l e. GenLocated l e -> e
unLoc [XRec (GhcPass 'Renamed) (Maybe Role)]
[GenLocated (SrcAnn NoEpAnns) (Maybe Role)]
annots
              Maybe (LRoleAnnotDecl (GhcPass 'Renamed))
_                              -> Int -> Maybe Role -> [Maybe Role]
forall a. Int -> a -> [a]
replicate Int
num_exps Maybe Role
forall a. Maybe a
Nothing
        default_roles :: [Role]
default_roles = [ForAllTyFlag] -> [Maybe Role] -> [Role]
build_default_roles [ForAllTyFlag]
argflags [Maybe Role]
role_annots

        build_default_roles :: [ForAllTyFlag] -> [Maybe Role] -> [Role]
build_default_roles (ForAllTyFlag
argf : [ForAllTyFlag]
argfs) (Maybe Role
m_annot : [Maybe Role]
ras)
          | ForAllTyFlag -> Bool
isVisibleForAllTyFlag ForAllTyFlag
argf
          = (Maybe Role
m_annot Maybe Role -> Role -> Role
forall a. Maybe a -> a -> a
`orElse` Role
default_role) Role -> [Role] -> [Role]
forall a. a -> [a] -> [a]
: [ForAllTyFlag] -> [Maybe Role] -> [Role]
build_default_roles [ForAllTyFlag]
argfs [Maybe Role]
ras
        build_default_roles (ForAllTyFlag
_argf : [ForAllTyFlag]
argfs) [Maybe Role]
ras
          = Role
Nominal Role -> [Role] -> [Role]
forall a. a -> [a] -> [a]
: [ForAllTyFlag] -> [Maybe Role] -> [Role]
build_default_roles [ForAllTyFlag]
argfs [Maybe Role]
ras
        build_default_roles [] [] = []
        build_default_roles [ForAllTyFlag]
_ [Maybe Role]
_ = String -> SDoc -> [Role]
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"initialRoleEnv1 (2)"
                                           ([SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat [TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tc, [Maybe Role] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Maybe Role]
role_annots])

        default_role :: Role
default_role
          | TyCon -> Bool
isClassTyCon TyCon
tc               = Role
Nominal
          -- Note [Default roles for abstract TyCons in hs-boot/hsig]
          | HscSource
HsBootFile <- HscSource
hsc_src
          , TyCon -> Bool
isAbstractTyCon TyCon
tc            = Role
Representational
          | HscSource
HsigFile   <- HscSource
hsc_src
          , TyCon -> Bool
isAbstractTyCon TyCon
tc            = Role
Nominal
          | Bool
otherwise                     = Role
Phantom

-- Note [Default roles for abstract TyCons in hs-boot/hsig]
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-- What should the default role for an abstract TyCon be?
--
-- Originally, we inferred phantom role for abstract TyCons
-- in hs-boot files, because the type variables were never used.
--
-- This was silly, because the role of the abstract TyCon
-- was required to match the implementation, and the roles of
-- data types are almost never phantom.  Thus, in ticket #9204,
-- the default was changed so be representational (the most common case).  If
-- the implementing data type was actually nominal, you'd get an easy
-- to understand error, and add the role annotation yourself.
--
-- Then Backpack was added, and with it we added role *subtyping*
-- the matching judgment: if an abstract TyCon has a nominal
-- parameter, it's OK to implement it with a representational
-- parameter.  But now, the representational default is not a good
-- one, because you should *only* request representational if
-- you're planning to do coercions. To be maximally flexible
-- with what data types you will accept, you want the default
-- for hsig files is nominal.  We don't allow role subtyping
-- with hs-boot files (it's good practice to give an exactly
-- accurate role here, because any types that use the abstract
-- type will propagate the role information.)

irGroup :: RoleEnv -> [TyCon] -> RoleEnv
irGroup :: RoleEnv -> [TyCon] -> RoleEnv
irGroup RoleEnv
env [TyCon]
tcs
  = let (RoleEnv
env', Bool
update) = RoleEnv -> RoleM () -> (RoleEnv, Bool)
runRoleM RoleEnv
env (RoleM () -> (RoleEnv, Bool)) -> RoleM () -> (RoleEnv, Bool)
forall a b. (a -> b) -> a -> b
$ (TyCon -> RoleM ()) -> [TyCon] -> RoleM ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ TyCon -> RoleM ()
irTyCon [TyCon]
tcs in
    if Bool
update
    then RoleEnv -> [TyCon] -> RoleEnv
irGroup RoleEnv
env' [TyCon]
tcs
    else RoleEnv
env'

irTyCon :: TyCon -> RoleM ()
irTyCon :: TyCon -> RoleM ()
irTyCon TyCon
tc
  | TyCon -> Bool
isAlgTyCon TyCon
tc
  = do { [Role]
old_roles <- TyCon -> RoleM [Role]
lookupRoles TyCon
tc
       ; Bool -> RoleM () -> RoleM ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
unless ((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]
old_roles) (RoleM () -> RoleM ()) -> RoleM () -> RoleM ()
forall a b. (a -> b) -> a -> b
$  -- also catches data families,
                                                -- which don't want or need role inference
         TyCon -> RoleM () -> RoleM ()
forall a. TyCon -> RoleM a -> RoleM a
irTcTyVars TyCon
tc (RoleM () -> RoleM ()) -> RoleM () -> RoleM ()
forall a b. (a -> b) -> a -> b
$
         do { (PredType -> RoleM ()) -> [PredType] -> RoleM ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ (VarSet -> PredType -> RoleM ()
irType VarSet
emptyVarSet) (TyCon -> [PredType]
tyConStupidTheta TyCon
tc)  -- See #8958
            ; Maybe Class -> (Class -> RoleM ()) -> RoleM ()
forall (m :: * -> *) a. Monad m => Maybe a -> (a -> m ()) -> m ()
whenIsJust (TyCon -> Maybe Class
tyConClass_maybe TyCon
tc) Class -> RoleM ()
irClass
            ; (DataCon -> RoleM ()) -> [DataCon] -> RoleM ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ DataCon -> RoleM ()
irDataCon (AlgTyConRhs -> [DataCon]
visibleDataCons (AlgTyConRhs -> [DataCon]) -> AlgTyConRhs -> [DataCon]
forall a b. (a -> b) -> a -> b
$ TyCon -> AlgTyConRhs
algTyConRhs TyCon
tc) }}

  | Just PredType
ty <- TyCon -> Maybe PredType
synTyConRhs_maybe TyCon
tc
  = TyCon -> RoleM () -> RoleM ()
forall a. TyCon -> RoleM a -> RoleM a
irTcTyVars TyCon
tc (RoleM () -> RoleM ()) -> RoleM () -> RoleM ()
forall a b. (a -> b) -> a -> b
$
    VarSet -> PredType -> RoleM ()
irType VarSet
emptyVarSet PredType
ty

  | Bool
otherwise
  = () -> RoleM ()
forall a. a -> RoleM a
forall (m :: * -> *) a. Monad m => a -> m a
return ()

-- any type variable used in an associated type must be Nominal
irClass :: Class -> RoleM ()
irClass :: Class -> RoleM ()
irClass Class
cls
  = (TyCon -> RoleM ()) -> [TyCon] -> RoleM ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ TyCon -> RoleM ()
ir_at (Class -> [TyCon]
classATs Class
cls)
  where
    cls_tvs :: [Id]
cls_tvs    = Class -> [Id]
classTyVars Class
cls
    cls_tv_set :: VarSet
cls_tv_set = [Id] -> VarSet
mkVarSet [Id]
cls_tvs

    ir_at :: TyCon -> RoleM ()
ir_at TyCon
at_tc
      = (Id -> RoleM ()) -> [Id] -> RoleM ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ (Role -> Id -> RoleM ()
updateRole Role
Nominal) [Id]
nvars
      where nvars :: [Id]
nvars = (Id -> Bool) -> [Id] -> [Id]
forall a. (a -> Bool) -> [a] -> [a]
filter (Id -> VarSet -> Bool
`elemVarSet` VarSet
cls_tv_set) ([Id] -> [Id]) -> [Id] -> [Id]
forall a b. (a -> b) -> a -> b
$ TyCon -> [Id]
tyConTyVars TyCon
at_tc

-- See Note [Role inference]
irDataCon :: DataCon -> RoleM ()
irDataCon :: DataCon -> RoleM ()
irDataCon DataCon
datacon
  = [Id] -> RoleM () -> RoleM ()
forall a. [Id] -> RoleM a -> RoleM a
setRoleInferenceVars [Id]
univ_tvs (RoleM () -> RoleM ()) -> RoleM () -> RoleM ()
forall a b. (a -> b) -> a -> b
$
    [Id] -> (VarSet -> RoleM ()) -> RoleM ()
forall a. [Id] -> (VarSet -> RoleM a) -> RoleM a
irExTyVars [Id]
ex_tvs ((VarSet -> RoleM ()) -> RoleM ())
-> (VarSet -> RoleM ()) -> RoleM ()
forall a b. (a -> b) -> a -> b
$ \ VarSet
ex_var_set ->
      do (PredType -> RoleM ()) -> [PredType] -> RoleM ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ (VarSet -> PredType -> RoleM ()
irType VarSet
ex_var_set) ([EqSpec] -> [PredType]
eqSpecPreds [EqSpec]
eq_spec [PredType] -> [PredType] -> [PredType]
forall a. [a] -> [a] -> [a]
++ [PredType]
theta [PredType] -> [PredType] -> [PredType]
forall a. [a] -> [a] -> [a]
++ (Scaled PredType -> PredType) -> [Scaled PredType] -> [PredType]
forall a b. (a -> b) -> [a] -> [b]
map Scaled PredType -> PredType
forall a. Scaled a -> a
scaledThing [Scaled PredType]
arg_tys)
         (PredType -> RoleM ()) -> [PredType] -> RoleM ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ (VarSet -> PredType -> RoleM ()
markNominal VarSet
ex_var_set) ((Id -> PredType) -> [Id] -> [PredType]
forall a b. (a -> b) -> [a] -> [b]
map Id -> PredType
tyVarKind [Id]
ex_tvs [PredType] -> [PredType] -> [PredType]
forall a. [a] -> [a] -> [a]
++ (Scaled PredType -> PredType) -> [Scaled PredType] -> [PredType]
forall a b. (a -> b) -> [a] -> [b]
map Scaled PredType -> PredType
forall a. Scaled a -> PredType
scaledMult [Scaled PredType]
arg_tys)  -- Field multiplicities are nominal (#18799)
      -- See Note [Role-checking data constructor arguments]
  where
    ([Id]
univ_tvs, [Id]
ex_tvs, [EqSpec]
eq_spec, [PredType]
theta, [Scaled PredType]
arg_tys, PredType
_res_ty)
      = DataCon
-> ([Id], [Id], [EqSpec], [PredType], [Scaled PredType], PredType)
dataConFullSig DataCon
datacon

