{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE RankNTypes #-}
{-# LANGUAGE TupleSections #-}
{-# LANGUAGE TypeFamilies #-}

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

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

-}

-- | Typechecking patterns
module GHC.Tc.Gen.Pat
   ( tcLetPat
   , newLetBndr
   , LetBndrSpec(..)
   , tcCheckPat, tcCheckPat_O, tcInferPat
   , tcPats
   , addDataConStupidTheta
   )
where

import GHC.Prelude

import {-# SOURCE #-}   GHC.Tc.Gen.Expr( tcSyntaxOp, tcSyntaxOpGen, tcInferRho )

import GHC.Hs
import GHC.Hs.Syn.Type
import GHC.Rename.Utils
import GHC.Tc.Errors.Types
import GHC.Tc.Gen.Sig( TcPragEnv, lookupPragEnv, addInlinePrags )
import GHC.Tc.Utils.Monad
import GHC.Tc.Utils.Instantiate
import GHC.Types.FieldLabel
import GHC.Types.Id
import GHC.Types.Var
import GHC.Types.Name
import GHC.Types.Name.Reader
import GHC.Core.Multiplicity
import GHC.Tc.Utils.Concrete ( hasFixedRuntimeRep_syntactic )
import GHC.Tc.Utils.Env
import GHC.Tc.Utils.TcMType
import GHC.Tc.Zonk.TcType
import GHC.Core.TyCo.Ppr ( pprTyVars )
import GHC.Tc.Utils.TcType
import GHC.Tc.Utils.Unify
import GHC.Tc.Gen.HsType
import GHC.Builtin.Types
import GHC.Tc.Types.Evidence
import GHC.Tc.Types.Origin
import GHC.Core.TyCon
import GHC.Core.Type
import GHC.Core.Coercion
import GHC.Core.DataCon
import GHC.Core.PatSyn
import GHC.Core.ConLike
import GHC.Builtin.Names
import GHC.Types.Basic hiding (SuccessFlag(..))
import GHC.Driver.DynFlags
import GHC.Types.SrcLoc
import GHC.Types.Var.Set
import GHC.Utils.Misc
import GHC.Utils.Outputable as Outputable
import GHC.Utils.Panic
import GHC.Utils.Panic.Plain
import qualified GHC.LanguageExtensions as LangExt
import Control.Arrow  ( second )
import Control.Monad
import GHC.Data.FastString
import qualified Data.List.NonEmpty as NE

import GHC.Data.List.SetOps ( getNth )
import Language.Haskell.Syntax.Basic (FieldLabelString(..))

import Data.List( partition )

{-
************************************************************************
*                                                                      *
                External interface
*                                                                      *
************************************************************************
-}

tcLetPat :: (Name -> Maybe TcId)
         -> LetBndrSpec
         -> LPat GhcRn -> Scaled ExpSigmaTypeFRR
         -> TcM a
         -> TcM (LPat GhcTc, a)
tcLetPat :: forall a.
(Name -> Maybe TyCoVar)
-> LetBndrSpec
-> LPat GhcRn
-> Scaled ExpSigmaTypeFRR
-> TcM a
-> TcM (LPat GhcTc, a)
tcLetPat Name -> Maybe TyCoVar
sig_fn LetBndrSpec
no_gen LPat GhcRn
pat Scaled ExpSigmaTypeFRR
pat_ty TcM a
thing_inside
  = do { TcLevel
bind_lvl <- TcM TcLevel
getTcLevel
       ; let ctxt :: PatCtxt
ctxt = LetPat { pc_lvl :: TcLevel
pc_lvl    = TcLevel
bind_lvl
                           , pc_sig_fn :: Name -> Maybe TyCoVar
pc_sig_fn = Name -> Maybe TyCoVar
sig_fn
                           , pc_new :: LetBndrSpec
pc_new    = LetBndrSpec
no_gen }
             penv :: PatEnv
penv = PE { pe_lazy :: Bool
pe_lazy = Bool
True
                       , pe_ctxt :: PatCtxt
pe_ctxt = PatCtxt
ctxt
                       , pe_orig :: CtOrigin
pe_orig = CtOrigin
PatOrigin }

       ; Scaled ExpSigmaTypeFRR -> Checker (LPat GhcRn) (LPat GhcTc)
tc_lpat Scaled ExpSigmaTypeFRR
pat_ty PatEnv
penv LPat GhcRn
pat TcM a
thing_inside }

-----------------
tcPats :: HsMatchContext GhcTc
       -> [LPat GhcRn]             -- ^ atterns
       -> [Scaled ExpSigmaTypeFRR] -- ^ types of the patterns
       -> TcM a                    -- ^ checker for the body
       -> TcM ([LPat GhcTc], a)

-- This is the externally-callable wrapper function
-- Typecheck the patterns, extend the environment to bind the variables,
-- do the thing inside, use any existentially-bound dictionaries to
-- discharge parts of the returning LIE, and deal with pattern type
-- signatures

--   1. Initialise the PatState
--   2. Check the patterns
--   3. Check the body
--   4. Check that no existentials escape

tcPats :: forall a.
HsMatchContext GhcTc
-> [LPat GhcRn]
-> [Scaled ExpSigmaTypeFRR]
-> TcM a
-> TcM ([LPat GhcTc], a)
tcPats HsMatchContext GhcTc
ctxt [LPat GhcRn]
pats [Scaled ExpSigmaTypeFRR]
pat_tys TcM a
thing_inside
  = [Scaled ExpSigmaTypeFRR] -> Checker [LPat GhcRn] [LPat GhcTc]
tc_lpats [Scaled ExpSigmaTypeFRR]
pat_tys PatEnv
penv [LPat GhcRn]
pats TcM a
thing_inside
  where
    penv :: PatEnv
penv = PE { pe_lazy :: Bool
pe_lazy = Bool
False, pe_ctxt :: PatCtxt
pe_ctxt = HsMatchContext GhcTc -> PatCtxt
LamPat HsMatchContext GhcTc
ctxt, pe_orig :: CtOrigin
pe_orig = CtOrigin
PatOrigin }

tcInferPat :: FixedRuntimeRepContext
           -> HsMatchContext GhcTc
           -> LPat GhcRn
           -> TcM a
           -> TcM ((LPat GhcTc, a), TcSigmaTypeFRR)
tcInferPat :: forall a.
FixedRuntimeRepContext
-> HsMatchContext GhcTc
-> LPat GhcRn
-> TcM a
-> TcM ((LPat GhcTc, a), Type)
tcInferPat FixedRuntimeRepContext
frr_orig HsMatchContext GhcTc
ctxt LPat GhcRn
pat TcM a
thing_inside
  = FixedRuntimeRepContext
-> (ExpSigmaTypeFRR -> TcM (LPat GhcTc, a))
-> TcM ((LPat GhcTc, a), Type)
forall a.
FixedRuntimeRepContext
-> (ExpSigmaTypeFRR -> TcM a) -> TcM (a, Type)
tcInferFRR FixedRuntimeRepContext
frr_orig ((ExpSigmaTypeFRR -> TcM (LPat GhcTc, a))
 -> TcM ((LPat GhcTc, a), Type))
-> (ExpSigmaTypeFRR -> TcM (LPat GhcTc, a))
-> TcM ((LPat GhcTc, a), Type)
forall a b. (a -> b) -> a -> b
$ \ ExpSigmaTypeFRR
exp_ty ->
    Scaled ExpSigmaTypeFRR -> Checker (LPat GhcRn) (LPat GhcTc)
tc_lpat (ExpSigmaTypeFRR -> Scaled ExpSigmaTypeFRR
forall a. a -> Scaled a
unrestricted ExpSigmaTypeFRR
exp_ty) PatEnv
penv LPat GhcRn
pat TcM a
thing_inside
 where
    penv :: PatEnv
penv = PE { pe_lazy :: Bool
pe_lazy = Bool
False, pe_ctxt :: PatCtxt
pe_ctxt = HsMatchContext GhcTc -> PatCtxt
LamPat HsMatchContext GhcTc
ctxt, pe_orig :: CtOrigin
pe_orig = CtOrigin
PatOrigin }

tcCheckPat :: HsMatchContext GhcTc
           -> LPat GhcRn -> Scaled TcSigmaTypeFRR
           -> TcM a                     -- Checker for body
           -> TcM (LPat GhcTc, a)
tcCheckPat :: forall a.
HsMatchContext GhcTc
-> LPat GhcRn -> Scaled Type -> TcM a -> TcM (LPat GhcTc, a)
tcCheckPat HsMatchContext GhcTc
ctxt = HsMatchContext GhcTc
-> CtOrigin
-> LPat GhcRn
-> Scaled Type
-> TcM a
-> TcM (LPat GhcTc, a)
forall a.
HsMatchContext GhcTc
-> CtOrigin
-> LPat GhcRn
-> Scaled Type
-> TcM a
-> TcM (LPat GhcTc, a)
tcCheckPat_O HsMatchContext GhcTc
ctxt CtOrigin
PatOrigin

-- | A variant of 'tcPat' that takes a custom origin
tcCheckPat_O :: HsMatchContext GhcTc
             -> CtOrigin              -- ^ origin to use if the type needs inst'ing
             -> LPat GhcRn -> Scaled TcSigmaTypeFRR
             -> TcM a                 -- Checker for body
             -> TcM (LPat GhcTc, a)
tcCheckPat_O :: forall a.
HsMatchContext GhcTc
-> CtOrigin
-> LPat GhcRn
-> Scaled Type
-> TcM a
-> TcM (LPat GhcTc, a)
tcCheckPat_O HsMatchContext GhcTc
ctxt CtOrigin
orig LPat GhcRn
pat (Scaled Type
pat_mult Type
pat_ty) TcM a
thing_inside
  = Scaled ExpSigmaTypeFRR -> Checker (LPat GhcRn) (LPat GhcTc)
tc_lpat (Type -> ExpSigmaTypeFRR -> Scaled ExpSigmaTypeFRR
forall a. Type -> a -> Scaled a
Scaled Type
pat_mult (Type -> ExpSigmaTypeFRR
mkCheckExpType Type
pat_ty)) PatEnv
penv LPat GhcRn
pat TcM a
thing_inside
  where
    penv :: PatEnv
penv = PE { pe_lazy :: Bool
pe_lazy = Bool
False, pe_ctxt :: PatCtxt
pe_ctxt = HsMatchContext GhcTc -> PatCtxt
LamPat HsMatchContext GhcTc
ctxt, pe_orig :: CtOrigin
pe_orig = CtOrigin
orig }


{-
************************************************************************
*                                                                      *
                PatEnv, PatCtxt, LetBndrSpec
*                                                                      *
************************************************************************
-}

data PatEnv
  = PE { PatEnv -> Bool
pe_lazy :: Bool        -- True <=> lazy context, so no existentials allowed
       , PatEnv -> PatCtxt
pe_ctxt :: PatCtxt     -- Context in which the whole pattern appears
       , PatEnv -> CtOrigin
pe_orig :: CtOrigin    -- origin to use if the pat_ty needs inst'ing
       }

data PatCtxt
  = LamPat   -- Used for lambdas, case etc
       (HsMatchContext GhcTc)

  | LetPat   -- Used only for let(rec) pattern bindings
             -- See Note [Typing patterns in pattern bindings]
       { PatCtxt -> TcLevel
pc_lvl    :: TcLevel
                   -- Level of the binding group

       , PatCtxt -> Name -> Maybe TyCoVar
pc_sig_fn :: Name -> Maybe TcId
                   -- Tells the expected type
                   -- for binders with a signature

       , PatCtxt -> LetBndrSpec
pc_new :: LetBndrSpec
                -- How to make a new binder
       }        -- for binders without signatures

data LetBndrSpec
  = LetLclBndr            -- We are going to generalise, and wrap in an AbsBinds
                          -- so clone a fresh binder for the local monomorphic Id

  | LetGblBndr TcPragEnv  -- Generalisation plan is NoGen, so there isn't going
                          -- to be an AbsBinds; So we must bind the global version
                          -- of the binder right away.
                          -- And here is the inline-pragma information

instance Outputable LetBndrSpec where
  ppr :: LetBndrSpec -> SDoc
ppr LetBndrSpec
LetLclBndr      = String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"LetLclBndr"
  ppr (LetGblBndr {}) = String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"LetGblBndr"

makeLazy :: PatEnv -> PatEnv
makeLazy :: PatEnv -> PatEnv
makeLazy PatEnv
penv = PatEnv
penv { pe_lazy = True }

inPatBind :: PatEnv -> Bool
inPatBind :: PatEnv -> Bool
inPatBind (PE { pe_ctxt :: PatEnv -> PatCtxt
pe_ctxt = LetPat {} }) = Bool
True
inPatBind (PE { pe_ctxt :: PatEnv -> PatCtxt
pe_ctxt = LamPat {} }) = Bool
False

{- *********************************************************************
*                                                                      *
                Binders
*                                                                      *
********************************************************************* -}

tcPatBndr :: PatEnv -> Name -> Scaled ExpSigmaTypeFRR -> TcM (HsWrapper, TcId)
-- (coi, xp) = tcPatBndr penv x pat_ty
-- Then coi : pat_ty ~ typeof(xp)
--
tcPatBndr :: PatEnv
-> Name -> Scaled ExpSigmaTypeFRR -> TcM (HsWrapper, TyCoVar)
tcPatBndr penv :: PatEnv
penv@(PE { pe_ctxt :: PatEnv -> PatCtxt
pe_ctxt = LetPat { pc_lvl :: PatCtxt -> TcLevel
pc_lvl    = TcLevel
bind_lvl
                                      , pc_sig_fn :: PatCtxt -> Name -> Maybe TyCoVar
pc_sig_fn = Name -> Maybe TyCoVar
sig_fn
                                      , pc_new :: PatCtxt -> LetBndrSpec
pc_new    = LetBndrSpec
no_gen } })
          Name
bndr_name Scaled ExpSigmaTypeFRR
exp_pat_ty
  -- For the LetPat cases, see
  -- Note [Typechecking pattern bindings] in GHC.Tc.Gen.Bind

  | Just TyCoVar
bndr_id <- Name -> Maybe TyCoVar
sig_fn Name
bndr_name   -- There is a signature
  = do { HsWrapper
wrap <- PatEnv -> ExpSigmaTypeFRR -> Type -> TcM HsWrapper
tc_sub_type PatEnv
penv (Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR
forall a. Scaled a -> a
scaledThing Scaled ExpSigmaTypeFRR
exp_pat_ty) (TyCoVar -> Type
idType TyCoVar
bndr_id)
           -- See Note [Subsumption check at pattern variables]
       ; String -> SDoc -> TcRn ()
traceTc String
"tcPatBndr(sig)" (TyCoVar -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCoVar
bndr_id SDoc -> SDoc -> SDoc
forall doc. IsDoc doc => doc -> doc -> doc
$$ Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyCoVar -> Type
idType TyCoVar
bndr_id) SDoc -> SDoc -> SDoc
forall doc. IsDoc doc => doc -> doc -> doc
$$ Scaled ExpSigmaTypeFRR -> SDoc
forall a. Outputable a => a -> SDoc
ppr Scaled ExpSigmaTypeFRR
exp_pat_ty)
       ; (HsWrapper, TyCoVar) -> TcM (HsWrapper, TyCoVar)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (HsWrapper
wrap, TyCoVar
bndr_id) }

  | Bool
otherwise                          -- No signature
  = do { (TcCoercionN
co, Type
bndr_ty) <- case Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR
forall a. Scaled a -> a
scaledThing Scaled ExpSigmaTypeFRR
exp_pat_ty of
             Check Type
pat_ty    -> TcLevel
-> Type -> IOEnv (Env TcGblEnv TcLclEnv) (TcCoercionN, Type)
promoteTcType TcLevel
bind_lvl Type
pat_ty
             Infer InferResult
infer_res -> Bool
-> IOEnv (Env TcGblEnv TcLclEnv) (TcCoercionN, Type)
-> IOEnv (Env TcGblEnv TcLclEnv) (TcCoercionN, Type)
forall a. HasCallStack => Bool -> a -> a
assert (TcLevel
bind_lvl TcLevel -> TcLevel -> Bool
forall a. Eq a => a -> a -> Bool
== InferResult -> TcLevel
ir_lvl InferResult
infer_res) (IOEnv (Env TcGblEnv TcLclEnv) (TcCoercionN, Type)
 -> IOEnv (Env TcGblEnv TcLclEnv) (TcCoercionN, Type))
-> IOEnv (Env TcGblEnv TcLclEnv) (TcCoercionN, Type)
-> IOEnv (Env TcGblEnv TcLclEnv) (TcCoercionN, Type)
forall a b. (a -> b) -> a -> b
$
                                -- If we were under a constructor that bumped the
                                -- level, we'd be in checking mode (see tcConArg)
                                -- hence this assertion
                                do { Type
bndr_ty <- InferResult -> TcM Type
inferResultToType InferResult
infer_res
                                   ; (TcCoercionN, Type)
-> IOEnv (Env TcGblEnv TcLclEnv) (TcCoercionN, Type)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (Type -> TcCoercionN
mkNomReflCo Type
bndr_ty, Type
bndr_ty) }
       ; let bndr_mult :: Type
bndr_mult = Scaled ExpSigmaTypeFRR -> Type
forall a. Scaled a -> Type
scaledMult Scaled ExpSigmaTypeFRR
exp_pat_ty
       ; TyCoVar
bndr_id <- LetBndrSpec -> Name -> Type -> Type -> TcM TyCoVar
newLetBndr LetBndrSpec
no_gen Name
bndr_name Type
bndr_mult Type
bndr_ty
       ; String -> SDoc -> TcRn ()
traceTc String
"tcPatBndr(nosig)" ([SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat [ TcLevel -> SDoc
forall a. Outputable a => a -> SDoc
ppr TcLevel
bind_lvl
                                          , Scaled ExpSigmaTypeFRR -> SDoc
forall a. Outputable a => a -> SDoc
ppr Scaled ExpSigmaTypeFRR
exp_pat_ty, Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
bndr_ty, TcCoercionN -> SDoc
forall a. Outputable a => a -> SDoc
ppr TcCoercionN
co
                                          , TyCoVar -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCoVar
bndr_id ])
       ; (HsWrapper, TyCoVar) -> TcM (HsWrapper, TyCoVar)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (TcCoercionN -> HsWrapper
mkWpCastN TcCoercionN
co, TyCoVar
bndr_id) }

tcPatBndr PatEnv
_ Name
bndr_name Scaled ExpSigmaTypeFRR
pat_ty
  = do { let pat_mult :: Type
pat_mult = Scaled ExpSigmaTypeFRR -> Type
forall a. Scaled a -> Type
scaledMult Scaled ExpSigmaTypeFRR
pat_ty
       ; Type
pat_ty <- ExpSigmaTypeFRR -> TcM Type
expTypeToType (Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR
forall a. Scaled a -> a
scaledThing Scaled ExpSigmaTypeFRR
pat_ty)
       ; String -> SDoc -> TcRn ()
traceTc String
"tcPatBndr(not let)" (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
bndr_name SDoc -> SDoc -> SDoc
forall doc. IsDoc doc => doc -> doc -> doc
$$ Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
pat_ty)
       ; (HsWrapper, TyCoVar) -> TcM (HsWrapper, TyCoVar)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (HsWrapper
idHsWrapper, Name -> Type -> Type -> TyCoVar
mkLocalIdOrCoVar Name
bndr_name Type
pat_mult Type
pat_ty) }
               -- We should not have "OrCoVar" here, this is a bug (#17545)
               -- Whether or not there is a sig is irrelevant,
               -- as this is local

newLetBndr :: LetBndrSpec -> Name -> Mult -> TcType -> TcM TcId
-- Make up a suitable Id for the pattern-binder.
-- See Note [Typechecking pattern bindings], item (4) in GHC.Tc.Gen.Bind
--
-- In the polymorphic case when we are going to generalise
--    (plan InferGen, no_gen = LetLclBndr), generate a "monomorphic version"
--    of the Id; the original name will be bound to the polymorphic version
--    by the AbsBinds
-- In the monomorphic case when we are not going to generalise
--    (plan NoGen, no_gen = LetGblBndr) there is no AbsBinds,
--    and we use the original name directly
newLetBndr :: LetBndrSpec -> Name -> Type -> Type -> TcM TyCoVar
newLetBndr LetBndrSpec
LetLclBndr Name
name Type
w Type
ty
  = do { Name
mono_name <- Name -> TcM Name
cloneLocalName Name
name
       ; TyCoVar -> TcM TyCoVar
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (HasDebugCallStack => Name -> Type -> Type -> TyCoVar
Name -> Type -> Type -> TyCoVar
mkLocalId Name
mono_name Type
w Type
ty) }
newLetBndr (LetGblBndr TcPragEnv
prags) Name
name Type
w Type
ty
  = TyCoVar -> [LSig GhcRn] -> TcM TyCoVar
addInlinePrags (HasDebugCallStack => Name -> Type -> Type -> TyCoVar
Name -> Type -> Type -> TyCoVar
mkLocalId Name
name Type
w Type
ty) (TcPragEnv -> Name -> [LSig GhcRn]
lookupPragEnv TcPragEnv
prags Name
name)

tc_sub_type :: PatEnv -> ExpSigmaType -> TcSigmaType -> TcM HsWrapper
-- tcSubTypeET with the UserTypeCtxt specialised to GenSigCtxt
-- Used during typechecking patterns
tc_sub_type :: PatEnv -> ExpSigmaTypeFRR -> Type -> TcM HsWrapper
tc_sub_type PatEnv
penv ExpSigmaTypeFRR
t1 Type
t2 = CtOrigin
-> UserTypeCtxt -> ExpSigmaTypeFRR -> Type -> TcM HsWrapper
tcSubTypePat (PatEnv -> CtOrigin
pe_orig PatEnv
penv) UserTypeCtxt
GenSigCtxt ExpSigmaTypeFRR
t1 Type
t2

{- Note [Subsumption check at pattern variables]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When we come across a variable with a type signature, we need to do a
subsumption, not equality, check against the context type.  e.g.

    data T = MkT (forall a. a->a)
      f :: forall b. [b]->[b]
      MkT f = blah

Since 'blah' returns a value of type T, its payload is a polymorphic
function of type (forall a. a->a).  And that's enough to bind the
less-polymorphic function 'f', but we need some impedance matching
to witness the instantiation.


