{-# LANGUAGE DataKinds           #-}
{-# LANGUAGE FlexibleContexts    #-}
{-# LANGUAGE MonadComprehensions #-}
{-# LANGUAGE RankNTypes          #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TypeFamilies        #-}
{-# LANGUAGE ViewPatterns        #-}
{-# LANGUAGE RecursiveDo        #-}

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

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

-}

-- | Typechecking user-specified @MonoTypes@
module GHC.Tc.Gen.HsType (
        -- Type signatures
        kcClassSigType, tcClassSigType,
        tcHsSigType, tcHsSigWcType,
        tcHsPartialSigType,
        tcStandaloneKindSig,
        funsSigCtxt, addSigCtxt, pprSigCtxt,

        tcHsClsInstType,
        tcHsDeriv, tcDerivStrategy,
        tcHsTypeApp,
        UserTypeCtxt(..),
        bindImplicitTKBndrs_Tv, bindImplicitTKBndrs_Skol,
            bindImplicitTKBndrs_Q_Tv, bindImplicitTKBndrs_Q_Skol,
        bindExplicitTKBndrs_Tv, bindExplicitTKBndrs_Skol,
            bindExplicitTKBndrs_Q_Tv, bindExplicitTKBndrs_Q_Skol,

        bindOuterFamEqnTKBndrs_Q_Tv, bindOuterFamEqnTKBndrs,
        tcOuterTKBndrs, scopedSortOuter, outerTyVars, outerTyVarBndrs,
        bindOuterSigTKBndrs_Tv,
        tcExplicitTKBndrs,
        bindNamedWildCardBinders,

        -- Type checking type and class decls, and instances thereof
        bindTyClTyVars, bindTyClTyVarsAndZonk,
        tcFamTyPats,
        etaExpandAlgTyCon, tcbVisibilities,

          -- tyvars
        zonkAndScopedSort,

        -- Kind-checking types
        -- No kind generalisation, no checkValidType
        InitialKindStrategy(..),
        SAKS_or_CUSK(..),
        ContextKind(..),
        kcDeclHeader, checkForDuplicateScopedTyVars,
        tcHsLiftedType,   tcHsOpenType,
        tcHsLiftedTypeNC, tcHsOpenTypeNC,
        tcInferLHsType, tcInferLHsTypeKind, tcInferLHsTypeUnsaturated,
        tcCheckLHsType,
        tcHsContext, tcLHsPredType,

        kindGeneralizeAll,

        -- Sort-checking kinds
        tcLHsKindSig, checkDataKindSig, DataSort(..),
        checkClassKindSig,

        -- Multiplicity
        tcMult,

        -- Pattern type signatures
        tcHsPatSigType,
        HoleMode(..),

        -- Error messages
        funAppCtxt, addTyConFlavCtxt
   ) where

import GHC.Prelude hiding ( head, init, last, tail )

import GHC.Hs
import GHC.Rename.Utils
import GHC.Tc.Errors.Types
import GHC.Tc.Utils.Monad
import GHC.Tc.Types.Origin
import GHC.Tc.Types.Constraint
import GHC.Tc.Utils.Env
import GHC.Tc.Utils.TcMType
import GHC.Tc.Validity
import GHC.Tc.Utils.Unify
import GHC.IfaceToCore
import GHC.Tc.Solver
import GHC.Tc.Utils.Zonk
import GHC.Tc.Utils.TcType
import GHC.Tc.Utils.Instantiate ( tcInstInvisibleTyBinders, tcInstInvisibleTyBindersN,
                                  tcInstInvisibleTyBinder, tcSkolemiseInvisibleBndrs,
                                  tcInstTypeBndrs )

import GHC.Core.Type
import GHC.Core.Predicate
import GHC.Core.TyCo.Rep
import GHC.Core.TyCo.Ppr

import GHC.Builtin.Types.Prim
import GHC.Types.Error
import GHC.Types.Name.Env
import GHC.Types.Name.Reader( lookupLocalRdrOcc )
import GHC.Types.Var
import GHC.Types.Var.Set
import GHC.Core.TyCon
import GHC.Core.ConLike
import GHC.Core.DataCon
import GHC.Core.Class
import GHC.Types.Name
import GHC.Types.Var.Env
import GHC.Builtin.Types
import GHC.Types.Basic
import GHC.Types.SrcLoc
import GHC.Types.Unique
import GHC.Types.Unique.FM
import GHC.Utils.Misc
import GHC.Types.Unique.Supply
import GHC.Utils.Outputable
import GHC.Utils.Panic
import GHC.Utils.Panic.Plain
import GHC.Builtin.Names hiding ( wildCardName )
import GHC.Driver.Session
import qualified GHC.LanguageExtensions as LangExt

import GHC.Data.FastString
import GHC.Data.List.Infinite ( Infinite (..) )
import qualified GHC.Data.List.Infinite as Inf
import GHC.Data.List.SetOps
import GHC.Data.Maybe
import GHC.Data.Bag( unitBag )

import Data.Function ( on )
import Data.List.NonEmpty ( NonEmpty(..), nonEmpty )
import qualified Data.List.NonEmpty as NE
import Data.List ( find, mapAccumL )
import Control.Monad
import Data.Tuple( swap )