irType :: VarSet -> Type -> RoleM ()
irType :: VarSet -> PredType -> RoleM ()
irType = VarSet -> PredType -> RoleM ()
go
  where
    go :: VarSet -> PredType -> RoleM ()
go VarSet
lcls PredType
ty                 | Just PredType
ty' <- PredType -> Maybe PredType
coreView PredType
ty -- #14101
                               = VarSet -> PredType -> RoleM ()
go VarSet
lcls PredType
ty'
    go VarSet
lcls (TyVarTy Id
tv)       = Bool -> RoleM () -> RoleM ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
unless (Id
tv Id -> VarSet -> Bool
`elemVarSet` VarSet
lcls) (RoleM () -> RoleM ()) -> RoleM () -> RoleM ()
forall a b. (a -> b) -> a -> b
$
                                 Role -> Id -> RoleM ()
updateRole Role
Representational Id
tv
    go VarSet
lcls (AppTy PredType
t1 PredType
t2)      = VarSet -> PredType -> RoleM ()
go VarSet
lcls PredType
t1 RoleM () -> RoleM () -> RoleM ()
forall a b. RoleM a -> RoleM b -> RoleM b
forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> VarSet -> PredType -> RoleM ()
markNominal VarSet
lcls PredType
t2
    go VarSet
lcls (TyConApp TyCon
tc [PredType]
tys)  = do { [Role]
roles <- TyCon -> RoleM [Role]
lookupRolesX TyCon
tc
                                    ; (Role -> PredType -> RoleM ()) -> [Role] -> [PredType] -> RoleM ()
forall (m :: * -> *) a b c.
Applicative m =>
(a -> b -> m c) -> [a] -> [b] -> m ()
zipWithM_ (VarSet -> Role -> PredType -> RoleM ()
go_app VarSet
lcls) [Role]
roles [PredType]
tys }
    go VarSet
lcls (ForAllTy ForAllTyBinder
tvb PredType
ty)  = do { let tv :: Id
tv = ForAllTyBinder -> Id
forall tv argf. VarBndr tv argf -> tv
binderVar ForAllTyBinder
tvb
                                          lcls' :: VarSet
lcls' = VarSet -> Id -> VarSet
extendVarSet VarSet
lcls Id
tv
                                    ; VarSet -> PredType -> RoleM ()
markNominal VarSet
lcls (Id -> PredType
tyVarKind Id
tv)
                                    ; VarSet -> PredType -> RoleM ()
go VarSet
lcls' PredType
ty }
    go VarSet
lcls (FunTy FunTyFlag
_ PredType
w PredType
arg PredType
res)  = VarSet -> PredType -> RoleM ()
markNominal VarSet
lcls PredType
w RoleM () -> RoleM () -> RoleM ()
forall a b. RoleM a -> RoleM b -> RoleM b
forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> VarSet -> PredType -> RoleM ()
go VarSet
lcls PredType
arg RoleM () -> RoleM () -> RoleM ()
forall a b. RoleM a -> RoleM b -> RoleM b
forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> VarSet -> PredType -> RoleM ()
go VarSet
lcls PredType
res
    go VarSet
_    (LitTy {})         = () -> RoleM ()
forall a. a -> RoleM a
forall (m :: * -> *) a. Monad m => a -> m a
return ()
      -- See Note [Coercions in role inference]
    go VarSet
lcls (CastTy PredType
ty KindCoercion
_)      = VarSet -> PredType -> RoleM ()
go VarSet
lcls PredType
ty
    go VarSet
_    (CoercionTy KindCoercion
_)     = () -> RoleM ()
forall a. a -> RoleM a
forall (m :: * -> *) a. Monad m => a -> m a
return ()

    go_app :: VarSet -> Role -> PredType -> RoleM ()
go_app VarSet
_ Role
Phantom PredType
_ = () -> RoleM ()
forall a. a -> RoleM a
forall (m :: * -> *) a. Monad m => a -> m a
return ()                 -- nothing to do here
    go_app VarSet
lcls Role
Nominal PredType
ty = VarSet -> PredType -> RoleM ()
markNominal VarSet
lcls PredType
ty  -- all vars below here are N
    go_app VarSet
lcls Role
Representational PredType
ty = VarSet -> PredType -> RoleM ()
go VarSet
lcls PredType
ty

irTcTyVars :: TyCon -> RoleM a -> RoleM a
irTcTyVars :: forall a. TyCon -> RoleM a -> RoleM a
irTcTyVars TyCon
tc RoleM a
thing
  = Name -> RoleM a -> RoleM a
forall a. Name -> RoleM a -> RoleM a
setRoleInferenceTc (TyCon -> Name
tyConName TyCon
tc) (RoleM a -> RoleM a) -> RoleM a -> RoleM a
forall a b. (a -> b) -> a -> b
$ [Id] -> RoleM a
go (TyCon -> [Id]
tyConTyVars TyCon
tc)
  where
    go :: [Id] -> RoleM a
go []       = RoleM a
thing
    go (Id
tv:[Id]
tvs) = do { VarSet -> PredType -> RoleM ()
markNominal VarSet
emptyVarSet (Id -> PredType
tyVarKind Id
tv)
                     ; Id -> RoleM a -> RoleM a
forall a. Id -> RoleM a -> RoleM a
addRoleInferenceVar Id
tv (RoleM a -> RoleM a) -> RoleM a -> RoleM a
forall a b. (a -> b) -> a -> b
$ [Id] -> RoleM a
go [Id]
tvs }

irExTyVars :: [TyVar] -> (TyVarSet -> RoleM a) -> RoleM a
irExTyVars :: forall a. [Id] -> (VarSet -> RoleM a) -> RoleM a
irExTyVars [Id]
orig_tvs VarSet -> RoleM a
thing = VarSet -> [Id] -> RoleM a
go VarSet
emptyVarSet [Id]
orig_tvs
  where
    go :: VarSet -> [Id] -> RoleM a
go VarSet
lcls []       = VarSet -> RoleM a
thing VarSet
lcls
    go VarSet
lcls (Id
tv:[Id]
tvs) = do { VarSet -> PredType -> RoleM ()
markNominal VarSet
lcls (Id -> PredType
tyVarKind Id
tv)
                          ; VarSet -> [Id] -> RoleM a
go (VarSet -> Id -> VarSet
extendVarSet VarSet
lcls Id
tv) [Id]
tvs }

markNominal :: TyVarSet   -- local variables
            -> Type -> RoleM ()
markNominal :: VarSet -> PredType -> RoleM ()
markNominal VarSet
lcls PredType
ty = let nvars :: [Id]
nvars = FV -> [Id]
fvVarList (VarSet -> FV -> FV
FV.delFVs VarSet
lcls (FV -> FV) -> FV -> FV
forall a b. (a -> b) -> a -> b
$ PredType -> FV
get_ty_vars PredType
ty) in
                      (Id -> RoleM ()) -> [Id] -> RoleM ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ (Role -> Id -> RoleM ()
updateRole Role
Nominal) [Id]
nvars
  where
     -- get_ty_vars gets all the tyvars (no covars!) from a type *without*
     -- recurring into coercions. Recall: coercions are totally ignored during
     -- role inference. See [Coercions in role inference]
    get_ty_vars :: Type -> FV
    get_ty_vars :: PredType -> FV
get_ty_vars PredType
t                 | Just PredType
t' <- PredType -> Maybe PredType
coreView PredType
t -- #20999
                                  = PredType -> FV
get_ty_vars PredType
t'
    get_ty_vars (TyVarTy Id
tv)      = Id -> FV
unitFV Id
tv
    get_ty_vars (AppTy PredType
t1 PredType
t2)     = PredType -> FV
get_ty_vars PredType
t1 FV -> FV -> FV
`unionFV` PredType -> FV
get_ty_vars PredType
t2
    get_ty_vars (FunTy FunTyFlag
_ PredType
w PredType
t1 PredType
t2) = PredType -> FV
get_ty_vars PredType
w FV -> FV -> FV
`unionFV` PredType -> FV
get_ty_vars PredType
t1 FV -> FV -> FV
`unionFV` PredType -> FV
get_ty_vars PredType
t2
    get_ty_vars (TyConApp TyCon
_ [PredType]
tys)  = (PredType -> FV) -> [PredType] -> FV
forall a. (a -> FV) -> [a] -> FV
mapUnionFV PredType -> FV
get_ty_vars [PredType]
tys
    get_ty_vars (ForAllTy ForAllTyBinder
tvb PredType
ty) = ForAllTyBinder -> FV -> FV
tyCoFVsBndr ForAllTyBinder
tvb (PredType -> FV
get_ty_vars PredType
ty)
    get_ty_vars (LitTy {})        = FV
emptyFV
    get_ty_vars (CastTy PredType
ty KindCoercion
_)     = PredType -> FV
get_ty_vars PredType
ty
    get_ty_vars (CoercionTy KindCoercion
_)    = FV
emptyFV

-- like lookupRoles, but with Nominal tags at the end for oversaturated TyConApps
lookupRolesX :: TyCon -> RoleM [Role]
lookupRolesX :: TyCon -> RoleM [Role]
lookupRolesX TyCon
tc
  = do { [Role]
roles <- TyCon -> RoleM [Role]
lookupRoles TyCon
tc
       ; [Role] -> RoleM [Role]
forall a. a -> RoleM a
forall (m :: * -> *) a. Monad m => a -> m a
return ([Role] -> RoleM [Role]) -> [Role] -> RoleM [Role]
forall a b. (a -> b) -> a -> b
$ [Role]
roles [Role] -> [Role] -> [Role]
forall a. [a] -> [a] -> [a]
++ Role -> [Role]
forall a. a -> [a]
repeat Role
Nominal }

-- gets the roles either from the environment or the tycon
lookupRoles :: TyCon -> RoleM [Role]
lookupRoles :: TyCon -> RoleM [Role]
lookupRoles TyCon
tc
  = do { RoleEnv
env <- RoleM RoleEnv
getRoleEnv
       ; case RoleEnv -> Name -> Maybe [Role]
forall a. NameEnv a -> Name -> Maybe a
lookupNameEnv RoleEnv
env (TyCon -> Name
tyConName TyCon
tc) of
           Just [Role]
roles -> [Role] -> RoleM [Role]
forall a. a -> RoleM a
forall (m :: * -> *) a. Monad m => a -> m a
return [Role]
roles
           Maybe [Role]
Nothing    -> [Role] -> RoleM [Role]
forall a. a -> RoleM a
forall (m :: * -> *) a. Monad m => a -> m a
return ([Role] -> RoleM [Role]) -> [Role] -> RoleM [Role]
forall a b. (a -> b) -> a -> b
$ TyCon -> [Role]
tyConRoles TyCon
tc }

-- tries to update a role; won't ever update a role "downwards"
updateRole :: Role -> TyVar -> RoleM ()
updateRole :: Role -> Id -> RoleM ()
updateRole Role
role Id
tv
  = do { VarPositions
var_ns <- RoleM VarPositions
getVarNs
       ; Name
name <- RoleM Name
getTyConName
       ; case VarPositions -> Id -> Maybe Int
forall a. VarEnv a -> Id -> Maybe a
lookupVarEnv VarPositions
var_ns Id
tv of
           Maybe Int
Nothing -> String -> SDoc -> RoleM ()
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"updateRole" (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
name SDoc -> SDoc -> SDoc
forall doc. IsDoc doc => doc -> doc -> doc
$$ Id -> SDoc
forall a. Outputable a => a -> SDoc
ppr Id
tv SDoc -> SDoc -> SDoc
forall doc. IsDoc doc => doc -> doc -> doc
$$ VarPositions -> SDoc
forall a. Outputable a => a -> SDoc
ppr VarPositions
var_ns)
           Just Int
n  -> Name -> Int -> Role -> RoleM ()
updateRoleEnv Name
name Int
n Role
role }