************************************************************************
*                                                                      *
                The main worker functions
*                                                                      *
************************************************************************

Note [Nesting]
~~~~~~~~~~~~~~
tcPat takes a "thing inside" over which the pattern scopes.  This is partly
so that tcPat can extend the environment for the thing_inside, but also
so that constraints arising in the thing_inside can be discharged by the
pattern.

This does not work so well for the ErrCtxt carried by the monad: we don't
want the error-context for the pattern to scope over the RHS.
Hence the getErrCtxt/setErrCtxt stuff in tcMultiple
-}

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

type Checker inp out =  forall r.
                          PatEnv
                       -> inp
                       -> TcM r      -- Thing inside
                       -> TcM ( out
                              , r    -- Result of thing inside
                              )

tcMultiple_ :: Checker inp () -> PatEnv -> [inp] -> TcM r -> TcM r
tcMultiple_ :: forall inp r. Checker inp () -> PatEnv -> [inp] -> TcM r -> TcM r
tcMultiple_ Checker inp ()
tc_pat PatEnv
penv [inp]
args TcM r
thing_inside
  = do { ([()]
_, r
res) <- Checker inp () -> Checker [inp] [()]
forall inp out. Checker inp out -> Checker [inp] [out]
tcMultiple PatEnv -> inp -> TcM r -> TcM ((), r)
Checker inp ()
tc_pat PatEnv
penv [inp]
args TcM r
thing_inside
       ; r -> TcM r
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return r
res }

tcMultiple :: Checker inp out -> Checker [inp] [out]
tcMultiple :: forall inp out. Checker inp out -> Checker [inp] [out]
tcMultiple Checker inp out
tc_pat PatEnv
penv [inp]
args TcM r
thing_inside
  = do  { [ErrCtxt]
err_ctxt <- TcM [ErrCtxt]
getErrCtxt
        ; let loop :: PatEnv -> [inp] -> TcM ([out], r)
loop PatEnv
_ []
                = do { r
res <- TcM r
thing_inside
                     ; ([out], r) -> TcM ([out], r)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ([], r
res) }

              loop PatEnv
penv (inp
arg:[inp]
args)
                = do { (out
p', ([out]
ps', r
res))
                                <- PatEnv -> inp -> TcM ([out], r) -> TcM (out, ([out], r))
Checker inp out
tc_pat PatEnv
penv inp
arg (TcM ([out], r) -> TcM (out, ([out], r)))
-> TcM ([out], r) -> TcM (out, ([out], r))
forall a b. (a -> b) -> a -> b
$
                                   [ErrCtxt] -> TcM ([out], r) -> TcM ([out], r)
forall a. [ErrCtxt] -> TcM a -> TcM a
setErrCtxt [ErrCtxt]
err_ctxt (TcM ([out], r) -> TcM ([out], r))
-> TcM ([out], r) -> TcM ([out], r)
forall a b. (a -> b) -> a -> b
$
                                   PatEnv -> [inp] -> TcM ([out], r)
loop PatEnv
penv [inp]
args
                -- setErrCtxt: restore context before doing the next pattern
                -- See Note [Nesting] above

                     ; ([out], r) -> TcM ([out], r)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (out
p'out -> [out] -> [out]
forall a. a -> [a] -> [a]
:[out]
ps', r
res) }

        ; PatEnv -> [inp] -> TcM ([out], r)
loop PatEnv
penv [inp]
args }

--------------------
tc_lpat :: Scaled ExpSigmaTypeFRR
        -> Checker (LPat GhcRn) (LPat GhcTc)
tc_lpat :: Scaled ExpSigmaTypeFRR -> Checker (LPat GhcRn) (LPat GhcTc)
tc_lpat Scaled ExpSigmaTypeFRR
pat_ty PatEnv
penv (L SrcSpanAnnA
span Pat GhcRn
pat) TcM r
thing_inside
  = SrcSpanAnnA -> TcRn (LPat GhcTc, r) -> TcRn (LPat GhcTc, r)
forall ann a. SrcSpanAnn' ann -> TcRn a -> TcRn a
setSrcSpanA SrcSpanAnnA
span (TcRn (LPat GhcTc, r) -> TcRn (LPat GhcTc, r))
-> TcRn (LPat GhcTc, r) -> TcRn (LPat GhcTc, r)
forall a b. (a -> b) -> a -> b
$
    do  { (Pat GhcTc
pat', r
res) <- Pat GhcRn
-> (TcM r -> TcM (Pat GhcTc, r)) -> TcM r -> TcM (Pat GhcTc, r)
forall a b. Pat GhcRn -> (TcM a -> TcM b) -> TcM a -> TcM b
maybeWrapPatCtxt Pat GhcRn
pat (Scaled ExpSigmaTypeFRR -> Checker (Pat GhcRn) (Pat GhcTc)
tc_pat Scaled ExpSigmaTypeFRR
pat_ty PatEnv
penv Pat GhcRn
pat)
                                          TcM r
thing_inside
        ; (GenLocated SrcSpanAnnA (Pat GhcTc), r)
-> IOEnv
     (Env TcGblEnv TcLclEnv) (GenLocated SrcSpanAnnA (Pat GhcTc), r)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (SrcSpanAnnA -> Pat GhcTc -> GenLocated SrcSpanAnnA (Pat GhcTc)
forall l e. l -> e -> GenLocated l e
L SrcSpanAnnA
span Pat GhcTc
pat', r
res) }

tc_lpats :: [Scaled ExpSigmaTypeFRR]
         -> Checker [LPat GhcRn] [LPat GhcTc]
tc_lpats :: [Scaled ExpSigmaTypeFRR] -> Checker [LPat GhcRn] [LPat GhcTc]
tc_lpats [Scaled ExpSigmaTypeFRR]
tys PatEnv
penv [LPat GhcRn]
pats
  = Bool
-> SDoc
-> (TcM r -> TcM ([LPat GhcTc], r))
-> TcM r
-> TcM ([LPat GhcTc], r)
forall a. HasCallStack => Bool -> SDoc -> a -> a
assertPpr ([GenLocated SrcSpanAnnA (Pat GhcRn)]
-> [Scaled ExpSigmaTypeFRR] -> Bool
forall a b. [a] -> [b] -> Bool
equalLength [LPat GhcRn]
[GenLocated SrcSpanAnnA (Pat GhcRn)]
pats [Scaled ExpSigmaTypeFRR]
tys) ([GenLocated SrcSpanAnnA (Pat GhcRn)] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [LPat GhcRn]
[GenLocated SrcSpanAnnA (Pat GhcRn)]
pats SDoc -> SDoc -> SDoc
forall doc. IsDoc doc => doc -> doc -> doc
$$ [Scaled ExpSigmaTypeFRR] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Scaled ExpSigmaTypeFRR]
tys) ((TcM r -> TcM ([LPat GhcTc], r))
 -> TcM r -> TcM ([LPat GhcTc], r))
-> (TcM r -> TcM ([LPat GhcTc], r))
-> TcM r
-> TcM ([LPat GhcTc], r)
forall a b. (a -> b) -> a -> b
$
    Checker
  (GenLocated SrcSpanAnnA (Pat GhcRn), Scaled ExpSigmaTypeFRR)
  (GenLocated SrcSpanAnnA (Pat GhcTc))
-> Checker
     [(GenLocated SrcSpanAnnA (Pat GhcRn), Scaled ExpSigmaTypeFRR)]
     [GenLocated SrcSpanAnnA (Pat GhcTc)]
forall inp out. Checker inp out -> Checker [inp] [out]
tcMultiple (\ PatEnv
penv' (GenLocated SrcSpanAnnA (Pat GhcRn)
p,Scaled ExpSigmaTypeFRR
t) -> Scaled ExpSigmaTypeFRR -> Checker (LPat GhcRn) (LPat GhcTc)
tc_lpat Scaled ExpSigmaTypeFRR
t PatEnv
penv' LPat GhcRn
GenLocated SrcSpanAnnA (Pat GhcRn)
p)
               PatEnv
penv
               (String
-> [GenLocated SrcSpanAnnA (Pat GhcRn)]
-> [Scaled ExpSigmaTypeFRR]
-> [(GenLocated SrcSpanAnnA (Pat GhcRn), Scaled ExpSigmaTypeFRR)]
forall a b. HasDebugCallStack => String -> [a] -> [b] -> [(a, b)]
zipEqual String
"tc_lpats" [LPat GhcRn]
[GenLocated SrcSpanAnnA (Pat GhcRn)]
pats [Scaled ExpSigmaTypeFRR]
tys)

--------------------
-- See Note [Wrapper returned from tcSubMult] in GHC.Tc.Utils.Unify.
checkManyPattern :: Scaled a -> TcM HsWrapper
checkManyPattern :: forall a. Scaled a -> TcM HsWrapper
checkManyPattern Scaled a
pat_ty = CtOrigin -> Type -> Type -> TcM HsWrapper
tcSubMult CtOrigin
NonLinearPatternOrigin Type
ManyTy (Scaled a -> Type
forall a. Scaled a -> Type
scaledMult Scaled a
pat_ty)

tc_pat  :: Scaled ExpSigmaTypeFRR
        -- ^ Fully refined result type
        -> Checker (Pat GhcRn) (Pat GhcTc)
        -- ^ Translated pattern

tc_pat :: Scaled ExpSigmaTypeFRR -> Checker (Pat GhcRn) (Pat GhcTc)
tc_pat Scaled ExpSigmaTypeFRR
pat_ty PatEnv
penv Pat GhcRn
ps_pat TcM r
thing_inside = case Pat GhcRn
ps_pat of

  VarPat XVarPat GhcRn
x (L SrcSpanAnnN
l Name
name) -> do
        { (HsWrapper
wrap, TyCoVar
id) <- PatEnv
-> Name -> Scaled ExpSigmaTypeFRR -> TcM (HsWrapper, TyCoVar)
tcPatBndr PatEnv
penv Name
name Scaled ExpSigmaTypeFRR
pat_ty
        ; (r
res, HsWrapper
mult_wrap) <- Name -> Type -> TcM r -> TcM (r, HsWrapper)
forall a. Name -> Type -> TcM a -> TcM (a, HsWrapper)
tcCheckUsage Name
name (Scaled ExpSigmaTypeFRR -> Type
forall a. Scaled a -> Type
scaledMult Scaled ExpSigmaTypeFRR
pat_ty) (TcM r -> TcM (r, HsWrapper)) -> TcM r -> TcM (r, HsWrapper)
forall a b. (a -> b) -> a -> b
$
                              Name -> TyCoVar -> TcM r -> TcM r
forall a. Name -> TyCoVar -> TcM a -> TcM a
tcExtendIdEnv1 Name
name TyCoVar
id TcM r
thing_inside
            -- See Note [Wrapper returned from tcSubMult] in GHC.Tc.Utils.Unify.
        ; Type
pat_ty <- ExpSigmaTypeFRR -> TcM Type
forall (m :: * -> *). MonadIO m => ExpSigmaTypeFRR -> m Type
readExpType (Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR
forall a. Scaled a -> a
scaledThing Scaled ExpSigmaTypeFRR
pat_ty)
        ; (Pat GhcTc, r) -> TcM (Pat GhcTc, r)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (HsWrapper -> Pat GhcTc -> Type -> Pat GhcTc
mkHsWrapPat (HsWrapper
wrap HsWrapper -> HsWrapper -> HsWrapper
<.> HsWrapper
mult_wrap) (XVarPat GhcTc -> LIdP GhcTc -> Pat GhcTc
forall p. XVarPat p -> LIdP p -> Pat p
VarPat XVarPat GhcRn
XVarPat GhcTc
x (SrcSpanAnnN -> TyCoVar -> GenLocated SrcSpanAnnN TyCoVar
forall l e. l -> e -> GenLocated l e
L SrcSpanAnnN
l TyCoVar
id)) Type
pat_ty, r
res) }

  ParPat XParPat GhcRn
x LHsToken "(" GhcRn
lpar LPat GhcRn
pat LHsToken ")" GhcRn
rpar -> do
        { (GenLocated SrcSpanAnnA (Pat GhcTc)
pat', r
res) <- Scaled ExpSigmaTypeFRR -> Checker (LPat GhcRn) (LPat GhcTc)
tc_lpat Scaled ExpSigmaTypeFRR
pat_ty PatEnv
penv LPat GhcRn
pat TcM r
thing_inside
        ; (Pat GhcTc, r) -> TcM (Pat GhcTc, r)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (XParPat GhcTc
-> LHsToken "(" GhcTc
-> LPat GhcTc
-> LHsToken ")" GhcTc
-> Pat GhcTc
forall p.
XParPat p -> LHsToken "(" p -> LPat p -> LHsToken ")" p -> Pat p
ParPat XParPat GhcRn
XParPat GhcTc
x LHsToken "(" GhcRn
LHsToken "(" GhcTc
lpar LPat GhcTc
GenLocated SrcSpanAnnA (Pat GhcTc)
pat' LHsToken ")" GhcRn
LHsToken ")" GhcTc
rpar, r
res) }

  BangPat XBangPat GhcRn
x LPat GhcRn
pat -> do
        { (GenLocated SrcSpanAnnA (Pat GhcTc)
pat', r
res) <- Scaled ExpSigmaTypeFRR -> Checker (LPat GhcRn) (LPat GhcTc)
tc_lpat Scaled ExpSigmaTypeFRR
pat_ty PatEnv
penv LPat GhcRn
pat TcM r
thing_inside
        ; (Pat GhcTc, r) -> TcM (Pat GhcTc, r)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (XBangPat GhcTc -> LPat GhcTc -> Pat GhcTc
forall p. XBangPat p -> LPat p -> Pat p
BangPat XBangPat GhcRn
XBangPat GhcTc
x LPat GhcTc
GenLocated SrcSpanAnnA (Pat GhcTc)
pat', r
res) }

  LazyPat XLazyPat GhcRn
x LPat GhcRn
pat -> do
        { HsWrapper
mult_wrap <- Scaled ExpSigmaTypeFRR -> TcM HsWrapper
forall a. Scaled a -> TcM HsWrapper
checkManyPattern Scaled ExpSigmaTypeFRR
pat_ty
            -- See Note [Wrapper returned from tcSubMult] in GHC.Tc.Utils.Unify.
        ; (GenLocated SrcSpanAnnA (Pat GhcTc)
pat', (r
res, WantedConstraints
pat_ct))
                <- Scaled ExpSigmaTypeFRR -> Checker (LPat GhcRn) (LPat GhcTc)
tc_lpat Scaled ExpSigmaTypeFRR
pat_ty (PatEnv -> PatEnv
makeLazy PatEnv
penv) LPat GhcRn
pat (TcM (r, WantedConstraints)
 -> TcM (LPat GhcTc, (r, WantedConstraints)))
-> TcM (r, WantedConstraints)
-> TcM (LPat GhcTc, (r, WantedConstraints))
forall a b. (a -> b) -> a -> b
$
                   TcM r -> TcM (r, WantedConstraints)
forall a. TcM a -> TcM (a, WantedConstraints)
captureConstraints TcM r
thing_inside
                -- Ignore refined penv', revert to penv

        ; WantedConstraints -> TcRn ()
emitConstraints WantedConstraints
pat_ct
        -- captureConstraints/extendConstraints:
        --   see Note [Hopping the LIE in lazy patterns]

        -- Check that the expected pattern type is itself lifted
        ; Type
pat_ty <- ExpSigmaTypeFRR -> TcM Type
forall (m :: * -> *). MonadIO m => ExpSigmaTypeFRR -> m Type
readExpType (Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR
forall a. Scaled a -> a
scaledThing Scaled ExpSigmaTypeFRR
pat_ty)
        ; TcCoercionN
_ <- Maybe TypedThing -> Type -> Type -> TcM TcCoercionN
unifyType Maybe TypedThing
forall a. Maybe a
Nothing (HasDebugCallStack => Type -> Type
Type -> Type
typeKind Type
pat_ty) Type
liftedTypeKind

        ; (Pat GhcTc, r) -> TcM (Pat GhcTc, r)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (HsWrapper -> Pat GhcTc -> Type -> Pat GhcTc
mkHsWrapPat HsWrapper
mult_wrap (XLazyPat GhcTc -> LPat GhcTc -> Pat GhcTc
forall p. XLazyPat p -> LPat p -> Pat p
LazyPat XLazyPat GhcRn
XLazyPat GhcTc
x LPat GhcTc
GenLocated SrcSpanAnnA (Pat GhcTc)
pat') Type
pat_ty, r
res) }

  WildPat XWildPat GhcRn
_ -> do
        { HsWrapper
mult_wrap <- Scaled ExpSigmaTypeFRR -> TcM HsWrapper
forall a. Scaled a -> TcM HsWrapper
checkManyPattern Scaled ExpSigmaTypeFRR
pat_ty
            -- See Note [Wrapper returned from tcSubMult] in GHC.Tc.Utils.Unify.
        ; r
res <- TcM r
thing_inside
        ; Type
pat_ty <- ExpSigmaTypeFRR -> TcM Type
expTypeToType (Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR
forall a. Scaled a -> a
scaledThing Scaled ExpSigmaTypeFRR
pat_ty)
        ; (Pat GhcTc, r) -> TcM (Pat GhcTc, r)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (HsWrapper -> Pat GhcTc -> Type -> Pat GhcTc
mkHsWrapPat HsWrapper
mult_wrap (XWildPat GhcTc -> Pat GhcTc
forall p. XWildPat p -> Pat p
WildPat XWildPat GhcTc
Type
pat_ty) Type
pat_ty, r
res) }

  AsPat XAsPat GhcRn
x (L SrcSpanAnnN
nm_loc Name
name) LHsToken "@" GhcRn
at LPat GhcRn
pat -> do
        { HsWrapper
mult_wrap <- Scaled ExpSigmaTypeFRR -> TcM HsWrapper
forall a. Scaled a -> TcM HsWrapper
checkManyPattern Scaled ExpSigmaTypeFRR
pat_ty
            -- See Note [Wrapper returned from tcSubMult] in GHC.Tc.Utils.Unify.
        ; (HsWrapper
wrap, TyCoVar
bndr_id) <- SrcSpanAnnN -> TcM (HsWrapper, TyCoVar) -> TcM (HsWrapper, TyCoVar)
forall ann a. SrcSpanAnn' ann -> TcRn a -> TcRn a
setSrcSpanA SrcSpanAnnN
nm_loc (PatEnv
-> Name -> Scaled ExpSigmaTypeFRR -> TcM (HsWrapper, TyCoVar)
tcPatBndr PatEnv
penv Name
name Scaled ExpSigmaTypeFRR
pat_ty)
        ; (GenLocated SrcSpanAnnA (Pat GhcTc)
pat', r
res) <- Name
-> TyCoVar
-> IOEnv
     (Env TcGblEnv TcLclEnv) (GenLocated SrcSpanAnnA (Pat GhcTc), r)
-> IOEnv
     (Env TcGblEnv TcLclEnv) (GenLocated SrcSpanAnnA (Pat GhcTc), r)
forall a. Name -> TyCoVar -> TcM a -> TcM a
tcExtendIdEnv1 Name
name TyCoVar
bndr_id (IOEnv
   (Env TcGblEnv TcLclEnv) (GenLocated SrcSpanAnnA (Pat GhcTc), r)
 -> IOEnv
      (Env TcGblEnv TcLclEnv) (GenLocated SrcSpanAnnA (Pat GhcTc), r))
-> IOEnv
     (Env TcGblEnv TcLclEnv) (GenLocated SrcSpanAnnA (Pat GhcTc), r)
-> IOEnv
     (Env TcGblEnv TcLclEnv) (GenLocated SrcSpanAnnA (Pat GhcTc), r)
forall a b. (a -> b) -> a -> b
$
                         Scaled ExpSigmaTypeFRR -> Checker (LPat GhcRn) (LPat GhcTc)
tc_lpat (Scaled ExpSigmaTypeFRR
pat_ty Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR -> Scaled ExpSigmaTypeFRR
forall a b. Scaled a -> b -> Scaled b
`scaledSet`(Type -> ExpSigmaTypeFRR
mkCheckExpType (Type -> ExpSigmaTypeFRR) -> Type -> ExpSigmaTypeFRR
forall a b. (a -> b) -> a -> b
$ TyCoVar -> Type
idType TyCoVar
bndr_id))
                                 PatEnv
penv LPat GhcRn
pat TcM r
thing_inside
            -- NB: if we do inference on:
            --          \ (y@(x::forall a. a->a)) = e
            -- we'll fail.  The as-pattern infers a monotype for 'y', which then
            -- fails to unify with the polymorphic type for 'x'.  This could
            -- perhaps be fixed, but only with a bit more work.
            --
            -- If you fix it, don't forget the bindInstsOfPatIds!
        ; Type
pat_ty <- ExpSigmaTypeFRR -> TcM Type
forall (m :: * -> *). MonadIO m => ExpSigmaTypeFRR -> m Type
readExpType (Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR
forall a. Scaled a -> a
scaledThing Scaled ExpSigmaTypeFRR
pat_ty)
        ; (Pat GhcTc, r) -> TcM (Pat GhcTc, r)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (HsWrapper -> Pat GhcTc -> Type -> Pat GhcTc
mkHsWrapPat (HsWrapper
wrap HsWrapper -> HsWrapper -> HsWrapper
<.> HsWrapper
mult_wrap) (XAsPat GhcTc
-> LIdP GhcTc -> LHsToken "@" GhcTc -> LPat GhcTc -> Pat GhcTc
forall p. XAsPat p -> LIdP p -> LHsToken "@" p -> LPat p -> Pat p
AsPat XAsPat GhcRn
XAsPat GhcTc
x (SrcSpanAnnN -> TyCoVar -> GenLocated SrcSpanAnnN TyCoVar
forall l e. l -> e -> GenLocated l e
L SrcSpanAnnN
nm_loc TyCoVar
bndr_id) LHsToken "@" GhcRn
LHsToken "@" GhcTc
at LPat GhcTc
GenLocated SrcSpanAnnA (Pat GhcTc)
pat') Type
pat_ty, r
res) }

  ViewPat XViewPat GhcRn
_ LHsExpr GhcRn
expr LPat GhcRn
pat -> do
        { HsWrapper
mult_wrap <- Scaled ExpSigmaTypeFRR -> TcM HsWrapper
forall a. Scaled a -> TcM HsWrapper
checkManyPattern Scaled ExpSigmaTypeFRR
pat_ty
         -- See Note [Wrapper returned from tcSubMult] in GHC.Tc.Utils.Unify.
         --
         -- It should be possible to have view patterns at linear (or otherwise
         -- non-Many) multiplicity. But it is not clear at the moment what
         -- restriction need to be put in place, if any, for linear view
         -- patterns to desugar to type-correct Core.

        ; (GenLocated SrcSpanAnnA (HsExpr GhcTc)
expr',Type
expr_ty) <- LHsExpr GhcRn -> TcM (LHsExpr GhcTc, Type)
tcInferRho LHsExpr GhcRn
expr
               -- Note [View patterns and polymorphism]

         -- Expression must be a function
        ; let herald :: ExpectedFunTyOrigin
herald = HsExpr GhcRn -> ExpectedFunTyOrigin
ExpectedFunTyViewPat (HsExpr GhcRn -> ExpectedFunTyOrigin)
-> HsExpr GhcRn -> ExpectedFunTyOrigin
forall a b. (a -> b) -> a -> b
$ GenLocated SrcSpanAnnA (HsExpr GhcRn) -> HsExpr GhcRn
forall l e. GenLocated l e -> e
unLoc LHsExpr GhcRn
GenLocated SrcSpanAnnA (HsExpr GhcRn)
expr
        ; (HsWrapper
expr_wrap1, Scaled Type
_mult Type
inf_arg_ty, Type
inf_res_sigma)
            <- ExpectedFunTyOrigin
-> Maybe TypedThing
-> (Int, [Scaled Type])
-> Type
-> TcM (HsWrapper, Scaled Type, Type)
matchActualFunTySigma ExpectedFunTyOrigin
herald (TypedThing -> Maybe TypedThing
forall a. a -> Maybe a
Just (TypedThing -> Maybe TypedThing)
-> (HsExpr GhcRn -> TypedThing) -> HsExpr GhcRn -> Maybe TypedThing
forall b c a. (b -> c) -> (a -> b) -> a -> c
. HsExpr GhcRn -> TypedThing
HsExprRnThing (HsExpr GhcRn -> Maybe TypedThing)
-> HsExpr GhcRn -> Maybe TypedThing
forall a b. (a -> b) -> a -> b
$ GenLocated SrcSpanAnnA (HsExpr GhcRn) -> HsExpr GhcRn
forall l e. GenLocated l e -> e
unLoc LHsExpr GhcRn
GenLocated SrcSpanAnnA (HsExpr GhcRn)
expr) (Int
1,[]) Type
expr_ty
               -- See Note [View patterns and polymorphism]
               -- expr_wrap1 :: expr_ty "->" (inf_arg_ty -> inf_res_sigma)

         -- Check that overall pattern is more polymorphic than arg type
        ; HsWrapper
expr_wrap2 <- PatEnv -> ExpSigmaTypeFRR -> Type -> TcM HsWrapper
tc_sub_type PatEnv
penv (Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR
forall a. Scaled a -> a
scaledThing Scaled ExpSigmaTypeFRR
pat_ty) Type
inf_arg_ty
            -- expr_wrap2 :: pat_ty "->" inf_arg_ty

         -- Pattern must have inf_res_sigma
        ; (GenLocated SrcSpanAnnA (Pat GhcTc)
pat', r
res) <- Scaled ExpSigmaTypeFRR -> Checker (LPat GhcRn) (LPat GhcTc)
tc_lpat (Scaled ExpSigmaTypeFRR
pat_ty Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR -> Scaled ExpSigmaTypeFRR
forall a b. Scaled a -> b -> Scaled b
`scaledSet` Type -> ExpSigmaTypeFRR
mkCheckExpType Type
inf_res_sigma) PatEnv
penv LPat GhcRn
pat TcM r
thing_inside

        ; let Scaled Type
w ExpSigmaTypeFRR
h_pat_ty = Scaled ExpSigmaTypeFRR
pat_ty
        ; Type
pat_ty <- ExpSigmaTypeFRR -> TcM Type
forall (m :: * -> *). MonadIO m => ExpSigmaTypeFRR -> m Type
readExpType ExpSigmaTypeFRR
h_pat_ty
        ; let expr_wrap2' :: HsWrapper
expr_wrap2' = HsWrapper -> HsWrapper -> Scaled Type -> Type -> HsWrapper
mkWpFun HsWrapper
expr_wrap2 HsWrapper
idHsWrapper
                              (Type -> Type -> Scaled Type
forall a. Type -> a -> Scaled a
Scaled Type
w Type
pat_ty) Type
inf_res_sigma
          -- expr_wrap2' :: (inf_arg_ty -> inf_res_sigma) "->"
          --                (pat_ty -> inf_res_sigma)
          -- NB: pat_ty comes from matchActualFunTySigma, so it has a
          -- fixed RuntimeRep, as needed to call mkWpFun.
        ; let
              expr_wrap :: HsWrapper
expr_wrap = HsWrapper
expr_wrap2' HsWrapper -> HsWrapper -> HsWrapper
<.> HsWrapper
expr_wrap1 HsWrapper -> HsWrapper -> HsWrapper
<.> HsWrapper
mult_wrap

        ; (Pat GhcTc, r) -> TcM (Pat GhcTc, r)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ((Pat GhcTc, r) -> TcM (Pat GhcTc, r))
-> (Pat GhcTc, r) -> TcM (Pat GhcTc, r)
forall a b. (a -> b) -> a -> b
$ (XViewPat GhcTc -> LHsExpr GhcTc -> LPat GhcTc -> Pat GhcTc
forall p. XViewPat p -> LHsExpr p -> LPat p -> Pat p
ViewPat XViewPat GhcTc
Type
pat_ty (HsWrapper -> LHsExpr GhcTc -> LHsExpr GhcTc
mkLHsWrap HsWrapper
expr_wrap LHsExpr GhcTc
GenLocated SrcSpanAnnA (HsExpr GhcTc)
expr') LPat GhcTc
GenLocated SrcSpanAnnA (Pat GhcTc)
pat', r
res) }

{- Note [View patterns and polymorphism]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider this exotic example:
   pair :: forall a. Bool -> a -> forall b. b -> (a,b)

   f :: Int -> blah
   f (pair True -> x) = ...here (x :: forall b. b -> (Int,b))

The expression (pair True) should have type
    pair True :: Int -> forall b. b -> (Int,b)
so that it is ready to consume the incoming Int. It should be an
arrow type (t1 -> t2); hence using (tcInferRho expr).

Then, when taking that arrow apart we want to get a *sigma* type
(forall b. b->(Int,b)), because that's what we want to bind 'x' to.
Fortunately that's what matchActualFunTySigma returns anyway.
-}

-- Type signatures in patterns
-- See Note [Pattern coercions] below
  SigPat XSigPat GhcRn
_ LPat GhcRn
pat HsPatSigType (NoGhcTc GhcRn)
sig_ty -> do
        { (Type
inner_ty, [(Name, TyCoVar)]
tv_binds, [(Name, TyCoVar)]
wcs, HsWrapper
wrap) <- Bool
-> HsPatSigType GhcRn
-> ExpSigmaTypeFRR
-> TcM (Type, [(Name, TyCoVar)], [(Name, TyCoVar)], HsWrapper)
tcPatSig (PatEnv -> Bool
inPatBind PatEnv
penv)
                                                            HsPatSigType (NoGhcTc GhcRn)
HsPatSigType GhcRn
sig_ty (Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR
forall a. Scaled a -> a
scaledThing Scaled ExpSigmaTypeFRR
pat_ty)
                -- Using tcExtendNameTyVarEnv is appropriate here
                -- because we're not really bringing fresh tyvars into scope.
                -- We're *naming* existing tyvars. Note that it is OK for a tyvar
                -- from an outer scope to mention one of these tyvars in its kind.
        ; (GenLocated SrcSpanAnnA (Pat GhcTc)
pat', r
res) <- [(Name, TyCoVar)]
-> IOEnv
     (Env TcGblEnv TcLclEnv) (GenLocated SrcSpanAnnA (Pat GhcTc), r)
-> IOEnv
     (Env TcGblEnv TcLclEnv) (GenLocated SrcSpanAnnA (Pat GhcTc), r)
forall r. [(Name, TyCoVar)] -> TcM r -> TcM r
tcExtendNameTyVarEnv [(Name, TyCoVar)]
wcs      (IOEnv
   (Env TcGblEnv TcLclEnv) (GenLocated SrcSpanAnnA (Pat GhcTc), r)
 -> IOEnv
      (Env TcGblEnv TcLclEnv) (GenLocated SrcSpanAnnA (Pat GhcTc), r))
-> IOEnv
     (Env TcGblEnv TcLclEnv) (GenLocated SrcSpanAnnA (Pat GhcTc), r)
-> IOEnv
     (Env TcGblEnv TcLclEnv) (GenLocated SrcSpanAnnA (Pat GhcTc), r)
forall a b. (a -> b) -> a -> b
$
                         [(Name, TyCoVar)]
-> IOEnv
     (Env TcGblEnv TcLclEnv) (GenLocated SrcSpanAnnA (Pat GhcTc), r)
-> IOEnv
     (Env TcGblEnv TcLclEnv) (GenLocated SrcSpanAnnA (Pat GhcTc), r)
forall r. [(Name, TyCoVar)] -> TcM r -> TcM r
tcExtendNameTyVarEnv [(Name, TyCoVar)]
tv_binds (IOEnv
   (Env TcGblEnv TcLclEnv) (GenLocated SrcSpanAnnA (Pat GhcTc), r)
 -> IOEnv
      (Env TcGblEnv TcLclEnv) (GenLocated SrcSpanAnnA (Pat GhcTc), r))
-> IOEnv
     (Env TcGblEnv TcLclEnv) (GenLocated SrcSpanAnnA (Pat GhcTc), r)
-> IOEnv
     (Env TcGblEnv TcLclEnv) (GenLocated SrcSpanAnnA (Pat GhcTc), r)
forall a b. (a -> b) -> a -> b
$
                         Scaled ExpSigmaTypeFRR -> Checker (LPat GhcRn) (LPat GhcTc)
tc_lpat (Scaled ExpSigmaTypeFRR
pat_ty Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR -> Scaled ExpSigmaTypeFRR
forall a b. Scaled a -> b -> Scaled b
`scaledSet` Type -> ExpSigmaTypeFRR
mkCheckExpType Type
inner_ty) PatEnv
penv LPat GhcRn
pat TcM r
thing_inside
        ; Type
pat_ty <- ExpSigmaTypeFRR -> TcM Type
forall (m :: * -> *). MonadIO m => ExpSigmaTypeFRR -> m Type
readExpType (Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR
forall a. Scaled a -> a
scaledThing Scaled ExpSigmaTypeFRR
pat_ty)
        ; (Pat GhcTc, r) -> TcM (Pat GhcTc, r)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (HsWrapper -> Pat GhcTc -> Type -> Pat GhcTc
mkHsWrapPat HsWrapper
wrap (XSigPat GhcTc
-> LPat GhcTc -> HsPatSigType (NoGhcTc GhcTc) -> Pat GhcTc
forall p. XSigPat p -> LPat p -> HsPatSigType (NoGhcTc p) -> Pat p
SigPat XSigPat GhcTc
Type
inner_ty LPat GhcTc
GenLocated SrcSpanAnnA (Pat GhcTc)
pat' HsPatSigType (NoGhcTc GhcRn)
HsPatSigType (NoGhcTc GhcTc)
sig_ty) Type
pat_ty, r
res) }

------------------------
-- Lists, tuples, arrays

  -- Necessarily a built-in list pattern, not an overloaded list pattern.
  -- See Note [Desugaring overloaded list patterns].
  ListPat XListPat GhcRn
_ [LPat GhcRn]
pats -> do
        { (HsWrapper
coi, Type
elt_ty) <- (Type -> IOEnv (Env TcGblEnv TcLclEnv) (TcCoercionN, Type))
-> PatEnv -> ExpSigmaTypeFRR -> TcM (HsWrapper, Type)
forall a.
(Type -> TcM (TcCoercionN, a))
-> PatEnv -> ExpSigmaTypeFRR -> TcM (HsWrapper, a)
matchExpectedPatTy Type -> IOEnv (Env TcGblEnv TcLclEnv) (TcCoercionN, Type)
matchExpectedListTy PatEnv
penv (Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR
forall a. Scaled a -> a
scaledThing Scaled ExpSigmaTypeFRR
pat_ty)
        ; ([GenLocated SrcSpanAnnA (Pat GhcTc)]
pats', r
res) <- Checker
  (GenLocated SrcSpanAnnA (Pat GhcRn))
  (GenLocated SrcSpanAnnA (Pat GhcTc))
-> Checker
     [GenLocated SrcSpanAnnA (Pat GhcRn)]
     [GenLocated SrcSpanAnnA (Pat GhcTc)]
forall inp out. Checker inp out -> Checker [inp] [out]
tcMultiple (Scaled ExpSigmaTypeFRR -> Checker (LPat GhcRn) (LPat GhcTc)
tc_lpat (Scaled ExpSigmaTypeFRR
pat_ty Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR -> Scaled ExpSigmaTypeFRR
forall a b. Scaled a -> b -> Scaled b
`scaledSet` Type -> ExpSigmaTypeFRR
mkCheckExpType Type
elt_ty))
                                     PatEnv
penv [LPat GhcRn]
[GenLocated SrcSpanAnnA (Pat GhcRn)]
pats TcM r
thing_inside
        ; Type
pat_ty <- ExpSigmaTypeFRR -> TcM Type
forall (m :: * -> *). MonadIO m => ExpSigmaTypeFRR -> m Type
readExpType (Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR
forall a. Scaled a -> a
scaledThing Scaled ExpSigmaTypeFRR
pat_ty)
        ; (Pat GhcTc, r) -> TcM (Pat GhcTc, r)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (HsWrapper -> Pat GhcTc -> Type -> Pat GhcTc
mkHsWrapPat HsWrapper
coi
                         (XListPat GhcTc -> [LPat GhcTc] -> Pat GhcTc
forall p. XListPat p -> [LPat p] -> Pat p
ListPat XListPat GhcTc
Type
elt_ty [LPat GhcTc]
[GenLocated SrcSpanAnnA (Pat GhcTc)]
pats') Type
pat_ty, r
res)
}

  TuplePat XTuplePat GhcRn
_ [LPat GhcRn]
pats Boxity
boxity -> do
        { let arity :: Int
arity = [GenLocated SrcSpanAnnA (Pat GhcRn)] -> Int
forall a. [a] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length [LPat GhcRn]
[GenLocated SrcSpanAnnA (Pat GhcRn)]
pats
              tc :: TyCon
tc = Boxity -> Int -> TyCon
tupleTyCon Boxity
boxity Int
arity
              -- NB: tupleTyCon does not flatten 1-tuples
              -- See Note [Don't flatten tuples from HsSyn] in GHC.Core.Make
        ; Int -> TcRn ()
checkTupSize Int
arity
        ; (HsWrapper
coi, [Type]
arg_tys) <- (Type -> TcM (TcCoercionN, [Type]))
-> PatEnv -> ExpSigmaTypeFRR -> TcM (HsWrapper, [Type])
forall a.
(Type -> TcM (TcCoercionN, a))
-> PatEnv -> ExpSigmaTypeFRR -> TcM (HsWrapper, a)
matchExpectedPatTy (TyCon -> Type -> TcM (TcCoercionN, [Type])
matchExpectedTyConApp TyCon
tc)
                                               PatEnv
penv (Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR
forall a. Scaled a -> a
scaledThing Scaled ExpSigmaTypeFRR
pat_ty)
                     -- Unboxed tuples have RuntimeRep vars, which we discard:
                     -- See Note [Unboxed tuple RuntimeRep vars] in GHC.Core.TyCon
        ; let con_arg_tys :: [Type]
con_arg_tys = case Boxity
boxity of Boxity
Unboxed -> Int -> [Type] -> [Type]
forall a. Int -> [a] -> [a]
drop Int
arity [Type]
arg_tys
                                           Boxity
Boxed   -> [Type]
arg_tys
        ; ([GenLocated SrcSpanAnnA (Pat GhcTc)]
pats', r
res) <- [Scaled ExpSigmaTypeFRR] -> Checker [LPat GhcRn] [LPat GhcTc]
tc_lpats ((Type -> Scaled ExpSigmaTypeFRR)
-> [Type] -> [Scaled ExpSigmaTypeFRR]
forall a b. (a -> b) -> [a] -> [b]
map (Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR -> Scaled ExpSigmaTypeFRR
forall a b. Scaled a -> b -> Scaled b
scaledSet Scaled ExpSigmaTypeFRR
pat_ty (ExpSigmaTypeFRR -> Scaled ExpSigmaTypeFRR)
-> (Type -> ExpSigmaTypeFRR) -> Type -> Scaled ExpSigmaTypeFRR
forall b c a. (b -> c) -> (a -> b) -> a -> c
. Type -> ExpSigmaTypeFRR
mkCheckExpType) [Type]
con_arg_tys)
                                   PatEnv
penv [LPat GhcRn]
pats TcM r
thing_inside

        ; DynFlags
dflags <- IOEnv (Env TcGblEnv TcLclEnv) DynFlags
forall (m :: * -> *). HasDynFlags m => m DynFlags
getDynFlags

        -- Under flag control turn a pattern (x,y,z) into ~(x,y,z)
        -- so that we can experiment with lazy tuple-matching.
        -- This is a pretty odd place to make the switch, but
        -- it was easy to do.
        ; let
              unmangled_result :: Pat GhcTc
unmangled_result = XTuplePat GhcTc -> [LPat GhcTc] -> Boxity -> Pat GhcTc
forall p. XTuplePat p -> [LPat p] -> Boxity -> Pat p
TuplePat [Type]
XTuplePat GhcTc
con_arg_tys [LPat GhcTc]
[GenLocated SrcSpanAnnA (Pat GhcTc)]
pats' Boxity
boxity
                                 -- pat_ty /= pat_ty iff coi /= IdCo
              possibly_mangled_result :: Pat GhcTc
possibly_mangled_result
                | GeneralFlag -> DynFlags -> Bool
gopt GeneralFlag
Opt_IrrefutableTuples DynFlags
dflags Bool -> Bool -> Bool
&&
                  Boxity -> Bool
isBoxed Boxity
boxity   = XLazyPat GhcTc -> LPat GhcTc -> Pat GhcTc
forall p. XLazyPat p -> LPat p -> Pat p
LazyPat XLazyPat GhcTc
NoExtField
noExtField (Pat GhcTc -> GenLocated SrcSpanAnnA (Pat GhcTc)
forall a an. a -> LocatedAn an a
noLocA Pat GhcTc
unmangled_result)
                | Bool
otherwise        = Pat GhcTc
unmangled_result

        ; Type
pat_ty <- ExpSigmaTypeFRR -> TcM Type
forall (m :: * -> *). MonadIO m => ExpSigmaTypeFRR -> m Type
readExpType (Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR
forall a. Scaled a -> a
scaledThing Scaled ExpSigmaTypeFRR
pat_ty)
        ; Bool -> TcRn ()
forall (m :: * -> *). (HasCallStack, Applicative m) => Bool -> m ()
massert ([Type]
con_arg_tys [Type] -> [GenLocated SrcSpanAnnA (Pat GhcRn)] -> Bool
forall a b. [a] -> [b] -> Bool
`equalLength` [LPat GhcRn]
[GenLocated SrcSpanAnnA (Pat GhcRn)]
pats) -- Syntactically enforced
        ; (Pat GhcTc, r) -> TcM (Pat GhcTc, r)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (HsWrapper -> Pat GhcTc -> Type -> Pat GhcTc
mkHsWrapPat HsWrapper
coi Pat GhcTc
possibly_mangled_result Type
pat_ty, r
res)
        }

  SumPat XSumPat GhcRn
_ LPat GhcRn
pat Int
alt Int
arity  -> do
        { let tc :: TyCon
tc = Int -> TyCon
sumTyCon Int
arity
        ; (HsWrapper
coi, [Type]
arg_tys) <- (Type -> TcM (TcCoercionN, [Type]))
-> PatEnv -> ExpSigmaTypeFRR -> TcM (HsWrapper, [Type])
forall a.
(Type -> TcM (TcCoercionN, a))
-> PatEnv -> ExpSigmaTypeFRR -> TcM (HsWrapper, a)
matchExpectedPatTy (TyCon -> Type -> TcM (TcCoercionN, [Type])
matchExpectedTyConApp TyCon
tc)
                                               PatEnv
penv (Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR
forall a. Scaled a -> a
scaledThing Scaled ExpSigmaTypeFRR
pat_ty)
        ; -- Drop levity vars, we don't care about them here
          let con_arg_tys :: [Type]
con_arg_tys = Int -> [Type] -> [Type]
forall a. Int -> [a] -> [a]
drop Int
arity [Type]
arg_tys
        ; (GenLocated SrcSpanAnnA (Pat GhcTc)
pat', r
res) <- Scaled ExpSigmaTypeFRR -> Checker (LPat GhcRn) (LPat GhcTc)
tc_lpat (Scaled ExpSigmaTypeFRR
pat_ty Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR -> Scaled ExpSigmaTypeFRR
forall a b. Scaled a -> b -> Scaled b
`scaledSet` Type -> ExpSigmaTypeFRR
mkCheckExpType ([Type]
con_arg_tys [Type] -> Int -> Type
forall a. Outputable a => [a] -> Int -> a
`getNth` (Int
alt Int -> Int -> Int
forall a. Num a => a -> a -> a
- Int
1)))
                                 PatEnv
penv LPat GhcRn
pat TcM r
thing_inside
        ; Type
pat_ty <- ExpSigmaTypeFRR -> TcM Type
forall (m :: * -> *). MonadIO m => ExpSigmaTypeFRR -> m Type
readExpType (Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR
forall a. Scaled a -> a
scaledThing Scaled ExpSigmaTypeFRR
pat_ty)
        ; (Pat GhcTc, r) -> TcM (Pat GhcTc, r)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (HsWrapper -> Pat GhcTc -> Type -> Pat GhcTc
mkHsWrapPat HsWrapper
coi (XSumPat GhcTc -> LPat GhcTc -> Int -> Int -> Pat GhcTc
forall p. XSumPat p -> LPat p -> Int -> Int -> Pat p
SumPat [Type]
XSumPat GhcTc
con_arg_tys LPat GhcTc
GenLocated SrcSpanAnnA (Pat GhcTc)
pat' Int
alt Int
arity) Type
pat_ty
                 , r
res)
        }

------------------------
-- Data constructors
  ConPat XConPat GhcRn
_ XRec GhcRn (ConLikeP GhcRn)
con HsConPatDetails GhcRn
arg_pats ->
    PatEnv
-> GenLocated SrcSpanAnnN Name
-> Scaled ExpSigmaTypeFRR
-> HsConPatDetails GhcRn
-> TcM r
-> TcM (Pat GhcTc, r)
forall a.
PatEnv
-> GenLocated SrcSpanAnnN Name
-> Scaled ExpSigmaTypeFRR
-> HsConPatDetails GhcRn
-> TcM a
-> TcM (Pat GhcTc, a)
tcConPat PatEnv
penv XRec GhcRn (ConLikeP GhcRn)
GenLocated SrcSpanAnnN Name
con Scaled ExpSigmaTypeFRR
pat_ty HsConPatDetails GhcRn
arg_pats TcM r
thing_inside

------------------------
-- Literal patterns
  LitPat XLitPat GhcRn
x HsLit GhcRn
simple_lit -> do
        { let lit_ty :: Type
lit_ty = HsLit GhcRn -> Type
forall (p :: Pass). HsLit (GhcPass p) -> Type
hsLitType HsLit GhcRn
simple_lit
        ; HsWrapper
wrap   <- PatEnv -> ExpSigmaTypeFRR -> Type -> TcM HsWrapper
tc_sub_type PatEnv
penv (Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR
forall a. Scaled a -> a
scaledThing Scaled ExpSigmaTypeFRR
pat_ty) Type
lit_ty
        ; r
res    <- TcM r
thing_inside
        ; Type
pat_ty <- ExpSigmaTypeFRR -> TcM Type
forall (m :: * -> *). MonadIO m => ExpSigmaTypeFRR -> m Type
readExpType (Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR
forall a. Scaled a -> a
scaledThing Scaled ExpSigmaTypeFRR
pat_ty)
        ; (Pat GhcTc, r) -> TcM (Pat GhcTc, r)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ( HsWrapper -> Pat GhcTc -> Type -> Pat GhcTc
mkHsWrapPat HsWrapper
wrap (XLitPat GhcTc -> HsLit GhcTc -> Pat GhcTc
forall p. XLitPat p -> HsLit p -> Pat p
LitPat XLitPat GhcRn
XLitPat GhcTc
x (HsLit GhcRn -> HsLit GhcTc
forall (p1 :: Pass) (p2 :: Pass).
HsLit (GhcPass p1) -> HsLit (GhcPass p2)
convertLit HsLit GhcRn
simple_lit)) Type
pat_ty
                 , r
res) }

------------------------
-- Overloaded patterns: n, and n+k

-- In the case of a negative literal (the more complicated case),
-- we get
--
--   case v of (-5) -> blah
--
-- becoming
--
--   if v == (negate (fromInteger 5)) then blah else ...
--
-- There are two bits of rebindable syntax:
--   (==)   :: pat_ty -> neg_lit_ty -> Bool
--   negate :: lit_ty -> neg_lit_ty
-- where lit_ty is the type of the overloaded literal 5.
--
-- When there is no negation, neg_lit_ty and lit_ty are the same
  NPat XNPat GhcRn
_ (L SrcAnn NoEpAnns
l HsOverLit GhcRn
over_lit) Maybe (SyntaxExpr GhcRn)
mb_neg SyntaxExpr GhcRn
eq -> do
        { HsWrapper
mult_wrap <- Scaled ExpSigmaTypeFRR -> TcM HsWrapper
forall a. Scaled a -> TcM HsWrapper
checkManyPattern Scaled ExpSigmaTypeFRR
pat_ty
          -- See Note [Wrapper returned from tcSubMult] in GHC.Tc.Utils.Unify.
          --
          -- It may be possible to refine linear pattern so that they work in
          -- linear environments. But it is not clear how useful this is.
        ; let orig :: CtOrigin
orig = HsOverLit GhcRn -> CtOrigin
LiteralOrigin HsOverLit GhcRn
over_lit
        ; ((HsOverLit GhcTc
lit', Maybe SyntaxExprTc
mb_neg'), SyntaxExprTc
eq')
            <- CtOrigin
-> SyntaxExprRn
-> [SyntaxOpType]
-> ExpSigmaTypeFRR
-> ([Type] -> [Type] -> TcM (HsOverLit GhcTc, Maybe SyntaxExprTc))
-> TcM ((HsOverLit GhcTc, Maybe SyntaxExprTc), SyntaxExprTc)
forall a.
CtOrigin
-> SyntaxExprRn
-> [SyntaxOpType]
-> ExpSigmaTypeFRR
-> ([Type] -> [Type] -> TcM a)
-> TcM (a, SyntaxExprTc)
tcSyntaxOp CtOrigin
orig SyntaxExpr GhcRn
SyntaxExprRn
eq [ExpSigmaTypeFRR -> SyntaxOpType
SynType (Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR
forall a. Scaled a -> a
scaledThing Scaled ExpSigmaTypeFRR
pat_ty), SyntaxOpType
SynAny]
                          (Type -> ExpSigmaTypeFRR
mkCheckExpType Type
boolTy) (([Type] -> [Type] -> TcM (HsOverLit GhcTc, Maybe SyntaxExprTc))
 -> TcM ((HsOverLit GhcTc, Maybe SyntaxExprTc), SyntaxExprTc))
-> ([Type] -> [Type] -> TcM (HsOverLit GhcTc, Maybe SyntaxExprTc))
-> TcM ((HsOverLit GhcTc, Maybe SyntaxExprTc), SyntaxExprTc)
forall a b. (a -> b) -> a -> b
$
               \ [Type
neg_lit_ty] [Type]
_ ->
               let new_over_lit :: Type -> TcM (HsOverLit GhcTc)
new_over_lit Type
lit_ty = HsOverLit GhcRn -> ExpSigmaTypeFRR -> TcM (HsOverLit GhcTc)
newOverloadedLit HsOverLit GhcRn
over_lit
                                           (Type -> ExpSigmaTypeFRR
mkCheckExpType Type
lit_ty)
               in case Maybe (SyntaxExpr GhcRn)
mb_neg of
                 Maybe (SyntaxExpr GhcRn)
Nothing  -> (, Maybe SyntaxExprTc
forall a. Maybe a
Nothing) (HsOverLit GhcTc -> (HsOverLit GhcTc, Maybe SyntaxExprTc))
-> TcM (HsOverLit GhcTc)
-> TcM (HsOverLit GhcTc, Maybe SyntaxExprTc)
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> Type -> TcM (HsOverLit GhcTc)
new_over_lit Type
neg_lit_ty
                 Just SyntaxExpr GhcRn
neg -> -- Negative literal
                             -- The 'negate' is re-mappable syntax
                   (SyntaxExprTc -> Maybe SyntaxExprTc)
-> (HsOverLit GhcTc, SyntaxExprTc)
-> (HsOverLit GhcTc, Maybe SyntaxExprTc)
forall b c d. (b -> c) -> (d, b) -> (d, c)
forall (a :: * -> * -> *) b c d.
Arrow a =>
a b c -> a (d, b) (d, c)
second SyntaxExprTc -> Maybe SyntaxExprTc
forall a. a -> Maybe a
Just ((HsOverLit GhcTc, SyntaxExprTc)
 -> (HsOverLit GhcTc, Maybe SyntaxExprTc))
-> IOEnv (Env TcGblEnv TcLclEnv) (HsOverLit GhcTc, SyntaxExprTc)
-> TcM (HsOverLit GhcTc, Maybe SyntaxExprTc)
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$>
                   (CtOrigin
-> SyntaxExprRn
-> [SyntaxOpType]
-> ExpSigmaTypeFRR
-> ([Type] -> [Type] -> TcM (HsOverLit GhcTc))
-> IOEnv (Env TcGblEnv TcLclEnv) (HsOverLit GhcTc, SyntaxExprTc)
forall a.
CtOrigin
-> SyntaxExprRn
-> [SyntaxOpType]
-> ExpSigmaTypeFRR
-> ([Type] -> [Type] -> TcM a)
-> TcM (a, SyntaxExprTc)
tcSyntaxOp CtOrigin
orig SyntaxExpr GhcRn
SyntaxExprRn
neg [SyntaxOpType
SynRho] (Type -> ExpSigmaTypeFRR
mkCheckExpType Type
neg_lit_ty) (([Type] -> [Type] -> TcM (HsOverLit GhcTc))
 -> IOEnv (Env TcGblEnv TcLclEnv) (HsOverLit GhcTc, SyntaxExprTc))
-> ([Type] -> [Type] -> TcM (HsOverLit GhcTc))
-> IOEnv (Env TcGblEnv TcLclEnv) (HsOverLit GhcTc, SyntaxExprTc)
forall a b. (a -> b) -> a -> b
$
                    \ [Type
lit_ty] [Type]
_ -> Type -> TcM (HsOverLit GhcTc)
new_over_lit Type
lit_ty)
                     -- applied to a closed literal: linearity doesn't matter as
                     -- literals are typed in an empty environment, hence have
                     -- all multiplicities.

        ; r
res <- TcM r
thing_inside
        ; Type
pat_ty <- ExpSigmaTypeFRR -> TcM Type
forall (m :: * -> *). MonadIO m => ExpSigmaTypeFRR -> m Type
readExpType (Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR
forall a. Scaled a -> a
scaledThing Scaled ExpSigmaTypeFRR
pat_ty)
        ; (Pat GhcTc, r) -> TcM (Pat GhcTc, r)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (HsWrapper -> Pat GhcTc -> Type -> Pat GhcTc
mkHsWrapPat HsWrapper
mult_wrap (XNPat GhcTc
-> XRec GhcTc (HsOverLit GhcTc)
-> Maybe (SyntaxExpr GhcTc)
-> SyntaxExpr GhcTc
-> Pat GhcTc
forall p.
XNPat p
-> XRec p (HsOverLit p)
-> Maybe (SyntaxExpr p)
-> SyntaxExpr p
-> Pat p
NPat XNPat GhcTc
Type
pat_ty (SrcAnn NoEpAnns
-> HsOverLit GhcTc
-> GenLocated (SrcAnn NoEpAnns) (HsOverLit GhcTc)
forall l e. l -> e -> GenLocated l e
L SrcAnn NoEpAnns
l HsOverLit GhcTc
lit') Maybe (SyntaxExpr GhcTc)
Maybe SyntaxExprTc
mb_neg' SyntaxExpr GhcTc
SyntaxExprTc
eq') Type
pat_ty, r
res) }

{-
Note [NPlusK patterns]
~~~~~~~~~~~~~~~~~~~~~~
From