{-
        ----------------------------
                General notes
        ----------------------------

Unlike with expressions, type-checking types both does some checking and
desugars at the same time. This is necessary because we often want to perform
equality checks on the types right away, and it would be incredibly painful
to do this on un-desugared types. Luckily, desugared types are close enough
to HsTypes to make the error messages sane.

During type-checking, we perform as little validity checking as possible.
Generally, after type-checking, you will want to do validity checking, say
with GHC.Tc.Validity.checkValidType.

Validity checking
~~~~~~~~~~~~~~~~~
Some of the validity check could in principle be done by the kind checker,
but not all:

- During desugaring, we normalise by expanding type synonyms.  Only
  after this step can we check things like type-synonym saturation
  e.g.  type T k = k Int
        type S a = a
  Then (T S) is ok, because T is saturated; (T S) expands to (S Int);
  and then S is saturated.  This is a GHC extension.

- Similarly, also a GHC extension, we look through synonyms before complaining
  about the form of a class or instance declaration

- Ambiguity checks involve functional dependencies

Also, in a mutually recursive group of types, we can't look at the TyCon until we've
finished building the loop.  So to keep things simple, we postpone most validity
checking until step (3).

%************************************************************************
%*                                                                      *
              Check types AND do validity checking
*                                                                      *
************************************************************************

Note [Keeping implicitly quantified variables in order]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When the user implicitly quantifies over variables (say, in a type
signature), we need to come up with some ordering on these variables.
This is done by bumping the TcLevel, bringing the tyvars into scope,
and then type-checking the thing_inside. The constraints are all
wrapped in an implication, which is then solved. Finally, we can
zonk all the binders and then order them with scopedSort.

It's critical to solve before zonking and ordering in order to uncover
any unifications. You might worry that this eager solving could cause
trouble elsewhere. I don't think it will. Because it will solve only
in an increased TcLevel, it can't unify anything that was mentioned
elsewhere. Additionally, we require that the order of implicitly
quantified variables is manifest by the scope of these variables, so
we're not going to learn more information later that will help order
these variables.

Note [Recipe for checking a signature]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Kind-checking a user-written signature requires several steps:

 0. Bump the TcLevel
 1.   Bind any lexically-scoped type variables.
 2.   Generate constraints.
 3. Solve constraints.
 4. Sort any implicitly-bound variables into dependency order
 5. Promote tyvars and/or kind-generalize.
 6. Zonk.
 7. Check validity.

Very similar steps also apply when kind-checking a type or class
declaration.

The general pattern looks something like this.  (But NB every
specific instance varies in one way or another!)

    do { (tclvl, wanted, (spec_tkvs, ty))
              <- pushLevelAndSolveEqualitiesX "tc_top_lhs_type" $
                 bindImplicitTKBndrs_Skol sig_vars              $
                 <kind-check the type>

       ; spec_tkvs <- zonkAndScopedSort spec_tkvs

       ; reportUnsolvedEqualities skol_info spec_tkvs tclvl wanted

       ; let ty1 = mkSpecForAllTys spec_tkvs ty
       ; kvs <- kindGeneralizeAll ty1

       ; final_ty <- zonkTcTypeToType (mkInfForAllTys kvs ty1)

       ; checkValidType final_ty

This pattern is repeated many times in GHC.Tc.Gen.HsType,
GHC.Tc.Gen.Sig, and GHC.Tc.TyCl, with variations.  In more detail:

* pushLevelAndSolveEqualitiesX (Step 0, step 3) bumps the TcLevel,
  calls the thing inside to generate constraints, solves those
  constraints as much as possible, returning the residual unsolved
  constraints in 'wanted'.

* bindImplicitTKBndrs_Skol (Step 1) binds the user-specified type
  variables E.g.  when kind-checking f :: forall a. F a -> a we must
  bring 'a' into scope before kind-checking (F a -> a)

* zonkAndScopedSort (Step 4) puts those user-specified variables in
  the dependency order.  (For "implicit" variables the order is no
  user-specified.  E.g.  forall (a::k1) (b::k2). blah k1 and k2 are
  implicitly brought into scope.

* reportUnsolvedEqualities (Step 3 continued) reports any unsolved
  equalities, carefully wrapping them in an implication that binds the
  skolems.  We can't do that in pushLevelAndSolveEqualitiesX because
  that function doesn't have access to the skolems.

* kindGeneralize (Step 5). See Note [Kind generalisation]

* The final zonkTcTypeToType must happen after promoting/generalizing,
  because promoting and generalizing fill in metavariables.


Doing Step 3 (constraint solving) eagerly (rather than building an
implication constraint and solving later) is necessary for several
reasons:

* Exactly as for Solver.simplifyInfer: when generalising, we solve all
  the constraints we can so that we don't have to quantify over them
  or, since we don't quantify over constraints in kinds, float them
  and inhibit generalisation.

* Most signatures also bring implicitly quantified variables into
  scope, and solving is necessary to get these in the right order
  (Step 4) see Note [Keeping implicitly quantified variables in
  order]).

Note [Kind generalisation]
~~~~~~~~~~~~~~~~~~~~~~~~~~
Step 5 of Note [Recipe for checking a signature], namely
kind-generalisation, is done by
    kindGeneraliseAll
    kindGeneraliseSome
    kindGeneraliseNone

