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

-}

{-# LANGUAGE CPP, MultiWayIf, TupleSections #-}
{-# LANGUAGE FlexibleContexts #-}

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

module GHC.Tc.Utils.Instantiate (
       topSkolemise,
       topInstantiate, topInstantiateInferred,
       instCall, instDFunType, instStupidTheta, instTyVarsWith,
       newWanted, newWanteds,

       tcInstType, tcInstTypeBndrs,
       tcInstSkolTyVars, tcInstSkolTyVarsX, tcInstSkolTyVarsAt,
       tcSkolDFunType, tcSuperSkolTyVars, tcInstSuperSkolTyVarsX,

       freshenTyVarBndrs, freshenCoVarBndrsX,

       tcInstInvisibleTyBindersN, tcInstInvisibleTyBinders, tcInstInvisibleTyBinder,

       newOverloadedLit, mkOverLit,

       newClsInst,
       tcGetInsts, tcGetInstEnvs, getOverlapFlag,
       tcExtendLocalInstEnv,
       instCallConstraints, newMethodFromName,
       tcSyntaxName,

       -- Simple functions over evidence variables
       tyCoVarsOfWC,
       tyCoVarsOfCt, tyCoVarsOfCts,
    ) where

#include "GhclibHsVersions.h"

import GHC.Prelude

import {-# SOURCE #-}   GHC.Tc.Gen.Expr( tcCheckPolyExpr, tcSyntaxOp )
import {-# SOURCE #-}   GHC.Tc.Utils.Unify( unifyType, unifyKind )

import GHC.Types.Basic ( IntegralLit(..), SourceText(..) )
import GHC.Hs
import GHC.Tc.Utils.Zonk
import GHC.Tc.Utils.Monad
import GHC.Tc.Types.Constraint
import GHC.Core.Predicate
import GHC.Tc.Types.Origin
import GHC.Tc.Utils.Env
import GHC.Tc.Types.Evidence
import GHC.Core.InstEnv
import GHC.Builtin.Types  ( heqDataCon, eqDataCon, integerTyConName )
import GHC.Core    ( isOrphan )
import GHC.Tc.Instance.FunDeps
import GHC.Tc.Utils.TcMType
import GHC.Core.Type
import GHC.Core.Multiplicity
import GHC.Core.TyCo.Rep
import GHC.Core.TyCo.Ppr ( debugPprType )
import GHC.Tc.Utils.TcType
import GHC.Driver.Types
import GHC.Core.Class( Class )
import GHC.Types.Id.Make( mkDictFunId )
import GHC.Core( Expr(..) )  -- For the Coercion constructor
import GHC.Types.Id
import GHC.Types.Name
import GHC.Types.Var
import GHC.Core.DataCon
import GHC.Types.Var.Env
import GHC.Builtin.Names
import GHC.Types.SrcLoc as SrcLoc
import GHC.Driver.Session
import GHC.Utils.Misc
import GHC.Utils.Outputable
import GHC.Types.Basic ( TypeOrKind(..) )
import qualified GHC.LanguageExtensions as LangExt

import Data.List ( sortBy, mapAccumL )
import Control.Monad( unless )
import Data.Function ( on )

{-
************************************************************************
*                                                                      *
                Creating and emittind constraints
*                                                                      *
************************************************************************
-}

newMethodFromName
  :: CtOrigin              -- ^ why do we need this?
  -> Name                  -- ^ name of the method
  -> [TcRhoType]           -- ^ types with which to instantiate the class
  -> TcM (HsExpr GhcTc)
-- ^ Used when 'Name' is the wired-in name for a wired-in class method,
-- so the caller knows its type for sure, which should be of form
--
-- > forall a. C a => <blah>
--
-- 'newMethodFromName' is supposed to instantiate just the outer
-- type variable and constraint

newMethodFromName :: CtOrigin -> Name -> [TcRhoType] -> TcM (HsExpr GhcTc)
newMethodFromName CtOrigin
origin Name
name [TcRhoType]
ty_args
  = do { Id
id <- Name -> TcM Id
tcLookupId Name
name
              -- Use tcLookupId not tcLookupGlobalId; the method is almost
              -- always a class op, but with -XRebindableSyntax GHC is
              -- meant to find whatever thing is in scope, and that may
              -- be an ordinary function.

       ; let ty :: TcRhoType
ty = HasDebugCallStack => TcRhoType -> [TcRhoType] -> TcRhoType
TcRhoType -> [TcRhoType] -> TcRhoType
piResultTys (Id -> TcRhoType
idType Id
id) [TcRhoType]
ty_args
             ([TcRhoType]
theta, TcRhoType
_caller_knows_this) = TcRhoType -> ([TcRhoType], TcRhoType)
tcSplitPhiTy TcRhoType
ty
       ; HsWrapper
wrap <- ASSERT( not (isForAllTy ty) && isSingleton theta )
                 CtOrigin
-> [TcRhoType]
-> [TcRhoType]
-> IOEnv (Env TcGblEnv TcLclEnv) HsWrapper
instCall CtOrigin
origin [TcRhoType]
ty_args [TcRhoType]
theta

       ; HsExpr GhcTc -> TcM (HsExpr GhcTc)
forall (m :: * -> *) a. Monad m => a -> m a
return (HsWrapper -> HsExpr GhcTc -> HsExpr GhcTc
mkHsWrap HsWrapper
wrap (XVar GhcTc -> Located (IdP GhcTc) -> HsExpr GhcTc
forall p. XVar p -> Located (IdP p) -> HsExpr p
HsVar NoExtField
XVar GhcTc
noExtField (Id -> Located Id
forall e. e -> Located e
noLoc Id
id))) }

{-
************************************************************************
*                                                                      *
         Instantiation and skolemisation
*                                                                      *
************************************************************************