-- the state in the RoleM monad
data RoleInferenceState = RIS { RoleInferenceState -> RoleEnv
role_env  :: RoleEnv
                              , RoleInferenceState -> Bool
update    :: Bool }

-- the environment in the RoleM monad
type VarPositions = VarEnv Int

-- See [Role inference]
newtype RoleM a = RM { forall a.
RoleM a
-> Maybe Name
-> VarPositions
-> Int
-> RoleInferenceState
-> (a, RoleInferenceState)
unRM :: Maybe Name -- of the tycon
                            -> VarPositions
                            -> Int          -- size of VarPositions
                            -> RoleInferenceState
                            -> (a, RoleInferenceState) }
    deriving ((forall a b. (a -> b) -> RoleM a -> RoleM b)
-> (forall a b. a -> RoleM b -> RoleM a) -> Functor RoleM
forall a b. a -> RoleM b -> RoleM a
forall a b. (a -> b) -> RoleM a -> RoleM b
forall (f :: * -> *).
(forall a b. (a -> b) -> f a -> f b)
-> (forall a b. a -> f b -> f a) -> Functor f
$cfmap :: forall a b. (a -> b) -> RoleM a -> RoleM b
fmap :: forall a b. (a -> b) -> RoleM a -> RoleM b
$c<$ :: forall a b. a -> RoleM b -> RoleM a
<$ :: forall a b. a -> RoleM b -> RoleM a
Functor)

instance Applicative RoleM where
    pure :: forall a. a -> RoleM a
pure a
x = (Maybe Name
 -> VarPositions
 -> Int
 -> RoleInferenceState
 -> (a, RoleInferenceState))
-> RoleM a
forall a.
(Maybe Name
 -> VarPositions
 -> Int
 -> RoleInferenceState
 -> (a, RoleInferenceState))
-> RoleM a
RM ((Maybe Name
  -> VarPositions
  -> Int
  -> RoleInferenceState
  -> (a, RoleInferenceState))
 -> RoleM a)
-> (Maybe Name
    -> VarPositions
    -> Int
    -> RoleInferenceState
    -> (a, RoleInferenceState))
-> RoleM a
forall a b. (a -> b) -> a -> b
$ \Maybe Name
_ VarPositions
_ Int
_ RoleInferenceState
state -> (a
x, RoleInferenceState
state)
    <*> :: forall a b. RoleM (a -> b) -> RoleM a -> RoleM b
(<*>) = RoleM (a -> b) -> RoleM a -> RoleM b
forall (m :: * -> *) a b. Monad m => m (a -> b) -> m a -> m b
ap

instance Monad RoleM where
  RoleM a
a >>= :: forall a b. RoleM a -> (a -> RoleM b) -> RoleM b
>>= a -> RoleM b
f  = (Maybe Name
 -> VarPositions
 -> Int
 -> RoleInferenceState
 -> (b, RoleInferenceState))
-> RoleM b
forall a.
(Maybe Name
 -> VarPositions
 -> Int
 -> RoleInferenceState
 -> (a, RoleInferenceState))
-> RoleM a
RM ((Maybe Name
  -> VarPositions
  -> Int
  -> RoleInferenceState
  -> (b, RoleInferenceState))
 -> RoleM b)
-> (Maybe Name
    -> VarPositions
    -> Int
    -> RoleInferenceState
    -> (b, RoleInferenceState))
-> RoleM b
forall a b. (a -> b) -> a -> b
$ \Maybe Name
m_info VarPositions
vps Int
nvps RoleInferenceState
state ->
                  let (a
a', RoleInferenceState
state') = RoleM a
-> Maybe Name
-> VarPositions
-> Int
-> RoleInferenceState
-> (a, RoleInferenceState)
forall a.
RoleM a
-> Maybe Name
-> VarPositions
-> Int
-> RoleInferenceState
-> (a, RoleInferenceState)
unRM RoleM a
a Maybe Name
m_info VarPositions
vps Int
nvps RoleInferenceState
state in
                  RoleM b
-> Maybe Name
-> VarPositions
-> Int
-> RoleInferenceState
-> (b, RoleInferenceState)
forall a.
RoleM a
-> Maybe Name
-> VarPositions
-> Int
-> RoleInferenceState
-> (a, RoleInferenceState)
unRM (a -> RoleM b
f a
a') Maybe Name
m_info VarPositions
vps Int
nvps RoleInferenceState
state'

runRoleM :: RoleEnv -> RoleM () -> (RoleEnv, Bool)
runRoleM :: RoleEnv -> RoleM () -> (RoleEnv, Bool)
runRoleM RoleEnv
env RoleM ()
thing = (RoleEnv
env', Bool
update)
  where RIS { role_env :: RoleInferenceState -> RoleEnv
role_env = RoleEnv
env', update :: RoleInferenceState -> Bool
update = Bool
update }
          = ((), RoleInferenceState) -> RoleInferenceState
forall a b. (a, b) -> b
snd (((), RoleInferenceState) -> RoleInferenceState)
-> ((), RoleInferenceState) -> RoleInferenceState
forall a b. (a -> b) -> a -> b
$ RoleM ()
-> Maybe Name
-> VarPositions
-> Int
-> RoleInferenceState
-> ((), RoleInferenceState)
forall a.
RoleM a
-> Maybe Name
-> VarPositions
-> Int
-> RoleInferenceState
-> (a, RoleInferenceState)
unRM RoleM ()
thing Maybe Name
forall a. Maybe a
Nothing VarPositions
forall a. VarEnv a
emptyVarEnv Int
0 RoleInferenceState
state
        state :: RoleInferenceState
state = RIS { role_env :: RoleEnv
role_env  = RoleEnv
env
                    , update :: Bool
update    = Bool
False }

setRoleInferenceTc :: Name -> RoleM a -> RoleM a
setRoleInferenceTc :: forall a. Name -> RoleM a -> RoleM a
setRoleInferenceTc Name
name RoleM a
thing = (Maybe Name
 -> VarPositions
 -> Int
 -> RoleInferenceState
 -> (a, RoleInferenceState))
-> RoleM a
forall a.
(Maybe Name
 -> VarPositions
 -> Int
 -> RoleInferenceState
 -> (a, RoleInferenceState))
-> RoleM a
RM ((Maybe Name
  -> VarPositions
  -> Int
  -> RoleInferenceState
  -> (a, RoleInferenceState))
 -> RoleM a)
-> (Maybe Name
    -> VarPositions
    -> Int
    -> RoleInferenceState
    -> (a, RoleInferenceState))
-> RoleM a
forall a b. (a -> b) -> a -> b
$ \Maybe Name
m_name VarPositions
vps Int
nvps RoleInferenceState
state ->
                                Bool -> (a, RoleInferenceState) -> (a, RoleInferenceState)
forall a. HasCallStack => Bool -> a -> a
assert (Maybe Name -> Bool
forall a. Maybe a -> Bool
isNothing Maybe Name
m_name) ((a, RoleInferenceState) -> (a, RoleInferenceState))
-> (a, RoleInferenceState) -> (a, RoleInferenceState)
forall a b. (a -> b) -> a -> b
$
                                Bool -> (a, RoleInferenceState) -> (a, RoleInferenceState)
forall a. HasCallStack => Bool -> a -> a
assert (VarPositions -> Bool
forall a. VarEnv a -> Bool
isEmptyVarEnv VarPositions
vps) ((a, RoleInferenceState) -> (a, RoleInferenceState))
-> (a, RoleInferenceState) -> (a, RoleInferenceState)
forall a b. (a -> b) -> a -> b
$
                                Bool -> (a, RoleInferenceState) -> (a, RoleInferenceState)
forall a. HasCallStack => Bool -> a -> a
assert (Int
nvps Int -> Int -> Bool
forall a. Eq a => a -> a -> Bool
== Int
0) ((a, RoleInferenceState) -> (a, RoleInferenceState))
-> (a, RoleInferenceState) -> (a, RoleInferenceState)
forall a b. (a -> b) -> a -> b
$
                                RoleM a
-> Maybe Name
-> VarPositions
-> Int
-> RoleInferenceState
-> (a, RoleInferenceState)
forall a.
RoleM a
-> Maybe Name
-> VarPositions
-> Int
-> RoleInferenceState
-> (a, RoleInferenceState)
unRM RoleM a
thing (Name -> Maybe Name
forall a. a -> Maybe a
Just Name
name) VarPositions
vps Int
nvps RoleInferenceState
state

addRoleInferenceVar :: TyVar -> RoleM a -> RoleM a
addRoleInferenceVar :: forall a. Id -> RoleM a -> RoleM a
addRoleInferenceVar Id
tv RoleM a
thing
  = (Maybe Name
 -> VarPositions
 -> Int
 -> RoleInferenceState
 -> (a, RoleInferenceState))
-> RoleM a
forall a.
(Maybe Name
 -> VarPositions
 -> Int
 -> RoleInferenceState
 -> (a, RoleInferenceState))
-> RoleM a
RM ((Maybe Name
  -> VarPositions
  -> Int
  -> RoleInferenceState
  -> (a, RoleInferenceState))
 -> RoleM a)
-> (Maybe Name
    -> VarPositions
    -> Int
    -> RoleInferenceState
    -> (a, RoleInferenceState))
-> RoleM a
forall a b. (a -> b) -> a -> b
$ \Maybe Name
m_name VarPositions
vps Int
nvps RoleInferenceState
state ->
    Bool -> (a, RoleInferenceState) -> (a, RoleInferenceState)
forall a. HasCallStack => Bool -> a -> a
assert (Maybe Name -> Bool
forall a. Maybe a -> Bool
isJust Maybe Name
m_name) ((a, RoleInferenceState) -> (a, RoleInferenceState))
-> (a, RoleInferenceState) -> (a, RoleInferenceState)
forall a b. (a -> b) -> a -> b
$
    RoleM a
-> Maybe Name
-> VarPositions
-> Int
-> RoleInferenceState
-> (a, RoleInferenceState)
forall a.
RoleM a
-> Maybe Name
-> VarPositions
-> Int
-> RoleInferenceState
-> (a, RoleInferenceState)
unRM RoleM a
thing Maybe Name
m_name (VarPositions -> Id -> Int -> VarPositions
forall a. VarEnv a -> Id -> a -> VarEnv a
extendVarEnv VarPositions
vps Id
tv Int
nvps) (Int
nvpsInt -> Int -> Int
forall a. Num a => a -> a -> a
+Int
1) RoleInferenceState
state