Here, we have to deal with the fact that metatyvars generated in the
type will have a bumped TcLevel, because explicit foralls raise the
TcLevel. To avoid these variables from ever being visible in the
surrounding context, we must obey the following dictum:

  Every metavariable in a type must either be
    (A) generalized, or
    (B) promoted, or        See Note [Promotion in signatures]
    (C) a cause to error    See Note [Naughty quantification candidates]
                            in GHC.Tc.Utils.TcMType

There are three steps (look at kindGeneraliseSome):

1. candidateQTyVarsOfType finds the free variables of the type or kind,
   to generalise

2. filterConstrainedCandidates filters out candidates that appear
   in the unsolved 'wanteds', and promotes the ones that get filtered out
   thereby.

3. quantifyTyVars quantifies the remaining type variables

The kindGeneralize functions do not require pre-zonking; they zonk as they
go.

kindGeneraliseAll specialises for the case where step (2) is vacuous.
kindGeneraliseNone specialises for the case where we do no quantification,
but we must still promote.

If you are actually doing kind-generalization, you need to bump the
level before generating constraints, as we will only generalize
variables with a TcLevel higher than the ambient one.
Hence the "pushLevel" in pushLevelAndSolveEqualities.

Note [Promotion in signatures]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If an unsolved metavariable in a signature is not generalized
(because we're not generalizing the construct -- e.g., pattern
sig -- or because the metavars are constrained -- see kindGeneralizeSome)
we need to promote to maintain (WantedInv) of Note [TcLevel invariants]
in GHC.Tc.Utils.TcType. Note that promotion is identical in effect to generalizing
and the reinstantiating with a fresh metavariable at the current level.
So in some sense, we generalize *all* variables, but then re-instantiate
some of them.

Here is an example of why we must promote:
  foo (x :: forall a. a -> Proxy b) = ...

In the pattern signature, `b` is unbound, and will thus be brought into
scope. We do not know its kind: it will be assigned kappa[2]. Note that
kappa is at TcLevel 2, because it is invented under a forall. (A priori,
the kind kappa might depend on `a`, so kappa rightly has a higher TcLevel
than the surrounding context.) This kappa cannot be solved for while checking
the pattern signature (which is not kind-generalized). When we are checking
the *body* of foo, though, we need to unify the type of x with the argument
type of bar. At this point, the ambient TcLevel is 1, and spotting a
metavariable with level 2 would violate the (WantedInv) invariant of
Note [TcLevel invariants]. So, instead of kind-generalizing,
we promote the metavariable to level 1. This is all done in kindGeneralizeNone.

-}

funsSigCtxt :: [LocatedN Name] -> UserTypeCtxt
-- Returns FunSigCtxt, with no redundant-context-reporting,
-- form a list of located names
funsSigCtxt :: [GenLocated SrcSpanAnnN Name] -> UserTypeCtxt
funsSigCtxt (L SrcSpanAnnN
_ Name
name1 : [GenLocated SrcSpanAnnN Name]
_) = Name -> ReportRedundantConstraints -> UserTypeCtxt
FunSigCtxt Name
name1 ReportRedundantConstraints
NoRRC
funsSigCtxt []              = String -> UserTypeCtxt
forall a. HasCallStack => String -> a
panic String
"funSigCtxt"