  case v of x + 5 -> blah

we get

  if v >= 5 then (\x -> blah) (v - 5) else ...

There are two bits of rebindable syntax:
  (>=) :: pat_ty -> lit1_ty -> Bool
  (-)  :: pat_ty -> lit2_ty -> var_ty

lit1_ty and lit2_ty could conceivably be different.
var_ty is the type inferred for x, the variable in the pattern.

Note that we need to type-check the literal twice, because it is used
twice, and may be used at different types. The second HsOverLit stored in the
AST is used for the subtraction operation.
-}

-- See Note [NPlusK patterns]
  NPlusKPat XNPlusKPat GhcRn
_ (L SrcSpanAnnN
nm_loc Name
name)
               (L SrcAnn NoEpAnns
loc HsOverLit GhcRn
lit) HsOverLit GhcRn
_ SyntaxExpr GhcRn
ge SyntaxExpr GhcRn
minus -> do
        { HsWrapper
mult_wrap <- Scaled ExpSigmaTypeFRR -> TcM HsWrapper
forall a. Scaled a -> TcM HsWrapper
checkManyPattern Scaled ExpSigmaTypeFRR
pat_ty
            -- See Note [Wrapper returned from tcSubMult] in GHC.Tc.Utils.Unify.
        ; let pat_exp_ty :: ExpSigmaTypeFRR
pat_exp_ty = Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR
forall a. Scaled a -> a
scaledThing Scaled ExpSigmaTypeFRR
pat_ty
              orig :: CtOrigin
orig = HsOverLit GhcRn -> CtOrigin
LiteralOrigin HsOverLit GhcRn
lit
        ; (HsOverLit GhcTc
lit1', SyntaxExprTc
ge')
            <- CtOrigin
-> SyntaxExprRn
-> [SyntaxOpType]
-> ExpSigmaTypeFRR
-> ([Type] -> [Type] -> TcM (HsOverLit GhcTc))
-> IOEnv (Env TcGblEnv TcLclEnv) (HsOverLit GhcTc, SyntaxExprTc)
forall a.
CtOrigin
-> SyntaxExprRn
-> [SyntaxOpType]
-> ExpSigmaTypeFRR
-> ([Type] -> [Type] -> TcM a)
-> TcM (a, SyntaxExprTc)
tcSyntaxOp CtOrigin
orig SyntaxExpr GhcRn
SyntaxExprRn
ge [ExpSigmaTypeFRR -> SyntaxOpType
SynType ExpSigmaTypeFRR
pat_exp_ty, SyntaxOpType
SynRho]
                                  (Type -> ExpSigmaTypeFRR
mkCheckExpType Type
boolTy) (([Type] -> [Type] -> TcM (HsOverLit GhcTc))
 -> IOEnv (Env TcGblEnv TcLclEnv) (HsOverLit GhcTc, SyntaxExprTc))
-> ([Type] -> [Type] -> TcM (HsOverLit GhcTc))
-> IOEnv (Env TcGblEnv TcLclEnv) (HsOverLit GhcTc, SyntaxExprTc)
forall a b. (a -> b) -> a -> b
$
               \ [Type
lit1_ty] [Type]
_ ->
               HsOverLit GhcRn -> ExpSigmaTypeFRR -> TcM (HsOverLit GhcTc)
newOverloadedLit HsOverLit GhcRn
lit (Type -> ExpSigmaTypeFRR
mkCheckExpType Type
lit1_ty)
        ; ((HsOverLit GhcTc
lit2', HsWrapper
minus_wrap, TyCoVar
bndr_id), SyntaxExprTc
minus')
            <- CtOrigin
-> SyntaxExprRn
-> [SyntaxOpType]
-> SyntaxOpType
-> ([Type] -> [Type] -> TcM (HsOverLit GhcTc, HsWrapper, TyCoVar))
-> TcM ((HsOverLit GhcTc, HsWrapper, TyCoVar), SyntaxExprTc)
forall a.
CtOrigin
-> SyntaxExprRn
-> [SyntaxOpType]
-> SyntaxOpType
-> ([Type] -> [Type] -> TcM a)
-> TcM (a, SyntaxExprTc)
tcSyntaxOpGen CtOrigin
orig SyntaxExpr GhcRn
SyntaxExprRn
minus [ExpSigmaTypeFRR -> SyntaxOpType
SynType ExpSigmaTypeFRR
pat_exp_ty, SyntaxOpType
SynRho] SyntaxOpType
SynAny (([Type] -> [Type] -> TcM (HsOverLit GhcTc, HsWrapper, TyCoVar))
 -> TcM ((HsOverLit GhcTc, HsWrapper, TyCoVar), SyntaxExprTc))
-> ([Type] -> [Type] -> TcM (HsOverLit GhcTc, HsWrapper, TyCoVar))
-> TcM ((HsOverLit GhcTc, HsWrapper, TyCoVar), SyntaxExprTc)
forall a b. (a -> b) -> a -> b
$
               \ [Type
lit2_ty, Type
var_ty] [Type]
_ ->
               do { HsOverLit GhcTc
lit2' <- HsOverLit GhcRn -> ExpSigmaTypeFRR -> TcM (HsOverLit GhcTc)
newOverloadedLit HsOverLit GhcRn
lit (Type -> ExpSigmaTypeFRR
mkCheckExpType Type
lit2_ty)
                  ; (HsWrapper
wrap, TyCoVar
bndr_id) <- SrcSpanAnnN -> TcM (HsWrapper, TyCoVar) -> TcM (HsWrapper, TyCoVar)
forall ann a. SrcSpanAnn' ann -> TcRn a -> TcRn a
setSrcSpanA SrcSpanAnnN
nm_loc (TcM (HsWrapper, TyCoVar) -> TcM (HsWrapper, TyCoVar))
-> TcM (HsWrapper, TyCoVar) -> TcM (HsWrapper, TyCoVar)
forall a b. (a -> b) -> a -> b
$
                                     PatEnv
-> Name -> Scaled ExpSigmaTypeFRR -> TcM (HsWrapper, TyCoVar)
tcPatBndr PatEnv
penv Name
name (ExpSigmaTypeFRR -> Scaled ExpSigmaTypeFRR
forall a. a -> Scaled a
unrestricted (ExpSigmaTypeFRR -> Scaled ExpSigmaTypeFRR)
-> ExpSigmaTypeFRR -> Scaled ExpSigmaTypeFRR
forall a b. (a -> b) -> a -> b
$ Type -> ExpSigmaTypeFRR
mkCheckExpType Type
var_ty)
                           -- co :: var_ty ~ idType bndr_id

                           -- minus_wrap is applicable to minus'
                  ; (HsOverLit GhcTc, HsWrapper, TyCoVar)
-> TcM (HsOverLit GhcTc, HsWrapper, TyCoVar)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (HsOverLit GhcTc
lit2', HsWrapper
wrap, TyCoVar
bndr_id) }

        ; Type
pat_ty <- ExpSigmaTypeFRR -> TcM Type
forall (m :: * -> *). MonadIO m => ExpSigmaTypeFRR -> m Type
readExpType ExpSigmaTypeFRR
pat_exp_ty

        -- The Report says that n+k patterns must be in Integral
        -- but it's silly to insist on this in the RebindableSyntax case
        ; IOEnv (Env TcGblEnv TcLclEnv) Bool -> TcRn () -> TcRn ()
forall (m :: * -> *). Monad m => m Bool -> m () -> m ()
unlessM (Extension -> IOEnv (Env TcGblEnv TcLclEnv) Bool
forall gbl lcl. Extension -> TcRnIf gbl lcl Bool
xoptM Extension
LangExt.RebindableSyntax) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
          do { Class
icls <- Name -> TcM Class
tcLookupClass Name
integralClassName
             ; CtOrigin -> [Type] -> TcRn ()
instStupidTheta CtOrigin
orig [Class -> [Type] -> Type
mkClassPred Class
icls [Type
pat_ty]] }

        ; r
res <- Name -> TyCoVar -> TcM r -> TcM r
forall a. Name -> TyCoVar -> TcM a -> TcM a
tcExtendIdEnv1 Name
name TyCoVar
bndr_id TcM r
thing_inside

        ; let minus'' :: SyntaxExprTc
minus'' = case SyntaxExprTc
minus' of
                          SyntaxExprTc
NoSyntaxExprTc -> String -> SDoc -> SyntaxExprTc
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"tc_pat NoSyntaxExprTc" (SyntaxExprTc -> SDoc
forall a. Outputable a => a -> SDoc
ppr SyntaxExprTc
minus')
                                   -- this should be statically avoidable
                                   -- Case (3) from Note [NoSyntaxExpr] in "GHC.Hs.Expr"
                          SyntaxExprTc { syn_expr :: SyntaxExprTc -> HsExpr GhcTc
syn_expr = HsExpr GhcTc
minus'_expr
                                       , syn_arg_wraps :: SyntaxExprTc -> [HsWrapper]
syn_arg_wraps = [HsWrapper]
minus'_arg_wraps
                                       , syn_res_wrap :: SyntaxExprTc -> HsWrapper
syn_res_wrap = HsWrapper
minus'_res_wrap }
                            -> SyntaxExprTc { syn_expr :: HsExpr GhcTc
syn_expr = HsExpr GhcTc
minus'_expr
                                            , syn_arg_wraps :: [HsWrapper]
syn_arg_wraps = [HsWrapper]
minus'_arg_wraps
                                            , syn_res_wrap :: HsWrapper
syn_res_wrap = HsWrapper
minus_wrap HsWrapper -> HsWrapper -> HsWrapper
<.> HsWrapper
minus'_res_wrap }
                             -- Oy. This should really be a record update, but
                             -- we get warnings if we try. #17783
              pat' :: Pat GhcTc
pat' = XNPlusKPat GhcTc
-> LIdP GhcTc
-> XRec GhcTc (HsOverLit GhcTc)
-> HsOverLit GhcTc
-> SyntaxExpr GhcTc
-> SyntaxExpr GhcTc
-> Pat GhcTc
forall p.
XNPlusKPat p
-> LIdP p
-> XRec p (HsOverLit p)
-> HsOverLit p
-> SyntaxExpr p
-> SyntaxExpr p
-> Pat p
NPlusKPat XNPlusKPat GhcTc
Type
pat_ty (SrcSpanAnnN -> TyCoVar -> GenLocated SrcSpanAnnN TyCoVar
forall l e. l -> e -> GenLocated l e
L SrcSpanAnnN
nm_loc TyCoVar
bndr_id) (SrcAnn NoEpAnns
-> HsOverLit GhcTc
-> GenLocated (SrcAnn NoEpAnns) (HsOverLit GhcTc)
forall l e. l -> e -> GenLocated l e
L SrcAnn NoEpAnns
loc HsOverLit GhcTc
lit1') HsOverLit GhcTc
lit2'
                               SyntaxExpr GhcTc
SyntaxExprTc
ge' SyntaxExpr GhcTc
SyntaxExprTc
minus''
        ; (Pat GhcTc, r) -> TcM (Pat GhcTc, r)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (HsWrapper -> Pat GhcTc -> Type -> Pat GhcTc
mkHsWrapPat HsWrapper
mult_wrap Pat GhcTc
pat' Type
pat_ty, r
res) }

-- Here we get rid of it and add the finalizers to the global environment.
-- See Note [Delaying modFinalizers in untyped splices] in GHC.Rename.Splice.
  SplicePat (HsUntypedSpliceTop ThModFinalizers
mod_finalizers Pat GhcRn
pat) HsUntypedSplice GhcRn
_ -> do
      { ThModFinalizers -> TcRn ()
addModFinalizersWithLclEnv ThModFinalizers
mod_finalizers
      ; Scaled ExpSigmaTypeFRR -> Checker (Pat GhcRn) (Pat GhcTc)
tc_pat Scaled ExpSigmaTypeFRR
pat_ty PatEnv
penv Pat GhcRn
pat TcM r
thing_inside }

  SplicePat (HsUntypedSpliceNested Name
_) HsUntypedSplice GhcRn
_ -> String -> TcM (Pat GhcTc, r)
forall a. HasCallStack => String -> a
panic String
"tc_pat: nested splice in splice pat"

  XPat (HsPatExpanded Pat GhcRn
lpat Pat GhcRn
rpat) -> do
    { (Pat GhcTc
rpat', r
res) <- Scaled ExpSigmaTypeFRR -> Checker (Pat GhcRn) (Pat GhcTc)
tc_pat Scaled ExpSigmaTypeFRR
pat_ty PatEnv
penv Pat GhcRn
rpat TcM r
thing_inside
    ; (Pat GhcTc, r) -> TcM (Pat GhcTc, r)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (XXPat GhcTc -> Pat GhcTc
forall p. XXPat p -> Pat p
XPat (XXPat GhcTc -> Pat GhcTc) -> XXPat GhcTc -> Pat GhcTc
forall a b. (a -> b) -> a -> b
$ Pat GhcRn -> Pat GhcTc -> XXPatGhcTc
ExpansionPat Pat GhcRn
lpat Pat GhcTc
rpat', r
res) }

{-
Note [Hopping the LIE in lazy patterns]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In a lazy pattern, we must *not* discharge constraints from the RHS
from dictionaries bound in the pattern.  E.g.
        f ~(C x) = 3
We can't discharge the Num constraint from dictionaries bound by
the pattern C!

So we have to make the constraints from thing_inside "hop around"
the pattern.  Hence the captureConstraints and emitConstraints.

The same thing ensures that equality constraints in a lazy match
are not made available in the RHS of the match. For example
        data T a where { T1 :: Int -> T Int; ... }
        f :: T a -> Int -> a
        f ~(T1 i) y = y
It's obviously not sound to refine a to Int in the right
hand side, because the argument might not match T1 at all!

Finally, a lazy pattern should not bind any existential type variables
because they won't be in scope when we do the desugaring


************************************************************************
*                                                                      *
            Pattern signatures   (pat :: type)
*                                                                      *
************************************************************************
-}

tcPatSig :: Bool                    -- True <=> pattern binding
         -> HsPatSigType GhcRn
         -> ExpSigmaType
         -> TcM (TcType,            -- The type to use for "inside" the signature
                 [(Name,TcTyVar)],  -- The new bit of type environment, binding
                                    -- the scoped type variables
                 [(Name,TcTyVar)],  -- The wildcards
                 HsWrapper)         -- Coercion due to unification with actual ty
                                    -- Of shape:  res_ty ~ sig_ty
tcPatSig :: Bool
-> HsPatSigType GhcRn
-> ExpSigmaTypeFRR
-> TcM (Type, [(Name, TyCoVar)], [(Name, TyCoVar)], HsWrapper)
tcPatSig Bool
in_pat_bind HsPatSigType GhcRn
sig ExpSigmaTypeFRR
res_ty
 = do  { ([(Name, TyCoVar)]
sig_wcs, [(Name, TyCoVar)]
sig_tvs, Type
sig_ty) <- UserTypeCtxt
-> HoleMode
-> HsPatSigType GhcRn
-> ContextKind
-> TcM ([(Name, TyCoVar)], [(Name, TyCoVar)], Type)
tcHsPatSigType UserTypeCtxt
PatSigCtxt HoleMode
HM_Sig HsPatSigType GhcRn
sig ContextKind
OpenKind
        -- sig_tvs are the type variables free in 'sig',
        -- and not already in scope. These are the ones
        -- that should be brought into scope

        ; case [(Name, TyCoVar)] -> Maybe (NonEmpty (Name, TyCoVar))
forall a. [a] -> Maybe (NonEmpty a)
NE.nonEmpty [(Name, TyCoVar)]
sig_tvs of
            Maybe (NonEmpty (Name, TyCoVar))
Nothing -> do {
                -- Just do the subsumption check and return
                  HsWrapper
wrap <- (TidyEnv -> ZonkM (TidyEnv, SDoc))
-> TcM HsWrapper -> TcM HsWrapper
forall a. (TidyEnv -> ZonkM (TidyEnv, SDoc)) -> TcM a -> TcM a
addErrCtxtM (Type -> TidyEnv -> ZonkM (TidyEnv, SDoc)
mk_msg Type
sig_ty) (TcM HsWrapper -> TcM HsWrapper) -> TcM HsWrapper -> TcM HsWrapper
forall a b. (a -> b) -> a -> b
$
                          CtOrigin
-> UserTypeCtxt -> ExpSigmaTypeFRR -> Type -> TcM HsWrapper
tcSubTypePat CtOrigin
PatSigOrigin UserTypeCtxt
PatSigCtxt ExpSigmaTypeFRR
res_ty Type
sig_ty
                ; (Type, [(Name, TyCoVar)], [(Name, TyCoVar)], HsWrapper)
-> TcM (Type, [(Name, TyCoVar)], [(Name, TyCoVar)], HsWrapper)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (Type
sig_ty, [], [(Name, TyCoVar)]
sig_wcs, HsWrapper
wrap)
                }
            Just NonEmpty (Name, TyCoVar)
sig_tvs_ne -> do
                -- Type signature binds at least one scoped type variable

                -- A pattern binding cannot bind scoped type variables
                -- It is more convenient to make the test here
                -- than in the renamer
              Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
when Bool
in_pat_bind
                (TcRnMessage -> TcRn ()
addErr (NonEmpty (Name, TyCoVar) -> TcRnMessage
TcRnCannotBindScopedTyVarInPatSig NonEmpty (Name, TyCoVar)
sig_tvs_ne))

              -- Now do a subsumption check of the pattern signature against res_ty
              HsWrapper
wrap <- (TidyEnv -> ZonkM (TidyEnv, SDoc))
-> TcM HsWrapper -> TcM HsWrapper
forall a. (TidyEnv -> ZonkM (TidyEnv, SDoc)) -> TcM a -> TcM a
addErrCtxtM (Type -> TidyEnv -> ZonkM (TidyEnv, SDoc)
mk_msg Type
sig_ty) (TcM HsWrapper -> TcM HsWrapper) -> TcM HsWrapper -> TcM HsWrapper
forall a b. (a -> b) -> a -> b
$
                      CtOrigin
-> UserTypeCtxt -> ExpSigmaTypeFRR -> Type -> TcM HsWrapper
tcSubTypePat CtOrigin
PatSigOrigin UserTypeCtxt
PatSigCtxt ExpSigmaTypeFRR
res_ty Type
sig_ty

              -- Phew!
              (Type, [(Name, TyCoVar)], [(Name, TyCoVar)], HsWrapper)
-> TcM (Type, [(Name, TyCoVar)], [(Name, TyCoVar)], HsWrapper)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (Type
sig_ty, [(Name, TyCoVar)]
sig_tvs, [(Name, TyCoVar)]
sig_wcs, HsWrapper
wrap)
       }
  where
    mk_msg :: Type -> TidyEnv -> ZonkM (TidyEnv, SDoc)
mk_msg Type
sig_ty TidyEnv
tidy_env
       = do { (TidyEnv
tidy_env, Type
sig_ty) <- TidyEnv -> Type -> ZonkM (TidyEnv, Type)
zonkTidyTcType TidyEnv
tidy_env Type
sig_ty
            ; Type
res_ty <- ExpSigmaTypeFRR -> ZonkM Type
forall (m :: * -> *). MonadIO m => ExpSigmaTypeFRR -> m Type
readExpType ExpSigmaTypeFRR
res_ty   -- should be filled in by now
            ; (TidyEnv
tidy_env, Type
res_ty) <- TidyEnv -> Type -> ZonkM (TidyEnv, Type)
zonkTidyTcType TidyEnv
tidy_env Type
res_ty
            ; let msg :: SDoc
msg = [SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat [ SDoc -> Int -> SDoc -> SDoc
hang (String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"When checking that the pattern signature:")
                                  Int
4 (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
sig_ty)
                             , Int -> SDoc -> SDoc
nest Int
2 (SDoc -> Int -> SDoc -> SDoc
hang (String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"fits the type of its context:")
                                          Int
2 (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
res_ty)) ]
            ; (TidyEnv, SDoc) -> ZonkM (TidyEnv, SDoc)
forall a. a -> ZonkM a
forall (m :: * -> *) a. Monad m => a -> m a
return (TidyEnv
tidy_env, SDoc
msg) }


{- *********************************************************************
*                                                                      *
        Most of the work for constructors is here
        (the rest is in the ConPatIn case of tc_pat)
*                                                                      *
************************************************************************

[Pattern matching indexed data types]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider the following declarations:

  data family Map k :: * -> *
  data instance Map (a, b) v = MapPair (Map a (Pair b v))

and a case expression

  case x :: Map (Int, c) w of MapPair m -> ...