setRoleInferenceVars :: [TyVar] -> RoleM a -> RoleM a
setRoleInferenceVars :: forall a. [Id] -> RoleM a -> RoleM a
setRoleInferenceVars [Id]
tvs RoleM a
thing
  = (Maybe Name
 -> VarPositions
 -> Int
 -> RoleInferenceState
 -> (a, RoleInferenceState))
-> RoleM a
forall a.
(Maybe Name
 -> VarPositions
 -> Int
 -> RoleInferenceState
 -> (a, RoleInferenceState))
-> RoleM a
RM ((Maybe Name
  -> VarPositions
  -> Int
  -> RoleInferenceState
  -> (a, RoleInferenceState))
 -> RoleM a)
-> (Maybe Name
    -> VarPositions
    -> Int
    -> RoleInferenceState
    -> (a, RoleInferenceState))
-> RoleM a
forall a b. (a -> b) -> a -> b
$ \Maybe Name
m_name VarPositions
_vps Int
_nvps RoleInferenceState
state ->
    Bool -> (a, RoleInferenceState) -> (a, RoleInferenceState)
forall a. HasCallStack => Bool -> a -> a
assert (Maybe Name -> Bool
forall a. Maybe a -> Bool
isJust Maybe Name
m_name) ((a, RoleInferenceState) -> (a, RoleInferenceState))
-> (a, RoleInferenceState) -> (a, RoleInferenceState)
forall a b. (a -> b) -> a -> b
$
    RoleM a
-> Maybe Name
-> VarPositions
-> Int
-> RoleInferenceState
-> (a, RoleInferenceState)
forall a.
RoleM a
-> Maybe Name
-> VarPositions
-> Int
-> RoleInferenceState
-> (a, RoleInferenceState)
unRM RoleM a
thing Maybe Name
m_name ([(Id, Int)] -> VarPositions
forall a. [(Id, a)] -> VarEnv a
mkVarEnv ([Id] -> [Int] -> [(Id, Int)]
forall a b. [a] -> [b] -> [(a, b)]
zip [Id]
tvs [Int
0..])) (String -> Int
forall a. HasCallStack => String -> a
panic String
"setRoleInferenceVars")
         RoleInferenceState
state

getRoleEnv :: RoleM RoleEnv
getRoleEnv :: RoleM RoleEnv
getRoleEnv = (Maybe Name
 -> VarPositions
 -> Int
 -> RoleInferenceState
 -> (RoleEnv, RoleInferenceState))
-> RoleM RoleEnv
forall a.
(Maybe Name
 -> VarPositions
 -> Int
 -> RoleInferenceState
 -> (a, RoleInferenceState))
-> RoleM a
RM ((Maybe Name
  -> VarPositions
  -> Int
  -> RoleInferenceState
  -> (RoleEnv, RoleInferenceState))
 -> RoleM RoleEnv)
-> (Maybe Name
    -> VarPositions
    -> Int
    -> RoleInferenceState
    -> (RoleEnv, RoleInferenceState))
-> RoleM RoleEnv
forall a b. (a -> b) -> a -> b
$ \Maybe Name
_ VarPositions
_ Int
_ state :: RoleInferenceState
state@(RIS { role_env :: RoleInferenceState -> RoleEnv
role_env = RoleEnv
env }) -> (RoleEnv
env, RoleInferenceState
state)

getVarNs :: RoleM VarPositions
getVarNs :: RoleM VarPositions
getVarNs = (Maybe Name
 -> VarPositions
 -> Int
 -> RoleInferenceState
 -> (VarPositions, RoleInferenceState))
-> RoleM VarPositions
forall a.
(Maybe Name
 -> VarPositions
 -> Int
 -> RoleInferenceState
 -> (a, RoleInferenceState))
-> RoleM a
RM ((Maybe Name
  -> VarPositions
  -> Int
  -> RoleInferenceState
  -> (VarPositions, RoleInferenceState))
 -> RoleM VarPositions)
-> (Maybe Name
    -> VarPositions
    -> Int
    -> RoleInferenceState
    -> (VarPositions, RoleInferenceState))
-> RoleM VarPositions
forall a b. (a -> b) -> a -> b
$ \Maybe Name
_ VarPositions
vps Int
_ RoleInferenceState
state -> (VarPositions
vps, RoleInferenceState
state)

getTyConName :: RoleM Name
getTyConName :: RoleM Name
getTyConName = (Maybe Name
 -> VarPositions
 -> Int
 -> RoleInferenceState
 -> (Name, RoleInferenceState))
-> RoleM Name
forall a.
(Maybe Name
 -> VarPositions
 -> Int
 -> RoleInferenceState
 -> (a, RoleInferenceState))
-> RoleM a
RM ((Maybe Name
  -> VarPositions
  -> Int
  -> RoleInferenceState
  -> (Name, RoleInferenceState))
 -> RoleM Name)
-> (Maybe Name
    -> VarPositions
    -> Int
    -> RoleInferenceState
    -> (Name, RoleInferenceState))
-> RoleM Name
forall a b. (a -> b) -> a -> b
$ \Maybe Name
m_name VarPositions
_ Int
_ RoleInferenceState
state ->
                    case Maybe Name
m_name of
                      Maybe Name
Nothing   -> String -> (Name, RoleInferenceState)
forall a. HasCallStack => String -> a
panic String
"getTyConName"
                      Just Name
name -> (Name
name, RoleInferenceState
state)

updateRoleEnv :: Name -> Int -> Role -> RoleM ()
updateRoleEnv :: Name -> Int -> Role -> RoleM ()
updateRoleEnv Name
name Int
n Role
role
  = (Maybe Name
 -> VarPositions
 -> Int
 -> RoleInferenceState
 -> ((), RoleInferenceState))
-> RoleM ()
forall a.
(Maybe Name
 -> VarPositions
 -> Int
 -> RoleInferenceState
 -> (a, RoleInferenceState))
-> RoleM a
RM ((Maybe Name
  -> VarPositions
  -> Int
  -> RoleInferenceState
  -> ((), RoleInferenceState))
 -> RoleM ())
-> (Maybe Name
    -> VarPositions
    -> Int
    -> RoleInferenceState
    -> ((), RoleInferenceState))
-> RoleM ()
forall a b. (a -> b) -> a -> b
$ \Maybe Name
_ VarPositions
_ Int
_ state :: RoleInferenceState
state@(RIS { role_env :: RoleInferenceState -> RoleEnv
role_env = RoleEnv
role_env }) -> ((),
         case RoleEnv -> Name -> Maybe [Role]
forall a. NameEnv a -> Name -> Maybe a
lookupNameEnv RoleEnv
role_env Name
name of
           Maybe [Role]
Nothing -> String -> SDoc -> RoleInferenceState
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"updateRoleEnv" (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
name)
           Just [Role]
roles -> let ([Role]
before, Role
old_role : [Role]
after) = Int -> [Role] -> ([Role], [Role])
forall a. Int -> [a] -> ([a], [a])
splitAt Int
n [Role]
roles in
                         if Role
role Role -> Role -> Bool
`ltRole` Role
old_role
                         then let roles' :: [Role]
roles' = [Role]
before [Role] -> [Role] -> [Role]
forall a. [a] -> [a] -> [a]
++ Role
role Role -> [Role] -> [Role]
forall a. a -> [a] -> [a]
: [Role]
after
                                  role_env' :: RoleEnv
role_env' = RoleEnv -> Name -> [Role] -> RoleEnv
forall a. NameEnv a -> Name -> a -> NameEnv a
extendNameEnv RoleEnv
role_env Name
name [Role]
roles' in
                              RIS { role_env :: RoleEnv
role_env = RoleEnv
role_env', update :: Bool
update = Bool
True }
                         else RoleInferenceState
state )


{- *********************************************************************
*                                                                      *
                Building implicits
*                                                                      *
********************************************************************* -}

addTyConsToGblEnv :: [TyCon] -> TcM (TcGblEnv, ThBindEnv)
-- Given a [TyCon], add to the TcGblEnv
--   * extend the TypeEnv with the tycons
--   * extend the TypeEnv with their implicitTyThings
--   * extend the TypeEnv with any default method Ids
--   * add bindings for record selectors
-- Return separately the TH levels of these bindings,
-- to be added to a LclEnv later.
addTyConsToGblEnv :: [TyCon] -> TcM (TcGblEnv, ThBindEnv)
addTyConsToGblEnv [TyCon]
tyclss
  = [TyCon] -> TcM (TcGblEnv, ThBindEnv) -> TcM (TcGblEnv, ThBindEnv)
forall r. [TyCon] -> TcM r -> TcM r
tcExtendTyConEnv [TyCon]
tyclss                    (TcM (TcGblEnv, ThBindEnv) -> TcM (TcGblEnv, ThBindEnv))
-> TcM (TcGblEnv, ThBindEnv) -> TcM (TcGblEnv, ThBindEnv)
forall a b. (a -> b) -> a -> b
$
    [TyThing] -> TcM (TcGblEnv, ThBindEnv) -> TcM (TcGblEnv, ThBindEnv)
forall r. [TyThing] -> TcM r -> TcM r
tcExtendGlobalEnvImplicit [TyThing]
implicit_things  (TcM (TcGblEnv, ThBindEnv) -> TcM (TcGblEnv, ThBindEnv))
-> TcM (TcGblEnv, ThBindEnv) -> TcM (TcGblEnv, ThBindEnv)
forall a b. (a -> b) -> a -> b
$
    [Id] -> TcM (TcGblEnv, ThBindEnv) -> TcM (TcGblEnv, ThBindEnv)
forall a. [Id] -> TcM a -> TcM a
tcExtendGlobalValEnv [Id]
def_meth_ids          (TcM (TcGblEnv, ThBindEnv) -> TcM (TcGblEnv, ThBindEnv))
-> TcM (TcGblEnv, ThBindEnv) -> TcM (TcGblEnv, ThBindEnv)
forall a b. (a -> b) -> a -> b
$
    do { String -> SDoc -> TcM ()
traceTc String
"tcAddTyCons" (SDoc -> TcM ()) -> SDoc -> TcM ()
forall a b. (a -> b) -> a -> b
$ [SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat
            [ String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"tycons" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [TyCon] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TyCon]
tyclss
            , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"implicits" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [TyThing] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TyThing]
implicit_things ]
       ; TcGblEnv
gbl_env <- [(Id, LHsBind (GhcPass 'Renamed))] -> TcM TcGblEnv
tcRecSelBinds ([TyCon] -> [(Id, LHsBind (GhcPass 'Renamed))]
mkRecSelBinds [TyCon]
tyclss)
       ; ThBindEnv
th_bndrs <- [TyThing] -> TcM ThBindEnv
tcTyThBinders [TyThing]
implicit_things
       ; (TcGblEnv, ThBindEnv) -> TcM (TcGblEnv, ThBindEnv)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (TcGblEnv
gbl_env, ThBindEnv
th_bndrs)
       }
 where
   implicit_things :: [TyThing]
implicit_things = (TyCon -> [TyThing]) -> [TyCon] -> [TyThing]
forall (t :: * -> *) a b. Foldable t => (a -> [b]) -> t a -> [b]
concatMap TyCon -> [TyThing]
implicitTyConThings [TyCon]
tyclss
   def_meth_ids :: [Id]
def_meth_ids    = [TyCon] -> [Id]
mkDefaultMethodIds [TyCon]
tyclss

mkDefaultMethodIds :: [TyCon] -> [Id]
-- We want to put the default-method Ids (both vanilla and generic)
-- into the type environment so that they are found when we typecheck
-- the filled-in default methods of each instance declaration
-- See Note [Default method Ids and Template Haskell]
mkDefaultMethodIds :: [TyCon] -> [Id]
mkDefaultMethodIds [TyCon]
tycons
  = [ Name -> PredType -> Id
mkExportedVanillaId Name
dm_name (Class -> Id -> DefMethSpec PredType -> PredType
mkDefaultMethodType Class
cls Id
sel_id DefMethSpec PredType
dm_spec)
    | TyCon
tc <- [TyCon]
tycons
    , Just Class
cls <- [TyCon -> Maybe Class
tyConClass_maybe TyCon
tc]
    , (Id
sel_id, Just (Name
dm_name, DefMethSpec PredType
dm_spec)) <- Class -> [(Id, DefMethInfo)]
classOpItems Class
cls ]