addSigCtxt :: Outputable hs_ty => UserTypeCtxt -> LocatedA hs_ty -> TcM a -> TcM a
addSigCtxt :: forall hs_ty a.
Outputable hs_ty =>
UserTypeCtxt -> LocatedA hs_ty -> TcM a -> TcM a
addSigCtxt UserTypeCtxt
ctxt LocatedA hs_ty
hs_ty TcM a
thing_inside
  = SrcSpan -> TcM a -> TcM a
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan (LocatedA hs_ty -> SrcSpan
forall a e. GenLocated (SrcSpanAnn' a) e -> SrcSpan
getLocA LocatedA hs_ty
hs_ty) (TcM a -> TcM a) -> TcM a -> TcM a
forall a b. (a -> b) -> a -> b
$
    SDoc -> TcM a -> TcM a
forall a. SDoc -> TcM a -> TcM a
addErrCtxt (UserTypeCtxt -> LocatedA hs_ty -> SDoc
forall hs_ty.
Outputable hs_ty =>
UserTypeCtxt -> LocatedA hs_ty -> SDoc
pprSigCtxt UserTypeCtxt
ctxt LocatedA hs_ty
hs_ty) (TcM a -> TcM a) -> TcM a -> TcM a
forall a b. (a -> b) -> a -> b
$
    TcM a
thing_inside

pprSigCtxt :: Outputable hs_ty => UserTypeCtxt -> LocatedA hs_ty -> SDoc
-- (pprSigCtxt ctxt <extra> <type>)
-- prints    In the type signature for 'f':
--              f :: <type>
-- The <extra> is either empty or "the ambiguity check for"
pprSigCtxt :: forall hs_ty.
Outputable hs_ty =>
UserTypeCtxt -> LocatedA hs_ty -> SDoc
pprSigCtxt UserTypeCtxt
ctxt LocatedA hs_ty
hs_ty
  | Just Name
n <- UserTypeCtxt -> Maybe Name
isSigMaybe UserTypeCtxt
ctxt
  = SDoc -> Arity -> SDoc -> SDoc
hang (String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"In the type signature:")
       Arity
2 (Name -> SDoc
forall a. OutputableBndr a => a -> SDoc
pprPrefixOcc Name
n SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> LocatedA hs_ty -> SDoc
forall a. Outputable a => a -> SDoc
ppr LocatedA hs_ty
hs_ty)

  | Bool
otherwise
  = SDoc -> Arity -> SDoc -> SDoc
hang (String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"In" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> UserTypeCtxt -> SDoc
pprUserTypeCtxt UserTypeCtxt
ctxt SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<> SDoc
forall doc. IsLine doc => doc
colon)
       Arity
2 (LocatedA hs_ty -> SDoc
forall a. Outputable a => a -> SDoc
ppr LocatedA hs_ty
hs_ty)

tcHsSigWcType :: UserTypeCtxt -> LHsSigWcType GhcRn -> TcM Type
-- This one is used when we have a LHsSigWcType, but in
-- a place where wildcards aren't allowed. The renamer has
-- already checked this, so we can simply ignore it.
tcHsSigWcType :: UserTypeCtxt -> LHsSigWcType GhcRn -> TcM Type
tcHsSigWcType UserTypeCtxt
ctxt LHsSigWcType GhcRn
sig_ty = UserTypeCtxt -> LHsSigType GhcRn -> TcM Type
tcHsSigType UserTypeCtxt
ctxt (LHsSigWcType GhcRn -> LHsSigType GhcRn
forall pass. LHsSigWcType pass -> LHsSigType pass
dropWildCards LHsSigWcType GhcRn
sig_ty)