As explained by [Wrappers for data instance tycons] in GHC.Types.Id.Make, the
worker/wrapper types for MapPair are

  $WMapPair :: forall a b v. Map a (Map a b v) -> Map (a, b) v
  $wMapPair :: forall a b v. Map a (Map a b v) -> :R123Map a b v

So, the type of the scrutinee is Map (Int, c) w, but the tycon of MapPair is
:R123Map, which means the straight use of boxySplitTyConApp would give a type
error.  Hence, the smart wrapper function boxySplitTyConAppWithFamily calls
boxySplitTyConApp with the family tycon Map instead, which gives us the family
type list {(Int, c), w}.  To get the correct split for :R123Map, we need to
unify the family type list {(Int, c), w} with the instance types {(a, b), v}
(provided by tyConFamInst_maybe together with the family tycon).  This
unification yields the substitution [a -> Int, b -> c, v -> w], which gives us
the split arguments for the representation tycon :R123Map as {Int, c, w}

In other words, boxySplitTyConAppWithFamily implicitly takes the coercion

  Co123Map a b v :: {Map (a, b) v ~ :R123Map a b v}

moving between representation and family type into account.  To produce type
correct Core, this coercion needs to be used to case the type of the scrutinee
from the family to the representation type.  This is achieved by
unwrapFamInstScrutinee using a CoPat around the result pattern.

Now it might appear seem as if we could have used the previous GADT type
refinement infrastructure of refineAlt and friends instead of the explicit
unification and CoPat generation.  However, that would be wrong.  Why?  The
whole point of GADT refinement is that the refinement is local to the case
alternative.  In contrast, the substitution generated by the unification of
the family type list and instance types needs to be propagated to the outside.
Imagine that in the above example, the type of the scrutinee would have been
(Map x w), then we would have unified {x, w} with {(a, b), v}, yielding the
substitution [x -> (a, b), v -> w].  In contrast to GADT matching, the
instantiation of x with (a, b) must be global; ie, it must be valid in *all*
alternatives of the case expression, whereas in the GADT case it might vary
between alternatives.

RIP GADT refinement: refinements have been replaced by the use of explicit
equality constraints that are used in conjunction with implication constraints
to express the local scope of GADT refinements.