Note [Skolemisation]
~~~~~~~~~~~~~~~~~~~~
topSkolemise decomposes and skolemises a type, returning a type
with no top level foralls or (=>)

Examples:

  topSkolemise (forall a. Ord a => a -> a)
    =  ( wp, [a], [d:Ord a], a->a )
    where wp = /\a. \(d:Ord a). <hole> a d

  topSkolemise  (forall a. Ord a => forall b. Eq b => a->b->b)
    =  ( wp, [a,b], [d1:Ord a,d2:Eq b], a->b->b )
    where wp = /\a.\(d1:Ord a)./\b.\(d2:Ord b). <hole> a d1 b d2

This second example is the reason for the recursive 'go'
function in topSkolemise: we must remove successive layers
of foralls and (=>).

In general,
  if      topSkolemise ty = (wrap, tvs, evs, rho)
    and   e :: rho
  then    wrap e :: ty
    and   'wrap' binds {tvs, evs}

-}

topSkolemise :: TcSigmaType
             -> TcM ( HsWrapper
                    , [(Name,TyVar)]     -- All skolemised variables
                    , [EvVar]            -- All "given"s
                    , TcRhoType )
-- See Note [Skolemisation]
topSkolemise :: TcRhoType -> TcM (HsWrapper, [(Name, Id)], [Id], TcRhoType)
topSkolemise TcRhoType
ty
  = TCvSubst
-> HsWrapper
-> [(Name, Id)]
-> [Id]
-> TcRhoType
-> TcM (HsWrapper, [(Name, Id)], [Id], TcRhoType)
go TCvSubst
init_subst HsWrapper
idHsWrapper [] [] TcRhoType
ty
  where
    init_subst :: TCvSubst
init_subst = InScopeSet -> TCvSubst
mkEmptyTCvSubst (VarSet -> InScopeSet
mkInScopeSet (TcRhoType -> VarSet
tyCoVarsOfType TcRhoType
ty))

    -- Why recursive?  See Note [Skolemisation]
    go :: TCvSubst
-> HsWrapper
-> [(Name, Id)]
-> [Id]
-> TcRhoType
-> TcM (HsWrapper, [(Name, Id)], [Id], TcRhoType)
go TCvSubst
subst HsWrapper
wrap [(Name, Id)]
tv_prs [Id]
ev_vars TcRhoType
ty
      | ([Id]
tvs, [TcRhoType]
theta, TcRhoType
inner_ty) <- TcRhoType -> ([Id], [TcRhoType], TcRhoType)
tcSplitSigmaTy TcRhoType
ty
      , Bool -> Bool
not ([Id] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [Id]
tvs Bool -> Bool -> Bool
&& [TcRhoType] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [TcRhoType]
theta)
      = do { (TCvSubst
subst', [Id]
tvs1) <- TCvSubst -> [Id] -> TcM (TCvSubst, [Id])
tcInstSkolTyVarsX TCvSubst
subst [Id]
tvs
           ; [Id]
ev_vars1       <- [TcRhoType] -> TcM [Id]
newEvVars (HasCallStack => TCvSubst -> [TcRhoType] -> [TcRhoType]
TCvSubst -> [TcRhoType] -> [TcRhoType]
substTheta TCvSubst
subst' [TcRhoType]
theta)
           ; TCvSubst
-> HsWrapper
-> [(Name, Id)]
-> [Id]
-> TcRhoType
-> TcM (HsWrapper, [(Name, Id)], [Id], TcRhoType)
go TCvSubst
subst'
                (HsWrapper
wrap HsWrapper -> HsWrapper -> HsWrapper
<.> [Id] -> HsWrapper
mkWpTyLams [Id]
tvs1 HsWrapper -> HsWrapper -> HsWrapper
<.> [Id] -> HsWrapper
mkWpLams [Id]
ev_vars1)
                ([(Name, Id)]
tv_prs [(Name, Id)] -> [(Name, Id)] -> [(Name, Id)]
forall a. [a] -> [a] -> [a]
++ ((Id -> Name) -> [Id] -> [Name]
forall a b. (a -> b) -> [a] -> [b]
map Id -> Name
tyVarName [Id]
tvs [Name] -> [Id] -> [(Name, Id)]
forall a b. [a] -> [b] -> [(a, b)]
`zip` [Id]
tvs1))
                ([Id]
ev_vars [Id] -> [Id] -> [Id]
forall a. [a] -> [a] -> [a]
++ [Id]
ev_vars1)
                TcRhoType
inner_ty }

      | Bool
otherwise
      = (HsWrapper, [(Name, Id)], [Id], TcRhoType)
-> TcM (HsWrapper, [(Name, Id)], [Id], TcRhoType)
forall (m :: * -> *) a. Monad m => a -> m a
return (HsWrapper
wrap, [(Name, Id)]
tv_prs, [Id]
ev_vars, HasCallStack => TCvSubst -> TcRhoType -> TcRhoType
TCvSubst -> TcRhoType -> TcRhoType
substTy TCvSubst
subst TcRhoType
ty)
        -- substTy is a quick no-op on an empty substitution

-- | Instantiate all outer type variables
-- and any context. Never looks through arrows.
topInstantiate :: CtOrigin -> TcSigmaType -> TcM (HsWrapper, TcRhoType)
-- if    topInstantiate ty = (wrap, rho)
-- and   e :: ty
-- then  wrap e :: rho  (that is, wrap :: ty "->" rho)
-- NB: always returns a rho-type, with no top-level forall or (=>)
topInstantiate :: CtOrigin -> TcRhoType -> TcM (HsWrapper, TcRhoType)
topInstantiate = Bool -> CtOrigin -> TcRhoType -> TcM (HsWrapper, TcRhoType)
top_instantiate Bool
True

-- | Instantiate all outer 'Inferred' binders
-- and any context. Never looks through arrows or specified type variables.
-- Used for visible type application.
topInstantiateInferred :: CtOrigin -> TcSigmaType
                       -> TcM (HsWrapper, TcSigmaType)
-- if    topInstantiate ty = (wrap, rho)
-- and   e :: ty
-- then  wrap e :: rho
-- NB: may return a sigma-type
topInstantiateInferred :: CtOrigin -> TcRhoType -> TcM (HsWrapper, TcRhoType)
topInstantiateInferred = Bool -> CtOrigin -> TcRhoType -> TcM (HsWrapper, TcRhoType)
top_instantiate Bool
False

top_instantiate :: Bool   -- True  <=> instantiate *all* variables
                          -- False <=> instantiate only the inferred ones
                -> CtOrigin -> TcSigmaType -> TcM (HsWrapper, TcRhoType)
top_instantiate :: Bool -> CtOrigin -> TcRhoType -> TcM (HsWrapper, TcRhoType)
top_instantiate Bool
inst_all CtOrigin
orig TcRhoType
ty
  | ([TyVarBinder]
binders, TcRhoType
phi) <- TcRhoType -> ([TyVarBinder], TcRhoType)
tcSplitForAllVarBndrs TcRhoType
ty
  , ([TcRhoType]
theta, TcRhoType
rho)   <- TcRhoType -> ([TcRhoType], TcRhoType)
tcSplitPhiTy TcRhoType
phi
  , Bool -> Bool
not ([TyVarBinder] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [TyVarBinder]
binders Bool -> Bool -> Bool
&& [TcRhoType] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [TcRhoType]
theta)
  = do { let ([TyVarBinder]
inst_bndrs, [TyVarBinder]
leave_bndrs) = (TyVarBinder -> Bool)
-> [TyVarBinder] -> ([TyVarBinder], [TyVarBinder])
forall a. (a -> Bool) -> [a] -> ([a], [a])
span TyVarBinder -> Bool
forall tv. VarBndr tv ArgFlag -> Bool
should_inst [TyVarBinder]
binders
             ([TcRhoType]
inst_theta, [TcRhoType]
leave_theta)
               | [TyVarBinder] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [TyVarBinder]
leave_bndrs = ([TcRhoType]
theta, [])
               | Bool
otherwise        = ([], [TcRhoType]
theta)
             in_scope :: InScopeSet
in_scope    = VarSet -> InScopeSet
mkInScopeSet (TcRhoType -> VarSet
tyCoVarsOfType TcRhoType
ty)
             empty_subst :: TCvSubst
empty_subst = InScopeSet -> TCvSubst
mkEmptyTCvSubst InScopeSet
in_scope
             inst_tvs :: [Id]
inst_tvs    = [TyVarBinder] -> [Id]
forall tv argf. [VarBndr tv argf] -> [tv]
binderVars [TyVarBinder]
inst_bndrs
       ; (TCvSubst
subst, [Id]
inst_tvs') <- (TCvSubst -> Id -> IOEnv (Env TcGblEnv TcLclEnv) (TCvSubst, Id))
-> TCvSubst -> [Id] -> TcM (TCvSubst, [Id])
forall (m :: * -> *) acc x y.
Monad m =>
(acc -> x -> m (acc, y)) -> acc -> [x] -> m (acc, [y])
mapAccumLM TCvSubst -> Id -> IOEnv (Env TcGblEnv TcLclEnv) (TCvSubst, Id)
newMetaTyVarX TCvSubst
empty_subst [Id]
inst_tvs
       ; let inst_theta' :: [TcRhoType]
inst_theta' = HasCallStack => TCvSubst -> [TcRhoType] -> [TcRhoType]
TCvSubst -> [TcRhoType] -> [TcRhoType]
substTheta TCvSubst
subst [TcRhoType]
inst_theta
             sigma' :: TcRhoType
sigma'      = HasCallStack => TCvSubst -> TcRhoType -> TcRhoType
TCvSubst -> TcRhoType -> TcRhoType
substTy TCvSubst
subst ([TyVarBinder] -> TcRhoType -> TcRhoType
mkForAllTys [TyVarBinder]
leave_bndrs (TcRhoType -> TcRhoType) -> TcRhoType -> TcRhoType
forall a b. (a -> b) -> a -> b
$
                                          [TcRhoType] -> TcRhoType -> TcRhoType
mkPhiTy [TcRhoType]
leave_theta TcRhoType
rho)
             inst_tv_tys' :: [TcRhoType]
inst_tv_tys' = [Id] -> [TcRhoType]
mkTyVarTys [Id]
inst_tvs'

       ; HsWrapper
wrap1 <- CtOrigin
-> [TcRhoType]
-> [TcRhoType]
-> IOEnv (Env TcGblEnv TcLclEnv) HsWrapper
instCall CtOrigin
orig [TcRhoType]
inst_tv_tys' [TcRhoType]
inst_theta'
       ; String -> SDoc -> TcRn ()
traceTc String
"Instantiating"
                 ([SDoc] -> SDoc
vcat [ String -> SDoc
text String
"all tyvars?" SDoc -> SDoc -> SDoc
<+> Bool -> SDoc
forall a. Outputable a => a -> SDoc
ppr Bool
inst_all
                       , String -> SDoc
text String
"origin" SDoc -> SDoc -> SDoc
<+> CtOrigin -> SDoc
pprCtOrigin CtOrigin
orig
                       , String -> SDoc
text String
"type" SDoc -> SDoc -> SDoc
<+> TcRhoType -> SDoc
debugPprType TcRhoType
ty
                       , String -> SDoc
text String
"theta" SDoc -> SDoc -> SDoc
<+> [TcRhoType] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TcRhoType]
theta
                       , String -> SDoc
text String
"leave_bndrs" SDoc -> SDoc -> SDoc
<+> [TyVarBinder] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TyVarBinder]
leave_bndrs
                       , String -> SDoc
text String
"with" SDoc -> SDoc -> SDoc
<+> [SDoc] -> SDoc
vcat ((TcRhoType -> SDoc) -> [TcRhoType] -> [SDoc]
forall a b. (a -> b) -> [a] -> [b]
map TcRhoType -> SDoc
debugPprType [TcRhoType]
inst_tv_tys')
                       , String -> SDoc
text String
"theta:" SDoc -> SDoc -> SDoc
<+>  [TcRhoType] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TcRhoType]
inst_theta' ])

       ; (HsWrapper
wrap2, TcRhoType
rho2) <-
           if [TyVarBinder] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [TyVarBinder]
leave_bndrs   -- NB: if inst_all is True then leave_bndrs = []

         -- account for types like forall a. Num a => forall b. Ord b => ...
           then Bool -> CtOrigin -> TcRhoType -> TcM (HsWrapper, TcRhoType)
top_instantiate Bool
inst_all CtOrigin
orig TcRhoType
sigma'

         -- but don't loop if there were any un-inst'able tyvars
           else (HsWrapper, TcRhoType) -> TcM (HsWrapper, TcRhoType)
forall (m :: * -> *) a. Monad m => a -> m a
return (HsWrapper
idHsWrapper, TcRhoType
sigma')

       ; (HsWrapper, TcRhoType) -> TcM (HsWrapper, TcRhoType)
forall (m :: * -> *) a. Monad m => a -> m a
return (HsWrapper
wrap2 HsWrapper -> HsWrapper -> HsWrapper
<.> HsWrapper
wrap1, TcRhoType
rho2) }

  | Bool
otherwise = (HsWrapper, TcRhoType) -> TcM (HsWrapper, TcRhoType)
forall (m :: * -> *) a. Monad m => a -> m a
return (HsWrapper
idHsWrapper, TcRhoType
ty)
  where

    should_inst :: VarBndr tv ArgFlag -> Bool
should_inst VarBndr tv ArgFlag
bndr
      | Bool
inst_all  = Bool
True
      | Bool
otherwise = VarBndr tv ArgFlag -> ArgFlag
forall tv argf. VarBndr tv argf -> argf
binderArgFlag VarBndr tv ArgFlag