kcClassSigType :: [LocatedN Name] -> LHsSigType GhcRn -> TcM ()
-- This is a special form of tcClassSigType that is used during the
-- kind-checking phase to infer the kind of class variables. Cf. tc_lhs_sig_type.
-- Importantly, this does *not* kind-generalize. Consider
--   class SC f where
--     meth :: forall a (x :: f a). Proxy x -> ()
-- When instantiating Proxy with kappa, we must unify kappa := f a. But we're
-- still working out the kind of f, and thus f a will have a coercion in it.
-- Coercions block unification (Note [Equalities with incompatible kinds] in
-- TcCanonical) and so we fail to unify. If we try to kind-generalize, we'll
-- end up promoting kappa to the top level (because kind-generalization is
-- normally done right before adding a binding to the context), and then we
-- can't set kappa := f a, because a is local.
kcClassSigType :: [GenLocated SrcSpanAnnN Name] -> LHsSigType GhcRn -> TcM ()
kcClassSigType [GenLocated SrcSpanAnnN Name]
names
    sig_ty :: LHsSigType GhcRn
sig_ty@(L SrcSpanAnnA
_ (HsSig { sig_bndrs :: forall pass. HsSigType pass -> HsOuterSigTyVarBndrs pass
sig_bndrs = HsOuterSigTyVarBndrs GhcRn
hs_outer_bndrs, sig_body :: forall pass. HsSigType pass -> LHsType pass
sig_body = LHsType GhcRn
hs_ty }))
  = UserTypeCtxt
-> GenLocated SrcSpanAnnA (HsSigType GhcRn) -> TcM () -> TcM ()
forall hs_ty a.
Outputable hs_ty =>
UserTypeCtxt -> LocatedA hs_ty -> TcM a -> TcM a
addSigCtxt ([GenLocated SrcSpanAnnN Name] -> UserTypeCtxt
funsSigCtxt [GenLocated SrcSpanAnnN Name]
names) LHsSigType GhcRn
GenLocated SrcSpanAnnA (HsSigType GhcRn)
sig_ty (TcM () -> TcM ()) -> TcM () -> TcM ()
forall a b. (a -> b) -> a -> b
$
    do { (HsOuterTyVarBndrs Specificity GhcTc, Type)
_ <- HsOuterSigTyVarBndrs GhcRn
-> TcM Type -> TcM (HsOuterTyVarBndrs Specificity GhcTc, Type)
forall a.
HsOuterSigTyVarBndrs GhcRn
-> TcM a -> TcM (HsOuterTyVarBndrs Specificity GhcTc, a)
bindOuterSigTKBndrs_Tv HsOuterSigTyVarBndrs GhcRn
hs_outer_bndrs    (TcM Type -> TcM (HsOuterTyVarBndrs Specificity GhcTc, Type))
-> TcM Type -> TcM (HsOuterTyVarBndrs Specificity GhcTc, Type)
forall a b. (a -> b) -> a -> b
$
              LHsType GhcRn -> Type -> TcM Type
tcLHsType LHsType GhcRn
hs_ty Type
liftedTypeKind
       ; () -> TcM ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return () }

tcClassSigType :: [LocatedN Name] -> LHsSigType GhcRn -> TcM Type
-- Does not do validity checking
tcClassSigType :: [GenLocated SrcSpanAnnN Name] -> LHsSigType GhcRn -> TcM Type
tcClassSigType [GenLocated SrcSpanAnnN Name]
names LHsSigType GhcRn
sig_ty
  = UserTypeCtxt
-> GenLocated SrcSpanAnnA (HsSigType GhcRn) -> TcM Type -> TcM Type
forall hs_ty a.
Outputable hs_ty =>
UserTypeCtxt -> LocatedA hs_ty -> TcM a -> TcM a
addSigCtxt UserTypeCtxt
sig_ctxt LHsSigType GhcRn
GenLocated SrcSpanAnnA (HsSigType GhcRn)
sig_ty (TcM Type -> TcM Type) -> TcM Type -> TcM Type
forall a b. (a -> b) -> a -> b
$
    do { SkolemInfo
skol_info <- SkolemInfoAnon -> IOEnv (Env TcGblEnv TcLclEnv) SkolemInfo
forall (m :: * -> *). MonadIO m => SkolemInfoAnon -> m SkolemInfo
mkSkolemInfo SkolemInfoAnon
skol_info_anon
       ; (Implication
implic, Type
ty) <- SkolemInfo
-> LHsSigType GhcRn -> ContextKind -> TcM (Implication, Type)
tc_lhs_sig_type SkolemInfo
skol_info LHsSigType GhcRn
sig_ty (Type -> ContextKind
TheKind Type
liftedTypeKind)
       ; Implication -> TcM ()
emitImplication Implication
implic
       ; Type -> TcM Type
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return Type
ty }
       -- Do not zonk-to-Type, nor perform a validity check
       -- We are in a knot with the class and associated types
       -- Zonking and validity checking is done by tcClassDecl
       --
       -- No need to fail here if the type has an error:
       --   If we're in the kind-checking phase, the solveEqualities
       --     in kcTyClGroup catches the error
       --   If we're in the type-checking phase, the solveEqualities
       --     in tcClassDecl1 gets it
       -- Failing fast here degrades the error message in, e.g., tcfail135:
       --   class Foo f where
       --     baa :: f a -> f
       -- If we fail fast, we're told that f has kind `k1` when we wanted `*`.
       -- It should be that f has kind `k2 -> *`, but we never get a chance
       -- to run the solver where the kind of f is touchable. This is
       -- painfully delicate.
  where
    sig_ctxt :: UserTypeCtxt
sig_ctxt = [GenLocated SrcSpanAnnN Name] -> UserTypeCtxt
funsSigCtxt [GenLocated SrcSpanAnnN Name]
names
    skol_info_anon :: SkolemInfoAnon
skol_info_anon = UserTypeCtxt -> SkolemInfoAnon
SigTypeSkol UserTypeCtxt
sig_ctxt