Note [Freshen existentials]
~~~~~~~~~~~~~~~~~~~~~~~~~~~
It is essential that these existentials are freshened.
Otherwise, if we have something like
  case (a :: Ex, b :: Ex) of (MkEx ..., MkEx ...) -> ...
we'll give both unpacked existential variables the
same name, leading to shadowing.

-}

--      Running example:
-- MkT :: forall a b c. (a~[b]) => b -> c -> T a
--       with scrutinee of type (T ty)

tcConPat :: PatEnv -> LocatedN Name
         -> Scaled ExpSigmaTypeFRR    -- Type of the pattern
         -> HsConPatDetails GhcRn -> TcM a
         -> TcM (Pat GhcTc, a)
tcConPat :: forall a.
PatEnv
-> GenLocated SrcSpanAnnN Name
-> Scaled ExpSigmaTypeFRR
-> HsConPatDetails GhcRn
-> TcM a
-> TcM (Pat GhcTc, a)
tcConPat PatEnv
penv con_lname :: GenLocated SrcSpanAnnN Name
con_lname@(L SrcSpanAnnN
_ Name
con_name) Scaled ExpSigmaTypeFRR
pat_ty HsConPatDetails GhcRn
arg_pats TcM a
thing_inside
  = do  { ConLike
con_like <- Name -> TcM ConLike
tcLookupConLike Name
con_name
        ; case ConLike
con_like of
            RealDataCon DataCon
data_con -> GenLocated SrcSpanAnnN Name
-> DataCon
-> Scaled ExpSigmaTypeFRR
-> Checker (HsConPatDetails GhcRn) (Pat GhcTc)
tcDataConPat GenLocated SrcSpanAnnN Name
con_lname DataCon
data_con Scaled ExpSigmaTypeFRR
pat_ty
                                                 PatEnv
penv HsConPatDetails GhcRn
arg_pats TcM a
thing_inside
            PatSynCon PatSyn
pat_syn -> GenLocated SrcSpanAnnN Name
-> PatSyn
-> Scaled ExpSigmaTypeFRR
-> Checker (HsConPatDetails GhcRn) (Pat GhcTc)
tcPatSynPat GenLocated SrcSpanAnnN Name
con_lname PatSyn
pat_syn Scaled ExpSigmaTypeFRR
pat_ty
                                             PatEnv
penv HsConPatDetails GhcRn
arg_pats TcM a
thing_inside
        }

-- Warn when pattern matching on a GADT or a pattern synonym
-- when MonoLocalBinds is off.
warnMonoLocalBinds :: TcM ()
warnMonoLocalBinds :: TcRn ()
warnMonoLocalBinds
  = do { Bool
mono_local_binds <- Extension -> IOEnv (Env TcGblEnv TcLclEnv) Bool
forall gbl lcl. Extension -> TcRnIf gbl lcl Bool
xoptM Extension
LangExt.MonoLocalBinds
       ; Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
unless Bool
mono_local_binds (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
           TcRnMessage -> TcRn ()
addDiagnostic TcRnMessage
TcRnGADTMonoLocalBinds
           -- We used to require the GADTs or TypeFamilies extension
           -- to pattern match on a GADT (#2905, #7156)
           --
           -- In #20485 this was made into a warning.
       }

tcDataConPat :: LocatedN Name -> DataCon
             -> Scaled ExpSigmaTypeFRR        -- Type of the pattern
             -> Checker (HsConPatDetails GhcRn) (Pat GhcTc)
tcDataConPat :: GenLocated SrcSpanAnnN Name
-> DataCon
-> Scaled ExpSigmaTypeFRR
-> Checker (HsConPatDetails GhcRn) (Pat GhcTc)
tcDataConPat (L SrcSpanAnnN
con_span Name
con_name) DataCon
data_con Scaled ExpSigmaTypeFRR
pat_ty_scaled
             PatEnv
penv HsConPatDetails GhcRn
arg_pats TcM r
thing_inside
  = do  { let tycon :: TyCon
tycon = DataCon -> TyCon
dataConTyCon DataCon
data_con
                  -- For data families this is the representation tycon
              ([TyCoVar]
univ_tvs, [TyCoVar]
ex_tvs, [EqSpec]
eq_spec, [Type]
theta, [Scaled Type]
arg_tys, Type
_)
                = DataCon
-> ([TyCoVar], [TyCoVar], [EqSpec], [Type], [Scaled Type], Type)
dataConFullSig DataCon
data_con
              header :: GenLocated SrcSpanAnnN ConLike
header = SrcSpanAnnN -> ConLike -> GenLocated SrcSpanAnnN ConLike
forall l e. l -> e -> GenLocated l e
L SrcSpanAnnN
con_span (DataCon -> ConLike
RealDataCon DataCon
data_con)

          -- Instantiate the constructor type variables [a->ty]
          -- This may involve doing a family-instance coercion,
          -- and building a wrapper
        ; (HsWrapper
wrap, [Type]
ctxt_res_tys) <- PatEnv
-> TyCon -> Scaled ExpSigmaTypeFRR -> TcM (HsWrapper, [Type])
matchExpectedConTy PatEnv
penv TyCon
tycon Scaled ExpSigmaTypeFRR
pat_ty_scaled
        ; Type
pat_ty <- ExpSigmaTypeFRR -> TcM Type
forall (m :: * -> *). MonadIO m => ExpSigmaTypeFRR -> m Type
readExpType (Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR
forall a. Scaled a -> a
scaledThing Scaled ExpSigmaTypeFRR
pat_ty_scaled)

          -- Add the stupid theta
        ; SrcSpanAnnN -> TcRn () -> TcRn ()
forall ann a. SrcSpanAnn' ann -> TcRn a -> TcRn a
setSrcSpanA SrcSpanAnnN
con_span (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$ DataCon -> [Type] -> TcRn ()
addDataConStupidTheta DataCon
data_con [Type]
ctxt_res_tys

        -- Check that this isn't a GADT pattern match
        -- in situations in which that isn't allowed.
        ; let all_arg_tys :: [Type]
all_arg_tys = [EqSpec] -> [Type]
eqSpecPreds [EqSpec]
eq_spec [Type] -> [Type] -> [Type]
forall a. [a] -> [a] -> [a]
++ [Type]
theta [Type] -> [Type] -> [Type]
forall a. [a] -> [a] -> [a]
++ ((Scaled Type -> Type) -> [Scaled Type] -> [Type]
forall a b. (a -> b) -> [a] -> [b]
map Scaled Type -> Type
forall a. Scaled a -> a
scaledThing [Scaled Type]
arg_tys)
        ; ConLike -> [TyCoVar] -> [Type] -> PatEnv -> TcRn ()
checkGADT (DataCon -> ConLike
RealDataCon DataCon
data_con) [TyCoVar]
ex_tvs [Type]
all_arg_tys PatEnv
penv

        ; Subst
tenv1 <- CtOrigin -> [TyCoVar] -> [Type] -> TcM Subst
instTyVarsWith CtOrigin
PatOrigin [TyCoVar]
univ_tvs [Type]
ctxt_res_tys
                  -- NB: Do not use zipTvSubst!  See #14154
                  -- We want to create a well-kinded substitution, so
                  -- that the instantiated type is well-kinded

        ; let mc :: HsMatchContext GhcTc
mc = case PatEnv -> PatCtxt
pe_ctxt PatEnv
penv of
                     LamPat HsMatchContext GhcTc
mc -> HsMatchContext GhcTc
mc
                     LetPat {} -> HsMatchContext GhcTc
forall p. HsMatchContext p
PatBindRhs
        ; SkolemInfo
skol_info <- SkolemInfoAnon -> IOEnv (Env TcGblEnv TcLclEnv) SkolemInfo
forall (m :: * -> *). MonadIO m => SkolemInfoAnon -> m SkolemInfo
mkSkolemInfo (ConLike -> HsMatchContext GhcTc -> SkolemInfoAnon
PatSkol (DataCon -> ConLike
RealDataCon DataCon
data_con) HsMatchContext GhcTc
mc)
        ; (Subst
tenv, [TyCoVar]
ex_tvs') <- SkolemInfo -> Subst -> [TyCoVar] -> TcM (Subst, [TyCoVar])
tcInstSuperSkolTyVarsX SkolemInfo
skol_info Subst
tenv1 [TyCoVar]
ex_tvs
                     -- Get location from monad, not from ex_tvs
                     -- This freshens: See Note [Freshen existentials]
                     -- Why "super"? See Note [Binding when looking up instances]
                     -- in GHC.Core.InstEnv.

        ; let arg_tys' :: [Scaled Type]
arg_tys'       = HasDebugCallStack => Subst -> [Scaled Type] -> [Scaled Type]
Subst -> [Scaled Type] -> [Scaled Type]
substScaledTys Subst
tenv [Scaled Type]
arg_tys
              pat_mult :: Type
pat_mult       = Scaled ExpSigmaTypeFRR -> Type
forall a. Scaled a -> Type
scaledMult Scaled ExpSigmaTypeFRR
pat_ty_scaled
              arg_tys_scaled :: [Scaled Type]
arg_tys_scaled = (Scaled Type -> Scaled Type) -> [Scaled Type] -> [Scaled Type]
forall a b. (a -> b) -> [a] -> [b]
map (Type -> Scaled Type -> Scaled Type
forall a. Type -> Scaled a -> Scaled a
scaleScaled Type
pat_mult) [Scaled Type]
arg_tys'
              con_like :: ConLike
con_like       = DataCon -> ConLike
RealDataCon DataCon
data_con

        -- This check is necessary to uphold the invariant that 'tcConArgs'
        -- is given argument types with a fixed runtime representation.
        -- See test case T20363.
        ; DataCon -> [Scaled Type] -> TcRn ()
checkFixedRuntimeRep DataCon
data_con [Scaled Type]
arg_tys'

        ; String -> SDoc -> TcRn ()
traceTc String
"tcConPat" ([SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat [ String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"con_name:" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
con_name
                                   , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"univ_tvs:" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [TyCoVar] -> SDoc
pprTyVars [TyCoVar]
univ_tvs
                                   , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"ex_tvs:" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [TyCoVar] -> SDoc
pprTyVars [TyCoVar]
ex_tvs
                                   , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"eq_spec:" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [EqSpec] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [EqSpec]
eq_spec
                                   , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"theta:" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [Type] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Type]
theta
                                   , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"ex_tvs':" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [TyCoVar] -> SDoc
pprTyVars [TyCoVar]
ex_tvs'
                                   , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"ctxt_res_tys:" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [Type] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Type]
ctxt_res_tys
                                   , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"pat_ty:" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
pat_ty
                                   , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"arg_tys':" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [Scaled Type] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Scaled Type]
arg_tys'
                                   , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"arg_pats" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> HsConDetails
  (HsConPatTyArg GhcRn)
  (GenLocated SrcSpanAnnA (Pat GhcRn))
  (HsRecFields GhcRn (GenLocated SrcSpanAnnA (Pat GhcRn)))
-> SDoc
forall a. Outputable a => a -> SDoc
ppr HsConPatDetails GhcRn
HsConDetails
  (HsConPatTyArg GhcRn)
  (GenLocated SrcSpanAnnA (Pat GhcRn))
  (HsRecFields GhcRn (GenLocated SrcSpanAnnA (Pat GhcRn)))
arg_pats ])

        ; ([(HsConPatTyArg GhcRn, TyCoVar)]
univ_ty_args, [(HsConPatTyArg GhcRn, TyCoVar)]
ex_ty_args) <- ConLike
-> HsConPatDetails GhcRn
-> TcM
     ([(HsConPatTyArg GhcRn, TyCoVar)],
      [(HsConPatTyArg GhcRn, TyCoVar)])
splitConTyArgs ConLike
con_like HsConPatDetails GhcRn
arg_pats

        ; if [TyCoVar] -> Bool
forall a. [a] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [TyCoVar]
ex_tvs Bool -> Bool -> Bool
&& [EqSpec] -> Bool
forall a. [a] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [EqSpec]
eq_spec Bool -> Bool -> Bool
&& [Type] -> Bool
forall a. [a] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [Type]
theta
          then do { -- The common case; no class bindings etc
                    -- (see Note [Arrows and patterns])
                    (HsConDetails
  (HsConPatTyArg GhcRn)
  (GenLocated SrcSpanAnnA (Pat GhcTc))
  (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc)))
arg_pats', r
res) <- Subst
-> PatEnv
-> [(HsConPatTyArg GhcRn, TyCoVar)]
-> TcM
     (HsConDetails
        (HsConPatTyArg GhcRn)
        (GenLocated SrcSpanAnnA (Pat GhcTc))
        (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
      r)
-> TcM
     (HsConDetails
        (HsConPatTyArg GhcRn)
        (GenLocated SrcSpanAnnA (Pat GhcTc))
        (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
      r)
forall a.
Subst
-> PatEnv -> [(HsConPatTyArg GhcRn, TyCoVar)] -> TcM a -> TcM a
tcConTyArgs Subst
tenv PatEnv
penv [(HsConPatTyArg GhcRn, TyCoVar)]
univ_ty_args (TcM
   (HsConDetails
      (HsConPatTyArg GhcRn)
      (GenLocated SrcSpanAnnA (Pat GhcTc))
      (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
    r)
 -> TcM
      (HsConDetails
         (HsConPatTyArg GhcRn)
         (GenLocated SrcSpanAnnA (Pat GhcTc))
         (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
       r))
-> TcM
     (HsConDetails
        (HsConPatTyArg GhcRn)
        (GenLocated SrcSpanAnnA (Pat GhcTc))
        (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
      r)
-> TcM
     (HsConDetails
        (HsConPatTyArg GhcRn)
        (GenLocated SrcSpanAnnA (Pat GhcTc))
        (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
      r)
forall a b. (a -> b) -> a -> b
$
                                        ConLike
-> [Scaled Type]
-> Checker (HsConPatDetails GhcRn) (HsConPatDetails GhcTc)
tcConValArgs ConLike
con_like [Scaled Type]
arg_tys_scaled
                                                     PatEnv
penv HsConPatDetails GhcRn
arg_pats TcM r
thing_inside
                  ; let res_pat :: Pat GhcTc
res_pat = ConPat { pat_con :: XRec GhcTc (ConLikeP GhcTc)
pat_con = XRec GhcTc (ConLikeP GhcTc)
GenLocated SrcSpanAnnN ConLike
header
                                         , pat_args :: HsConPatDetails GhcTc
pat_args = HsConPatDetails GhcTc
HsConDetails
  (HsConPatTyArg GhcRn)
  (GenLocated SrcSpanAnnA (Pat GhcTc))
  (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc)))
arg_pats'
                                         , pat_con_ext :: XConPat GhcTc
pat_con_ext = ConPatTc
                                           { cpt_tvs :: [TyCoVar]
cpt_tvs = [], cpt_dicts :: [TyCoVar]
cpt_dicts = []
                                           , cpt_binds :: TcEvBinds
cpt_binds = TcEvBinds
emptyTcEvBinds
                                           , cpt_arg_tys :: [Type]
cpt_arg_tys = [Type]
ctxt_res_tys
                                           , cpt_wrap :: HsWrapper
cpt_wrap = HsWrapper
idHsWrapper
                                           }
                                         }

                  ; (Pat GhcTc, r) -> TcM (Pat GhcTc, r)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (HsWrapper -> Pat GhcTc -> Type -> Pat GhcTc
mkHsWrapPat HsWrapper
wrap Pat GhcTc
res_pat Type
pat_ty, r
res) }

          else do   -- The general case, with existential,
                    -- and local equality constraints
        { let theta' :: [Type]
theta'     = HasDebugCallStack => Subst -> [Type] -> [Type]
Subst -> [Type] -> [Type]
substTheta Subst
tenv ([EqSpec] -> [Type]
eqSpecPreds [EqSpec]
eq_spec [Type] -> [Type] -> [Type]
forall a. [a] -> [a] -> [a]
++ [Type]
theta)
                           -- order is *important* as we generate the list of
                           -- dictionary binders from theta'

        ; Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
when (Bool -> Bool
not ([EqSpec] -> Bool
forall a. [a] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [EqSpec]
eq_spec) Bool -> Bool -> Bool
|| (Type -> Bool) -> [Type] -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
any Type -> Bool
isEqPred [Type]
theta) TcRn ()
warnMonoLocalBinds

        ; [TyCoVar]
given <- [Type] -> TcM [TyCoVar]
newEvVars [Type]
theta'
        ; (TcEvBinds
ev_binds, (HsConDetails
  (HsConPatTyArg GhcRn)
  (GenLocated SrcSpanAnnA (Pat GhcTc))
  (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc)))
arg_pats', r
res))
             <- -- See Note [Type applications in patterns] (W4)
                Subst
-> PatEnv
-> [(HsConPatTyArg GhcRn, TyCoVar)]
-> TcM
     (TcEvBinds,
      (HsConDetails
         (HsConPatTyArg GhcRn)
         (GenLocated SrcSpanAnnA (Pat GhcTc))
         (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
       r))
-> TcM
     (TcEvBinds,
      (HsConDetails
         (HsConPatTyArg GhcRn)
         (GenLocated SrcSpanAnnA (Pat GhcTc))
         (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
       r))
forall a.
Subst
-> PatEnv -> [(HsConPatTyArg GhcRn, TyCoVar)] -> TcM a -> TcM a
tcConTyArgs Subst
tenv PatEnv
penv [(HsConPatTyArg GhcRn, TyCoVar)]
univ_ty_args                       (TcM
   (TcEvBinds,
    (HsConDetails
       (HsConPatTyArg GhcRn)
       (GenLocated SrcSpanAnnA (Pat GhcTc))
       (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
     r))
 -> TcM
      (TcEvBinds,
       (HsConDetails
          (HsConPatTyArg GhcRn)
          (GenLocated SrcSpanAnnA (Pat GhcTc))
          (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
        r)))
-> TcM
     (TcEvBinds,
      (HsConDetails
         (HsConPatTyArg GhcRn)
         (GenLocated SrcSpanAnnA (Pat GhcTc))
         (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
       r))
-> TcM
     (TcEvBinds,
      (HsConDetails
         (HsConPatTyArg GhcRn)
         (GenLocated SrcSpanAnnA (Pat GhcTc))
         (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
       r))
forall a b. (a -> b) -> a -> b
$
                SkolemInfoAnon
-> [TyCoVar]
-> [TyCoVar]
-> TcM
     (HsConDetails
        (HsConPatTyArg GhcRn)
        (GenLocated SrcSpanAnnA (Pat GhcTc))
        (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
      r)
-> TcM
     (TcEvBinds,
      (HsConDetails
         (HsConPatTyArg GhcRn)
         (GenLocated SrcSpanAnnA (Pat GhcTc))
         (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
       r))
forall result.
SkolemInfoAnon
-> [TyCoVar] -> [TyCoVar] -> TcM result -> TcM (TcEvBinds, result)
checkConstraints (SkolemInfo -> SkolemInfoAnon
getSkolemInfo SkolemInfo
skol_info) [TyCoVar]
ex_tvs' [TyCoVar]
given (TcM
   (HsConDetails
      (HsConPatTyArg GhcRn)
      (GenLocated SrcSpanAnnA (Pat GhcTc))
      (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
    r)
 -> TcM
      (TcEvBinds,
       (HsConDetails
          (HsConPatTyArg GhcRn)
          (GenLocated SrcSpanAnnA (Pat GhcTc))
          (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
        r)))
-> TcM
     (HsConDetails
        (HsConPatTyArg GhcRn)
        (GenLocated SrcSpanAnnA (Pat GhcTc))
        (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
      r)
-> TcM
     (TcEvBinds,
      (HsConDetails
         (HsConPatTyArg GhcRn)
         (GenLocated SrcSpanAnnA (Pat GhcTc))
         (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
       r))
forall a b. (a -> b) -> a -> b
$
                Subst
-> PatEnv
-> [(HsConPatTyArg GhcRn, TyCoVar)]
-> TcM
     (HsConDetails
        (HsConPatTyArg GhcRn)
        (GenLocated SrcSpanAnnA (Pat GhcTc))
        (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
      r)
-> TcM
     (HsConDetails
        (HsConPatTyArg GhcRn)
        (GenLocated SrcSpanAnnA (Pat GhcTc))
        (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
      r)
forall a.
Subst
-> PatEnv -> [(HsConPatTyArg GhcRn, TyCoVar)] -> TcM a -> TcM a
tcConTyArgs Subst
tenv PatEnv
penv [(HsConPatTyArg GhcRn, TyCoVar)]
ex_ty_args                         (TcM
   (HsConDetails
      (HsConPatTyArg GhcRn)
      (GenLocated SrcSpanAnnA (Pat GhcTc))
      (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
    r)
 -> TcM
      (HsConDetails
         (HsConPatTyArg GhcRn)
         (GenLocated SrcSpanAnnA (Pat GhcTc))
         (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
       r))
-> TcM
     (HsConDetails
        (HsConPatTyArg GhcRn)
        (GenLocated SrcSpanAnnA (Pat GhcTc))
        (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
      r)
-> TcM
     (HsConDetails
        (HsConPatTyArg GhcRn)
        (GenLocated SrcSpanAnnA (Pat GhcTc))
        (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
      r)
forall a b. (a -> b) -> a -> b
$
                ConLike
-> [Scaled Type]
-> Checker (HsConPatDetails GhcRn) (HsConPatDetails GhcTc)
tcConValArgs ConLike
con_like [Scaled Type]
arg_tys_scaled PatEnv
penv HsConPatDetails GhcRn
arg_pats TcM r
thing_inside

        ; let res_pat :: Pat GhcTc
res_pat = ConPat
                { pat_con :: XRec GhcTc (ConLikeP GhcTc)
pat_con   = XRec GhcTc (ConLikeP GhcTc)
GenLocated SrcSpanAnnN ConLike
header
                , pat_args :: HsConPatDetails GhcTc
pat_args  = HsConPatDetails GhcTc
HsConDetails
  (HsConPatTyArg GhcRn)
  (GenLocated SrcSpanAnnA (Pat GhcTc))
  (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc)))
arg_pats'
                , pat_con_ext :: XConPat GhcTc
pat_con_ext = ConPatTc
                  { cpt_tvs :: [TyCoVar]
cpt_tvs   = [TyCoVar]
ex_tvs'
                  , cpt_dicts :: [TyCoVar]
cpt_dicts = [TyCoVar]
given
                  , cpt_binds :: TcEvBinds
cpt_binds = TcEvBinds
ev_binds
                  , cpt_arg_tys :: [Type]
cpt_arg_tys = [Type]
ctxt_res_tys
                  , cpt_wrap :: HsWrapper
cpt_wrap  = HsWrapper
idHsWrapper
                  }
                }
        ; (Pat GhcTc, r) -> TcM (Pat GhcTc, r)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (HsWrapper -> Pat GhcTc -> Type -> Pat GhcTc
mkHsWrapPat HsWrapper
wrap Pat GhcTc
res_pat Type
pat_ty, r
res)
        } }

tcPatSynPat :: LocatedN Name -> PatSyn
            -> Scaled ExpSigmaType         -- ^ Type of the pattern
            -> Checker (HsConPatDetails GhcRn) (Pat GhcTc)
tcPatSynPat :: GenLocated SrcSpanAnnN Name
-> PatSyn
-> Scaled ExpSigmaTypeFRR
-> Checker (HsConPatDetails GhcRn) (Pat GhcTc)
tcPatSynPat (L SrcSpanAnnN
con_span Name
con_name) PatSyn
pat_syn Scaled ExpSigmaTypeFRR
pat_ty PatEnv
penv HsConPatDetails GhcRn
arg_pats TcM r
thing_inside
  = do  { let ([TyCoVar]
univ_tvs, [Type]
req_theta, [TyCoVar]
ex_tvs, [Type]
prov_theta, [Scaled Type]
arg_tys, Type
ty) = PatSyn
-> ([TyCoVar], [Type], [TyCoVar], [Type], [Scaled Type], Type)
patSynSig PatSyn
pat_syn

        ; (Subst
subst, [TyCoVar]
univ_tvs') <- [TyCoVar] -> TcM (Subst, [TyCoVar])
newMetaTyVars [TyCoVar]
univ_tvs

        -- Check that we aren't matching on a GADT-like pattern synonym
        -- in situations in which that isn't allowed.
        ; let all_arg_tys :: [Type]
all_arg_tys = Type
ty Type -> [Type] -> [Type]
forall a. a -> [a] -> [a]
: [Type]
prov_theta [Type] -> [Type] -> [Type]
forall a. [a] -> [a] -> [a]
++ ((Scaled Type -> Type) -> [Scaled Type] -> [Type]
forall a b. (a -> b) -> [a] -> [b]
map Scaled Type -> Type
forall a. Scaled a -> a
scaledThing [Scaled Type]
arg_tys)
        ; ConLike -> [TyCoVar] -> [Type] -> PatEnv -> TcRn ()
checkGADT (PatSyn -> ConLike
PatSynCon PatSyn
pat_syn) [TyCoVar]
ex_tvs [Type]
all_arg_tys PatEnv
penv

        ; SkolemInfo
skol_info <- case PatEnv -> PatCtxt
pe_ctxt PatEnv
penv of
                            LamPat HsMatchContext GhcTc
mc -> SkolemInfoAnon -> IOEnv (Env TcGblEnv TcLclEnv) SkolemInfo
forall (m :: * -> *). MonadIO m => SkolemInfoAnon -> m SkolemInfo
mkSkolemInfo (ConLike -> HsMatchContext GhcTc -> SkolemInfoAnon
PatSkol (PatSyn -> ConLike
PatSynCon PatSyn
pat_syn) HsMatchContext GhcTc
mc)
                            LetPat {} -> SkolemInfo -> IOEnv (Env TcGblEnv TcLclEnv) SkolemInfo
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return SkolemInfo
HasCallStack => SkolemInfo
unkSkol -- Doesn't matter

        ; (Subst
tenv, [TyCoVar]
ex_tvs') <- SkolemInfo -> Subst -> [TyCoVar] -> TcM (Subst, [TyCoVar])
tcInstSuperSkolTyVarsX SkolemInfo
skol_info Subst
subst [TyCoVar]
ex_tvs
           -- This freshens: Note [Freshen existentials]

        ; let ty' :: Type
ty'         = HasDebugCallStack => Subst -> Type -> Type
Subst -> Type -> Type
substTy Subst
tenv Type
ty
              arg_tys' :: [Scaled Type]
arg_tys'    = HasDebugCallStack => Subst -> [Scaled Type] -> [Scaled Type]
Subst -> [Scaled Type] -> [Scaled Type]
substScaledTys Subst
tenv [Scaled Type]
arg_tys
              pat_mult :: Type
pat_mult    = Scaled ExpSigmaTypeFRR -> Type
forall a. Scaled a -> Type
scaledMult Scaled ExpSigmaTypeFRR
pat_ty
              arg_tys_scaled :: [Scaled Type]
arg_tys_scaled = (Scaled Type -> Scaled Type) -> [Scaled Type] -> [Scaled Type]
forall a b. (a -> b) -> [a] -> [b]
map (Type -> Scaled Type -> Scaled Type
forall a. Type -> Scaled a -> Scaled a
scaleScaled Type
pat_mult) [Scaled Type]
arg_tys'
              prov_theta' :: [Type]
prov_theta' = HasDebugCallStack => Subst -> [Type] -> [Type]
Subst -> [Type] -> [Type]
substTheta Subst
tenv [Type]
prov_theta
              req_theta' :: [Type]
req_theta'  = HasDebugCallStack => Subst -> [Type] -> [Type]
Subst -> [Type] -> [Type]
substTheta Subst
tenv [Type]
req_theta
              con_like :: ConLike
con_like    = PatSyn -> ConLike
PatSynCon PatSyn
pat_syn

        ; Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
when ((Type -> Bool) -> [Type] -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
any Type -> Bool
isEqPred [Type]
prov_theta) TcRn ()
warnMonoLocalBinds

        ; HsWrapper
mult_wrap <- Scaled ExpSigmaTypeFRR -> TcM HsWrapper
forall a. Scaled a -> TcM HsWrapper
checkManyPattern Scaled ExpSigmaTypeFRR
pat_ty
            -- See Note [Wrapper returned from tcSubMult] in GHC.Tc.Utils.Unify.

        ; ([(HsConPatTyArg GhcRn, TyCoVar)]
univ_ty_args, [(HsConPatTyArg GhcRn, TyCoVar)]
ex_ty_args) <- ConLike
-> HsConPatDetails GhcRn
-> TcM
     ([(HsConPatTyArg GhcRn, TyCoVar)],
      [(HsConPatTyArg GhcRn, TyCoVar)])
splitConTyArgs ConLike
con_like HsConPatDetails GhcRn