bndr ArgFlag -> ArgFlag -> Bool
forall a. Eq a => a -> a -> Bool
== ArgFlag
Inferred

instTyVarsWith :: CtOrigin -> [TyVar] -> [TcType] -> TcM TCvSubst
-- Use this when you want to instantiate (forall a b c. ty) with
-- types [ta, tb, tc], but when the kinds of 'a' and 'ta' might
-- not yet match (perhaps because there are unsolved constraints; #14154)
-- If they don't match, emit a kind-equality to promise that they will
-- eventually do so, and thus make a kind-homongeneous substitution.
instTyVarsWith :: CtOrigin -> [Id] -> [TcRhoType] -> TcM TCvSubst
instTyVarsWith CtOrigin
orig [Id]
tvs [TcRhoType]
tys
  = TCvSubst -> [Id] -> [TcRhoType] -> TcM TCvSubst
go TCvSubst
emptyTCvSubst [Id]
tvs [TcRhoType]
tys
  where
    go :: TCvSubst -> [Id] -> [TcRhoType] -> TcM TCvSubst
go TCvSubst
subst [] []
      = TCvSubst -> TcM TCvSubst
forall (m :: * -> *) a. Monad m => a -> m a
return TCvSubst
subst
    go TCvSubst
subst (Id
tv:[Id]
tvs) (TcRhoType
ty:[TcRhoType]
tys)
      | TcRhoType
tv_kind HasDebugCallStack => TcRhoType -> TcRhoType -> Bool
TcRhoType -> TcRhoType -> Bool
`tcEqType` TcRhoType
ty_kind
      = TCvSubst -> [Id] -> [TcRhoType] -> TcM TCvSubst
go (TCvSubst -> Id -> TcRhoType -> TCvSubst
extendTvSubstAndInScope TCvSubst
subst Id
tv TcRhoType
ty) [Id]
tvs [TcRhoType]
tys
      | Bool
otherwise
      = do { Coercion
co <- CtOrigin
-> TypeOrKind -> Role -> TcRhoType -> TcRhoType -> TcM Coercion
emitWantedEq CtOrigin
orig TypeOrKind
KindLevel Role
Nominal TcRhoType
ty_kind TcRhoType
tv_kind
           ; TCvSubst -> [Id] -> [TcRhoType] -> TcM TCvSubst
go (TCvSubst -> Id -> TcRhoType -> TCvSubst
extendTvSubstAndInScope TCvSubst
subst Id
tv (TcRhoType
ty TcRhoType -> Coercion -> TcRhoType
`mkCastTy` Coercion
co)) [Id]
tvs [TcRhoType]
tys }
      where
        tv_kind :: TcRhoType
tv_kind = HasCallStack => TCvSubst -> TcRhoType -> TcRhoType
TCvSubst -> TcRhoType -> TcRhoType
substTy TCvSubst
subst (Id -> TcRhoType
tyVarKind Id
tv)
        ty_kind :: TcRhoType
ty_kind = HasDebugCallStack => TcRhoType -> TcRhoType
TcRhoType -> TcRhoType
tcTypeKind TcRhoType
ty

    go TCvSubst
_ [Id]
_ [TcRhoType]
_ = String -> SDoc -> TcM TCvSubst
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"instTysWith" ([Id] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Id]
tvs SDoc -> SDoc -> SDoc
$$ [TcRhoType] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TcRhoType]
tys)


{-
************************************************************************
*                                                                      *
            Instantiating a call
*                                                                      *
************************************************************************

Note [Handling boxed equality]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The solver deals entirely in terms of unboxed (primitive) equality.
There should never be a boxed Wanted equality. Ever. But, what if
we are calling `foo :: forall a. (F a ~ Bool) => ...`? That equality
is boxed, so naive treatment here would emit a boxed Wanted equality.

So we simply check for this case and make the right boxing of evidence.

-}

----------------
instCall :: CtOrigin -> [TcType] -> TcThetaType -> TcM HsWrapper
-- Instantiate the constraints of a call
--      (instCall o tys theta)
-- (a) Makes fresh dictionaries as necessary for the constraints (theta)
-- (b) Throws these dictionaries into the LIE
-- (c) Returns an HsWrapper ([.] tys dicts)

instCall :: CtOrigin
-> [TcRhoType]
-> [TcRhoType]
-> IOEnv (Env TcGblEnv TcLclEnv) HsWrapper
instCall CtOrigin
orig [TcRhoType]
tys [TcRhoType]
theta
  = do  { HsWrapper
dict_app <- CtOrigin -> [TcRhoType] -> IOEnv (Env TcGblEnv TcLclEnv) HsWrapper
instCallConstraints CtOrigin
orig [TcRhoType]
theta
        ; HsWrapper -> IOEnv (Env TcGblEnv TcLclEnv) HsWrapper
forall (m :: * -> *) a. Monad m => a -> m a
return (HsWrapper
dict_app HsWrapper -> HsWrapper -> HsWrapper
<.> [TcRhoType] -> HsWrapper
mkWpTyApps [TcRhoType]
tys) }

----------------
instCallConstraints :: CtOrigin -> TcThetaType -> TcM HsWrapper
-- Instantiates the TcTheta, puts all constraints thereby generated
-- into the LIE, and returns a HsWrapper to enclose the call site.

instCallConstraints :: CtOrigin -> [TcRhoType] -> IOEnv (Env TcGblEnv TcLclEnv) HsWrapper
instCallConstraints CtOrigin
orig [TcRhoType]
preds
  | [TcRhoType] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [TcRhoType]
preds
  = HsWrapper -> IOEnv (Env TcGblEnv TcLclEnv) HsWrapper
forall (m :: * -> *) a. Monad m => a -> m a
return HsWrapper
idHsWrapper
  | Bool
otherwise
  = do { [EvTerm]
evs <- (TcRhoType -> IOEnv (Env TcGblEnv TcLclEnv) EvTerm)
-> [TcRhoType] -> IOEnv (Env TcGblEnv TcLclEnv) [EvTerm]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM TcRhoType -> IOEnv (Env TcGblEnv TcLclEnv) EvTerm
go [TcRhoType]
preds
       ; String -> SDoc -> TcRn ()
traceTc String
"instCallConstraints" ([EvTerm] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [EvTerm]
evs)
       ; HsWrapper -> IOEnv (Env TcGblEnv TcLclEnv) HsWrapper
forall (m :: * -> *) a. Monad m => a -> m a
return ([EvTerm] -> HsWrapper
mkWpEvApps [EvTerm]
evs) }
  where
    go :: TcPredType -> TcM EvTerm
    go :: TcRhoType -> IOEnv (Env TcGblEnv TcLclEnv) EvTerm
go TcRhoType
pred
     | Just (Role
Nominal, TcRhoType
ty1, TcRhoType
ty2) <- TcRhoType -> Maybe (Role, TcRhoType, TcRhoType)
getEqPredTys_maybe TcRhoType
pred -- Try short-cut #1
     = do  { Coercion
co <- Maybe (HsExpr GhcRn) -> TcRhoType -> TcRhoType -> TcM Coercion
unifyType Maybe (HsExpr GhcRn)
forall a. Maybe a
Nothing TcRhoType
ty1 TcRhoType
ty2
           ; EvTerm -> IOEnv (Env TcGblEnv TcLclEnv) EvTerm
forall (m :: * -> *) a. Monad m => a -> m a
return (Coercion -> EvTerm
evCoercion Coercion
co) }

       -- Try short-cut #2
     | Just (TyCon
tc, args :: [TcRhoType]
args@[TcRhoType
_, TcRhoType
_, TcRhoType
ty1, TcRhoType
ty2]) <- HasDebugCallStack => TcRhoType -> Maybe (TyCon, [TcRhoType])
TcRhoType -> Maybe (TyCon, [TcRhoType])
splitTyConApp_maybe TcRhoType
pred
     , TyCon
tc TyCon -> Unique -> Bool
forall a. Uniquable a => a -> Unique -> Bool
`hasKey` Unique
heqTyConKey
     = do { Coercion
co <- Maybe (HsExpr GhcRn) -> TcRhoType -> TcRhoType -> TcM Coercion
unifyType Maybe (HsExpr GhcRn)
forall a. Maybe a
Nothing TcRhoType
ty1 TcRhoType
ty2
          ; EvTerm -> IOEnv (Env TcGblEnv TcLclEnv) EvTerm
forall (m :: * -> *) a. Monad m => a -> m a
return (Id -> [TcRhoType] -> [EvExpr] -> EvTerm
evDFunApp (DataCon -> Id
dataConWrapId DataCon
heqDataCon) [TcRhoType]
args [Coercion -> EvExpr
forall b. Coercion -> Expr b
Coercion Coercion
co]) }

     | Bool
otherwise
     = CtOrigin -> TcRhoType -> IOEnv (Env TcGblEnv TcLclEnv) EvTerm
emitWanted CtOrigin
orig TcRhoType
pred

instDFunType :: DFunId -> [DFunInstType]
             -> TcM ( [TcType]      -- instantiated argument types
                    , TcThetaType ) -- instantiated constraint
-- See Note [DFunInstType: instantiating types] in GHC.Core.InstEnv
instDFunType :: Id -> [DFunInstType] -> TcM ([TcRhoType], [TcRhoType])
instDFunType Id
dfun_id [DFunInstType]
dfun_inst_tys
  = do { (TCvSubst
subst, [TcRhoType]
inst_tys) <- TCvSubst -> [Id] -> [DFunInstType] -> TcM (TCvSubst, [TcRhoType])
go TCvSubst
empty_subst [Id]
dfun_tvs [DFunInstType]
dfun_inst_tys
       ; ([TcRhoType], [TcRhoType]) -> TcM ([TcRhoType], [TcRhoType])
forall (m :: * -> *) a. Monad m => a -> m a
return ([TcRhoType]
inst_tys, HasCallStack => TCvSubst -> [TcRhoType] -> [TcRhoType]
TCvSubst -> [TcRhoType] -> [TcRhoType]
substTheta TCvSubst
subst [TcRhoType]
dfun_theta) }
  where
    dfun_ty :: TcRhoType
dfun_ty = Id -> TcRhoType
idType Id
dfun_id
    ([Id]
dfun_tvs, [TcRhoType]
dfun_theta, TcRhoType
_) = TcRhoType -> ([Id], [TcRhoType], TcRhoType)
tcSplitSigmaTy TcRhoType
dfun_ty
    empty_subst :: TCvSubst
empty_subst = InScopeSet -> TCvSubst
mkEmptyTCvSubst (VarSet -> InScopeSet
mkInScopeSet (TcRhoType -> VarSet
tyCoVarsOfType TcRhoType
dfun_ty))
                  -- With quantified constraints, the
                  -- type of a dfun may not be closed

    go :: TCvSubst -> [TyVar] -> [DFunInstType] -> TcM (TCvSubst, [TcType])
    go :: TCvSubst -> [Id] -> [DFunInstType] -> TcM (TCvSubst, [TcRhoType])
go TCvSubst
subst [] [] = (TCvSubst, [TcRhoType]) -> TcM (TCvSubst, [TcRhoType])
forall (m :: * -> *) a. Monad m => a -> m a
return (TCvSubst
subst, [])
    go TCvSubst
subst (Id
tv:[Id]
tvs) (Just TcRhoType
ty : [DFunInstType]
mb_tys)
      = do { (TCvSubst
subst', [TcRhoType]
tys) <- TCvSubst -> [Id] -> [DFunInstType] -> TcM (TCvSubst, [TcRhoType])
go (TCvSubst -> Id -> TcRhoType -> TCvSubst
extendTvSubstAndInScope TCvSubst
subst Id
tv TcRhoType
ty)
                                 [Id]
tvs
                                 [DFunInstType]
mb_tys
           ; (TCvSubst, [TcRhoType]) -> TcM (TCvSubst, [TcRhoType])
forall (m :: * -> *) a. Monad m => a -> m a
return (TCvSubst
subst', TcRhoType
ty TcRhoType -> [TcRhoType] -> [TcRhoType]
forall a. a -> [a] -> [a]
: [TcRhoType]
tys) }
    go TCvSubst
subst (Id
tv:[Id]
tvs) (DFunInstType
Nothing : [DFunInstType]
mb_tys)
      = do { (TCvSubst
subst', Id
tv') <- TCvSubst -> Id -> IOEnv (Env TcGblEnv TcLclEnv) (TCvSubst, Id)
newMetaTyVarX TCvSubst
subst Id
tv
           ; (TCvSubst
subst'', [TcRhoType]
tys) <- TCvSubst -> [Id] -> [DFunInstType] -> TcM (TCvSubst, [TcRhoType])
go TCvSubst
subst' [Id]
tvs [DFunInstType]
mb_tys
           ; (TCvSubst, [TcRhoType]) -> TcM (TCvSubst, [TcRhoType])
forall (m :: * -> *) a. Monad m => a -> m a
return (TCvSubst
subst'', Id -> TcRhoType
mkTyVarTy Id
tv' TcRhoType -> [TcRhoType] -> [TcRhoType]
forall a. a -> [a] -> [a]
: [TcRhoType]
tys) }
    go TCvSubst
_ [Id]
_ [DFunInstType]
_ = String -> SDoc -> TcM (TCvSubst, [TcRhoType])
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"instDFunTypes" (Id -> SDoc
forall a. Outputable a => a -> SDoc
ppr Id
dfun_id SDoc -> SDoc -> SDoc
$$ [DFunInstType] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [DFunInstType]
dfun_inst_tys)

----------------
instStupidTheta :: CtOrigin -> TcThetaType -> TcM ()