tcHsSigType :: UserTypeCtxt -> LHsSigType GhcRn -> TcM Type
-- Does validity checking
-- See Note [Recipe for checking a signature]
tcHsSigType :: UserTypeCtxt -> LHsSigType GhcRn -> TcM Type
tcHsSigType UserTypeCtxt
ctxt LHsSigType GhcRn
sig_ty
  = UserTypeCtxt
-> GenLocated SrcSpanAnnA (HsSigType GhcRn) -> TcM Type -> TcM Type
forall hs_ty a.
Outputable hs_ty =>
UserTypeCtxt -> LocatedA hs_ty -> TcM a -> TcM a
addSigCtxt UserTypeCtxt
ctxt LHsSigType GhcRn
GenLocated SrcSpanAnnA (HsSigType GhcRn)
sig_ty (TcM Type -> TcM Type) -> TcM Type -> TcM Type
forall a b. (a -> b) -> a -> b
$
    do { String -> SDoc -> TcM ()
traceTc String
"tcHsSigType {" (GenLocated SrcSpanAnnA (HsSigType GhcRn) -> SDoc
forall a. Outputable a => a -> SDoc
ppr LHsSigType GhcRn
GenLocated SrcSpanAnnA (HsSigType GhcRn)
sig_ty)
       ; SkolemInfo
skol_info <- SkolemInfoAnon -> IOEnv (Env TcGblEnv TcLclEnv) SkolemInfo
forall (m :: * -> *). MonadIO m => SkolemInfoAnon -> m SkolemInfo
mkSkolemInfo SkolemInfoAnon
skol_info
          -- Generalise here: see Note [Kind generalisation]
       ; (Implication
implic, Type
ty) <- SkolemInfo
-> LHsSigType GhcRn -> ContextKind -> TcM (Implication, Type)
tc_lhs_sig_type SkolemInfo
skol_info LHsSigType GhcRn
sig_ty  (UserTypeCtxt -> ContextKind
expectedKindInCtxt UserTypeCtxt
ctxt)

       -- Float out constraints, failing fast if not possible
       -- See Note [Failure in local type signatures] in GHC.Tc.Solver
       ; String -> SDoc -> TcM ()
traceTc String
"tcHsSigType 2" (Implication -> SDoc
forall a. Outputable a => a -> SDoc
ppr Implication
implic)
       ; WantedConstraints -> TcM ()
simplifyAndEmitFlatConstraints (Bag Implication -> WantedConstraints
mkImplicWC (Implication -> Bag Implication
forall a. a -> Bag a
unitBag Implication
implic))

       ; Type
ty <- Type -> TcM Type
zonkTcType Type
ty
       ; UserTypeCtxt -> Type -> TcM ()
checkValidType UserTypeCtxt
ctxt Type
ty
       ; String -> SDoc -> TcM ()
traceTc String
"end tcHsSigType }" (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
ty)
       ; Type -> TcM Type
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return Type
ty }
  where
    skol_info :: SkolemInfoAnon
skol_info = UserTypeCtxt -> SkolemInfoAnon
SigTypeSkol UserTypeCtxt
ctxt