arg_pats

        ; HsWrapper
wrap <- PatEnv -> ExpSigmaTypeFRR -> Type -> TcM HsWrapper
tc_sub_type PatEnv
penv (Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR
forall a. Scaled a -> a
scaledThing Scaled ExpSigmaTypeFRR
pat_ty) Type
ty'

        ; String -> SDoc -> TcRn ()
traceTc String
"tcPatSynPat" (SDoc -> TcRn ()) -> SDoc -> TcRn ()
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
"Pat syn:" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> PatSyn -> SDoc
forall a. Outputable a => a -> SDoc
ppr PatSyn
pat_syn
               , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"Expected type:" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Scaled ExpSigmaTypeFRR -> SDoc
forall a. Outputable a => a -> SDoc
ppr Scaled ExpSigmaTypeFRR
pat_ty
               , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"Pat res ty:" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
ty'
               , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"ex_tvs':" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [TyCoVar] -> SDoc
pprTyVars [TyCoVar]
ex_tvs'
               , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"prov_theta':" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [Type] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Type]
prov_theta'
               , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"req_theta':" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [Type] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Type]
req_theta'
               , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"arg_tys':" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [Scaled Type] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Scaled Type]
arg_tys'
               , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"univ_ty_args:" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [(HsConPatTyArg GhcRn, TyCoVar)] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [(HsConPatTyArg GhcRn, TyCoVar)]
univ_ty_args
               , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"ex_ty_args:" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [(HsConPatTyArg GhcRn, TyCoVar)] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [(HsConPatTyArg GhcRn, TyCoVar)]
ex_ty_args ]

        ; HsWrapper
req_wrap <- CtOrigin -> [Type] -> [Type] -> TcM HsWrapper
instCall (Name -> CtOrigin
OccurrenceOf Name
con_name) ([TyCoVar] -> [Type]
mkTyVarTys [TyCoVar]
univ_tvs') [Type]
req_theta'
                      -- Origin (OccurrenceOf con_name):
                      -- see Note [Call-stack tracing of pattern synonyms]
        ; String -> SDoc -> TcRn ()
traceTc String
"instCall" (HsWrapper -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsWrapper
req_wrap)

          -- Pattern synonyms can never have representation-polymorphic argument types,
          -- as checked in 'GHC.Tc.Gen.Sig.tcPatSynSig' (see use of 'FixedRuntimeRepPatSynSigArg')
          -- and 'GHC.Tc.TyCl.PatSyn.tcInferPatSynDecl'.
          -- (If you want to lift this restriction, use 'hasFixedRuntimeRep' here, to match
          -- 'tcDataConPat'.)
        ; let
            bad_arg_tys :: [(Int, Scaled Type)]
            bad_arg_tys :: [(Int, Scaled Type)]
bad_arg_tys = ((Int, Scaled Type) -> Bool)
-> [(Int, Scaled Type)] -> [(Int, Scaled Type)]
forall a. (a -> Bool) -> [a] -> [a]
filter (\ (Int
_, Scaled Type
_ Type
arg_ty) -> HasDebugCallStack => Type -> Maybe Levity
Type -> Maybe Levity
typeLevity_maybe Type
arg_ty Maybe Levity -> Maybe Levity -> Bool
forall a. Eq a => a -> a -> Bool
== Maybe Levity
forall a. Maybe a
Nothing)
                        ([(Int, Scaled Type)] -> [(Int, Scaled Type)])
-> [(Int, Scaled Type)] -> [(Int, Scaled Type)]
forall a b. (a -> b) -> a -> b
$ [Int] -> [Scaled Type] -> [(Int, Scaled Type)]
forall a b. [a] -> [b] -> [(a, b)]
zip [Int
0..] [Scaled Type]
arg_tys'
        ; Bool -> SDoc -> TcRn ()
forall (m :: * -> *).
(HasCallStack, Applicative m) =>
Bool -> SDoc -> m ()
massertPpr ([(Int, Scaled Type)] -> Bool
forall a. [a] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [(Int, Scaled Type)]
bad_arg_tys) (SDoc -> TcRn ()) -> SDoc -> TcRn ()
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
"tcPatSynPat: pattern arguments do not have a fixed RuntimeRep"
                 , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"bad_arg_tys:" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [(Int, Scaled Type)] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [(Int, Scaled Type)]
bad_arg_tys ]

        ; String -> SDoc -> TcRn ()
traceTc String
"checkConstraints {" SDoc
forall doc. IsOutput doc => doc
Outputable.empty
        ; [TyCoVar]
prov_dicts' <- [Type] -> TcM [TyCoVar]
newEvVars [Type]
prov_theta'
        ; (TcEvBinds
ev_binds, (HsConDetails
  (HsConPatTyArg GhcRn)
  (GenLocated SrcSpanAnnA (Pat GhcTc))
  (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc)))
arg_pats', r
res))
             <- -- See Note [Type applications in patterns] (W4)
                Subst
-> PatEnv
-> [(HsConPatTyArg GhcRn, TyCoVar)]
-> TcM
     (TcEvBinds,
      (HsConDetails
         (HsConPatTyArg GhcRn)
         (GenLocated SrcSpanAnnA (Pat GhcTc))
         (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
       r))
-> TcM
     (TcEvBinds,
      (HsConDetails
         (HsConPatTyArg GhcRn)
         (GenLocated SrcSpanAnnA (Pat GhcTc))
         (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
       r))
forall a.
Subst
-> PatEnv -> [(HsConPatTyArg GhcRn, TyCoVar)] -> TcM a -> TcM a
tcConTyArgs Subst
tenv PatEnv
penv [(HsConPatTyArg GhcRn, TyCoVar)]
univ_ty_args                             (TcM
   (TcEvBinds,
    (HsConDetails
       (HsConPatTyArg GhcRn)
       (GenLocated SrcSpanAnnA (Pat GhcTc))
       (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
     r))
 -> TcM
      (TcEvBinds,
       (HsConDetails
          (HsConPatTyArg GhcRn)
          (GenLocated SrcSpanAnnA (Pat GhcTc))
          (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
        r)))
-> TcM
     (TcEvBinds,
      (HsConDetails
         (HsConPatTyArg GhcRn)
         (GenLocated SrcSpanAnnA (Pat GhcTc))
         (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
       r))
-> TcM
     (TcEvBinds,
      (HsConDetails
         (HsConPatTyArg GhcRn)
         (GenLocated SrcSpanAnnA (Pat GhcTc))
         (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
       r))
forall a b. (a -> b) -> a -> b
$
                SkolemInfoAnon
-> [TyCoVar]
-> [TyCoVar]
-> TcM
     (HsConDetails
        (HsConPatTyArg GhcRn)
        (GenLocated SrcSpanAnnA (Pat GhcTc))
        (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
      r)
-> TcM
     (TcEvBinds,
      (HsConDetails
         (HsConPatTyArg GhcRn)
         (GenLocated SrcSpanAnnA (Pat GhcTc))
         (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
       r))
forall result.
SkolemInfoAnon
-> [TyCoVar] -> [TyCoVar] -> TcM result -> TcM (TcEvBinds, result)
checkConstraints (SkolemInfo -> SkolemInfoAnon
getSkolemInfo SkolemInfo
skol_info) [TyCoVar]
ex_tvs' [TyCoVar]
prov_dicts' (TcM
   (HsConDetails
      (HsConPatTyArg GhcRn)
      (GenLocated SrcSpanAnnA (Pat GhcTc))
      (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
    r)
 -> TcM
      (TcEvBinds,
       (HsConDetails
          (HsConPatTyArg GhcRn)
          (GenLocated SrcSpanAnnA (Pat GhcTc))
          (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
        r)))
-> TcM
     (HsConDetails
        (HsConPatTyArg GhcRn)
        (GenLocated SrcSpanAnnA (Pat GhcTc))
        (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
      r)
-> TcM
     (TcEvBinds,
      (HsConDetails
         (HsConPatTyArg GhcRn)
         (GenLocated SrcSpanAnnA (Pat GhcTc))
         (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
       r))
forall a b. (a -> b) -> a -> b
$
                Subst
-> PatEnv
-> [(HsConPatTyArg GhcRn, TyCoVar)]
-> TcM
     (HsConDetails
        (HsConPatTyArg GhcRn)
        (GenLocated SrcSpanAnnA (Pat GhcTc))
        (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
      r)
-> TcM
     (HsConDetails
        (HsConPatTyArg GhcRn)
        (GenLocated SrcSpanAnnA (Pat GhcTc))
        (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
      r)
forall a.
Subst
-> PatEnv -> [(HsConPatTyArg GhcRn, TyCoVar)] -> TcM a -> TcM a
tcConTyArgs Subst
tenv PatEnv
penv [(HsConPatTyArg GhcRn, TyCoVar)]
ex_ty_args                               (TcM
   (HsConDetails
      (HsConPatTyArg GhcRn)
      (GenLocated SrcSpanAnnA (Pat GhcTc))
      (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
    r)
 -> TcM
      (HsConDetails
         (HsConPatTyArg GhcRn)
         (GenLocated SrcSpanAnnA (Pat GhcTc))
         (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
       r))
-> TcM
     (HsConDetails
        (HsConPatTyArg GhcRn)
        (GenLocated SrcSpanAnnA (Pat GhcTc))
        (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
      r)
-> TcM
     (HsConDetails
        (HsConPatTyArg GhcRn)
        (GenLocated SrcSpanAnnA (Pat GhcTc))
        (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
      r)
forall a b. (a -> b) -> a -> b
$
                ConLike
-> [Scaled Type]
-> Checker (HsConPatDetails GhcRn) (HsConPatDetails GhcTc)
tcConValArgs ConLike
con_like [Scaled Type]
arg_tys_scaled PatEnv
penv HsConPatDetails GhcRn
arg_pats             (TcM r -> TcM (HsConPatDetails GhcTc, r))
-> TcM r -> TcM (HsConPatDetails GhcTc, r)
forall a b. (a -> b) -> a -> b
$
                TcM r
thing_inside
        ; String -> SDoc -> TcRn ()
traceTc String
"checkConstraints }" (TcEvBinds -> SDoc
forall a. Outputable a => a -> SDoc
ppr TcEvBinds
ev_binds)

        ; let res_pat :: Pat GhcTc
res_pat = ConPat { pat_con :: XRec GhcTc (ConLikeP GhcTc)
pat_con   = SrcSpanAnnN -> ConLike -> GenLocated SrcSpanAnnN ConLike
forall l e. l -> e -> GenLocated l e
L SrcSpanAnnN
con_span (ConLike -> GenLocated SrcSpanAnnN ConLike)
-> ConLike -> GenLocated SrcSpanAnnN ConLike
forall a b. (a -> b) -> a -> b
$ PatSyn -> ConLike
PatSynCon PatSyn
pat_syn
                               , pat_args :: HsConPatDetails GhcTc
pat_args  = HsConPatDetails GhcTc
HsConDetails
  (HsConPatTyArg GhcRn)
  (GenLocated SrcSpanAnnA (Pat GhcTc))
  (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc)))
arg_pats'
                               , pat_con_ext :: XConPat GhcTc
pat_con_ext = ConPatTc
                                 { cpt_tvs :: [TyCoVar]
cpt_tvs   = [TyCoVar]
ex_tvs'
                                 , cpt_dicts :: [TyCoVar]
cpt_dicts = [TyCoVar]
prov_dicts'
                                 , cpt_binds :: TcEvBinds
cpt_binds = TcEvBinds
ev_binds
                                 , cpt_arg_tys :: [Type]
cpt_arg_tys = [TyCoVar] -> [Type]
mkTyVarTys [TyCoVar]
univ_tvs'
                                 , cpt_wrap :: HsWrapper
cpt_wrap  = HsWrapper
req_wrap
                                 }
                               }
        ; Type
pat_ty <- ExpSigmaTypeFRR -> TcM Type
forall (m :: * -> *). MonadIO m => ExpSigmaTypeFRR -> m Type
readExpType (Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR
forall a. Scaled a -> a
scaledThing Scaled ExpSigmaTypeFRR
pat_ty)
        ; (Pat GhcTc, r) -> TcM (Pat GhcTc, r)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (HsWrapper -> Pat GhcTc -> Type -> Pat GhcTc
mkHsWrapPat (HsWrapper
wrap HsWrapper -> HsWrapper -> HsWrapper
<.> HsWrapper
mult_wrap) Pat GhcTc
res_pat Type
pat_ty, r
res) }

checkFixedRuntimeRep :: DataCon -> [Scaled TcSigmaTypeFRR] -> TcM ()
checkFixedRuntimeRep :: DataCon -> [Scaled Type] -> TcRn ()
checkFixedRuntimeRep DataCon
data_con [Scaled Type]
arg_tys
  = (Int -> Scaled Type -> TcRn ())
-> [Int] -> [Scaled Type] -> TcRn ()
forall (m :: * -> *) a b c.
Applicative m =>
(a -> b -> m c) -> [a] -> [b] -> m ()
zipWithM_ Int -> Scaled Type -> TcRn ()
check_one [Int
1..] [Scaled Type]
arg_tys
  where
    check_one :: Int -> Scaled Type -> TcRn ()
check_one Int
i Scaled Type
arg_ty = HasDebugCallStack => FixedRuntimeRepContext -> Type -> TcRn ()
FixedRuntimeRepContext -> Type -> TcRn ()
hasFixedRuntimeRep_syntactic
                            (DataCon -> Int -> FixedRuntimeRepContext
FRRDataConPatArg DataCon
data_con Int
i)
                            (Scaled Type -> Type
forall a. Scaled a -> a
scaledThing Scaled Type
arg_ty)

{- Note [Call-stack tracing of pattern synonyms]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider
   f :: HasCallStack => blah

   pattern Annotated :: HasCallStack => (CallStack, a) -> a
   pattern Annotated x <- (f -> x)

When we pattern-match against `Annotated` we will call `f`, and must
pass a call-stack.  We may want `Annotated` itself to propagate the call
stack, so we give it a HasCallStack constraint too.  But then we expect
to see `Annotated` in the call stack.

This is achieve easily, but a bit trickily.  When we instantiate
Annotated's "required" constraints, in tcPatSynPat, give them a
CtOrigin of (OccurrenceOf "Annotated"). That way the special magic
in GHC.Tc.Solver.Dict.solveCallStack which deals with CallStack
constraints will kick in: that logic only fires on constraints
whose Origin is (OccurrenceOf f).

See also Note [Overview of implicit CallStacks] in GHC.Tc.Types.Evidence
and Note [Solving CallStack constraints] in GHC.Tc.Solver.Types
-}
----------------------------
-- | Convenient wrapper for calling a matchExpectedXXX function
matchExpectedPatTy :: (TcRhoType -> TcM (TcCoercionN, a))
                    -> PatEnv -> ExpSigmaTypeFRR -> TcM (HsWrapper, a)
-- See Note [Matching polytyped patterns]
-- Returns a wrapper : pat_ty ~R inner_ty
matchExpectedPatTy :: forall a.
(Type -> TcM (TcCoercionN, a))
-> PatEnv -> ExpSigmaTypeFRR -> TcM (HsWrapper, a)
matchExpectedPatTy Type -> TcM (TcCoercionN, a)
inner_match (PE { pe_orig :: PatEnv -> CtOrigin
pe_orig = CtOrigin
orig }) ExpSigmaTypeFRR
pat_ty
  = do { Type
pat_ty <- ExpSigmaTypeFRR -> TcM Type
expTypeToType ExpSigmaTypeFRR
pat_ty
       ; (HsWrapper
wrap, Type
pat_rho) <- CtOrigin -> Type -> TcM (HsWrapper, Type)
topInstantiate CtOrigin
orig Type
pat_ty
       ; (TcCoercionN
co, a
res) <- Type -> TcM (TcCoercionN, a)
inner_match Type
pat_rho
       ; String -> SDoc -> TcRn ()
traceTc String
"matchExpectedPatTy" (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
pat_ty SDoc -> SDoc -> SDoc
forall doc. IsDoc doc => doc -> doc -> doc
$$ HsWrapper -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsWrapper
wrap)
       ; (HsWrapper, a) -> TcM (HsWrapper, a)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (TcCoercionN -> HsWrapper
mkWpCastN (TcCoercionN -> TcCoercionN
mkSymCo TcCoercionN
co) HsWrapper -> HsWrapper -> HsWrapper
<.> HsWrapper
wrap, a
res) }

----------------------------
matchExpectedConTy :: PatEnv
                   -> TyCon
                       -- ^ The TyCon that this data constructor actually returns.
                       -- In the case of a data family, this is
                       -- the /representation/ TyCon.
                   -> Scaled ExpSigmaTypeFRR
                       -- ^ The type of the pattern.
                       -- In the case of a data family, this would
                       -- mention the /family/ TyCon
                   -> TcM (HsWrapper, [TcSigmaType])
-- See Note [Matching constructor patterns]
-- Returns a wrapper : pat_ty "->" T ty1 ... tyn
matchExpectedConTy :: PatEnv
-> TyCon -> Scaled ExpSigmaTypeFRR -> TcM (HsWrapper, [Type])
matchExpectedConTy (PE { pe_orig :: PatEnv -> CtOrigin
pe_orig = CtOrigin
orig }) TyCon
data_tc Scaled ExpSigmaTypeFRR
exp_pat_ty
  | Just (TyCon
fam_tc, [Type]
fam_args, CoAxiom Unbranched
co_tc) <- TyCon -> Maybe (TyCon, [Type], CoAxiom Unbranched)
tyConFamInstSig_maybe TyCon
data_tc
         -- Comments refer to Note [Matching constructor patterns]
         -- co_tc :: forall a. T [a] ~ T7 a
  = do { Type
pat_ty <- ExpSigmaTypeFRR -> TcM Type
expTypeToType (Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR
forall a. Scaled a -> a
scaledThing Scaled ExpSigmaTypeFRR
exp_pat_ty)
       ; (HsWrapper
wrap, Type
pat_rho) <- CtOrigin -> Type -> TcM (HsWrapper, Type)
topInstantiate CtOrigin
orig Type
pat_ty

       ; (Subst
subst, [TyCoVar]
tvs') <- [TyCoVar] -> TcM (Subst, [TyCoVar])
newMetaTyVars (TyCon -> [TyCoVar]
tyConTyVars TyCon
data_tc)
             -- tys = [ty1,ty2]

       ; String -> SDoc -> TcRn ()
traceTc String
"matchExpectedConTy" ([SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat [TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
data_tc,
                                             [TyCoVar] -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyCon -> [TyCoVar]
tyConTyVars TyCon
data_tc),
                                             TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
fam_tc, [Type] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Type]
fam_args,
                                             Scaled ExpSigmaTypeFRR -> SDoc
forall a. Outputable a => a -> SDoc
ppr Scaled ExpSigmaTypeFRR
exp_pat_ty,
                                             Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
pat_ty,
                                             Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
pat_rho, HsWrapper -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsWrapper
wrap])
       ; TcCoercionN
co1 <- Maybe TypedThing -> Type -> Type -> TcM TcCoercionN
unifyType Maybe TypedThing
forall a. Maybe a
Nothing (TyCon -> [Type] -> Type
mkTyConApp TyCon
fam_tc (HasDebugCallStack => Subst -> [Type] -> [Type]
Subst -> [Type] -> [Type]
substTys Subst
subst [Type]
fam_args)) Type
pat_rho
             -- co1 : T (ty1,ty2) ~N pat_rho
             -- could use tcSubType here... but it's the wrong way round
             -- for actual vs. expected in error messages.

       ; let tys' :: [Type]
tys' = [TyCoVar] -> [Type]
mkTyVarTys [TyCoVar]
tvs'
             co2 :: TcCoercionN
co2 = Role
-> CoAxiom Unbranched -> [Type] -> [TcCoercionN] -> TcCoercionN
mkUnbranchedAxInstCo Role
Representational CoAxiom Unbranched
co_tc [Type]
tys' []
             -- co2 : T (ty1,ty2) ~R T7 ty1 ty2

             full_co :: TcCoercionN
full_co = HasDebugCallStack => TcCoercionN -> TcCoercionN
TcCoercionN -> TcCoercionN
mkSubCo (TcCoercionN -> TcCoercionN
mkSymCo TcCoercionN
co1) TcCoercionN -> TcCoercionN -> TcCoercionN
`mkTransCo` TcCoercionN
co2
             -- full_co :: pat_rho ~R T7 ty1 ty2

       ; (HsWrapper, [Type]) -> TcM (HsWrapper, [Type])
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ( TcCoercionN -> HsWrapper
mkWpCastR TcCoercionN
full_co HsWrapper -> HsWrapper -> HsWrapper
<.> HsWrapper
wrap, [Type]
tys') }

  | Bool
otherwise
  = do { Type
pat_ty <- ExpSigmaTypeFRR -> TcM Type
expTypeToType (Scaled ExpSigmaTypeFRR -> ExpSigmaTypeFRR
forall a. Scaled a -> a
scaledThing Scaled ExpSigmaTypeFRR
exp_pat_ty)
       ; (HsWrapper
wrap, Type
pat_rho) <- CtOrigin -> Type -> TcM (HsWrapper, Type)
topInstantiate CtOrigin
orig Type
pat_ty
       ; (TcCoercionN
coi, [Type]
tys) <- TyCon -> Type -> TcM (TcCoercionN, [Type])
matchExpectedTyConApp TyCon
data_tc Type
pat_rho
       ; (HsWrapper, [Type]) -> TcM (HsWrapper, [Type])
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (TcCoercionN -> HsWrapper
mkWpCastN (TcCoercionN -> TcCoercionN
mkSymCo TcCoercionN
coi) HsWrapper -> HsWrapper -> HsWrapper
<.> HsWrapper
wrap, [Type]
tys) }

{-
Note [Matching constructor patterns]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Suppose (coi, tys) = matchExpectedConType data_tc pat_ty

 * In the simple case, pat_ty = tc tys

 * If pat_ty is a polytype, we want to instantiate it
   This is like part of a subsumption check.  Eg
      f :: (forall a. [a]) -> blah
      f [] = blah

 * In a type family case, suppose we have
          data family T a
          data instance T (p,q) = A p | B q
       Then we'll have internally generated
              data T7 p q = A p | B q
              axiom coT7 p q :: T (p,q) ~ T7 p q

       So if pat_ty = T (ty1,ty2), we return (coi, [ty1,ty2]) such that
           coi = coi2 . coi1 : T7 t ~ pat_ty
           coi1 : T (ty1,ty2) ~ pat_ty
           coi2 : T7 ty1 ty2 ~ T (ty1,ty2)

   For families we do all this matching here, not in the unifier,
   because we never want a whisper of the data_tycon to appear in
   error messages; it's a purely internal thing
-}

{- Note [Type applications in patterns]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Type applications in patterns are enabled by -XTypeAbstractions.
For example:
   f :: Either (Maybe a) [b] -> blah
   f (Left @x @[y] (v::Maybe x)) = blah

How should we typecheck them?  The basic plan is pretty simple, and is
all done in tcConTyArgs. For each type argument:

* Step 1:
    * bind the newly-in-scope type variables (here `x` or `y`) to
      unification variables, say `x0` or `y0`

    * typecheck the type argument, `@x` or `@[y]` to get the
      types `x0` or `[y0]`.

    This step is done by `tcHsPatSigType`, similar to the way we
    deal with pattern signatures.

* Step 2: Unify those types with the type arguments we expect from
  the context, in this case (Maybe a) and [b].  These unifications
  will (perhaps after the constraint solver has done its work)
  unify   x0 := Maybe a
          y0 := b
  Thus we learn that x stands for (Maybe a) and y for b.

* Step 3: Extend the lexical context to bind `x` to `x0` and
  `y` to `y0`, and typecheck the body of the pattern match.

However there are several quite tricky wrinkles.

(W1) Surprisingly, we can discard the coercions arising from
     these unifications.  The *only* thing the unification does is
     to side-effect those unification variables, so that we know
     what type x and y stand for; and cause an error if the equality
     is not soluble.  It's a bit like a constraint arising
     from a functional dependency, where we don't use the evidence.

(W2) Note that both here and in pattern signatures the unification may
     not even end up unifying the variable.  For example
       type S a b = a
       f :: Maybe a -> Bool
       f (Just @(S a b) x) = True :: b
     In Step 2 we will unify (S a0 b0 ~ a), which succeeds, but has no
     effect on the unification variable b0, to which 'b' is bound.
     Later, in the RHS, we find that b0 must be Bool, and unify it there.
     All is fine.

(W3) The order of the arguments to the /data constructor/ may differ from
     the order of the arguments to the /type constructor/. Example
         data T a b where { MkT :: forall c d. (c,d) -> T d c }
         f :: T Int Bool -> blah
         f (MkT @x @y p) = ...
     The /first/ type argument to `MkT`, namely `@x` corresponds to the
     /second/ argument to `T` in the type `T Int Bool`.  So `x` is bound
     to `Bool` -- not to `Int`!.  That is why splitConTyArgs uses
     conLikeUserTyVarBinders to match up with the user-supplied type arguments
     in the pattern, not dataConUnivTyVars/dataConExTyVars.

(W4) A similar story works for existentials, but it is subtly different
     (#19847).  Consider
         data T a where { MkT :: forall a b. a -> b -> T a }
         f :: T Int -> blah
         f (MkT @x @y v w) = blah
     Here we create a fresh unification variables x0,y0 for x,y and
     unify x0~Int, y0~b, where b is the fresh existential variable bound by
     the pattern. But
       * (x0~Int) must be /outside/ the implication constraint
       * (y0~b)   must be /inside/ it
     (and hence x0 and y0 themselves must have different levels).
     Thus:
         x0[1]~Int,  (forall[2] b. (y0[2]~b, ...constraints-from-blah...))

     We need (x0~Int) /outside/ so that it can influence the type of the
     pattern in an inferred setting, e.g.
         g :: T _ -> blah
         g (MkT @Int @y v w) = blah
     Here we want to infer `g` to have type `T Int -> blah`. If the
     (x0~Int) was inside the implication, and the the constructor bound
     equality constraints, `x0` would be untouchable. This was the root
     cause of #19847.

     We need (y0~b) to be /inside/ the implication, so that `b` is in
     scope.  In fact, we may actually /need/ equalities bound by the
     implication to prove the equality constraint we generate.
     Example   data T a where
                 MkT :: forall p q. T (p,q)
               f :: T (Int,Bool) -> blah
               f (MkT @Int @Bool) = ...
     We get the implication
        forall[2] p q. (p,q)~(Int,Bool) => (p ~ Int, q ~ Bool, ...)
     where the Given comes from the GADT match, while (p~Int, q~Bool)
     comes from matching the type arguments.

     Wow.  That's all quite subtle! See the long discussion on #19847.  We
     must treat universal and existential arguments separately, even though