mkDefaultMethodType :: Class -> Id -> DefMethSpec Type -> Type
-- Returns the top-level type of the default method
mkDefaultMethodType :: Class -> Id -> DefMethSpec PredType -> PredType
mkDefaultMethodType Class
_ Id
sel_id DefMethSpec PredType
VanillaDM        = Id -> PredType
idType Id
sel_id
mkDefaultMethodType Class
cls Id
_   (GenericDM PredType
dm_ty) = [ForAllTyBinder] -> [PredType] -> PredType -> PredType
(() :: Constraint) =>
[ForAllTyBinder] -> [PredType] -> PredType -> PredType
mkSigmaTy [ForAllTyBinder]
tv_bndrs [PredType
pred] PredType
dm_ty
   where
     pred :: PredType
pred      = Class -> [PredType] -> PredType
mkClassPred Class
cls ([Id] -> [PredType]
mkTyVarTys ([TyConBinder] -> [Id]
forall tv argf. [VarBndr tv argf] -> [tv]
binderVars [TyConBinder]
cls_bndrs))
     cls_bndrs :: [TyConBinder]
cls_bndrs = TyCon -> [TyConBinder]
tyConBinders (Class -> TyCon
classTyCon Class
cls)
     tv_bndrs :: [ForAllTyBinder]
tv_bndrs  = [VarBndr Id Specificity] -> [ForAllTyBinder]
forall a. [VarBndr a Specificity] -> [VarBndr a ForAllTyFlag]
tyVarSpecToBinders ([VarBndr Id Specificity] -> [ForAllTyBinder])
-> [VarBndr Id Specificity] -> [ForAllTyBinder]
forall a b. (a -> b) -> a -> b
$ [TyConBinder] -> [VarBndr Id Specificity]
tyConInvisTVBinders [TyConBinder]
cls_bndrs
     -- NB: the Class doesn't have TyConBinders; we reach into its
     --     TyCon to get those.  We /do/ need the TyConBinders because
     --     we need the correct visibility: these default methods are
     --     used in code generated by the fill-in for missing
     --     methods in instances (GHC.Tc.TyCl.Instance.mkDefMethBind), and
     --     then typechecked.  So we need the right visibility info
     --     (#13998)

{-
************************************************************************
*                                                                      *
                Building record selectors
*                                                                      *
************************************************************************
-}

{-
Note [Default method Ids and Template Haskell]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider this (#4169):
   class Numeric a where
     fromIntegerNum :: a
     fromIntegerNum = ...

   ast :: Q [Dec]
   ast = [d| instance Numeric Int |]

When we typecheck 'ast' we have done the first pass over the class decl
(in tcTyClDecls), but we have not yet typechecked the default-method
declarations (because they can mention value declarations).  So we
must bring the default method Ids into scope first (so they can be seen
when typechecking the [d| .. |] quote, and typecheck them later.
-}

{-
************************************************************************
*                                                                      *
                Building record selectors
*                                                                      *
************************************************************************
-}

tcRecSelBinds :: [(Id, LHsBind GhcRn)] -> TcM TcGblEnv
tcRecSelBinds :: [(Id, LHsBind (GhcPass 'Renamed))] -> TcM TcGblEnv
tcRecSelBinds [(Id, LHsBind (GhcPass 'Renamed))]
sel_bind_prs
  = [Id] -> TcM TcGblEnv -> TcM TcGblEnv
forall a. [Id] -> TcM a -> TcM a
tcExtendGlobalValEnv [Id
sel_id | (L SrcSpanAnnA
_ (XSig (IdSig Id
sel_id))) <- [GenLocated SrcSpanAnnA (Sig (GhcPass 'Renamed))]
sigs] (TcM TcGblEnv -> TcM TcGblEnv) -> TcM TcGblEnv -> TcM TcGblEnv
forall a b. (a -> b) -> a -> b
$
    do { ([(RecFlag, Bag (GenLocated SrcSpanAnnA (HsBindLR GhcTc GhcTc)))]
rec_sel_binds, TcGblEnv
tcg_env) <- TcRn
  ([(RecFlag, Bag (GenLocated SrcSpanAnnA (HsBindLR GhcTc GhcTc)))],
   TcGblEnv)
-> TcRn
     ([(RecFlag, Bag (GenLocated SrcSpanAnnA (HsBindLR GhcTc GhcTc)))],
      TcGblEnv)
forall a. TcRn a -> TcRn a
discardWarnings (TcRn
   ([(RecFlag, Bag (GenLocated SrcSpanAnnA (HsBindLR GhcTc GhcTc)))],
    TcGblEnv)
 -> TcRn
      ([(RecFlag, Bag (GenLocated SrcSpanAnnA (HsBindLR GhcTc GhcTc)))],
       TcGblEnv))
-> TcRn
     ([(RecFlag, Bag (GenLocated SrcSpanAnnA (HsBindLR GhcTc GhcTc)))],
      TcGblEnv)
-> TcRn
     ([(RecFlag, Bag (GenLocated SrcSpanAnnA (HsBindLR GhcTc GhcTc)))],
      TcGblEnv)
forall a b. (a -> b) -> a -> b
$
                                     -- See Note [Impredicative record selectors]
                                     Extension
-> TcRn
     ([(RecFlag, Bag (GenLocated SrcSpanAnnA (HsBindLR GhcTc GhcTc)))],
      TcGblEnv)
-> TcRn
     ([(RecFlag, Bag (GenLocated SrcSpanAnnA (HsBindLR GhcTc GhcTc)))],
      TcGblEnv)
forall gbl lcl a. Extension -> TcRnIf gbl lcl a -> TcRnIf gbl lcl a
setXOptM Extension
LangExt.ImpredicativeTypes (TcRn
   ([(RecFlag, Bag (GenLocated SrcSpanAnnA (HsBindLR GhcTc GhcTc)))],
    TcGblEnv)
 -> TcRn
      ([(RecFlag, Bag (GenLocated SrcSpanAnnA (HsBindLR GhcTc GhcTc)))],
       TcGblEnv))
-> TcRn
     ([(RecFlag, Bag (GenLocated SrcSpanAnnA (HsBindLR GhcTc GhcTc)))],
      TcGblEnv)
-> TcRn
     ([(RecFlag, Bag (GenLocated SrcSpanAnnA (HsBindLR GhcTc GhcTc)))],
      TcGblEnv)
forall a b. (a -> b) -> a -> b
$
                                     TopLevelFlag
-> [(RecFlag, LHsBinds (GhcPass 'Renamed))]
-> [LSig (GhcPass 'Renamed)]
-> TcM TcGblEnv
-> TcM ([(RecFlag, LHsBinds GhcTc)], TcGblEnv)
forall thing.
TopLevelFlag
-> [(RecFlag, LHsBinds (GhcPass 'Renamed))]
-> [LSig (GhcPass 'Renamed)]
-> TcM thing
-> TcM ([(RecFlag, LHsBinds GhcTc)], thing)
tcValBinds TopLevelFlag
TopLevel [(RecFlag, LHsBinds (GhcPass 'Renamed))]
[(RecFlag,
  Bag
    (GenLocated
       SrcSpanAnnA (HsBindLR (GhcPass 'Renamed) (GhcPass 'Renamed))))]
binds [LSig (GhcPass 'Renamed)]
[GenLocated SrcSpanAnnA (Sig (GhcPass 'Renamed))]
sigs TcM TcGblEnv
forall gbl lcl. TcRnIf gbl lcl gbl
getGblEnv
       ; TcGblEnv -> TcM TcGblEnv
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (TcGblEnv
tcg_env TcGblEnv -> [LHsBinds GhcTc] -> TcGblEnv
`addTypecheckedBinds` ((RecFlag, Bag (GenLocated SrcSpanAnnA (HsBindLR GhcTc GhcTc)))
 -> Bag (GenLocated SrcSpanAnnA (HsBindLR GhcTc GhcTc)))
-> [(RecFlag, Bag (GenLocated SrcSpanAnnA (HsBindLR GhcTc GhcTc)))]
-> [Bag (GenLocated SrcSpanAnnA (HsBindLR GhcTc GhcTc))]
forall a b. (a -> b) -> [a] -> [b]
map (RecFlag, Bag (GenLocated SrcSpanAnnA (HsBindLR GhcTc GhcTc)))
-> Bag (GenLocated SrcSpanAnnA (HsBindLR GhcTc GhcTc))
forall a b. (a, b) -> b
snd [(RecFlag, Bag (GenLocated SrcSpanAnnA (HsBindLR GhcTc GhcTc)))]
rec_sel_binds) }
  where
    sigs :: [GenLocated SrcSpanAnnA (Sig (GhcPass 'Renamed))]
sigs = [ SrcSpanAnnA
-> Sig (GhcPass 'Renamed)
-> GenLocated SrcSpanAnnA (Sig (GhcPass 'Renamed))
forall l e. l -> e -> GenLocated l e
L (SrcSpan -> SrcSpanAnnA
forall ann. SrcSpan -> SrcAnn ann
noAnnSrcSpan SrcSpan
loc) (XXSig (GhcPass 'Renamed) -> Sig (GhcPass 'Renamed)
forall pass. XXSig pass -> Sig pass
XSig (XXSig (GhcPass 'Renamed) -> Sig (GhcPass 'Renamed))
-> XXSig (GhcPass 'Renamed) -> Sig (GhcPass 'Renamed)
forall a b. (a -> b) -> a -> b
$ Id -> IdSig
IdSig Id
sel_id)
                                             | (Id
sel_id, GenLocated
  SrcSpanAnnA (HsBindLR (GhcPass 'Renamed) (GhcPass 'Renamed))
_) <- [(Id, LHsBind (GhcPass 'Renamed))]
[(Id,
  GenLocated
    SrcSpanAnnA (HsBindLR (GhcPass 'Renamed) (GhcPass 'Renamed)))]
sel_bind_prs
                                             , let loc :: SrcSpan
loc = Id -> SrcSpan
forall a. NamedThing a => a -> SrcSpan
getSrcSpan Id
sel_id ]
    binds :: [(RecFlag,
  Bag
    (GenLocated
       SrcSpanAnnA (HsBindLR (GhcPass 'Renamed) (GhcPass 'Renamed))))]
binds = [(RecFlag
NonRecursive, GenLocated
  SrcSpanAnnA (HsBindLR (GhcPass 'Renamed) (GhcPass 'Renamed))
-> Bag
     (GenLocated
        SrcSpanAnnA (HsBindLR (GhcPass 'Renamed) (GhcPass 'Renamed)))
forall a. a -> Bag a
unitBag GenLocated
  SrcSpanAnnA (HsBindLR (GhcPass 'Renamed) (GhcPass 'Renamed))
bind) | (Id
_, GenLocated
  SrcSpanAnnA (HsBindLR (GhcPass 'Renamed) (GhcPass 'Renamed))
bind) <- [(Id, LHsBind (GhcPass 'Renamed))]
[(Id,
  GenLocated
    SrcSpanAnnA (HsBindLR (GhcPass 'Renamed) (GhcPass 'Renamed)))]
sel_bind_prs]