-- Similar to instCall, but only emit the constraints in the LIE
-- Used exclusively for the 'stupid theta' of a data constructor
instStupidTheta :: CtOrigin -> [TcRhoType] -> TcRn ()
instStupidTheta CtOrigin
orig [TcRhoType]
theta
  = do  { HsWrapper
_co <- CtOrigin -> [TcRhoType] -> IOEnv (Env TcGblEnv TcLclEnv) HsWrapper
instCallConstraints CtOrigin
orig [TcRhoType]
theta -- Discard the coercion
        ; () -> TcRn ()
forall (m :: * -> *) a. Monad m => a -> m a
return () }


{- *********************************************************************
*                                                                      *
         Instantiating Kinds
*                                                                      *
********************************************************************* -}

-- | Given ty::forall k1 k2. k, instantiate all the invisible forall-binders
--   returning ty @kk1 @kk2 :: k[kk1/k1, kk2/k1]
tcInstInvisibleTyBinders :: TcType -> TcKind -> TcM (TcType, TcKind)
tcInstInvisibleTyBinders :: TcRhoType -> TcRhoType -> TcM (TcRhoType, TcRhoType)
tcInstInvisibleTyBinders TcRhoType
ty TcRhoType
kind
  = do { ([TcRhoType]
extra_args, TcRhoType
kind') <- Int -> TcRhoType -> TcM ([TcRhoType], TcRhoType)
tcInstInvisibleTyBindersN Int
n_invis TcRhoType
kind
       ; (TcRhoType, TcRhoType) -> TcM (TcRhoType, TcRhoType)
forall (m :: * -> *) a. Monad m => a -> m a
return (TcRhoType -> [TcRhoType] -> TcRhoType
mkAppTys TcRhoType
ty [TcRhoType]
extra_args, TcRhoType
kind') }
  where
    n_invis :: Int
n_invis = TcRhoType -> Int
invisibleTyBndrCount TcRhoType
kind

tcInstInvisibleTyBindersN :: Int -> TcKind -> TcM ([TcType], TcKind)
tcInstInvisibleTyBindersN :: Int -> TcRhoType -> TcM ([TcRhoType], TcRhoType)
tcInstInvisibleTyBindersN Int
0 TcRhoType
kind
  = ([TcRhoType], TcRhoType) -> TcM ([TcRhoType], TcRhoType)
forall (m :: * -> *) a. Monad m => a -> m a
return ([], TcRhoType
kind)
tcInstInvisibleTyBindersN Int
n TcRhoType
ty
  = Int -> TCvSubst -> TcRhoType -> TcM ([TcRhoType], TcRhoType)
forall t.
(Ord t, Num t) =>
t -> TCvSubst -> TcRhoType -> TcM ([TcRhoType], TcRhoType)
go Int
n TCvSubst
empty_subst TcRhoType
ty
  where
    empty_subst :: TCvSubst
empty_subst = InScopeSet -> TCvSubst
mkEmptyTCvSubst (VarSet -> InScopeSet
mkInScopeSet (TcRhoType -> VarSet
tyCoVarsOfType TcRhoType
ty))

    go :: t -> TCvSubst -> TcRhoType -> TcM ([TcRhoType], TcRhoType)
go t
n TCvSubst
subst TcRhoType
kind
      | t
n t -> t -> Bool
forall a. Ord a => a -> a -> Bool
> t
0
      , Just (TyBinder
bndr, TcRhoType
body) <- TcRhoType -> Maybe (TyBinder, TcRhoType)
tcSplitPiTy_maybe TcRhoType
kind
      , TyBinder -> Bool
isInvisibleBinder TyBinder
bndr
      = do { (TCvSubst
subst', TcRhoType
arg) <- TCvSubst -> TyBinder -> TcM (TCvSubst, TcRhoType)
tcInstInvisibleTyBinder TCvSubst
subst TyBinder
bndr
           ; ([TcRhoType]
args, TcRhoType
inner_ty) <- t -> TCvSubst -> TcRhoType -> TcM ([TcRhoType], TcRhoType)
go (t
nt -> t -> t
forall a. Num a => a -> a -> a
-t
1) TCvSubst
subst' TcRhoType
body
           ; ([TcRhoType], TcRhoType) -> TcM ([TcRhoType], TcRhoType)
forall (m :: * -> *) a. Monad m => a -> m a
return (TcRhoType
argTcRhoType -> [TcRhoType] -> [TcRhoType]
forall a. a -> [a] -> [a]
:[TcRhoType]
args, TcRhoType
inner_ty) }
      | Bool
otherwise
      = ([TcRhoType], TcRhoType) -> TcM ([TcRhoType], TcRhoType)
forall (m :: * -> *) a. Monad m => a -> m a
return ([], HasCallStack => TCvSubst -> TcRhoType -> TcRhoType
TCvSubst -> TcRhoType -> TcRhoType
substTy TCvSubst
subst TcRhoType
kind)

-- | Used only in *types*
tcInstInvisibleTyBinder :: TCvSubst -> TyBinder -> TcM (TCvSubst, TcType)
tcInstInvisibleTyBinder :: TCvSubst -> TyBinder -> TcM (TCvSubst, TcRhoType)
tcInstInvisibleTyBinder TCvSubst
subst (Named (Bndr Id
tv ArgFlag
_))
  = do { (TCvSubst
subst', Id
tv') <- TCvSubst -> Id -> IOEnv (Env TcGblEnv TcLclEnv) (TCvSubst, Id)
newMetaTyVarX TCvSubst
subst Id
tv
       ; (TCvSubst, TcRhoType) -> TcM (TCvSubst, TcRhoType)
forall (m :: * -> *) a. Monad m => a -> m a
return (TCvSubst
subst', Id -> TcRhoType
mkTyVarTy Id
tv') }

tcInstInvisibleTyBinder TCvSubst
subst (Anon AnonArgFlag
af Scaled TcRhoType
ty)
  | Just (Coercion -> TcM TcRhoType
mk, TcRhoType
k1, TcRhoType
k2) <- TcRhoType
-> Maybe (Coercion -> TcM TcRhoType, TcRhoType, TcRhoType)
get_eq_tys_maybe (HasCallStack => TCvSubst -> TcRhoType -> TcRhoType
TCvSubst -> TcRhoType -> TcRhoType
substTy TCvSubst
subst (Scaled TcRhoType -> TcRhoType
forall a. Scaled a -> a
scaledThing Scaled TcRhoType
ty))
    -- Equality is the *only* constraint currently handled in types.
    -- See Note [Constraints in kinds] in GHC.Core.TyCo.Rep
  = ASSERT( af == InvisArg )
    do { Coercion
co <- Maybe (HsType GhcRn) -> TcRhoType -> TcRhoType -> TcM Coercion
unifyKind Maybe (HsType GhcRn)
forall a. Maybe a
Nothing TcRhoType
k1 TcRhoType
k2
       ; TcRhoType
arg' <- Coercion -> TcM TcRhoType
mk Coercion
co
       ; (TCvSubst, TcRhoType) -> TcM (TCvSubst, TcRhoType)
forall (m :: * -> *) a. Monad m => a -> m a
return (TCvSubst
subst, TcRhoType
arg') }

  | Bool
otherwise  -- This should never happen
               -- See GHC.Core.TyCo.Rep Note [Constraints in kinds]
  = String -> SDoc -> TcM (TCvSubst, TcRhoType)
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"tcInvisibleTyBinder" (Scaled TcRhoType -> SDoc
forall a. Outputable a => a -> SDoc
ppr Scaled TcRhoType
ty)

-------------------------------
get_eq_tys_maybe :: Type
                 -> Maybe ( Coercion -> TcM Type
                             -- given a coercion proving t1 ~# t2, produce the
                             -- right instantiation for the TyBinder at hand
                          , Type  -- t1
                          , Type  -- t2
                          )
-- See Note [Constraints in kinds] in GHC.Core.TyCo.Rep
get_eq_tys_maybe :: TcRhoType
-> Maybe (Coercion -> TcM TcRhoType, TcRhoType, TcRhoType)
get_eq_tys_maybe TcRhoType
ty
  -- Lifted heterogeneous equality (~~)
  | Just (TyCon
tc, [TcRhoType
_, TcRhoType
_, TcRhoType
k1, TcRhoType
k2]) <- HasDebugCallStack => TcRhoType -> Maybe (TyCon, [TcRhoType])
TcRhoType -> Maybe (TyCon, [TcRhoType])
splitTyConApp_maybe TcRhoType
ty
  , TyCon
tc TyCon -> Unique -> Bool
forall a. Uniquable a => a -> Unique -> Bool
`hasKey` Unique
heqTyConKey
  = (Coercion -> TcM TcRhoType, TcRhoType, TcRhoType)
-> Maybe (Coercion -> TcM TcRhoType, TcRhoType, TcRhoType)
forall a. a -> Maybe a
Just (\Coercion
co -> Coercion -> TcRhoType -> TcRhoType -> TcM TcRhoType
mkHEqBoxTy Coercion
co TcRhoType
k1 TcRhoType
k2, TcRhoType
k1, TcRhoType
k2)

  -- Lifted homogeneous equality (~)
  | Just (TyCon
tc, [TcRhoType
_, TcRhoType
k1, TcRhoType
k2]) <- HasDebugCallStack => TcRhoType -> Maybe (TyCon, [TcRhoType])
TcRhoType -> Maybe (TyCon, [TcRhoType])
splitTyConApp_maybe TcRhoType
ty
  , TyCon
tc TyCon -> Unique -> Bool
forall a. Uniquable a => a -> Unique -> Bool
`hasKey` Unique
eqTyConKey
  = (Coercion -> TcM TcRhoType, TcRhoType, TcRhoType)
-> Maybe (Coercion -> TcM TcRhoType, TcRhoType, TcRhoType)
forall a. a -> Maybe a
Just (\Coercion
co -> Coercion -> TcRhoType -> TcRhoType -> TcM TcRhoType
mkEqBoxTy Coercion
co TcRhoType
k1 TcRhoType
k2, TcRhoType
k1, TcRhoType
k2)

  | Bool
otherwise
  = Maybe (Coercion -> TcM TcRhoType, TcRhoType, TcRhoType)
forall a. Maybe a
Nothing

-- | This takes @a ~# b@ and returns @a ~~ b@.
mkHEqBoxTy :: TcCoercion -> Type -> Type -> TcM Type
-- monadic just for convenience with mkEqBoxTy
mkHEqBoxTy :: Coercion -> TcRhoType -> TcRhoType -> TcM TcRhoType
mkHEqBoxTy Coercion
co TcRhoType
ty1 TcRhoType
ty2
  = TcRhoType -> TcM TcRhoType
forall (m :: * -> *) a. Monad m => a -> m a
return (TcRhoType -> TcM TcRhoType) -> TcRhoType -> TcM TcRhoType
forall a b. (a -> b) -> a -> b
$
    TyCon -> [TcRhoType] -> TcRhoType
mkTyConApp (DataCon -> TyCon
promoteDataCon DataCon
heqDataCon) [TcRhoType
k1, TcRhoType
k2, TcRhoType
ty1, TcRhoType
ty2, Coercion -> TcRhoType
mkCoercionTy Coercion
co]
  where k1 :: TcRhoType
k1 = HasDebugCallStack => TcRhoType -> TcRhoType
TcRhoType -> TcRhoType
tcTypeKind TcRhoType
ty1
        k2 :: TcRhoType
k2 = HasDebugCallStack => TcRhoType -> TcRhoType
TcRhoType -> TcRhoType
tcTypeKind TcRhoType
ty2

-- | This takes @a ~# b@ and returns @a ~ b@.
mkEqBoxTy :: TcCoercion -> Type -> Type -> TcM Type
mkEqBoxTy :: Coercion -> TcRhoType -> TcRhoType -> TcM TcRhoType
mkEqBoxTy Coercion
co TcRhoType
ty1 TcRhoType
ty2
  = TcRhoType -> TcM TcRhoType
forall (m :: * -> *) a. Monad m => a -> m a
return (TcRhoType -> TcM TcRhoType) -> TcRhoType -> TcM TcRhoType
forall a b. (a -> b) -> a -> b
$
    TyCon -> [TcRhoType] -> TcRhoType
mkTyConApp (DataCon -> TyCon
promoteDataCon DataCon
eqDataCon) [TcRhoType
k, TcRhoType
ty1, TcRhoType
ty2, Coercion -> TcRhoType
mkCoercionTy Coercion
co]
  where k :: TcRhoType
k = HasDebugCallStack => TcRhoType -> TcRhoType
TcRhoType -> TcRhoType
tcTypeKind TcRhoType
ty1

{- *********************************************************************
*                                                                      *
        SkolemTvs (immutable)
*                                                                      *
********************************************************************* -}

tcInstType :: ([TyVar] -> TcM (TCvSubst, [TcTyVar]))
                   -- ^ How to instantiate the type variables
           -> Id                                           -- ^ Type to instantiate
           -> TcM ([(Name, TcTyVar)], TcThetaType, TcType) -- ^ Result
                -- (type vars, preds (incl equalities), rho)
tcInstType :: ([Id] -> TcM (TCvSubst, [Id]))
-> Id -> TcM ([(Name, Id)], [TcRhoType], TcRhoType)
tcInstType [Id] -> TcM (TCvSubst, [Id])
inst_tyvars Id
id
  | [Id] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [Id]
tyvars   -- There may be overloading despite no type variables;
                  --      (?x :: Int) => Int -> Int
  = ([(Name, Id)], [TcRhoType], TcRhoType)
-> TcM ([(Name, Id)], [TcRhoType], TcRhoType)
forall (m :: * -> *) a. Monad m => a -> m a
return ([], [TcRhoType]
theta, TcRhoType
tau)
  | Bool
otherwise
  = do { (TCvSubst
subst, [Id]
tyvars') <- [Id] -> TcM (TCvSubst, [Id])