     they are all mixed up (W3).  The function splitConTyArgs separates the
     universals from existentials; and we build the implication between
     typechecking the two sets:
           tcConTyArgs ... univ_ty_args    $
           checkConstraints ...            $
           tcConTyArgs ... ex_ty_args      $
           ..typecheck body..
     You can see this code shape in tcDataConPat and tcPatSynPat.

     Where pattern synonyms are involved, this two-level split may not be
     enough.  See #22328 for the story.
-}

tcConValArgs :: ConLike
             -> [Scaled TcSigmaTypeFRR]
             -> Checker (HsConPatDetails GhcRn) (HsConPatDetails GhcTc)
tcConValArgs :: ConLike
-> [Scaled Type]
-> Checker (HsConPatDetails GhcRn) (HsConPatDetails GhcTc)
tcConValArgs ConLike
con_like [Scaled Type]
arg_tys PatEnv
penv HsConPatDetails GhcRn
con_args TcM r
thing_inside = case HsConPatDetails GhcRn
con_args of
  PrefixCon [HsConPatTyArg (NoGhcTc GhcRn)]
type_args [LPat GhcRn]
arg_pats -> do
        -- NB: type_args already dealt with
        -- See Note [Type applications in patterns]
        { Bool -> TcRnMessage -> TcRn ()
checkTc (Int
con_arity Int -> Int -> Bool
forall a. Eq a => a -> a -> Bool
== Int
no_of_args)     -- Check correct arity
                  (TyThing -> Int -> Int -> TcRnMessage
TcRnArityMismatch (ConLike -> TyThing
AConLike ConLike
con_like) Int
con_arity Int
no_of_args)

        ; let pats_w_tys :: [(GenLocated SrcSpanAnnA (Pat GhcRn), Scaled Type)]
pats_w_tys = String
-> [GenLocated SrcSpanAnnA (Pat GhcRn)]
-> [Scaled Type]
-> [(GenLocated SrcSpanAnnA (Pat GhcRn), Scaled Type)]
forall a b. HasDebugCallStack => String -> [a] -> [b] -> [(a, b)]
zipEqual String
"tcConArgs" [LPat GhcRn]
[GenLocated SrcSpanAnnA (Pat GhcRn)]
arg_pats [Scaled Type]
arg_tys
        ; ([GenLocated SrcSpanAnnA (Pat GhcTc)]
arg_pats', r
res) <- Checker
  (GenLocated SrcSpanAnnA (Pat GhcRn), Scaled Type)
  (GenLocated SrcSpanAnnA (Pat GhcTc))
-> Checker
     [(GenLocated SrcSpanAnnA (Pat GhcRn), Scaled Type)]
     [GenLocated SrcSpanAnnA (Pat GhcTc)]
forall inp out. Checker inp out -> Checker [inp] [out]
tcMultiple PatEnv -> (LPat GhcRn, Scaled Type) -> TcM r -> TcM (LPat GhcTc, r)
PatEnv
-> (GenLocated SrcSpanAnnA (Pat GhcRn), Scaled Type)
-> TcM r
-> IOEnv
     (Env TcGblEnv TcLclEnv) (GenLocated SrcSpanAnnA (Pat GhcTc), r)
Checker (LPat GhcRn, Scaled Type) (LPat GhcTc)
Checker
  (GenLocated SrcSpanAnnA (Pat GhcRn), Scaled Type)
  (GenLocated SrcSpanAnnA (Pat GhcTc))
tcConArg PatEnv
penv [(GenLocated SrcSpanAnnA (Pat GhcRn), Scaled Type)]
pats_w_tys TcM r
thing_inside

        ; (HsConDetails
   (HsConPatTyArg GhcRn)
   (GenLocated SrcSpanAnnA (Pat GhcTc))
   (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
 r)
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (HsConDetails
        (HsConPatTyArg GhcRn)
        (GenLocated SrcSpanAnnA (Pat GhcTc))
        (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
      r)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ([HsConPatTyArg GhcRn]
-> [GenLocated SrcSpanAnnA (Pat GhcTc)]
-> HsConDetails
     (HsConPatTyArg GhcRn)
     (GenLocated SrcSpanAnnA (Pat GhcTc))
     (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc)))
forall tyarg arg rec.
[tyarg] -> [arg] -> HsConDetails tyarg arg rec
PrefixCon [HsConPatTyArg (NoGhcTc GhcRn)]
[HsConPatTyArg GhcRn]
type_args [GenLocated SrcSpanAnnA (Pat GhcTc)]
arg_pats', r
res) }
    where
      con_arity :: Int
con_arity  = ConLike -> Int
conLikeArity ConLike
con_like
      no_of_args :: Int
no_of_args = [GenLocated SrcSpanAnnA (Pat GhcRn)] -> Int
forall a. [a] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length [LPat GhcRn]
[GenLocated SrcSpanAnnA (Pat GhcRn)]
arg_pats

  InfixCon LPat GhcRn
p1 LPat GhcRn
p2 -> do
        { Bool -> TcRnMessage -> TcRn ()
checkTc (Int
con_arity Int -> Int -> Bool
forall a. Eq a => a -> a -> Bool
== Int
2)      -- Check correct arity
                  (TyThing -> Int -> Int -> TcRnMessage
TcRnArityMismatch (ConLike -> TyThing
AConLike ConLike
con_like) Int
con_arity Int
2)
        ; let [Scaled Type
arg_ty1,Scaled Type
arg_ty2] = [Scaled Type]
arg_tys       -- This can't fail after the arity check
        ; ([GenLocated SrcSpanAnnA (Pat GhcTc)
p1',GenLocated SrcSpanAnnA (Pat GhcTc)
p2'], r
res) <- Checker
  (GenLocated SrcSpanAnnA (Pat GhcRn), Scaled Type)
  (GenLocated SrcSpanAnnA (Pat GhcTc))
-> Checker
     [(GenLocated SrcSpanAnnA (Pat GhcRn), Scaled Type)]
     [GenLocated SrcSpanAnnA (Pat GhcTc)]
forall inp out. Checker inp out -> Checker [inp] [out]
tcMultiple PatEnv -> (LPat GhcRn, Scaled Type) -> TcM r -> TcM (LPat GhcTc, r)
PatEnv
-> (GenLocated SrcSpanAnnA (Pat GhcRn), Scaled Type)
-> TcM r
-> IOEnv
     (Env TcGblEnv TcLclEnv) (GenLocated SrcSpanAnnA (Pat GhcTc), r)
Checker (LPat GhcRn, Scaled Type) (LPat GhcTc)
Checker
  (GenLocated SrcSpanAnnA (Pat GhcRn), Scaled Type)
  (GenLocated SrcSpanAnnA (Pat GhcTc))
tcConArg PatEnv
penv [(LPat GhcRn
GenLocated SrcSpanAnnA (Pat GhcRn)
p1,Scaled Type
arg_ty1),(LPat GhcRn
GenLocated SrcSpanAnnA (Pat GhcRn)
p2,Scaled Type
arg_ty2)]
                                                  TcM r
thing_inside
        ; (HsConDetails
   (HsConPatTyArg GhcRn)
   (GenLocated SrcSpanAnnA (Pat GhcTc))
   (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
 r)
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (HsConDetails
        (HsConPatTyArg GhcRn)
        (GenLocated SrcSpanAnnA (Pat GhcTc))
        (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
      r)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (GenLocated SrcSpanAnnA (Pat GhcTc)
-> GenLocated SrcSpanAnnA (Pat GhcTc)
-> HsConDetails
     (HsConPatTyArg GhcRn)
     (GenLocated SrcSpanAnnA (Pat GhcTc))
     (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc)))
forall tyarg arg rec. arg -> arg -> HsConDetails tyarg arg rec
InfixCon GenLocated SrcSpanAnnA (Pat GhcTc)
p1' GenLocated SrcSpanAnnA (Pat GhcTc)
p2', r
res) }
    where
      con_arity :: Int
con_arity  = ConLike -> Int
conLikeArity ConLike
con_like

  RecCon (HsRecFields [LHsRecField GhcRn (LPat GhcRn)]
rpats Maybe (XRec GhcRn RecFieldsDotDot)
dd) -> do
        { ([GenLocated
   SrcSpanAnnA
   (HsFieldBind
      (GenLocated (SrcAnn NoEpAnns) (FieldOcc GhcTc))
      (GenLocated SrcSpanAnnA (Pat GhcTc)))]
rpats', r
res) <- Checker
  (GenLocated
     SrcSpanAnnA
     (HsFieldBind
        (GenLocated (SrcAnn NoEpAnns) (FieldOcc GhcRn))
        (GenLocated SrcSpanAnnA (Pat GhcRn))))
  (GenLocated
     SrcSpanAnnA
     (HsFieldBind
        (GenLocated (SrcAnn NoEpAnns) (FieldOcc GhcTc))
        (GenLocated SrcSpanAnnA (Pat GhcTc))))
-> Checker
     [GenLocated
        SrcSpanAnnA
        (HsFieldBind
           (GenLocated (SrcAnn NoEpAnns) (FieldOcc GhcRn))
           (GenLocated SrcSpanAnnA (Pat GhcRn)))]
     [GenLocated
        SrcSpanAnnA
        (HsFieldBind
           (GenLocated (SrcAnn NoEpAnns) (FieldOcc GhcTc))
           (GenLocated SrcSpanAnnA (Pat GhcTc)))]
forall inp out. Checker inp out -> Checker [inp] [out]
tcMultiple PatEnv
-> LHsRecField GhcRn (LPat GhcRn)
-> TcM r
-> TcM (LHsRecField GhcTc (LPat GhcTc), r)
PatEnv
-> GenLocated
     SrcSpanAnnA
     (HsFieldBind
        (GenLocated (SrcAnn NoEpAnns) (FieldOcc GhcRn))
        (GenLocated SrcSpanAnnA (Pat GhcRn)))
-> TcM r
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (GenLocated
        SrcSpanAnnA
        (HsFieldBind
           (GenLocated (SrcAnn NoEpAnns) (FieldOcc GhcTc))
           (GenLocated SrcSpanAnnA (Pat GhcTc))),
      r)
Checker
  (LHsRecField GhcRn (LPat GhcRn)) (LHsRecField GhcTc (LPat GhcTc))
Checker
  (GenLocated
     SrcSpanAnnA
     (HsFieldBind
        (GenLocated (SrcAnn NoEpAnns) (FieldOcc GhcRn))
        (GenLocated SrcSpanAnnA (Pat GhcRn))))
  (GenLocated
     SrcSpanAnnA
     (HsFieldBind
        (GenLocated (SrcAnn NoEpAnns) (FieldOcc GhcTc))
        (GenLocated SrcSpanAnnA (Pat GhcTc))))
tc_field PatEnv
penv [LHsRecField GhcRn (LPat GhcRn)]
[GenLocated
   SrcSpanAnnA
   (HsFieldBind
      (GenLocated (SrcAnn NoEpAnns) (FieldOcc GhcRn))
      (GenLocated SrcSpanAnnA (Pat GhcRn)))]
rpats TcM r
thing_inside
        ; (HsConDetails
   (HsConPatTyArg GhcRn)
   (GenLocated SrcSpanAnnA (Pat GhcTc))
   (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
 r)
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (HsConDetails
        (HsConPatTyArg GhcRn)
        (GenLocated SrcSpanAnnA (Pat GhcTc))
        (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))),
      r)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))
-> HsConDetails
     (HsConPatTyArg GhcRn)
     (GenLocated SrcSpanAnnA (Pat GhcTc))
     (HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc)))
forall tyarg arg rec. rec -> HsConDetails tyarg arg rec
RecCon ([LHsRecField GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))]
-> Maybe (XRec GhcTc RecFieldsDotDot)
-> HsRecFields GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))
forall p arg.
[LHsRecField p arg]
-> Maybe (XRec p RecFieldsDotDot) -> HsRecFields p arg
HsRecFields [LHsRecField GhcTc (GenLocated SrcSpanAnnA (Pat GhcTc))]
[GenLocated
   SrcSpanAnnA
   (HsFieldBind
      (GenLocated (SrcAnn NoEpAnns) (FieldOcc GhcTc))
      (GenLocated SrcSpanAnnA (Pat GhcTc)))]
rpats' Maybe (XRec GhcRn RecFieldsDotDot)
Maybe (XRec GhcTc RecFieldsDotDot)
dd), r
res) }
    where
      tc_field :: Checker (LHsRecField GhcRn (LPat GhcRn))
                          (LHsRecField GhcTc (LPat GhcTc))
      tc_field :: Checker
  (LHsRecField GhcRn (LPat GhcRn)) (LHsRecField GhcTc (LPat GhcTc))
tc_field PatEnv
penv
               (L SrcSpanAnnA
l (HsFieldBind XHsFieldBind (GenLocated (SrcAnn NoEpAnns) (FieldOcc GhcRn))
ann (L SrcAnn NoEpAnns
loc (FieldOcc XCFieldOcc GhcRn
sel (L SrcSpanAnnN
lr RdrName
rdr))) GenLocated SrcSpanAnnA (Pat GhcRn)
pat Bool
pun))
               TcM r
thing_inside
        = do { TyCoVar
sel'   <- Name -> TcM TyCoVar
tcLookupId XCFieldOcc GhcRn
Name
sel
             ; Scaled Type
pat_ty <- SrcAnn NoEpAnns -> TcRn (Scaled Type) -> TcRn (Scaled Type)
forall ann a. SrcSpanAnn' ann -> TcRn a -> TcRn a
setSrcSpanA SrcAnn NoEpAnns
loc (TcRn (Scaled Type) -> TcRn (Scaled Type))
-> TcRn (Scaled Type) -> TcRn (Scaled Type)
forall a b. (a -> b) -> a -> b
$ Name -> FastString -> TcRn (Scaled Type)
find_field_ty XCFieldOcc GhcRn
Name
sel
                                            (OccName -> FastString
occNameFS (OccName -> FastString) -> OccName -> FastString
forall a b. (a -> b) -> a -> b
$ RdrName -> OccName
rdrNameOcc RdrName
rdr)
             ; (GenLocated SrcSpanAnnA (Pat GhcTc)
pat', r
res) <- PatEnv -> (LPat GhcRn, Scaled Type) -> TcM r -> TcM (LPat GhcTc, r)
Checker (LPat GhcRn, Scaled Type) (LPat GhcTc)
tcConArg PatEnv
penv (LPat GhcRn
GenLocated SrcSpanAnnA (Pat GhcRn)
pat, Scaled Type
pat_ty) TcM r
thing_inside
             ; (GenLocated
   SrcSpanAnnA
   (HsFieldBind
      (GenLocated (SrcAnn NoEpAnns) (FieldOcc GhcTc))
      (GenLocated SrcSpanAnnA (Pat GhcTc))),
 r)
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (GenLocated
        SrcSpanAnnA
        (HsFieldBind
           (GenLocated (SrcAnn NoEpAnns) (FieldOcc GhcTc))
           (GenLocated SrcSpanAnnA (Pat GhcTc))),
      r)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (SrcSpanAnnA
-> HsFieldBind
     (GenLocated (SrcAnn NoEpAnns) (FieldOcc GhcTc))
     (GenLocated SrcSpanAnnA (Pat GhcTc))
-> GenLocated
     SrcSpanAnnA
     (HsFieldBind
        (GenLocated (SrcAnn NoEpAnns) (FieldOcc GhcTc))
        (GenLocated SrcSpanAnnA (Pat GhcTc)))
forall l e. l -> e -> GenLocated l e
L SrcSpanAnnA
l (XHsFieldBind (GenLocated (SrcAnn NoEpAnns) (FieldOcc GhcTc))
-> GenLocated (SrcAnn NoEpAnns) (FieldOcc GhcTc)
-> GenLocated SrcSpanAnnA (Pat GhcTc)
-> Bool
-> HsFieldBind
     (GenLocated (SrcAnn NoEpAnns) (FieldOcc GhcTc))
     (GenLocated SrcSpanAnnA (Pat GhcTc))
forall lhs rhs.
XHsFieldBind lhs -> lhs -> rhs -> Bool -> HsFieldBind lhs rhs
HsFieldBind XHsFieldBind (GenLocated (SrcAnn NoEpAnns) (FieldOcc GhcRn))
XHsFieldBind (GenLocated (SrcAnn NoEpAnns) (FieldOcc GhcTc))
ann (SrcAnn NoEpAnns
-> FieldOcc GhcTc -> GenLocated (SrcAnn NoEpAnns) (FieldOcc GhcTc)
forall l e. l -> e -> GenLocated l e
L SrcAnn NoEpAnns
loc (XCFieldOcc GhcTc -> XRec GhcTc RdrName -> FieldOcc GhcTc
forall pass. XCFieldOcc pass -> XRec pass RdrName -> FieldOcc pass
FieldOcc XCFieldOcc GhcTc
TyCoVar
sel' (SrcSpanAnnN -> RdrName -> GenLocated SrcSpanAnnN RdrName
forall l e. l -> e -> GenLocated l e
L SrcSpanAnnN
lr RdrName
rdr))) GenLocated SrcSpanAnnA (Pat GhcTc)
pat'
                                                                        Bool
pun), r
res) }


      find_field_ty :: Name -> FastString -> TcM (Scaled TcType)
      find_field_ty :: Name -> FastString -> TcRn (Scaled Type)
find_field_ty Name
sel FastString
lbl
        = case [Scaled Type
ty | (FieldLabel
fl, Scaled Type
ty) <- [(FieldLabel, Scaled Type)]
field_tys, FieldLabel -> Name
flSelector FieldLabel
fl Name -> Name -> Bool
forall a. Eq a => a -> a -> Bool
== Name
sel ] of

                -- No matching field; chances are this field label comes from some
                -- other record type (or maybe none).  If this happens, just fail,
                -- otherwise we get crashes later (#8570), and similar:
                --      f (R { foo = (a,b) }) = a+b
                -- If foo isn't one of R's fields, we don't want to crash when
                -- typechecking the "a+b".
           [] -> TcRnMessage -> TcRn (Scaled Type)
forall a. TcRnMessage -> TcRn a
failWith (Name -> FieldLabelString -> TcRnMessage
badFieldConErr (ConLike -> Name
forall a. NamedThing a => a -> Name
getName ConLike
con_like) (FastString -> FieldLabelString
FieldLabelString FastString
lbl))

                -- The normal case, when the field comes from the right constructor
           (Scaled Type
pat_ty : [Scaled Type]
extras) -> do
                String -> SDoc -> TcRn ()
traceTc String
"find_field" (Scaled Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Scaled Type
pat_ty SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [Scaled Type] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Scaled Type]
extras)
                Bool -> TcRn (Scaled Type) -> TcRn (Scaled Type)
forall a. HasCallStack => Bool -> a -> a
assert ([Scaled Type] -> Bool
forall a. [a] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [Scaled Type]
extras) (Scaled Type -> TcRn (Scaled Type)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return Scaled Type
pat_ty)

      field_tys :: [(FieldLabel, Scaled TcType)]
      field_tys :: [(FieldLabel, Scaled Type)]
field_tys = [FieldLabel] -> [Scaled Type] -> [(FieldLabel, Scaled Type)]
forall a b. [a] -> [b] -> [(a, b)]
zip (ConLike -> [FieldLabel]
conLikeFieldLabels ConLike
con_like) [Scaled Type]
arg_tys
          -- Don't use zipEqual! If the constructor isn't really a record, then
          -- dataConFieldLabels will be empty (and each field in the pattern
          -- will generate an error below).


splitConTyArgs :: ConLike -> HsConPatDetails GhcRn
               -> TcM ( [(HsConPatTyArg GhcRn, TyVar)]    -- Universals
                      , [(HsConPatTyArg GhcRn, TyVar)] )  -- Existentials
-- See Note [Type applications in patterns] (W4)
-- This function is monadic only because of the error check
-- for too many type arguments
splitConTyArgs :: ConLike
-> HsConPatDetails GhcRn
-> TcM
     ([(HsConPatTyArg GhcRn, TyCoVar)],
      [(HsConPatTyArg GhcRn, TyCoVar)])
splitConTyArgs ConLike
con_like (PrefixCon [HsConPatTyArg (NoGhcTc GhcRn)]
type_args [LPat GhcRn]
_)
  = do { Bool -> TcRnMessage -> TcRn ()
checkTc ([HsConPatTyArg (NoGhcTc GhcRn)]
[HsConPatTyArg GhcRn]
type_args [HsConPatTyArg GhcRn] -> [TyCoVar] -> Bool
forall a b. [a] -> [b] -> Bool
`leLength` [TyCoVar]
con_spec_bndrs)
                 (ConLike -> Int -> Int -> TcRnMessage
TcRnTooManyTyArgsInConPattern ConLike
con_like
                          ([TyCoVar] -> Int
forall a. [a] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length [TyCoVar]
con_spec_bndrs) ([HsConPatTyArg GhcRn] -> Int
forall a. [a] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length [HsConPatTyArg (NoGhcTc GhcRn)]
[HsConPatTyArg GhcRn]
type_args))
       ; if [TyCoVar] -> Bool
forall a. [a] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [TyCoVar]
ex_tvs  -- Short cut common case
         then ([(HsConPatTyArg GhcRn, TyCoVar)],
 [(HsConPatTyArg GhcRn, TyCoVar)])
-> TcM
     ([(HsConPatTyArg GhcRn, TyCoVar)],
      [(HsConPatTyArg GhcRn, TyCoVar)])
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ([(HsConPatTyArg GhcRn, TyCoVar)]
bndr_ty_arg_prs, [])
         else ([(HsConPatTyArg GhcRn, TyCoVar)],
 [(HsConPatTyArg GhcRn, TyCoVar)])
-> TcM
     ([(HsConPatTyArg GhcRn, TyCoVar)],
      [(HsConPatTyArg GhcRn, TyCoVar)])
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (((HsConPatTyArg GhcRn, TyCoVar) -> Bool)
-> [(HsConPatTyArg GhcRn, TyCoVar)]
-> ([(HsConPatTyArg GhcRn, TyCoVar)],
    [(HsConPatTyArg GhcRn, TyCoVar)])
forall a. (a -> Bool) -> [a] -> ([a], [a])
partition (HsConPatTyArg GhcRn, TyCoVar) -> Bool
is_universal [(HsConPatTyArg GhcRn, TyCoVar)]
bndr_ty_arg_prs) }
  where
    ex_tvs :: [TyCoVar]
ex_tvs = ConLike -> [TyCoVar]
conLikeExTyCoVars ConLike
con_like
    con_spec_bndrs :: [TyCoVar]
con_spec_bndrs = [ TyCoVar
tv | Bndr TyCoVar
tv Specificity
SpecifiedSpec <- ConLike -> [VarBndr TyCoVar Specificity]
conLikeUserTyVarBinders ConLike
con_like ]
        -- conLikeUserTyVarBinders: see (W3) in
        --    Note [Type applications in patterns]
        -- SpecifiedSpec: forgetting to filter out inferred binders led to #20443

    bndr_ty_arg_prs :: [(HsConPatTyArg GhcRn, TyCoVar)]
bndr_ty_arg_prs = [HsConPatTyArg (NoGhcTc GhcRn)]
[HsConPatTyArg GhcRn]
type_args [HsConPatTyArg GhcRn]
-> [TyCoVar] -> [(HsConPatTyArg GhcRn, TyCoVar)]
forall a b. [a] -> [b] -> [(a, b)]
`zip` [TyCoVar]
con_spec_bndrs
                      -- The zip truncates to length(type_args)

    is_universal :: (HsConPatTyArg GhcRn, TyCoVar) -> Bool
is_universal (HsConPatTyArg GhcRn
_, TyCoVar
tv) = Bool -> Bool
not (TyCoVar
tv TyCoVar -> [TyCoVar] -> Bool
forall a. Eq a => a -> [a] -> Bool
forall (t :: * -> *) a. (Foldable t, Eq a) => a -> t a -> Bool
`elem` [TyCoVar]
ex_tvs)
         -- See Note [DataCon user type variable binders] in GHC.Core.DataCon
         -- especially INVARIANT(dataConTyVars).

splitConTyArgs ConLike
_ (RecCon {})   = ([(HsConPatTyArg GhcRn, TyCoVar)],
 [(HsConPatTyArg GhcRn, TyCoVar)])
-> TcM
     ([(HsConPatTyArg GhcRn, TyCoVar)],
      [(HsConPatTyArg GhcRn, TyCoVar)])
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ([], []) -- No type args in RecCon
splitConTyArgs ConLike
_ (InfixCon {}) = ([(HsConPatTyArg GhcRn, TyCoVar)],
 [(HsConPatTyArg GhcRn, TyCoVar)])
-> TcM
     ([(HsConPatTyArg GhcRn, TyCoVar)],
      [(HsConPatTyArg GhcRn, TyCoVar)])
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ([], []) -- No type args in InfixCon

tcConTyArgs :: Subst -> PatEnv -> [(HsConPatTyArg GhcRn, TyVar)]
            -> TcM a -> TcM a
tcConTyArgs :: forall a.
Subst
-> PatEnv -> [(HsConPatTyArg GhcRn, TyCoVar)] -> TcM a -> TcM a
tcConTyArgs Subst
tenv PatEnv
penv [(HsConPatTyArg GhcRn, TyCoVar)]
prs TcM a
thing_inside
  = Checker (HsConPatTyArg GhcRn, TyCoVar) ()
-> PatEnv -> [(HsConPatTyArg GhcRn, TyCoVar)] -> TcM a -> TcM a
forall inp r. Checker inp () -> PatEnv -> [inp] -> TcM r -> TcM r
tcMultiple_ (Subst -> Checker (HsConPatTyArg GhcRn, TyCoVar) ()
tcConTyArg Subst
tenv) PatEnv
penv [(HsConPatTyArg GhcRn, TyCoVar)]
prs TcM a
thing_inside

tcConTyArg :: Subst -> Checker (HsConPatTyArg GhcRn, TyVar) ()
tcConTyArg :: Subst -> Checker (HsConPatTyArg GhcRn, TyCoVar) ()
tcConTyArg Subst
tenv PatEnv
penv (HsConPatTyArg LHsToken "@" GhcRn
_ HsPatSigType GhcRn
rn_ty, TyCoVar
con_tv) TcM r
thing_inside
  = do { ([(Name, TyCoVar)]
sig_wcs, [(Name, TyCoVar)]
sig_ibs, Type
arg_ty) <- UserTypeCtxt
-> HoleMode
-> HsPatSigType GhcRn
-> ContextKind
-> TcM ([(Name, TyCoVar)], [(Name, TyCoVar)], Type)
tcHsPatSigType UserTypeCtxt
TypeAppCtxt HoleMode
HM_TyAppPat HsPatSigType GhcRn
rn_ty ContextKind
AnyKind
               -- AnyKind is a bit suspect: it really should be the kind gotten
               -- from instantiating the constructor type. But this would be
               -- hard to get right, because earlier type patterns might influence
               -- the kinds of later patterns. In any case, it all gets checked
               -- by the calls to unifyType below which unifies kinds

       ; case [(Name, TyCoVar)] -> Maybe (NonEmpty (Name, TyCoVar))
forall a. [a] -> Maybe (NonEmpty a)
NE.nonEmpty [(Name, TyCoVar)]
sig_ibs of
           Just NonEmpty (Name, TyCoVar)
sig_ibs_ne | PatEnv -> Bool
inPatBind PatEnv
penv ->
             TcRnMessage -> TcRn ()
addErr (NonEmpty (Name, TyCoVar) -> TcRnMessage
TcRnCannotBindTyVarsInPatBind NonEmpty (Name, TyCoVar)
sig_ibs_ne)
           Maybe (NonEmpty (Name, TyCoVar))
_ -> () -> TcRn ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (f :: * -> *) a. Applicative f => a -> f a
pure ()

          -- This unification is straight from Figure 7 of
          -- "Type Variables in Patterns", Haskell'18
          -- OK to drop coercions here. These unifications are all about
          -- guiding inference based on a user-written type annotation
          -- See Note [Type applications in patterns] (W1)
       ; TcCoercionN
_ <- Maybe TypedThing -> Type -> Type -> TcM TcCoercionN
unifyType Maybe TypedThing
forall a. Maybe a
Nothing Type
arg_ty (Subst -> TyCoVar -> Type
substTyVar Subst
tenv TyCoVar
con_tv)

       ; r
result <- [(Name, TyCoVar)] -> TcM r -> TcM r
forall r. [(Name, TyCoVar)] -> TcM r -> TcM r
tcExtendNameTyVarEnv [(Name, TyCoVar)]
sig_wcs (TcM r -> TcM r) -> TcM r -> TcM r
forall a b. (a -> b) -> a -> b
$
                   [(Name, TyCoVar)] -> TcM r -> TcM r
forall r. [(Name, TyCoVar)] -> TcM r -> TcM r
tcExtendNameTyVarEnv [(Name, TyCoVar)]
sig_ibs (TcM r -> TcM r) -> TcM r -> TcM r
forall a b. (a -> b) -> a -> b
$
                   TcM r
thing_inside
             -- NB: Because we call tConTyArgs twice, once for universals and
             --     once for existentials; so this brings things into scope
             --     "out of left-right order". But it doesn't matter; the renamer
             --     has dealt with all that.

       ; ((), r) -> TcM ((), r)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ((), r
result) }

tcConArg :: Checker (LPat GhcRn, Scaled TcSigmaType) (LPat GhcTc)
tcConArg :: Checker (LPat GhcRn, Scaled Type) (LPat GhcTc)
tcConArg PatEnv
penv (LPat GhcRn
arg_pat, Scaled Type
arg_mult Type
arg_ty)
  = Scaled ExpSigmaTypeFRR -> Checker (LPat GhcRn) (LPat GhcTc)
tc_lpat (Type -> ExpSigmaTypeFRR -> Scaled ExpSigmaTypeFRR
forall a. Type -> a -> Scaled a
Scaled Type
arg_mult (Type -> ExpSigmaTypeFRR
mkCheckExpType Type
arg_ty)) PatEnv
penv LPat GhcRn
arg_pat

addDataConStupidTheta :: DataCon -> [TcType] -> TcM ()
-- Instantiate the "stupid theta" of the data con, and throw
-- the constraints into the constraint set.
-- See Note [The stupid context] in GHC.Core.DataCon.
addDataConStupidTheta :: DataCon -> [Type] -> TcRn ()
addDataConStupidTheta DataCon
data_con [Type]
inst_tys
  | [Type] -> Bool
forall a. [a] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [Type]
stupid_theta = () -> TcRn ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ()
  | Bool
otherwise         = CtOrigin -> [Type] -> TcRn ()
instStupidTheta CtOrigin
origin [Type]
inst_theta
  where
    origin :: CtOrigin
origin = Name -> CtOrigin
OccurrenceOf (DataCon -> Name
dataConName DataCon
data_con)
        -- The origin should always report "occurrence of C"
        -- even when C occurs in a pattern
    stupid_theta :: [Type]
stupid_theta = DataCon -> [Type]
dataConStupidTheta DataCon
data_con
    univ_tvs :: [TyCoVar]
univ_tvs     = DataCon -> [TyCoVar]
dataConUnivTyVars DataCon
data_con
    tenv :: Subst
tenv = [TyCoVar] -> [Type] -> Subst
HasDebugCallStack => [TyCoVar] -> [Type] -> Subst
zipTvSubst [TyCoVar]
univ_tvs ([TyCoVar] -> [Type] -> [Type]
forall b a. [b] -> [a] -> [a]
takeList [TyCoVar]
univ_tvs [Type]
inst_tys)
         -- NB: inst_tys can be longer than the univ tyvars
         --     because the constructor might have existentials
    inst_theta :: [Type]
inst_theta = HasDebugCallStack => Subst -> [Type] -> [Type]
Subst -> [Type] -> [Type]
substTheta Subst
tenv [Type]
stupid_theta

{-
Note [Arrows and patterns]
~~~~~~~~~~~~~~~~~~~~~~~~~~
(Oct 07) Arrow notation has the odd property that it involves
"holes in the scope". For example:
  expr :: Arrow a => a () Int
  expr = proc (y,z) -> do
          x <- term -< y
          expr' -< x