tc_lhs_sig_type :: SkolemInfo -> LHsSigType GhcRn
               -> ContextKind -> TcM (Implication, TcType)
-- Kind-checks/desugars an 'LHsSigType',
--   solve equalities,
--   and then kind-generalizes.
-- This will never emit constraints, as it uses solveEqualities internally.
-- No validity checking or zonking
-- Returns also an implication for the unsolved constraints
tc_lhs_sig_type :: SkolemInfo
-> LHsSigType GhcRn -> ContextKind -> TcM (Implication, Type)
tc_lhs_sig_type SkolemInfo
skol_info full_hs_ty :: LHsSigType GhcRn
full_hs_ty@(L SrcSpanAnnA
loc (HsSig { sig_bndrs :: forall pass. HsSigType pass -> HsOuterSigTyVarBndrs pass
sig_bndrs = HsOuterSigTyVarBndrs GhcRn
hs_outer_bndrs
                                                   , sig_body :: forall pass. HsSigType pass -> LHsType pass
sig_body = LHsType GhcRn
hs_ty })) ContextKind
ctxt_kind
  = SrcSpanAnnA -> TcM (Implication, Type) -> TcM (Implication, Type)
forall ann a. SrcSpanAnn' ann -> TcRn a -> TcRn a
setSrcSpanA SrcSpanAnnA
loc (TcM (Implication, Type) -> TcM (Implication, Type))
-> TcM (Implication, Type) -> TcM (Implication, Type)
forall a b. (a -> b) -> a -> b
$
    do { (TcLevel
tc_lvl, WantedConstraints
wanted, (Type
exp_kind, (HsOuterTyVarBndrs Specificity GhcTc
outer_bndrs, Type
ty)))
              <- String
-> TcM (Type, (HsOuterTyVarBndrs Specificity GhcTc, Type))
-> TcM
     (TcLevel, WantedConstraints,
      (Type, (HsOuterTyVarBndrs Specificity GhcTc, Type)))
forall a. String -> TcM a -> TcM (TcLevel, WantedConstraints, a)
pushLevelAndSolveEqualitiesX String
"tc_lhs_sig_type" (TcM (Type, (HsOuterTyVarBndrs Specificity GhcTc, Type))
 -> TcM
      (TcLevel, WantedConstraints,
       (Type, (HsOuterTyVarBndrs Specificity GhcTc, Type))))
-> TcM (Type, (HsOuterTyVarBndrs Specificity GhcTc, Type))
-> TcM
     (TcLevel, WantedConstraints,
      (Type, (HsOuterTyVarBndrs Specificity GhcTc, Type)))
forall a b. (a -> b) -> a -> b
$
                 -- See Note [Failure in local type signatures]
                 do { Type
exp_kind <- ContextKind -> TcM Type
newExpectedKind ContextKind
ctxt_kind
                          -- See Note [Escaping kind in type signatures]
                    ; (HsOuterTyVarBndrs Specificity GhcTc, Type)
stuff <- SkolemInfo
-> HsOuterSigTyVarBndrs GhcRn
-> TcM Type
-> TcM (HsOuterTyVarBndrs Specificity GhcTc, Type)
forall flag a.
OutputableBndrFlag flag 'Renamed =>
SkolemInfo
-> HsOuterTyVarBndrs flag GhcRn
-> TcM a
-> TcM (HsOuterTyVarBndrs flag GhcTc, a)
tcOuterTKBndrs SkolemInfo
skol_info HsOuterSigTyVarBndrs GhcRn
hs_outer_bndrs (TcM Type -> TcM (HsOuterTyVarBndrs Specificity GhcTc, Type))
-> TcM Type -> TcM (HsOuterTyVarBndrs Specificity GhcTc, Type)
forall a b. (a -> b) -> a -> b
$
                               LHsType GhcRn -> Type -> TcM Type
tcLHsType LHsType GhcRn
hs_ty Type
exp_kind
                    ; (Type, (HsOuterTyVarBndrs Specificity GhcTc, Type))
-> TcM (Type, (HsOuterTyVarBndrs Specificity GhcTc, Type))
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (Type
exp_kind, (HsOuterTyVarBndrs Specificity GhcTc, Type)
stuff) }

       -- Default any unconstrained variables free in the kind
       -- See Note [Escaping kind in type signatures]
       ; CandidatesQTvs
exp_kind_dvs <- Type -> TcM CandidatesQTvs
candidateQTyVarsOfType Type
exp_kind
       ; CandidatesQTvs -> (TidyEnv -> TcM (TidyEnv, SDoc)) -> TcM ()
doNotQuantifyTyVars CandidatesQTvs
exp_kind_dvs (Type -> TidyEnv -> TcM (TidyEnv, SDoc)
mk_doc Type
exp_kind)

       ; String -> SDoc -> TcM ()
traceTc String
"tc_lhs_sig_type" (HsOuterSigTyVarBndrs GhcRn -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsOuterSigTyVarBndrs GhcRn
hs_outer_bndrs SDoc -> SDoc -> SDoc
forall doc. IsDoc doc => doc -> doc -> doc
$$ HsOuterTyVarBndrs Specificity GhcTc -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsOuterTyVarBndrs Specificity GhcTc
outer_bndrs)
       ; HsOuterTyVarBndrs Specificity GhcTc
outer_bndrs <- HsOuterTyVarBndrs Specificity GhcTc
-> TcM (HsOuterTyVarBndrs Specificity GhcTc)
forall flag.
HsOuterTyVarBndrs flag GhcTc -> TcM (HsOuterTyVarBndrs flag GhcTc)
scopedSortOuter HsOuterTyVarBndrs Specificity GhcTc
outer_bndrs