inst_tyvars [Id]
tyvars
       ; let tv_prs :: [(Name, Id)]
tv_prs  = (Id -> Name) -> [Id] -> [Name]
forall a b. (a -> b) -> [a] -> [b]
map Id -> Name
tyVarName [Id]
tyvars [Name] -> [Id] -> [(Name, Id)]
forall a b. [a] -> [b] -> [(a, b)]
`zip` [Id]
tyvars'
             subst' :: TCvSubst
subst'  = TCvSubst -> VarSet -> TCvSubst
extendTCvInScopeSet TCvSubst
subst (TcRhoType -> VarSet
tyCoVarsOfType TcRhoType
rho)
       ; ([(Name, Id)], [TcRhoType], TcRhoType)
-> TcM ([(Name, Id)], [TcRhoType], TcRhoType)
forall (m :: * -> *) a. Monad m => a -> m a
return ([(Name, Id)]
tv_prs, HasCallStack => TCvSubst -> [TcRhoType] -> [TcRhoType]
TCvSubst -> [TcRhoType] -> [TcRhoType]
substTheta TCvSubst
subst' [TcRhoType]
theta, HasCallStack => TCvSubst -> TcRhoType -> TcRhoType
TCvSubst -> TcRhoType -> TcRhoType
substTy TCvSubst
subst' TcRhoType
tau) }
  where
    ([Id]
tyvars, TcRhoType
rho) = TcRhoType -> ([Id], TcRhoType)
tcSplitForAllTys (Id -> TcRhoType
idType Id
id)
    ([TcRhoType]
theta, TcRhoType
tau)  = TcRhoType -> ([TcRhoType], TcRhoType)
tcSplitPhiTy TcRhoType
rho

tcInstTypeBndrs :: Id -> TcM ([(Name, InvisTVBinder)], TcThetaType, TcType)
                     -- (type vars, preds (incl equalities), rho)
-- Instantiate the binders of a type signature with TyVarTvs
tcInstTypeBndrs :: Id -> TcM ([(Name, InvisTVBinder)], [TcRhoType], TcRhoType)
tcInstTypeBndrs Id
id
  | [InvisTVBinder] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [InvisTVBinder]
tyvars   -- There may be overloading despite no type variables;
                  --      (?x :: Int) => Int -> Int
  = ([(Name, InvisTVBinder)], [TcRhoType], TcRhoType)
-> TcM ([(Name, InvisTVBinder)], [TcRhoType], TcRhoType)
forall (m :: * -> *) a. Monad m => a -> m a
return ([], [TcRhoType]
theta, TcRhoType
tau)
  | Bool
otherwise
  = do { (TCvSubst
subst, [InvisTVBinder]
tyvars') <- (TCvSubst
 -> InvisTVBinder
 -> IOEnv (Env TcGblEnv TcLclEnv) (TCvSubst, InvisTVBinder))
-> TCvSubst
-> [InvisTVBinder]
-> IOEnv (Env TcGblEnv TcLclEnv) (TCvSubst, [InvisTVBinder])
forall (m :: * -> *) acc x y.
Monad m =>
(acc -> x -> m (acc, y)) -> acc -> [x] -> m (acc, [y])
mapAccumLM TCvSubst
-> InvisTVBinder
-> IOEnv (Env TcGblEnv TcLclEnv) (TCvSubst, InvisTVBinder)
inst_invis_bndr TCvSubst
emptyTCvSubst [InvisTVBinder]
tyvars
       ; let tv_prs :: [(Name, InvisTVBinder)]
tv_prs  = (InvisTVBinder -> Name) -> [InvisTVBinder] -> [Name]
forall a b. (a -> b) -> [a] -> [b]
map (Id -> Name
tyVarName (Id -> Name) -> (InvisTVBinder -> Id) -> InvisTVBinder -> Name
forall b c a. (b -> c) -> (a -> b) -> a -> c
. InvisTVBinder -> Id
forall tv argf. VarBndr tv argf -> tv
binderVar) [InvisTVBinder]
tyvars [Name] -> [InvisTVBinder] -> [(Name, InvisTVBinder)]
forall a b. [a] -> [b] -> [(a, b)]
`zip` [InvisTVBinder]
tyvars'
             subst' :: TCvSubst
subst'  = TCvSubst -> VarSet -> TCvSubst
extendTCvInScopeSet TCvSubst
subst (TcRhoType -> VarSet
tyCoVarsOfType TcRhoType
rho)
       ; ([(Name, InvisTVBinder)], [TcRhoType], TcRhoType)
-> TcM ([(Name, InvisTVBinder)], [TcRhoType], TcRhoType)
forall (m :: * -> *) a. Monad m => a -> m a
return ([(Name, InvisTVBinder)]
tv_prs, HasCallStack => TCvSubst -> [TcRhoType] -> [TcRhoType]
TCvSubst -> [TcRhoType] -> [TcRhoType]
substTheta TCvSubst
subst' [TcRhoType]
theta, HasCallStack => TCvSubst -> TcRhoType -> TcRhoType
TCvSubst -> TcRhoType -> TcRhoType
substTy TCvSubst
subst' TcRhoType
tau) }
  where
    ([InvisTVBinder]
tyvars, TcRhoType
rho) = TcRhoType -> ([InvisTVBinder], TcRhoType)
splitForAllTysInvis (Id -> TcRhoType
idType Id
id)
    ([TcRhoType]
theta, TcRhoType
tau)  = TcRhoType -> ([TcRhoType], TcRhoType)
tcSplitPhiTy TcRhoType
rho

    inst_invis_bndr :: TCvSubst -> InvisTVBinder
                    -> TcM (TCvSubst, InvisTVBinder)
    inst_invis_bndr :: TCvSubst
-> InvisTVBinder
-> IOEnv (Env TcGblEnv TcLclEnv) (TCvSubst, InvisTVBinder)
inst_invis_bndr TCvSubst
subst (Bndr Id
tv Specificity
spec)
      = do { (TCvSubst
subst', Id
tv') <- TCvSubst -> Id -> IOEnv (Env TcGblEnv TcLclEnv) (TCvSubst, Id)
newMetaTyVarTyVarX TCvSubst
subst Id
tv
           ; (TCvSubst, InvisTVBinder)
-> IOEnv (Env TcGblEnv TcLclEnv) (TCvSubst, InvisTVBinder)
forall (m :: * -> *) a. Monad m => a -> m a
return (TCvSubst
subst', Id -> Specificity -> InvisTVBinder
forall var argf. var -> argf -> VarBndr var argf
Bndr Id
tv' Specificity
spec) }

tcSkolDFunType :: DFunId -> TcM ([TcTyVar], TcThetaType, TcType)
-- Instantiate a type signature with skolem constants.
-- We could give them fresh names, but no need to do so
tcSkolDFunType :: Id -> TcM ([Id], [TcRhoType], TcRhoType)
tcSkolDFunType Id
dfun
  = do { ([(Name, Id)]
tv_prs, [TcRhoType]
theta, TcRhoType
tau) <- ([Id] -> TcM (TCvSubst, [Id]))
-> Id -> TcM ([(Name, Id)], [TcRhoType], TcRhoType)
tcInstType [Id] -> TcM (TCvSubst, [Id])
tcInstSuperSkolTyVars Id
dfun
       ; ([Id], [TcRhoType], TcRhoType)
-> TcM ([Id], [TcRhoType], TcRhoType)
forall (m :: * -> *) a. Monad m => a -> m a
return (((Name, Id) -> Id) -> [(Name, Id)] -> [Id]
forall a b. (a -> b) -> [a] -> [b]
map (Name, Id) -> Id
forall a b. (a, b) -> b
snd [(Name, Id)]
tv_prs, [TcRhoType]
theta, TcRhoType
tau) }

tcSuperSkolTyVars :: [TyVar] -> (TCvSubst, [TcTyVar])
-- Make skolem constants, but do *not* give them new names, as above
-- Moreover, make them "super skolems"; see comments with superSkolemTv
-- see Note [Kind substitution when instantiating]
-- Precondition: tyvars should be ordered by scoping
tcSuperSkolTyVars :: [Id] -> (TCvSubst, [Id])
tcSuperSkolTyVars = (TCvSubst -> Id -> (TCvSubst, Id))
-> TCvSubst -> [Id] -> (TCvSubst, [Id])
forall (t :: * -> *) a b c.
Traversable t =>
(a -> b -> (a, c)) -> a -> t b -> (a, t c)
mapAccumL TCvSubst -> Id -> (TCvSubst, Id)
tcSuperSkolTyVar TCvSubst
emptyTCvSubst

tcSuperSkolTyVar :: TCvSubst -> TyVar -> (TCvSubst, TcTyVar)
tcSuperSkolTyVar :: TCvSubst -> Id -> (TCvSubst, Id)
tcSuperSkolTyVar TCvSubst
subst Id
tv
  = (TCvSubst -> Id -> Id -> TCvSubst
extendTvSubstWithClone TCvSubst
subst Id
tv Id
new_tv, Id
new_tv)
  where
    kind :: TcRhoType
kind   = TCvSubst -> TcRhoType -> TcRhoType
substTyUnchecked TCvSubst
subst (Id -> TcRhoType
tyVarKind Id
tv)
    new_tv :: Id
new_tv = Name -> TcRhoType -> TcTyVarDetails -> Id
mkTcTyVar (Id -> Name
tyVarName Id
tv) TcRhoType
kind TcTyVarDetails
superSkolemTv

-- | Given a list of @['TyVar']@, skolemize the type variables,
-- returning a substitution mapping the original tyvars to the
-- skolems, and the list of newly bound skolems.
tcInstSkolTyVars :: [TyVar] -> TcM (TCvSubst, [TcTyVar])
-- See Note [Skolemising type variables]
tcInstSkolTyVars :: [Id] -> TcM (TCvSubst, [Id])
tcInstSkolTyVars = TCvSubst -> [Id] -> TcM (TCvSubst, [Id])
tcInstSkolTyVarsX TCvSubst
emptyTCvSubst

tcInstSkolTyVarsX :: TCvSubst -> [TyVar] -> TcM (TCvSubst, [TcTyVar])
-- See Note [Skolemising type variables]
tcInstSkolTyVarsX :: TCvSubst -> [Id] -> TcM (TCvSubst, [Id])
tcInstSkolTyVarsX = Bool -> TCvSubst -> [Id] -> TcM (TCvSubst, [Id])
tcInstSkolTyVarsPushLevel Bool
False

tcInstSuperSkolTyVars :: [TyVar] -> TcM (TCvSubst, [TcTyVar])
-- See Note [Skolemising type variables]
tcInstSuperSkolTyVars :: [Id] -> TcM (TCvSubst, [Id])
tcInstSuperSkolTyVars = TCvSubst -> [Id] -> TcM (TCvSubst, [Id])
tcInstSuperSkolTyVarsX TCvSubst
emptyTCvSubst

tcInstSuperSkolTyVarsX :: TCvSubst -> [TyVar] -> TcM (TCvSubst, [TcTyVar])
-- See Note [Skolemising type variables]
tcInstSuperSkolTyVarsX :: TCvSubst -> [Id] -> TcM (TCvSubst, [Id])
tcInstSuperSkolTyVarsX TCvSubst
subst = Bool -> TCvSubst -> [Id] -> TcM (TCvSubst, [Id])
tcInstSkolTyVarsPushLevel Bool
True TCvSubst
subst

tcInstSkolTyVarsPushLevel :: Bool -> TCvSubst -> [TyVar]
                          -> TcM (TCvSubst, [TcTyVar])
-- Skolemise one level deeper, hence pushTcLevel
-- See Note [Skolemising type variables]
tcInstSkolTyVarsPushLevel :: Bool -> TCvSubst -> [Id] -> TcM (TCvSubst, [Id])
tcInstSkolTyVarsPushLevel Bool
overlappable TCvSubst
subst [Id]
tvs
  = do { TcLevel
tc_lvl <- TcM TcLevel
getTcLevel
       ; let pushed_lvl :: TcLevel
pushed_lvl = TcLevel -> TcLevel
pushTcLevel TcLevel
tc_lvl
       ; TcLevel -> Bool -> TCvSubst -> [Id] -> TcM (TCvSubst, [Id])
tcInstSkolTyVarsAt TcLevel
pushed_lvl Bool
overlappable TCvSubst
subst [Id]
tvs }

tcInstSkolTyVarsAt :: TcLevel -> Bool
                   -> TCvSubst -> [TyVar]
                   -> TcM (TCvSubst, [TcTyVar])
tcInstSkolTyVarsAt :: TcLevel -> Bool -> TCvSubst -> [Id] -> TcM (TCvSubst, [Id])
tcInstSkolTyVarsAt TcLevel
lvl Bool
overlappable TCvSubst
subst [Id]
tvs
  = (Name -> TcRhoType -> Id)
-> TCvSubst -> [Id] -> TcM (TCvSubst, [Id])
freshenTyCoVarsX Name -> TcRhoType -> Id
new_skol_tv TCvSubst
subst [Id]
tvs
  where
    details :: TcTyVarDetails
details = TcLevel -> Bool -> TcTyVarDetails
SkolemTv TcLevel
lvl Bool
overlappable
    new_skol_tv :: Name -> TcRhoType -> Id
new_skol_tv Name
name TcRhoType
kind = Name -> TcRhoType -> TcTyVarDetails -> Id
mkTcTyVar Name
name TcRhoType
kind TcTyVarDetails
details

------------------
freshenTyVarBndrs :: [TyVar] -> TcM (TCvSubst, [TyVar])
-- ^ Give fresh uniques to a bunch of TyVars, but they stay
--   as TyVars, rather than becoming TcTyVars
-- Used in 'GHC.Tc.Instance.Family.newFamInst', and 'GHC.Tc.Utils.Instantiate.newClsInst'
freshenTyVarBndrs :: [Id] -> TcM (TCvSubst, [Id])
freshenTyVarBndrs = (Name -> TcRhoType -> Id) -> [Id] -> TcM (TCvSubst, [Id])
freshenTyCoVars Name -> TcRhoType -> Id
mkTyVar

freshenCoVarBndrsX :: TCvSubst -> [CoVar] -> TcM (TCvSubst, [CoVar])
-- ^ Give fresh uniques to a bunch of CoVars
-- Used in "GHC.Tc.Instance.Family.newFamInst"
freshenCoVarBndrsX :: TCvSubst -> [Id] -> TcM (TCvSubst, [Id])
freshenCoVarBndrsX TCvSubst
subst = (Name -> TcRhoType -> Id)
-> TCvSubst -> [Id] -> TcM (TCvSubst, [Id])
freshenTyCoVarsX Name -> TcRhoType -> Id
mkCoVar TCvSubst
subst

------------------
freshenTyCoVars :: (Name -> Kind -> TyCoVar)
                -> [TyVar] -> TcM (TCvSubst, [TyCoVar])
freshenTyCoVars :: (Name -> TcRhoType -> Id) -> [Id] -> TcM (TCvSubst, [Id])
freshenTyCoVars Name -> TcRhoType -> Id
mk_tcv = (Name -> TcRhoType -> Id)
-> TCvSubst -> [Id] -> TcM (TCvSubst, [Id])