mkRecSelBinds :: [TyCon] -> [(Id, LHsBind GhcRn)]
-- NB We produce *un-typechecked* bindings, rather like 'deriving'
--    This makes life easier, because the later type checking will add
--    all necessary type abstractions and applications
mkRecSelBinds :: [TyCon] -> [(Id, LHsBind (GhcPass 'Renamed))]
mkRecSelBinds [TyCon]
tycons
  = ((TyCon, FieldLabel)
 -> (Id,
     GenLocated
       SrcSpanAnnA (HsBindLR (GhcPass 'Renamed) (GhcPass 'Renamed))))
-> [(TyCon, FieldLabel)]
-> [(Id,
     GenLocated
       SrcSpanAnnA (HsBindLR (GhcPass 'Renamed) (GhcPass 'Renamed)))]
forall a b. (a -> b) -> [a] -> [b]
map (TyCon, FieldLabel) -> (Id, LHsBind (GhcPass 'Renamed))
(TyCon, FieldLabel)
-> (Id,
    GenLocated
      SrcSpanAnnA (HsBindLR (GhcPass 'Renamed) (GhcPass 'Renamed)))
mkRecSelBind [ (TyCon
tc,FieldLabel
fld) | TyCon
tc <- [TyCon]
tycons
                                , FieldLabel
fld <- TyCon -> [FieldLabel]
tyConFieldLabels TyCon
tc ]

mkRecSelBind :: (TyCon, FieldLabel) -> (Id, LHsBind GhcRn)
mkRecSelBind :: (TyCon, FieldLabel) -> (Id, LHsBind (GhcPass 'Renamed))
mkRecSelBind (TyCon
tycon, FieldLabel
fl)
  = [ConLike]
-> RecSelParent
-> FieldLabel
-> FieldSelectors
-> (Id, LHsBind (GhcPass 'Renamed))
mkOneRecordSelector [ConLike]
all_cons (TyCon -> RecSelParent
RecSelData TyCon
tycon) FieldLabel
fl
        FieldSelectors
FieldSelectors  -- See Note [NoFieldSelectors and naughty record selectors]
  where
    all_cons :: [ConLike]
all_cons = (DataCon -> ConLike) -> [DataCon] -> [ConLike]
forall a b. (a -> b) -> [a] -> [b]
map DataCon -> ConLike
RealDataCon (TyCon -> [DataCon]
tyConDataCons TyCon
tycon)

mkOneRecordSelector :: [ConLike] -> RecSelParent -> FieldLabel -> FieldSelectors
                    -> (Id, LHsBind GhcRn)
mkOneRecordSelector :: [ConLike]
-> RecSelParent
-> FieldLabel
-> FieldSelectors
-> (Id, LHsBind (GhcPass 'Renamed))
mkOneRecordSelector [ConLike]
all_cons RecSelParent
idDetails FieldLabel
fl FieldSelectors
has_sel
  = (Id
sel_id, SrcSpanAnnA
-> HsBindLR (GhcPass 'Renamed) (GhcPass 'Renamed)
-> GenLocated
     SrcSpanAnnA (HsBindLR (GhcPass 'Renamed) (GhcPass 'Renamed))
forall l e. l -> e -> GenLocated l e
L (SrcSpan -> SrcSpanAnnA
forall ann. SrcSpan -> SrcAnn ann
noAnnSrcSpan SrcSpan
loc) HsBindLR (GhcPass 'Renamed) (GhcPass 'Renamed)
sel_bind)
  where
    loc :: SrcSpan
loc      = Name -> SrcSpan
forall a. NamedThing a => a -> SrcSpan
getSrcSpan Name
sel_name
    loc' :: SrcSpanAnnA
loc'     = SrcSpan -> SrcSpanAnnA
forall ann. SrcSpan -> SrcAnn ann
noAnnSrcSpan SrcSpan
loc
    locn :: SrcSpanAnnN
locn     = SrcSpan -> SrcSpanAnnN
forall ann. SrcSpan -> SrcAnn ann
noAnnSrcSpan SrcSpan
loc
    locc :: SrcAnn NoEpAnns
locc     = SrcSpan -> SrcAnn NoEpAnns
forall ann. SrcSpan -> SrcAnn ann
noAnnSrcSpan SrcSpan
loc
    lbl :: FieldLabelString
lbl      = FieldLabel -> FieldLabelString
flLabel FieldLabel
fl
    sel_name :: Name
sel_name = FieldLabel -> Name
flSelector FieldLabel
fl

    sel_id :: Id
sel_id = IdDetails -> Name -> PredType -> Id
mkExportedLocalId IdDetails
rec_details Name
sel_name PredType
sel_ty
    rec_details :: IdDetails
rec_details = RecSelId { sel_tycon :: RecSelParent
sel_tycon = RecSelParent
idDetails, sel_naughty :: Bool
sel_naughty = Bool
is_naughty }

    -- Find a representative constructor, con1
    cons_w_field :: [ConLike]
cons_w_field = [ConLike] -> [FieldLabelString] -> [ConLike]
conLikesWithFields [ConLike]
all_cons [FieldLabelString
lbl]
    con1 :: ConLike
con1 = Bool -> ConLike -> ConLike
forall a. HasCallStack => Bool -> a -> a
assert (Bool -> Bool
not ([ConLike] -> Bool
forall a. [a] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [ConLike]
cons_w_field)) (ConLike -> ConLike) -> ConLike -> ConLike
forall a b. (a -> b) -> a -> b
$ [ConLike] -> ConLike
forall a. HasCallStack => [a] -> a
head [ConLike]
cons_w_field

    -- Selector type; Note [Polymorphic selectors]
    field_ty :: PredType
field_ty    = ConLike -> FieldLabelString -> PredType
conLikeFieldType ConLike
con1 FieldLabelString
lbl
    data_tv_set :: VarSet
data_tv_set = [PredType] -> VarSet
tyCoVarsOfTypes (PredType
data_ty PredType -> [PredType] -> [PredType]
forall a. a -> [a] -> [a]
: [PredType]
req_theta)
    data_tvbs :: [VarBndr Id Specificity]
data_tvbs   = (VarBndr Id Specificity -> Bool)
-> [VarBndr Id Specificity] -> [VarBndr Id Specificity]
forall a. (a -> Bool) -> [a] -> [a]
filter (\VarBndr Id Specificity
tvb -> VarBndr Id Specificity -> Id
forall tv argf. VarBndr tv argf -> tv
binderVar VarBndr Id Specificity
tvb Id -> VarSet -> Bool
`elemVarSet` VarSet
data_tv_set) ([VarBndr Id Specificity] -> [VarBndr Id Specificity])
-> [VarBndr Id Specificity] -> [VarBndr Id Specificity]
forall a b. (a -> b) -> a -> b
$
                  ConLike -> [VarBndr Id Specificity]
conLikeUserTyVarBinders ConLike
con1

    -- is_naughty: see Note [Naughty record selectors]
    is_naughty :: Bool
is_naughty = Bool -> Bool
not (PredType -> VarSet
tyCoVarsOfType PredType
field_ty VarSet -> VarSet -> Bool
`subVarSet` VarSet
data_tv_set)
              Bool -> Bool -> Bool
|| FieldSelectors
has_sel FieldSelectors -> FieldSelectors -> Bool
forall a. Eq a => a -> a -> Bool
== FieldSelectors
NoFieldSelectors  -- No field selectors => all are naughty
                                              -- thus suppressing making a binding
                                              -- A slight hack!

    sel_ty :: PredType
sel_ty | Bool
is_naughty = PredType
unitTy  -- See Note [Naughty record selectors]
           | Bool
otherwise  = [ForAllTyBinder] -> PredType -> PredType
mkForAllTys ([VarBndr Id Specificity] -> [ForAllTyBinder]
forall a. [VarBndr a Specificity] -> [VarBndr a ForAllTyFlag]
tyVarSpecToBinders [VarBndr Id Specificity]
data_tvbs) (PredType -> PredType) -> PredType -> PredType
forall a b. (a -> b) -> a -> b
$
                          -- Urgh! See Note [The stupid context] in GHC.Core.DataCon
                          [PredType] -> PredType -> PredType
(() :: Constraint) => [PredType] -> PredType -> PredType
mkPhiTy (ConLike -> [PredType]
conLikeStupidTheta ConLike
con1) (PredType -> PredType) -> PredType -> PredType
forall a b. (a -> b) -> a -> b
$
                          -- req_theta is empty for normal DataCon
                          [PredType] -> PredType -> PredType
(() :: Constraint) => [PredType] -> PredType -> PredType
mkPhiTy [PredType]
req_theta                 (PredType -> PredType) -> PredType -> PredType
forall a b. (a -> b) -> a -> b
$
                          (() :: Constraint) => PredType -> PredType -> PredType
PredType -> PredType -> PredType
mkVisFunTyMany PredType
data_ty            (PredType -> PredType) -> PredType -> PredType
forall a b. (a -> b) -> a -> b
$
                            -- Record selectors are always typed with Many. We
                            -- could improve on it in the case where all the
                            -- fields in all the constructor have multiplicity Many.
                          PredType
field_ty