Here the 'proc (y,z)' binding scopes over the arrow tails but not the
arrow body (e.g 'term').  As things stand (bogusly) all the
constraints from the proc body are gathered together, so constraints
from 'term' will be seen by the tcPat for (y,z).  But we must *not*
bind constraints from 'term' here, because the desugarer will not make
these bindings scope over 'term'.

The Right Thing is not to confuse these constraints together. But for
now the Easy Thing is to ensure that we do not have existential or
GADT constraints in a 'proc', which we do by disallowing any
non-vanilla pattern match (i.e. one that introduces existential
variables or provided constraints), in tcDataConPat and tcPatSynPat.

We also short-cut the constraint simplification for such vanilla patterns,
so that we bind no constraints. Hence the 'fast path' in tcDataConPat;
which applies more generally (not just within 'proc'), as it's a good
plan in general to bypass the constraint simplification step entirely
when it's not needed.

Note [Pattern coercions]
~~~~~~~~~~~~~~~~~~~~~~~~
In principle, these program would be reasonable:

        f :: (forall a. a->a) -> Int
        f (x :: Int->Int) = x 3

        g :: (forall a. [a]) -> Bool
        g [] = True

In both cases, the function type signature restricts what arguments can be passed
in a call (to polymorphic ones).  The pattern type signature then instantiates this
type.  For example, in the first case,  (forall a. a->a) <= Int -> Int, and we
generate the translated term
        f = \x' :: (forall a. a->a).  let x = x' Int in x 3

From a type-system point of view, this is perfectly fine, but it's *very* seldom useful.
And it requires a significant amount of code to implement, because we need to decorate
the translated pattern with coercion functions (generated from the subsumption check
by tcSub).

So for now I'm just insisting on type *equality* in patterns.  No subsumption.

Old notes about desugaring, at a time when pattern coercions were handled:

A SigPat is a type coercion and must be handled one at a time.  We can't
combine them unless the type of the pattern inside is identical, and we don't
bother to check for that.  For example:

        data T = T1 Int | T2 Bool
        f :: (forall a. a -> a) -> T -> t
        f (g::Int->Int)   (T1 i) = T1 (g i)
        f (g::Bool->Bool) (T2 b) = T2 (g b)

We desugar this as follows:

        f = \ g::(forall a. a->a) t::T ->
            let gi = g Int
            in case t of { T1 i -> T1 (gi i)
                           other ->
            let gb = g Bool
            in case t of { T2 b -> T2 (gb b)
                           other -> fail }}

Note that we do not treat the first column of patterns as a
column of variables, because the coerced variables (gi, gb)
would be of different types.  So we get rather grotty code.
But I don't think this is a common case, and if it was we could
doubtless improve it.

Meanwhile, the strategy is:
        * treat each SigPat coercion (always non-identity coercions)
                as a separate block
        * deal with the stuff inside, and then wrap a binding round
                the result to bind the new variable (gi, gb, etc)


************************************************************************
*                                                                      *
\subsection{Errors and contexts}
*                                                                      *
************************************************************************

Note [Existential check]
~~~~~~~~~~~~~~~~~~~~~~~~
Lazy patterns can't bind existentials.  They arise in two ways:
  * Let bindings      let { C a b = e } in b
  * Twiddle patterns  f ~(C a b) = e
The pe_lazy field of PatEnv says whether we are inside a lazy
pattern (perhaps deeply)

See also Note [Typechecking pattern bindings] in GHC.Tc.Gen.Bind
-}

maybeWrapPatCtxt :: Pat GhcRn -> (TcM a -> TcM b) -> TcM a -> TcM b
-- Not all patterns are worth pushing a context
maybeWrapPatCtxt :: forall a b. Pat GhcRn -> (TcM a -> TcM b) -> TcM a -> TcM b
maybeWrapPatCtxt Pat GhcRn
pat TcM a -> TcM b
tcm TcM a
thing_inside
  | Bool -> Bool
not (Pat GhcRn -> Bool
forall {p}. Pat p -> Bool
worth_wrapping Pat GhcRn
pat) = TcM a -> TcM b
tcm TcM a
thing_inside
  | Bool
otherwise                = SDoc -> TcM b -> TcM b
forall a. SDoc -> TcM a -> TcM a
addErrCtxt SDoc
msg (TcM b -> TcM b) -> TcM b -> TcM b
forall a b. (a -> b) -> a -> b
$ TcM a -> TcM b
tcm (TcM a -> TcM b) -> TcM a -> TcM b
forall a b. (a -> b) -> a -> b
$ TcM a -> TcM a
forall a. TcM a -> TcM a
popErrCtxt TcM a
thing_inside
                               -- Remember to pop before doing thing_inside
  where
   worth_wrapping :: Pat p -> Bool
worth_wrapping (VarPat {}) = Bool
False
   worth_wrapping (ParPat {}) = Bool
False
   worth_wrapping (AsPat {})  = Bool
False
   worth_wrapping Pat p
_           = Bool
True
   msg :: SDoc
msg = SDoc -> Int -> SDoc -> SDoc
hang (String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"In the pattern:") Int
2 (Pat GhcRn -> SDoc
forall a. Outputable a => a -> SDoc
ppr Pat GhcRn
pat)

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

-- | Check that a pattern isn't a GADT, or doesn't have existential variables,
-- in a situation in which that is not permitted (inside a lazy pattern, or
-- in arrow notation).
checkGADT :: ConLike
          -> [TyVar] -- ^ existentials
          -> [Type]  -- ^ argument types
          -> PatEnv
          -> TcM ()
checkGADT :: ConLike -> [TyCoVar] -> [Type] -> PatEnv -> TcRn ()
checkGADT ConLike
conlike [TyCoVar]
ex_tvs [Type]
arg_tys = \case
  PE { pe_ctxt :: PatEnv -> PatCtxt
pe_ctxt = LetPat {} }
    -> () -> TcRn ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ()
  PE { pe_ctxt :: PatEnv -> PatCtxt
pe_ctxt = LamPat (ArrowMatchCtxt {}) }
    | Bool -> Bool
not (Bool -> Bool) -> Bool -> Bool
forall a b. (a -> b) -> a -> b
$ ConLike -> Bool
isVanillaConLike ConLike
conlike
    -- See Note [Arrows and patterns]
    -> TcRnMessage -> TcRn ()
forall a. TcRnMessage -> TcRn a
failWithTc TcRnMessage
TcRnArrowProcGADTPattern
  PE { pe_lazy :: PatEnv -> Bool
pe_lazy = Bool
True }
    | Bool
has_existentials
    -- See Note [Existential check]
    -> TcRnMessage -> TcRn ()
forall a. TcRnMessage -> TcRn a
failWithTc TcRnMessage
TcRnLazyGADTPattern
  PatEnv
_ -> () -> TcRn ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ()
  where
    has_existentials :: Bool
    has_existentials :: Bool
has_existentials = (TyCoVar -> Bool) -> [TyCoVar] -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
any (TyCoVar -> VarSet -> Bool
`elemVarSet` [Type] -> VarSet
tyCoVarsOfTypes [Type]
arg_tys) [TyCoVar]
ex_tvs