freshenTyCoVarsX Name -> TcRhoType -> Id
mk_tcv TCvSubst
emptyTCvSubst

freshenTyCoVarsX :: (Name -> Kind -> TyCoVar)
                 -> TCvSubst -> [TyCoVar]
                 -> TcM (TCvSubst, [TyCoVar])
freshenTyCoVarsX :: (Name -> TcRhoType -> Id)
-> TCvSubst -> [Id] -> TcM (TCvSubst, [Id])
freshenTyCoVarsX Name -> TcRhoType -> Id
mk_tcv = (TCvSubst -> Id -> IOEnv (Env TcGblEnv TcLclEnv) (TCvSubst, Id))
-> TCvSubst -> [Id] -> TcM (TCvSubst, [Id])
forall (m :: * -> *) acc x y.
Monad m =>
(acc -> x -> m (acc, y)) -> acc -> [x] -> m (acc, [y])
mapAccumLM ((Name -> TcRhoType -> Id)
-> TCvSubst -> Id -> IOEnv (Env TcGblEnv TcLclEnv) (TCvSubst, Id)
freshenTyCoVarX Name -> TcRhoType -> Id
mk_tcv)

freshenTyCoVarX :: (Name -> Kind -> TyCoVar)
                -> TCvSubst -> TyCoVar -> TcM (TCvSubst, TyCoVar)
-- This a complete freshening operation:
-- the skolems have a fresh unique, and a location from the monad
-- See Note [Skolemising type variables]
freshenTyCoVarX :: (Name -> TcRhoType -> Id)
-> TCvSubst -> Id -> IOEnv (Env TcGblEnv TcLclEnv) (TCvSubst, Id)
freshenTyCoVarX Name -> TcRhoType -> Id
mk_tcv TCvSubst
subst Id
tycovar
  = do { SrcSpan
loc  <- TcRn SrcSpan
getSrcSpanM
       ; Unique
uniq <- TcRnIf TcGblEnv TcLclEnv Unique
forall gbl lcl. TcRnIf gbl lcl Unique
newUnique
       ; let old_name :: Name
old_name = Id -> Name
tyVarName Id
tycovar
             new_name :: Name
new_name = Unique -> OccName -> SrcSpan -> Name
mkInternalName Unique
uniq (Name -> OccName
forall a. NamedThing a => a -> OccName
getOccName Name
old_name) SrcSpan
loc
             new_kind :: TcRhoType
new_kind = TCvSubst -> TcRhoType -> TcRhoType
substTyUnchecked TCvSubst
subst (Id -> TcRhoType
tyVarKind Id
tycovar)
             new_tcv :: Id
new_tcv  = Name -> TcRhoType -> Id
mk_tcv Name
new_name TcRhoType
new_kind
             subst1 :: TCvSubst
subst1   = TCvSubst -> Id -> Id -> TCvSubst
extendTCvSubstWithClone TCvSubst
subst Id
tycovar Id
new_tcv
       ; (TCvSubst, Id) -> IOEnv (Env TcGblEnv TcLclEnv) (TCvSubst, Id)
forall (m :: * -> *) a. Monad m => a -> m a
return (TCvSubst
subst1, Id
new_tcv) }

{- Note [Skolemising type variables]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The tcInstSkolTyVars family of functions instantiate a list of TyVars
to fresh skolem TcTyVars. Important notes:

a) Level allocation. We generally skolemise /before/ calling
   pushLevelAndCaptureConstraints.  So we want their level to the level
   of the soon-to-be-created implication, which has a level ONE HIGHER
   than the current level.  Hence the pushTcLevel.  It feels like a
   slight hack.

b) The [TyVar] should be ordered (kind vars first)
   See Note [Kind substitution when instantiating]

c) It's a complete freshening operation: the skolems have a fresh
   unique, and a location from the monad

d) The resulting skolems are
        non-overlappable for tcInstSkolTyVars,
   but overlappable for tcInstSuperSkolTyVars
   See GHC.Tc.Deriv.Infer Note [Overlap and deriving] for an example
   of where this matters.

Note [Kind substitution when instantiating]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When we instantiate a bunch of kind and type variables, first we
expect them to be topologically sorted.
Then we have to instantiate the kind variables, build a substitution
from old variables to the new variables, then instantiate the type
variables substituting the original kind.

Exemple: If we want to instantiate
  [(k1 :: *), (k2 :: *), (a :: k1 -> k2), (b :: k1)]
we want
  [(?k1 :: *), (?k2 :: *), (?a :: ?k1 -> ?k2), (?b :: ?k1)]
instead of the bogus
  [(?k1 :: *), (?k2 :: *), (?a :: k1 -> k2), (?b :: k1)]
-}

{- *********************************************************************
*                                                                      *
                Literals
*                                                                      *
********************************************************************* -}

{-
In newOverloadedLit we convert directly to an Int or Integer if we
know that's what we want.  This may save some time, by not
temporarily generating overloaded literals, but it won't catch all
cases (the rest are caught in lookupInst).

-}

newOverloadedLit :: HsOverLit GhcRn
                 -> ExpRhoType
                 -> TcM (HsOverLit GhcTc)
newOverloadedLit :: HsOverLit GhcRn -> ExpRhoType -> TcM (HsOverLit GhcTc)
newOverloadedLit
  lit :: HsOverLit GhcRn
lit@(OverLit { ol_val :: forall p. HsOverLit p -> OverLitVal
ol_val = OverLitVal
val, ol_ext :: forall p. HsOverLit p -> XOverLit p
ol_ext = XOverLit GhcRn
rebindable }) ExpRhoType
res_ty
  | Bool -> Bool
not Bool
XOverLit GhcRn
rebindable
  = do { TcRhoType
res_ty <- ExpRhoType -> TcM TcRhoType
expTypeToType ExpRhoType
res_ty
       ; DynFlags
dflags <- IOEnv (Env TcGblEnv TcLclEnv) DynFlags
forall (m :: * -> *). HasDynFlags m => m DynFlags
getDynFlags
       ; let platform :: Platform
platform = DynFlags -> Platform
targetPlatform DynFlags
dflags
       ; case Platform -> OverLitVal -> TcRhoType -> Maybe (HsExpr GhcTc)
shortCutLit Platform
platform OverLitVal
val TcRhoType
res_ty of
        -- Do not generate a LitInst for rebindable syntax.
        -- Reason: If we do, tcSimplify will call lookupInst, which
        --         will call tcSyntaxName, which does unification,
        --         which tcSimplify doesn't like
           Just HsExpr GhcTc
expr -> HsOverLit GhcTc -> TcM (HsOverLit GhcTc)
forall (m :: * -> *) a. Monad m => a -> m a
return (HsOverLit GhcRn
lit { ol_witness :: HsExpr GhcTc
ol_witness = HsExpr GhcTc
expr
                                    , ol_ext :: XOverLit GhcTc
ol_ext = Bool -> TcRhoType -> OverLitTc
OverLitTc Bool
False TcRhoType
res_ty })
           Maybe (HsExpr GhcTc)
Nothing   -> CtOrigin -> HsOverLit GhcRn -> ExpRhoType -> TcM (HsOverLit GhcTc)
newNonTrivialOverloadedLit CtOrigin
orig HsOverLit GhcRn
lit
                                                   (TcRhoType -> ExpRhoType
mkCheckExpType TcRhoType
res_ty) }

  | Bool
otherwise
  = CtOrigin -> HsOverLit GhcRn -> ExpRhoType -> TcM (HsOverLit GhcTc)
newNonTrivialOverloadedLit CtOrigin
orig HsOverLit GhcRn
lit ExpRhoType
res_ty
  where
    orig :: CtOrigin
orig = HsOverLit GhcRn -> CtOrigin
LiteralOrigin HsOverLit GhcRn
lit

-- Does not handle things that 'shortCutLit' can handle. See also
-- newOverloadedLit in GHC.Tc.Utils.Unify
newNonTrivialOverloadedLit :: CtOrigin
                           -> HsOverLit GhcRn
                           -> ExpRhoType
                           -> TcM (HsOverLit GhcTc)
newNonTrivialOverloadedLit :: CtOrigin -> HsOverLit GhcRn -> ExpRhoType -> TcM (HsOverLit GhcTc)
newNonTrivialOverloadedLit CtOrigin
orig
  lit :: HsOverLit GhcRn
lit@(OverLit { ol_val :: forall p. HsOverLit p -> OverLitVal
ol_val = OverLitVal
val, ol_witness :: forall p. HsOverLit p -> HsExpr p
ol_witness = HsVar XVar GhcRn
_ (L SrcSpan
_ IdP GhcRn
meth_name)
               , ol_ext :: forall p. HsOverLit p -> XOverLit p
ol_ext = XOverLit GhcRn
rebindable }) ExpRhoType
res_ty
  = do  { HsLit GhcTc
hs_lit <- OverLitVal -> TcM (HsLit GhcTc)
mkOverLit OverLitVal
val
        ; let lit_ty :: TcRhoType
lit_ty = HsLit GhcTc -> TcRhoType
forall (p :: Pass). HsLit (GhcPass p) -> TcRhoType
hsLitType HsLit GhcTc
hs_lit
        ; (()
_, SyntaxExprTc
fi') <- CtOrigin
-> SyntaxExprRn
-> [SyntaxOpType]
-> ExpRhoType
-> ([TcRhoType] -> [TcRhoType] -> TcRn ())
-> TcM ((), SyntaxExprTc)
forall a.
CtOrigin
-> SyntaxExprRn
-> [SyntaxOpType]
-> ExpRhoType
-> ([TcRhoType] -> [TcRhoType] -> TcM a)
-> TcM (a, SyntaxExprTc)
tcSyntaxOp CtOrigin
orig (Name -> SyntaxExprRn
mkRnSyntaxExpr IdP GhcRn
Name
meth_name)
                                      [TcRhoType -> SyntaxOpType
synKnownType TcRhoType
lit_ty] ExpRhoType
res_ty (([TcRhoType] -> [TcRhoType] -> TcRn ()) -> TcM ((), SyntaxExprTc))
-> ([TcRhoType] -> [TcRhoType] -> TcRn ())
-> TcM ((), SyntaxExprTc)
forall a b. (a -> b) -> a -> b
$
                      \[TcRhoType]
_ [TcRhoType]
_ -> () -> TcRn ()
forall (m :: * -> *) a. Monad m => a -> m a
return ()
        ; let L SrcSpan
_ HsExpr GhcTc
witness = SyntaxExprTc
-> [GenLocated SrcSpan (HsExpr GhcTc)]
-> GenLocated SrcSpan (HsExpr GhcTc)
nlHsSyntaxApps SyntaxExprTc
fi' [HsLit GhcTc -> GenLocated SrcSpan (HsExpr GhcTc)
forall (p :: Pass). HsLit (GhcPass p) -> LHsExpr (GhcPass p)
nlHsLit HsLit GhcTc
hs_lit]
        ; TcRhoType
res_ty <- ExpRhoType -> TcM TcRhoType
readExpType ExpRhoType
res_ty
        ; HsOverLit GhcTc -> TcM (HsOverLit GhcTc)
forall (m :: * -> *) a. Monad m => a -> m a
return (HsOverLit GhcRn
lit { ol_witness :: HsExpr GhcTc
ol_witness = HsExpr GhcTc
witness
                      , ol_ext :: XOverLit GhcTc
ol_ext = Bool -> TcRhoType -> OverLitTc
OverLitTc Bool
XOverLit GhcRn
rebindable TcRhoType
res_ty }) }
newNonTrivialOverloadedLit CtOrigin
_ HsOverLit GhcRn
lit ExpRhoType
_
  = String -> SDoc -> TcM (HsOverLit GhcTc)
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"newNonTrivialOverloadedLit" (HsOverLit GhcRn -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsOverLit GhcRn
lit)

------------
mkOverLit ::OverLitVal -> TcM (HsLit GhcTc)
mkOverLit :: OverLitVal -> TcM (HsLit GhcTc)
mkOverLit (HsIntegral IntegralLit
i)
  = do  { TcRhoType
integer_ty <- Name -> TcM TcRhoType
tcMetaTy Name
integerTyConName
        ; HsLit GhcTc -> TcM (HsLit GhcTc)
forall (m :: * -> *) a. Monad m => a -> m a
return (XHsInteger GhcTc -> Integer -> TcRhoType -> HsLit GhcTc
forall x. XHsInteger x -> Integer -> TcRhoType -> HsLit x
HsInteger (IntegralLit -> SourceText
il_text IntegralLit
i)
                            (IntegralLit -> Integer
il_value IntegralLit
i) TcRhoType
integer_ty) }

mkOverLit (HsFractional FractionalLit
r)
  = do  { TcRhoType
rat_ty <- Name -> TcM TcRhoType
tcMetaTy Name
rationalTyConName
        ; HsLit GhcTc -> TcM (HsLit GhcTc)
forall (m :: * -> *) a. Monad m => a -> m a
return (XHsRat GhcTc -> FractionalLit -> TcRhoType -> HsLit GhcTc
forall x. XHsRat x -> FractionalLit -> TcRhoType -> HsLit x
HsRat NoExtField
XHsRat GhcTc
noExtField FractionalLit
r TcRhoType
rat_ty) }

mkOverLit (HsIsString SourceText
src FastString