    -- Make the binding: sel (C2 { fld = x }) = x
    --                   sel (C7 { fld = x }) = x
    --    where cons_w_field = [C2,C7]
    sel_bind :: HsBindLR (GhcPass 'Renamed) (GhcPass 'Renamed)
sel_bind = Origin
-> GenLocated SrcSpanAnnN Name
-> [LMatch (GhcPass 'Renamed) (LHsExpr (GhcPass 'Renamed))]
-> HsBindLR (GhcPass 'Renamed) (GhcPass 'Renamed)
mkTopFunBind Origin
Generated GenLocated SrcSpanAnnN Name
sel_lname [LMatch (GhcPass 'Renamed) (LHsExpr (GhcPass 'Renamed))]
[GenLocated
   SrcSpanAnnA
   (Match (GhcPass 'Renamed) (LocatedA (HsExpr (GhcPass 'Renamed))))]
alts
      where
        alts :: [GenLocated
   SrcSpanAnnA
   (Match (GhcPass 'Renamed) (LocatedA (HsExpr (GhcPass 'Renamed))))]
alts | Bool
is_naughty = [HsMatchContext (GhcPass 'Renamed)
-> [LPat (GhcPass 'Renamed)]
-> LocatedA (HsExpr (GhcPass 'Renamed))
-> LMatch (GhcPass 'Renamed) (LocatedA (HsExpr (GhcPass 'Renamed)))
forall (p :: Pass) (body :: * -> *).
(Anno (Match (GhcPass p) (LocatedA (body (GhcPass p))))
 ~ SrcSpanAnnA,
 Anno (GRHS (GhcPass p) (LocatedA (body (GhcPass p))))
 ~ SrcAnn NoEpAnns) =>
HsMatchContext (GhcPass p)
-> [LPat (GhcPass p)]
-> LocatedA (body (GhcPass p))
-> LMatch (GhcPass p) (LocatedA (body (GhcPass p)))
mkSimpleMatch (LIdP (GhcPass 'Renamed) -> HsMatchContext (GhcPass 'Renamed)
forall p. LIdP p -> HsMatchContext p
mkPrefixFunRhs LIdP (GhcPass 'Renamed)
GenLocated SrcSpanAnnN Name
sel_lname)
                                           [] LocatedA (HsExpr (GhcPass 'Renamed))
unit_rhs]
             | Bool
otherwise =  (ConLike
 -> GenLocated
      SrcSpanAnnA
      (Match (GhcPass 'Renamed) (LocatedA (HsExpr (GhcPass 'Renamed)))))
-> [ConLike]
-> [GenLocated
      SrcSpanAnnA
      (Match (GhcPass 'Renamed) (LocatedA (HsExpr (GhcPass 'Renamed))))]
forall a b. (a -> b) -> [a] -> [b]
map ConLike
-> LMatch (GhcPass 'Renamed) (LocatedA (HsExpr (GhcPass 'Renamed)))
ConLike
-> GenLocated
     SrcSpanAnnA
     (Match (GhcPass 'Renamed) (LocatedA (HsExpr (GhcPass 'Renamed))))
mk_match [ConLike]
cons_w_field [GenLocated
   SrcSpanAnnA
   (Match (GhcPass 'Renamed) (LocatedA (HsExpr (GhcPass 'Renamed))))]
-> [GenLocated
      SrcSpanAnnA
      (Match (GhcPass 'Renamed) (LocatedA (HsExpr (GhcPass 'Renamed))))]
-> [GenLocated
      SrcSpanAnnA
      (Match (GhcPass 'Renamed) (LocatedA (HsExpr (GhcPass 'Renamed))))]
forall a. [a] -> [a] -> [a]
++ [GenLocated
   SrcSpanAnnA
   (Match (GhcPass 'Renamed) (LocatedA (HsExpr (GhcPass 'Renamed))))]
deflt
    mk_match :: ConLike
-> LMatch (GhcPass 'Renamed) (LocatedA (HsExpr (GhcPass 'Renamed)))
mk_match ConLike
con = HsMatchContext (GhcPass 'Renamed)
-> [LPat (GhcPass 'Renamed)]
-> LocatedA (HsExpr (GhcPass 'Renamed))
-> LMatch (GhcPass 'Renamed) (LocatedA (HsExpr (GhcPass 'Renamed)))
forall (p :: Pass) (body :: * -> *).
(Anno (Match (GhcPass p) (LocatedA (body (GhcPass p))))
 ~ SrcSpanAnnA,
 Anno (GRHS (GhcPass p) (LocatedA (body (GhcPass p))))
 ~ SrcAnn NoEpAnns) =>
HsMatchContext (GhcPass p)
-> [LPat (GhcPass p)]
-> LocatedA (body (GhcPass p))
-> LMatch (GhcPass p) (LocatedA (body (GhcPass p)))
mkSimpleMatch (LIdP (GhcPass 'Renamed) -> HsMatchContext (GhcPass 'Renamed)
forall p. LIdP p -> HsMatchContext p
mkPrefixFunRhs LIdP (GhcPass 'Renamed)
GenLocated SrcSpanAnnN Name
sel_lname)
                                 [SrcSpanAnnA
-> Pat (GhcPass 'Renamed)
-> GenLocated SrcSpanAnnA (Pat (GhcPass 'Renamed))
forall l e. l -> e -> GenLocated l e
L SrcSpanAnnA
loc' (ConLike -> Pat (GhcPass 'Renamed)
mk_sel_pat ConLike
con)]
                                 (SrcSpanAnnA
-> HsExpr (GhcPass 'Renamed)
-> LocatedA (HsExpr (GhcPass 'Renamed))
forall l e. l -> e -> GenLocated l e
L SrcSpanAnnA
loc' (XVar (GhcPass 'Renamed)
-> LIdP (GhcPass 'Renamed) -> HsExpr (GhcPass 'Renamed)
forall p. XVar p -> LIdP p -> HsExpr p
HsVar XVar (GhcPass 'Renamed)
NoExtField
noExtField (SrcSpanAnnN -> Name -> GenLocated SrcSpanAnnN Name
forall l e. l -> e -> GenLocated l e
L SrcSpanAnnN
locn Name
field_var)))
    mk_sel_pat :: ConLike -> Pat (GhcPass 'Renamed)
mk_sel_pat ConLike
con = XConPat (GhcPass 'Renamed)
-> XRec (GhcPass 'Renamed) (ConLikeP (GhcPass 'Renamed))
-> HsConPatDetails (GhcPass 'Renamed)
-> Pat (GhcPass 'Renamed)
forall p.
XConPat p -> XRec p (ConLikeP p) -> HsConPatDetails p -> Pat p
ConPat XConPat (GhcPass 'Renamed)
NoExtField
NoExtField (SrcSpanAnnN -> Name -> GenLocated SrcSpanAnnN Name
forall l e. l -> e -> GenLocated l e
L SrcSpanAnnN
locn (ConLike -> Name
forall a. NamedThing a => a -> Name
getName ConLike
con)) (HsRecFields
  (GhcPass 'Renamed)
  (GenLocated SrcSpanAnnA (Pat (GhcPass 'Renamed)))
-> HsConDetails
     (HsConPatTyArg (NoGhcTc (GhcPass 'Renamed)))
     (LPat (GhcPass 'Renamed))
     (HsRecFields
        (GhcPass 'Renamed)
        (GenLocated SrcSpanAnnA (Pat (GhcPass 'Renamed))))
forall tyarg arg rec. rec -> HsConDetails tyarg arg rec
RecCon HsRecFields
  (GhcPass 'Renamed)
  (GenLocated SrcSpanAnnA (Pat (GhcPass 'Renamed)))
rec_fields)
    rec_fields :: HsRecFields
  (GhcPass 'Renamed)
  (GenLocated SrcSpanAnnA (Pat (GhcPass 'Renamed)))
rec_fields = HsRecFields { rec_flds :: [LHsRecField
   (GhcPass 'Renamed)
   (GenLocated SrcSpanAnnA (Pat (GhcPass 'Renamed)))]
rec_flds = [LHsRecField
  (GhcPass 'Renamed)
  (GenLocated SrcSpanAnnA (Pat (GhcPass 'Renamed)))
LocatedAn
  AnnListItem
  (HsFieldBind
     (GenLocated (SrcAnn NoEpAnns) (FieldOcc (GhcPass 'Renamed)))
     (GenLocated SrcSpanAnnA (Pat (GhcPass 'Renamed))))
rec_field], rec_dotdot :: Maybe (XRec (GhcPass 'Renamed) RecFieldsDotDot)
rec_dotdot = Maybe (XRec (GhcPass 'Renamed) RecFieldsDotDot)
forall a. Maybe a
Nothing }
    rec_field :: LocatedAn
  AnnListItem
  (HsFieldBind
     (GenLocated (SrcAnn NoEpAnns) (FieldOcc (GhcPass 'Renamed)))
     (GenLocated SrcSpanAnnA (Pat (GhcPass 'Renamed))))
rec_field  = HsFieldBind
  (GenLocated (SrcAnn NoEpAnns) (FieldOcc (GhcPass 'Renamed)))
  (GenLocated SrcSpanAnnA (Pat (GhcPass 'Renamed)))
-> LocatedAn
     AnnListItem
     (HsFieldBind
        (GenLocated (SrcAnn NoEpAnns) (FieldOcc (GhcPass 'Renamed)))
        (GenLocated SrcSpanAnnA (Pat (GhcPass 'Renamed))))
forall a an. a -> LocatedAn an a
noLocA (HsFieldBind
                        { hfbAnn :: XHsFieldBind
  (GenLocated (SrcAnn NoEpAnns) (FieldOcc (GhcPass 'Renamed)))
hfbAnn = XHsFieldBind
  (GenLocated (SrcAnn NoEpAnns) (FieldOcc (GhcPass 'Renamed)))
EpAnn [AddEpAnn]
forall a. EpAnn a
noAnn
                        , hfbLHS :: GenLocated (SrcAnn NoEpAnns) (FieldOcc (GhcPass 'Renamed))
hfbLHS
                           = SrcAnn NoEpAnns
-> FieldOcc (GhcPass 'Renamed)
-> GenLocated (SrcAnn NoEpAnns) (FieldOcc (GhcPass 'Renamed))
forall l e. l -> e -> GenLocated l e
L SrcAnn NoEpAnns
locc (XCFieldOcc (GhcPass 'Renamed)
-> XRec (GhcPass 'Renamed) RdrName -> FieldOcc (GhcPass 'Renamed)
forall pass. XCFieldOcc pass -> XRec pass RdrName -> FieldOcc pass
FieldOcc XCFieldOcc (GhcPass 'Renamed)
Name
sel_name
                                      (SrcSpanAnnN -> RdrName -> GenLocated SrcSpanAnnN RdrName
forall l e. l -> e -> GenLocated l e
L SrcSpanAnnN
locn (RdrName -> GenLocated SrcSpanAnnN RdrName)
-> RdrName -> GenLocated SrcSpanAnnN RdrName
forall a b. (a -> b) -> a -> b
$ FastString -> RdrName
mkVarUnqual (FieldLabelString -> FastString
field_label FieldLabelString
lbl)))
                        , hfbRHS :: GenLocated SrcSpanAnnA (Pat (GhcPass 'Renamed))
hfbRHS
                           = SrcSpanAnnA
-> Pat (GhcPass 'Renamed)
-> GenLocated SrcSpanAnnA (Pat (GhcPass 'Renamed))
forall l e. l -> e -> GenLocated l e
L SrcSpanAnnA
loc' (XVarPat (GhcPass 'Renamed)
-> LIdP (GhcPass 'Renamed) -> Pat (GhcPass 'Renamed)
forall p. XVarPat p -> LIdP p -> Pat p
VarPat XVarPat (GhcPass 'Renamed)
NoExtField
noExtField (SrcSpanAnnN -> Name -> GenLocated SrcSpanAnnN Name
forall l e. l -> e -> GenLocated l e
L SrcSpanAnnN
locn Name
field_var))
                        , hfbPun :: Bool
hfbPun = Bool
False })
    sel_lname :: GenLocated SrcSpanAnnN Name
sel_lname = SrcSpanAnnN -> Name -> GenLocated SrcSpanAnnN Name
forall l e. l -> e -> GenLocated l e
L SrcSpanAnnN
locn Name
sel_name
    field_var :: Name
field_var = Unique -> OccName -> SrcSpan -> Name
mkInternalName (Int -> Unique
mkBuiltinUnique Int
1) (Name -> OccName
forall a. NamedThing a => a -> OccName
getOccName Name
sel_name) SrcSpan
loc