s) = HsLit GhcTc -> TcM (HsLit GhcTc)
forall (m :: * -> *) a. Monad m => a -> m a
return (XHsString GhcTc -> FastString -> HsLit GhcTc
forall x. XHsString x -> FastString -> HsLit x
HsString XHsString GhcTc
SourceText
src FastString
s)

{-
************************************************************************
*                                                                      *
                Re-mappable syntax

     Used only for arrow syntax -- find a way to nuke this
*                                                                      *
************************************************************************

Suppose we are doing the -XRebindableSyntax thing, and we encounter
a do-expression.  We have to find (>>) in the current environment, which is
done by the rename. Then we have to check that it has the same type as
Control.Monad.(>>).  Or, more precisely, a compatible type. One 'customer' had
this:

  (>>) :: HB m n mn => m a -> n b -> mn b

So the idea is to generate a local binding for (>>), thus:

        let then72 :: forall a b. m a -> m b -> m b
            then72 = ...something involving the user's (>>)...
        in
        ...the do-expression...

Now the do-expression can proceed using then72, which has exactly
the expected type.

In fact tcSyntaxName just generates the RHS for then72, because we only
want an actual binding in the do-expression case. For literals, we can
just use the expression inline.
-}

tcSyntaxName :: CtOrigin
             -> TcType                 -- ^ Type to instantiate it at
             -> (Name, HsExpr GhcRn)   -- ^ (Standard name, user name)
             -> TcM (Name, HsExpr GhcTc)
                                       -- ^ (Standard name, suitable expression)
-- USED ONLY FOR CmdTop (sigh) ***
-- See Note [CmdSyntaxTable] in "GHC.Hs.Expr"

tcSyntaxName :: CtOrigin
-> TcRhoType -> (Name, HsExpr GhcRn) -> TcM (Name, HsExpr GhcTc)
tcSyntaxName CtOrigin
orig TcRhoType
ty (Name
std_nm, HsVar XVar GhcRn
_ (L SrcSpan
_ IdP GhcRn
user_nm))
  | Name
std_nm Name -> Name -> Bool
forall a. Eq a => a -> a -> Bool
== IdP GhcRn
Name
user_nm
  = do HsExpr GhcTc
rhs <- CtOrigin -> Name -> [TcRhoType] -> TcM (HsExpr GhcTc)
newMethodFromName CtOrigin
orig Name
std_nm [TcRhoType
ty]
       (Name, HsExpr GhcTc) -> TcM (Name, HsExpr GhcTc)
forall (m :: * -> *) a. Monad m => a -> m a
return (Name
std_nm, HsExpr GhcTc
rhs)

tcSyntaxName CtOrigin
orig TcRhoType
ty (Name
std_nm, HsExpr GhcRn
user_nm_expr) = do
    Id
std_id <- Name -> TcM Id
tcLookupId Name
std_nm
    let
        -- C.f. newMethodAtLoc
        ([Id
tv], [TcRhoType]
_, TcRhoType
tau) = TcRhoType -> ([Id], [TcRhoType], TcRhoType)
tcSplitSigmaTy (Id -> TcRhoType
idType Id
std_id)
        sigma1 :: TcRhoType
sigma1         = HasCallStack => [Id] -> [TcRhoType] -> TcRhoType -> TcRhoType
[Id] -> [TcRhoType] -> TcRhoType -> TcRhoType
substTyWith [Id
tv] [TcRhoType
ty] TcRhoType
tau
        -- Actually, the "tau-type" might be a sigma-type in the
        -- case of locally-polymorphic methods.

    (TidyEnv -> TcM (TidyEnv, SDoc))
-> TcM (Name, HsExpr GhcTc) -> TcM (Name, HsExpr GhcTc)
forall a. (TidyEnv -> TcM (TidyEnv, SDoc)) -> TcM a -> TcM a
addErrCtxtM (HsExpr GhcRn
-> CtOrigin -> TcRhoType -> TidyEnv -> TcM (TidyEnv, SDoc)
syntaxNameCtxt HsExpr GhcRn
user_nm_expr CtOrigin
orig TcRhoType
sigma1) (TcM (Name, HsExpr GhcTc) -> TcM (Name, HsExpr GhcTc))
-> TcM (Name, HsExpr GhcTc) -> TcM (Name, HsExpr GhcTc)
forall a b. (a -> b) -> a -> b
$ do

        -- Check that the user-supplied thing has the
        -- same type as the standard one.
        -- Tiresome jiggling because tcCheckSigma takes a located expression
     SrcSpan
span <- TcRn SrcSpan
getSrcSpanM
     GenLocated SrcSpan (HsExpr GhcTc)
expr <- LHsExpr GhcRn
-> TcRhoType -> TcM (GenLocated SrcSpan (HsExpr GhcTc))
tcCheckPolyExpr (SrcSpan -> HsExpr GhcRn -> LHsExpr GhcRn
forall l e. l -> e -> GenLocated l e
L SrcSpan
span HsExpr GhcRn
user_nm_expr) TcRhoType
sigma1
     (Name, HsExpr GhcTc) -> TcM (Name, HsExpr GhcTc)
forall (m :: * -> *) a. Monad m => a -> m a
return (Name
std_nm, GenLocated SrcSpan (HsExpr GhcTc) -> HsExpr GhcTc
forall l e. GenLocated l e -> e
unLoc GenLocated SrcSpan (HsExpr GhcTc)
expr)

syntaxNameCtxt :: HsExpr GhcRn -> CtOrigin -> Type -> TidyEnv
               -> TcRn (TidyEnv, SDoc)
syntaxNameCtxt :: HsExpr GhcRn
-> CtOrigin -> TcRhoType -> TidyEnv -> TcM (TidyEnv, SDoc)
syntaxNameCtxt HsExpr GhcRn
name CtOrigin
orig TcRhoType
ty TidyEnv
tidy_env
  = do { CtLoc
inst_loc <- CtOrigin -> Maybe TypeOrKind -> TcM CtLoc
getCtLocM CtOrigin
orig (TypeOrKind -> Maybe TypeOrKind
forall a. a -> Maybe a
Just TypeOrKind
TypeLevel)
       ; let msg :: SDoc
msg = [SDoc] -> SDoc
vcat [ String -> SDoc
text String
"When checking that" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (HsExpr GhcRn -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsExpr GhcRn
name)
                          SDoc -> SDoc -> SDoc
<+> String -> SDoc
text String
"(needed by a syntactic construct)"
                        , Int -> SDoc -> SDoc
nest Int
2 (String -> SDoc
text String
"has the required type:"
                                  SDoc -> SDoc -> SDoc
<+> TcRhoType -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TidyEnv -> TcRhoType -> TcRhoType
tidyType TidyEnv
tidy_env TcRhoType
ty))
                        , Int -> SDoc -> SDoc
nest Int
2 (CtLoc -> SDoc
pprCtLoc CtLoc
inst_loc) ]
       ; (TidyEnv, SDoc) -> TcM (TidyEnv, SDoc)
forall (m :: * -> *) a. Monad m => a -> m a
return (TidyEnv
tidy_env, SDoc
msg) }

{-
************************************************************************
*                                                                      *
                Instances
*                                                                      *
************************************************************************
-}

getOverlapFlag :: Maybe OverlapMode -> TcM OverlapFlag
-- Construct the OverlapFlag from the global module flags,
-- but if the overlap_mode argument is (Just m),
--     set the OverlapMode to 'm'
getOverlapFlag :: Maybe OverlapMode -> TcM OverlapFlag
getOverlapFlag Maybe OverlapMode
overlap_mode
  = do  { DynFlags
dflags <- IOEnv (Env TcGblEnv TcLclEnv) DynFlags
forall (m :: * -> *). HasDynFlags m => m DynFlags
getDynFlags
        ; let overlap_ok :: Bool
overlap_ok    = Extension -> DynFlags -> Bool
xopt Extension
LangExt.OverlappingInstances DynFlags
dflags
              incoherent_ok :: Bool
incoherent_ok = Extension -> DynFlags -> Bool
xopt Extension
LangExt.IncoherentInstances  DynFlags
dflags
              use :: OverlapMode -> OverlapFlag
use OverlapMode
x = OverlapFlag :: OverlapMode -> Bool -> OverlapFlag
OverlapFlag { isSafeOverlap :: Bool
isSafeOverlap = DynFlags -> Bool
safeLanguageOn DynFlags
dflags
                                  , overlapMode :: OverlapMode
overlapMode   = OverlapMode
x }
              default_oflag :: OverlapFlag
default_oflag | Bool
incoherent_ok = OverlapMode -> OverlapFlag
use (SourceText -> OverlapMode
Incoherent SourceText
NoSourceText)
                            | Bool
overlap_ok    = OverlapMode -> OverlapFlag
use (SourceText -> OverlapMode
Overlaps SourceText
NoSourceText)
                            | Bool
otherwise     = OverlapMode -> OverlapFlag
use (SourceText -> OverlapMode
NoOverlap SourceText
NoSourceText)

              final_oflag :: OverlapFlag
final_oflag = OverlapFlag -> Maybe OverlapMode -> OverlapFlag
setOverlapModeMaybe OverlapFlag
default_oflag Maybe OverlapMode
overlap_mode
        ; OverlapFlag -> TcM OverlapFlag
forall (m :: * -> *) a. Monad m => a -> m a
return OverlapFlag
final_oflag }

tcGetInsts :: TcM [ClsInst]
-- Gets the local class instances.
tcGetInsts :: TcM [ClsInst]
tcGetInsts = (TcGblEnv -> [ClsInst])
-> IOEnv (Env TcGblEnv TcLclEnv) TcGblEnv -> TcM [ClsInst]
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap TcGblEnv -> [ClsInst]
tcg_insts IOEnv (Env TcGblEnv TcLclEnv) TcGblEnv
forall gbl lcl. TcRnIf gbl lcl gbl
getGblEnv

newClsInst :: Maybe OverlapMode -> Name -> [TyVar] -> ThetaType
           -> Class -> [Type] -> TcM ClsInst
newClsInst :: Maybe OverlapMode
-> Name
-> [Id]
-> [TcRhoType]
-> Class
-> [TcRhoType]
-> TcM ClsInst
newClsInst Maybe OverlapMode
overlap_mode Name
dfun_name [Id]
tvs [TcRhoType]
theta Class
clas [TcRhoType]
tys
  = do { (TCvSubst
subst, [Id]
tvs') <- [Id] -> TcM (TCvSubst, [Id])
freshenTyVarBndrs [Id]
tvs
             -- Be sure to freshen those type variables,
             -- so they are sure not to appear in any lookup
       ; let tys' :: [TcRhoType]
tys' = HasCallStack => TCvSubst -> [TcRhoType] -> [TcRhoType]
TCvSubst -> [TcRhoType] -> [TcRhoType]
substTys TCvSubst
subst [TcRhoType]
tys

             dfun :: Id
dfun = Name -> [Id] -> [TcRhoType] -> Class -> [TcRhoType] -> Id
mkDictFunId Name
dfun_name [Id]
tvs [TcRhoType]
theta Class
clas [TcRhoType]
tys
             -- The dfun uses the original 'tvs' because
             -- (a) they don't need to be fresh
             -- (b) they may be mentioned in the ib_binds field of
             --     an InstInfo, and in GHC.Tc.Utils.Env.pprInstInfoDetails it's
             --     helpful to use the same names

       ; OverlapFlag
oflag <- Maybe OverlapMode -> TcM OverlapFlag
getOverlapFlag Maybe OverlapMode
overlap_mode
       ; let inst :: ClsInst
inst = Id -> OverlapFlag -> [Id] -> Class -> [TcRhoType] -> ClsInst
mkLocalInstance Id
dfun OverlapFlag
oflag [Id]
tvs' Class
clas [TcRhoType]
tys'
       ; WarningFlag -> Bool -> SDoc -> TcRn ()
warnIfFlag WarningFlag
Opt_WarnOrphans
                    (IsOrphan -> Bool
isOrphan (ClsInst -> IsOrphan
is_orphan ClsInst
inst))
                    (ClsInst -> SDoc
instOrphWarn ClsInst
inst)
       ; ClsInst -> TcM ClsInst
forall (m :: * -> *) a. Monad m => a -> m a
return ClsInst
inst }

instOrphWarn :: ClsInst -> SDoc
instOrphWarn :: ClsInst -> SDoc
instOrphWarn ClsInst
inst
  = SDoc -> Int -> SDoc -> SDoc
hang (String -> SDoc
text String
"Orphan instance:") Int
2 (ClsInst -> SDoc
pprInstanceHdr ClsInst
inst)
    SDoc -> SDoc -> SDoc
$$ String -> SDoc
text String
"To avoid this"
    SDoc -> SDoc -> SDoc
$$ Int -> SDoc -> SDoc
nest Int
4 ([SDoc] -> SDoc
vcat [SDoc]
possibilities)
  where
    possibilities :: [SDoc]
possibilities =
      String -> SDoc
text String
"move the instance declaration to the module of the class or of the type, or" SDoc -> [SDoc] -> [SDoc]
forall a. a -> [a] -> [a]
:
      String -> SDoc
text String
"wrap the type with a newtype and declare the instance on the new type." SDoc -> [SDoc] -> [SDoc]
forall a. a -> [a] -> [a]
:
      []

tcExtendLocalInstEnv :: [ClsInst] -> TcM a -> TcM a
  -- Add new locally-defined instances
tcExtendLocalInstEnv :: [ClsInst] -> TcM a -> TcM a
tcExtendLocalInstEnv [ClsInst]
dfuns TcM a
thing_inside
 = do { [ClsInst] -> TcRn ()
traceDFuns [ClsInst]
dfuns
      ; TcGblEnv
env <- IOEnv (Env TcGblEnv TcLclEnv) TcGblEnv
forall gbl lcl. TcRnIf gbl lcl gbl
getGblEnv
      ; (InstEnv
inst_env', [ClsInst]
cls_insts') <- ((InstEnv, [ClsInst])
 -> ClsInst -> IOEnv (Env TcGblEnv TcLclEnv) (InstEnv, [ClsInst]))
-> (InstEnv, [ClsInst])
-> [ClsInst]
-> IOEnv (Env TcGblEnv TcLclEnv) (InstEnv, [ClsInst])
forall (t :: * -> *) (m :: * -> *) b a.
(Foldable t, Monad m) =>
(b -> a -> m b) -> b -> t a -> m b
foldlM (InstEnv, [ClsInst])
-> ClsInst -> IOEnv (Env TcGblEnv TcLclEnv) (InstEnv, [ClsInst])
addLocalInst
                                          (TcGblEnv -> InstEnv
tcg_inst_env TcGblEnv
env, TcGblEnv -> [ClsInst]
tcg_insts TcGblEnv
env)
                                          [ClsInst]
dfuns
      ; let env' :: TcGblEnv
env' = TcGblEnv
env { tcg_insts :: [ClsInst]
tcg_insts    = [ClsInst]
cls_insts'
                       , tcg_inst_env :: InstEnv
tcg_inst_env = InstEnv
inst_env' }
      ; TcGblEnv -> TcM a -> TcM a
forall gbl lcl a. gbl -> TcRnIf gbl lcl a -> TcRnIf gbl lcl a
setGblEnv TcGblEnv
env' TcM a
thing_inside }

addLocalInst :: (InstEnv, [ClsInst]) -> ClsInst -> TcM (InstEnv, [ClsInst])
-- Check that the proposed new instance is OK,
-- and then add it to the home inst env
-- If overwrite_inst, then we can overwrite a direct match
addLocalInst :: (InstEnv, [ClsInst])
-> ClsInst -> IOEnv (Env TcGblEnv TcLclEnv) (InstEnv, [ClsInst])
addLocalInst (InstEnv
home_ie, [ClsInst]
my_insts) ClsInst
ispec
   = do {
             -- Load imported instances, so that we report
             -- duplicates correctly

             -- 'matches'  are existing instance declarations that are less
             --            specific than the new one
             -- 'dups'     are those 'matches' that are equal to the new one
         ; Bool
isGHCi <- TcRn Bool
getIsGHCi
         ; ExternalPackageState
eps    <- TcRnIf TcGblEnv TcLclEnv ExternalPackageState
forall gbl lcl. TcRnIf gbl lcl ExternalPackageState
getEps
         ; TcGblEnv
tcg_env <- IOEnv (Env TcGblEnv TcLclEnv) TcGblEnv
forall gbl lcl. TcRnIf gbl lcl gbl
getGblEnv

           -- In GHCi, we *override* any identical instances
           -- that are also defined in the interactive context
           -- See Note [Override identical instances in GHCi]
         ; let home_ie' :: InstEnv
home_ie'
                 | Bool
isGHCi    = InstEnv -> ClsInst -> InstEnv
deleteFromInstEnv InstEnv
home_ie ClsInst
ispec
                 | Bool
otherwise = InstEnv
home_ie

               global_ie :: InstEnv
global_ie = ExternalPackageState -> InstEnv
eps_inst_env ExternalPackageState
eps
               inst_envs :: InstEnvs
inst_envs = InstEnvs :: InstEnv -> InstEnv -> VisibleOrphanModules -> InstEnvs
InstEnvs { ie_global :: InstEnv
ie_global  = InstEnv
global_ie
                                    , ie_local :: InstEnv
ie_local   = InstEnv
home_ie'
                                    , ie_visible :: VisibleOrphanModules
ie_visible = TcGblEnv -> VisibleOrphanModules
tcVisibleOrphanMods TcGblEnv
tcg_env }

             -- Check for inconsistent functional dependencies
         ; let inconsistent_ispecs :: [ClsInst]
inconsistent_ispecs = InstEnvs -> ClsInst -> [ClsInst]
checkFunDeps InstEnvs
inst_envs ClsInst
ispec
         ; Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
unless ([ClsInst] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [ClsInst]
inconsistent_ispecs) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
           ClsInst -> [ClsInst] -> TcRn ()
funDepErr ClsInst
ispec [ClsInst]
inconsistent_ispecs

             -- Check for duplicate instance decls.
         ; let ([Id]
_tvs, Class
cls, [TcRhoType]
tys) = ClsInst -> ([Id], Class, [TcRhoType])
instanceHead ClsInst
ispec
               ([InstMatch]
matches, [ClsInst]
_, [InstMatch]
_)  = Bool
-> InstEnvs
-> Class
-> [TcRhoType]
-> ([InstMatch], [ClsInst], [InstMatch])
lookupInstEnv Bool
False InstEnvs
inst_envs Class
cls [TcRhoType]
tys
               dups :: [ClsInst]
dups             = (ClsInst -> Bool) -> [ClsInst] -> [ClsInst]
forall a. (a -> Bool) -> [a] -> [a]
filter (ClsInst -> ClsInst -> Bool
identicalClsInstHead ClsInst
ispec) ((InstMatch -> ClsInst) -> [InstMatch] -> [ClsInst]
forall a b. (a -> b) -> [a] -> [b]
map InstMatch -> ClsInst
forall a b. (a, b) -> a
fst [InstMatch]
matches)
         ; Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
unless ([ClsInst] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [ClsInst]
dups) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
           ClsInst -> ClsInst -> TcRn ()
dupInstErr ClsInst
ispec ([ClsInst] -> ClsInst
forall a. [a] -> a
head [ClsInst]
dups)

         ; (InstEnv, [ClsInst])
-> IOEnv (Env TcGblEnv TcLclEnv) (InstEnv, [ClsInst])
forall (m :: * -> *) a. Monad m => a -> m a
return (InstEnv -> ClsInst -> InstEnv
extendInstEnv InstEnv
home_ie' ClsInst
ispec, ClsInst
ispec ClsInst -> [ClsInst] -> [ClsInst]
forall a. a -> [a] -> [a]
: [ClsInst]
my_insts) }

{-
Note [Signature files and type class instances]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Instances in signature files do not have an effect when compiling:
when you compile a signature against an implementation, you will
see the instances WHETHER OR NOT the instance is declared in
the file (this is because the signatures go in the EPS and we
can't filter them out easily.)  This is also why we cannot
place the instance in the hi file: it would show up as a duplicate,
and we don't have instance reexports anyway.

However, you might find them useful when typechecking against
a signature: the instance is a way of indicating to GHC that
some instance exists, in case downstream code uses it.

Implementing this is a little tricky.  Consider the following
situation (sigof03):

 module A where
     instance C T where ...

 module ASig where
     instance C T

When compiling ASig, A.hi is loaded, which brings its instances
into the EPS.  When we process the instance declaration in ASig,
we should ignore it for the purpose of doing a duplicate check,
since it's not actually a duplicate. But don't skip the check
entirely, we still want this to fail (tcfail221):

 module ASig where
     instance C T
     instance C T

Note that in some situations, the interface containing the type
class instances may not have been loaded yet at all.  The usual
situation when A imports another module which provides the
instances (sigof02m):

 module A(module B) where
     import B

See also Note [Signature lazy interface loading].  We can't
rely on this, however, since sometimes we'll have spurious
type class instances in the EPS, see #9422 (sigof02dm)

************************************************************************
*                                                                      *
        Errors and tracing
*                                                                      *
************************************************************************
-}

traceDFuns :: [ClsInst] -> TcRn ()
traceDFuns :: [ClsInst] -> TcRn ()
traceDFuns [ClsInst]
ispecs
  = String -> SDoc -> TcRn ()
traceTc String
"Adding instances:" ([SDoc] -> SDoc
vcat ((ClsInst -> SDoc) -> [ClsInst] -> [SDoc]
forall a b. (a -> b) -> [a] -> [b]
map ClsInst -> SDoc
pp [ClsInst]
ispecs))
  where
    pp :: ClsInst -> SDoc
pp ClsInst
ispec = SDoc -> Int -> SDoc -> SDoc
hang (Id -> SDoc
forall a. Outputable a => a -> SDoc
ppr (ClsInst -> Id
instanceDFunId ClsInst
ispec) SDoc -> SDoc -> SDoc
<+> SDoc
colon)
                  Int
2 (ClsInst -> SDoc
forall a. Outputable a => a -> SDoc
ppr ClsInst
ispec)
        -- Print the dfun name itself too

funDepErr :: ClsInst -> [ClsInst] -> TcRn ()
funDepErr :: ClsInst -> [ClsInst] -> TcRn ()
funDepErr ClsInst
ispec [ClsInst]
ispecs
  = SDoc -> [ClsInst] -> TcRn ()
addClsInstsErr (String -> SDoc
text String
"Functional dependencies conflict between instance declarations:")
                    (ClsInst
ispec ClsInst -> [ClsInst] -> [ClsInst]
forall a. a -> [a] -> [a]
: [ClsInst]
ispecs)

dupInstErr :: ClsInst -> ClsInst -> TcRn ()
dupInstErr :: ClsInst -> ClsInst -> TcRn ()
dupInstErr ClsInst
ispec ClsInst
dup_ispec
  = SDoc -> [ClsInst] -> TcRn ()
addClsInstsErr (String -> SDoc
text String
"Duplicate instance declarations:")
                    [ClsInst
ispec, ClsInst
dup_ispec]

addClsInstsErr :: SDoc -> [ClsInst] -> TcRn ()
addClsInstsErr :: SDoc -> [ClsInst] -> TcRn ()
addClsInstsErr SDoc
herald [ClsInst]
ispecs
  = SrcSpan -> TcRn () -> TcRn ()
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan (ClsInst -> SrcSpan
forall a. NamedThing a => a -> SrcSpan
getSrcSpan ([ClsInst] -> ClsInst
forall a. [a] -> a
head [ClsInst]
sorted)) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
    SDoc -> TcRn ()
addErr (SDoc -> Int -> SDoc -> SDoc
hang SDoc
herald Int
2 ([ClsInst] -> SDoc
pprInstances [ClsInst]
sorted))
 where
   sorted :: [ClsInst]
sorted = (ClsInst -> ClsInst -> Ordering) -> [ClsInst] -> [ClsInst]
forall a. (a -> a -> Ordering) -> [a] -> [a]
sortBy (SrcSpan -> SrcSpan -> Ordering
SrcLoc.leftmost_smallest (SrcSpan -> SrcSpan -> Ordering)
-> (ClsInst -> SrcSpan) -> ClsInst -> ClsInst -> Ordering
forall b c a. (b -> b -> c) -> (a -> b) -> a -> a -> c
`on` ClsInst -> SrcSpan
forall a. NamedThing a => a -> SrcSpan
getSrcSpan) [ClsInst]
ispecs
   -- The sortBy just arranges that instances are displayed in order
   -- of source location, which reduced wobbling in error messages,
   -- and is better for users