    -- Add catch-all default case unless the case is exhaustive
    -- We do this explicitly so that we get a nice error message that
    -- mentions this particular record selector
    deflt :: [GenLocated
   SrcSpanAnnA
   (Match (GhcPass 'Renamed) (LocatedA (HsExpr (GhcPass 'Renamed))))]
deflt | (ConLike -> Bool) -> [ConLike] -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
all ConLike -> Bool
dealt_with [ConLike]
all_cons = []
          | Bool
otherwise = [HsMatchContext (GhcPass 'Renamed)
-> [LPat (GhcPass 'Renamed)]
-> LocatedA (HsExpr (GhcPass 'Renamed))
-> LMatch (GhcPass 'Renamed) (LocatedA (HsExpr (GhcPass 'Renamed)))
forall (p :: Pass) (body :: * -> *).
(Anno (Match (GhcPass p) (LocatedA (body (GhcPass p))))
 ~ SrcSpanAnnA,
 Anno (GRHS (GhcPass p) (LocatedA (body (GhcPass p))))
 ~ SrcAnn NoEpAnns) =>
HsMatchContext (GhcPass p)
-> [LPat (GhcPass p)]
-> LocatedA (body (GhcPass p))
-> LMatch (GhcPass p) (LocatedA (body (GhcPass p)))
mkSimpleMatch HsMatchContext (GhcPass 'Renamed)
forall p. HsMatchContext p
CaseAlt
                            [SrcSpanAnnA
-> Pat (GhcPass 'Renamed)
-> GenLocated SrcSpanAnnA (Pat (GhcPass 'Renamed))
forall l e. l -> e -> GenLocated l e
L SrcSpanAnnA
loc' (XWildPat (GhcPass 'Renamed) -> Pat (GhcPass 'Renamed)
forall p. XWildPat p -> Pat p
WildPat XWildPat (GhcPass 'Renamed)
NoExtField
noExtField)]
                            (LHsExpr (GhcPass 'Renamed)
-> LHsExpr (GhcPass 'Renamed) -> LHsExpr (GhcPass 'Renamed)
forall (id :: Pass).
LHsExpr (GhcPass id)
-> LHsExpr (GhcPass id) -> LHsExpr (GhcPass id)
mkHsApp (SrcSpanAnnA
-> HsExpr (GhcPass 'Renamed)
-> LocatedA (HsExpr (GhcPass 'Renamed))
forall l e. l -> e -> GenLocated l e
L SrcSpanAnnA
loc' (XVar (GhcPass 'Renamed)
-> LIdP (GhcPass 'Renamed) -> HsExpr (GhcPass 'Renamed)
forall p. XVar p -> LIdP p -> HsExpr p
HsVar XVar (GhcPass 'Renamed)
NoExtField
noExtField
                                         (SrcSpanAnnN -> Name -> GenLocated SrcSpanAnnN Name
forall l e. l -> e -> GenLocated l e
L SrcSpanAnnN
locn (Id -> Name
forall a. NamedThing a => a -> Name
getName Id
rEC_SEL_ERROR_ID))))
                                     (SrcSpanAnnA
-> HsExpr (GhcPass 'Renamed)
-> LocatedA (HsExpr (GhcPass 'Renamed))
forall l e. l -> e -> GenLocated l e
L SrcSpanAnnA
loc' (XLitE (GhcPass 'Renamed)
-> HsLit (GhcPass 'Renamed) -> HsExpr (GhcPass 'Renamed)
forall p. XLitE p -> HsLit p -> HsExpr p
HsLit XLitE (GhcPass 'Renamed)
EpAnnCO
noComments HsLit (GhcPass 'Renamed)
msg_lit)))]

        -- Do not add a default case unless there are unmatched
        -- constructors.  We must take account of GADTs, else we
        -- get overlap warning messages from the pattern-match checker
        -- NB: we need to pass type args for the *representation* TyCon
        --     to dataConCannotMatch, hence the calculation of inst_tys
        --     This matters in data families
        --              data instance T Int a where
        --                 A :: { fld :: Int } -> T Int Bool
        --                 B :: { fld :: Int } -> T Int Char
    dealt_with :: ConLike -> Bool
    dealt_with :: ConLike -> Bool
dealt_with (PatSynCon PatSyn
_) = Bool
False -- We can't predict overlap
    dealt_with con :: ConLike
con@(RealDataCon DataCon
dc)
      = ConLike
con ConLike -> [ConLike] -> Bool
forall a. Eq a => a -> [a] -> Bool
forall (t :: * -> *) a. (Foldable t, Eq a) => a -> t a -> Bool
`elem` [ConLike]
cons_w_field Bool -> Bool -> Bool
|| [PredType] -> DataCon -> Bool
dataConCannotMatch [PredType]
inst_tys DataCon
dc
      where
        inst_tys :: [PredType]
inst_tys = DataCon -> [PredType]
dataConResRepTyArgs DataCon
dc

    ([Id]
_, [Id]
_, [EqSpec]
_, [PredType]
_, [PredType]
req_theta, [Scaled PredType]
_, PredType
data_ty) = ConLike
-> ([Id], [Id], [EqSpec], [PredType], [PredType],
    [Scaled PredType], PredType)
conLikeFullSig ConLike
con1

    unit_rhs :: LHsExpr (GhcPass 'Renamed)
unit_rhs = [LHsExpr (GhcPass 'Renamed)]
-> XExplicitTuple (GhcPass 'Renamed) -> LHsExpr (GhcPass 'Renamed)
forall (p :: Pass).
[LHsExpr (GhcPass p)]
-> XExplicitTuple (GhcPass p) -> LHsExpr (GhcPass p)
mkLHsTupleExpr [] XExplicitTuple (GhcPass 'Renamed)
NoExtField
noExtField
    msg_lit :: HsLit (GhcPass 'Renamed)
msg_lit = XHsStringPrim (GhcPass 'Renamed)
-> ByteString -> HsLit (GhcPass 'Renamed)
forall x. XHsStringPrim x -> ByteString -> HsLit x
HsStringPrim XHsStringPrim (GhcPass 'Renamed)
SourceText
NoSourceText (FastString -> ByteString
bytesFS (FieldLabelString -> FastString
field_label FieldLabelString
lbl))

{-
Note [Polymorphic selectors]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We take care to build the type of a polymorphic selector in the right
order, so that visible type application works according to the specification in
the GHC User's Guide (see the "Field selectors and TypeApplications" section).
We won't bother rehashing the entire specification in this Note, but the tricky
part is dealing with GADT constructor fields. Here is an appropriately tricky
example to illustrate the challenges:

  {-# LANGUAGE PolyKinds #-}
  data T a b where
    MkT :: forall b a x.
           { field1 :: forall c. (Num a, Show c) => (Either a c, Proxy b)
           , field2 :: x
           }
        -> T a b

Our goal is to obtain the following type for `field1`:

  field1 :: forall {k} (b :: k) a.
            T a b -> forall c. (Num a, Show c) => (Either a c, Proxy b)

(`field2` is naughty, per Note [Naughty record selectors], so we cannot turn
it into a top-level field selector.)

Some potential gotchas, inspired by #18023:

1. Since the user wrote `forall b a x.` in the type of `MkT`, we want the `b`
   to appear before the `a` when quantified in the type of `field1`.
2. On the other hand, we *don't* want to quantify `x` in the type of `field1`.
   This is because `x` does not appear in the GADT return type, so it is not
   needed in the selector type.
3. Because of PolyKinds, the kind of `b` is generalized to `k`. Moreover, since
   this `k` is not written in the source code, it is inferred (i.e., not
   available for explicit type applications) and thus written as {k} in the type
   of `field1`.

In order to address these gotchas, we start by looking at the
conLikeUserTyVarBinders, which gives the order and specificity of each binder.
This effectively solves (1) and (3). To solve (2), we filter the binders to
leave only those that are needed for the selector type.

Note [Naughty record selectors]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
A "naughty" field is one for which we can't define a record
selector, because an existential type variable would escape.  For example:
        data T = forall a. MkT { x,y::a }
We obviously can't define
        x (MkT v _) = v
Nevertheless we *do* put a RecSelId into the type environment
so that if the user tries to use 'x' as a selector we can bleat
helpfully, rather than saying unhelpfully that 'x' is not in scope.
Hence the sel_naughty flag, to identify record selectors that don't really exist.

In general, a field is "naughty" if its type mentions a type variable that
isn't in
  * the (original, user-written) result type of the constructor, or
  * the "required theta" for the constructor

Note that this *allows* GADT record selectors (Note [GADT record
selectors]) whose types may look like sel :: T [a] -> a

The "required theta" part is illustrated by test patsyn/should_run/records_run
where we have

  pattern ReadP :: Read a => a -> String
  pattern ReadP {readp} <- (read -> readp)

The selector is defined like this:

  $selreadp :: ReadP a => String -> a
  $selReadP s = readp s

Perfectly fine!  The (ReadP a) constraint lets us contructor a value
of type 'a' from a bare String.  NB: "required theta" is empty for
data cons (see conLikeFullSig), so this reasoning only bites for
patttern synonyms.

For naughty selectors we make a dummy binding
   sel = ()
so that the later type-check will add them to the environment, and they'll be
exported.  The function is never called, because the typechecker spots the
sel_naughty field.

Note [NoFieldSelectors and naughty record selectors]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Under NoFieldSelectors (see Note [NoFieldSelectors] in GHC.Rename.Env), record
selectors will not be in scope in the renamer.  However, for normal datatype
declarations we still generate the underlying selector functions, so they can be
used for constructing the dictionaries for HasField constraints (as described by
Note [HasField instances] in GHC.Tc.Instance.Class).  Hence the call to
mkOneRecordSelector in mkRecSelBind always uses FieldSelectors.

However, record pattern synonyms are not used with HasField, so when
NoFieldSelectors is used we do not need to generate selector functions.  Thus
mkPatSynRecSelBinds passes the current state of the FieldSelectors extension to
mkOneRecordSelector, and in the NoFieldSelectors case it will treat them as
"naughty" fields (see Note [Naughty record selectors]).

Why generate a naughty binding, rather than no binding at all? Because when
type-checking a record update, we need to look up Ids for the fields. In
particular, disambiguateRecordBinds calls lookupParents which needs to look up
the RecSelIds to determine the sel_tycon.

Note [GADT record selectors]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
For GADTs, we require that all constructors with a common field 'f' have the same
result type (modulo alpha conversion).  [Checked in GHC.Tc.TyCl.checkValidTyCon]
E.g.
        data T where
          T1 { f :: Maybe a } :: T [a]
          T2 { f :: Maybe a, y :: b  } :: T [a]
          T3 :: T Int

and now the selector takes that result type as its argument:
   f :: forall a. T [a] -> Maybe a

Details: the "real" types of T1,T2 are:
   T1 :: forall r a.   (r~[a]) => a -> T r
   T2 :: forall r a b. (r~[a]) => a -> b -> T r

So the selector loooks like this:
   f :: forall a. T [a] -> Maybe a
   f (a:*) (t:T [a])
     = case t of
         T1 c   (g:[a]~[c]) (v:Maybe c)       -> v `cast` Maybe (right (sym g))
         T2 c d (g:[a]~[c]) (v:Maybe c) (w:d) -> v `cast` Maybe (right (sym g))
         T3 -> error "T3 does not have field f"

Note the forall'd tyvars of the selector are just the free tyvars
of the result type; there may be other tyvars in the constructor's
type (e.g. 'b' in T2).

Note the need for casts in the result!

Note [Selector running example]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
It's OK to combine GADTs and type families.  Here's a running example:

        data instance T [a] where
          T1 { fld :: b } :: T [Maybe b]

The representation type looks like this
        data :R7T a where
          T1 { fld :: b } :: :R7T (Maybe b)

and there's coercion from the family type to the representation type
        :CoR7T a :: T [a] ~ :R7T a

The selector we want for fld looks like this:

        fld :: forall b. T [Maybe b] -> b
        fld = /\b. \(d::T [Maybe b]).
              case d `cast` :CoR7T (Maybe b) of
                T1 (x::b) -> x

The scrutinee of the case has type :R7T (Maybe b), which can be
gotten by applying the eq_spec to the univ_tvs of the data con.

Note [Impredicative record selectors]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
There are situations where generating code for record selectors requires the
use of ImpredicativeTypes. Here is one example (adapted from #18005):

  type S = (forall b. b -> b) -> Int
  data T = MkT {unT :: S}
         | Dummy

We want to generate HsBinds for unT that look something like this:

  unT :: S
  unT (MkT x) = x
  unT _       = recSelError "unT"#

Note that the type of recSelError is `forall r (a :: TYPE r). Addr# -> a`.
Therefore, when used in the right-hand side of `unT`, GHC attempts to
instantiate `a` with `(forall b. b -> b) -> Int`, which is impredicative.
To make sure that GHC is OK with this, we enable ImpredicativeTypes internally
when typechecking these HsBinds so that the user does not have to.
-}