       ; let [VarBndr TyVar Specificity]
outer_tv_bndrs :: [InvisTVBinder] = HsOuterTyVarBndrs Specificity GhcTc -> [VarBndr TyVar Specificity]
outerTyVarBndrs HsOuterTyVarBndrs Specificity GhcTc
outer_bndrs
             ty1 :: Type
ty1 = [VarBndr TyVar Specificity] -> Type -> Type
mkInvisForAllTys [VarBndr TyVar Specificity]
outer_tv_bndrs Type
ty
       ; [TyVar]
kvs <- SkolemInfo -> WantedConstraints -> Type -> TcM [TyVar]
kindGeneralizeSome SkolemInfo
skol_info WantedConstraints
wanted Type
ty1

       -- Build an implication for any as-yet-unsolved kind equalities
       -- See Note [Skolem escape in type signatures]
       ; Implication
implic <- SkolemInfoAnon
-> [TyVar] -> TcLevel -> WantedConstraints -> TcM Implication
buildTvImplication (SkolemInfo -> SkolemInfoAnon
getSkolemInfo SkolemInfo
skol_info) [TyVar]
kvs TcLevel
tc_lvl WantedConstraints
wanted

       ; (Implication, Type) -> TcM (Implication, Type)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (Implication
implic, [TyVar] -> Type -> Type
mkInfForAllTys [TyVar]
kvs Type
ty1) }
  where
    mk_doc :: Type -> TidyEnv -> TcM (TidyEnv, SDoc)
mk_doc Type
exp_kind TidyEnv
tidy_env
      = do { (TidyEnv
tidy_env2, Type
exp_kind) <- TidyEnv -> Type -> TcM (TidyEnv, Type)
zonkTidyTcType TidyEnv
tidy_env Type
exp_kind
           ; (TidyEnv, SDoc) -> TcM (TidyEnv, SDoc)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (TidyEnv
tidy_env2, SDoc -> Arity -> SDoc -> SDoc
hang (String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"The kind" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
exp_kind)
                                   Arity
2 (String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"of type signature:" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> GenLocated SrcSpanAnnA (HsSigType GhcRn) -> SDoc
forall a. Outputable a => a -> SDoc
ppr LHsSigType GhcRn
GenLocated SrcSpanAnnA (HsSigType GhcRn)
full_hs_ty)) }



{- Note [Escaping kind in type signatures]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider kind-checking the signature for `foo` (#19495):
  type family T (r :: RuntimeRep) :: TYPE r

  foo :: forall (r :: RuntimeRep). T r
  foo = ...

We kind-check the type with expected kind `TYPE delta` (see newExpectedKind),
where `delta :: RuntimeRep` is as-yet unknown. (We can't use `TYPE LiftedRep`
because we allow signatures like `foo :: Int#`.)

Suppose we are at level L currently.  We do this
  * pushLevelAndSolveEqualitiesX: moves to level L+1
  * newExpectedKind: allocates delta{L+1}
  * tcOuterTKBndrs: pushes the level again to L+2, binds skolem r{L+2}
  * kind-check the body (T r) :: TYPE delta{L+1}

Then
* We can't unify delta{L+1} with r{L+2}.
  And rightly so: skolem would escape.

* If delta{L+1} is unified with some-kind{L}, that is fine.
  This can happen
      \(x::a) -> let y :: a; y = x in ...(x :: Int#)...
  Here (x :: a :: TYPE gamma) is in the environment when we check
  the signature y::a.  We unify delta := gamma, and all is well.

* If delta{L+1} is unconstrained, we /must not/ quantify over it!
  E.g. Consider f :: Any   where Any :: forall k. k
  We kind-check this with expected kind TYPE kappa. We get
      Any @(TYPE kappa) :: TYPE kappa
  We don't want to generalise to     forall k. Any @k
  because that is ill-kinded: the kind of the body of the forall,
  (Any @k :: k) mentions the bound variable k.

  Instead we want to default it to LiftedRep.

  An alternative would be to promote it, similar to the monomorphism
  restriction, but the MR is pretty confusing.  Defaulting seems better

How does that defaulting happen?  Well, since we /currently/ default
RuntimeRep variables during generalisation, it'll happen in
kindGeneralize. But in principle we might allow generalisation over
RuntimeRep variables in future.  Moreover, what if we had
   kappa{L+1} := F alpha{L+1}
where F :: Type -> RuntimeRep.   Now it's alpha that is free in the kind
and it /won't/ be defaulted.

So we use doNotQuantifyTyVars to either default the free vars of
exp_kind (if possible), or error (if not).

Note [Skolem escape in type signatures]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
tcHsSigType is tricky.  Consider (T11142)
  foo :: forall b. (forall k (a :: k). SameKind a b) -> ()
This is ill-kinded because of a nested skolem-escape.

That will show up as an un-solvable constraint in the implication
returned by buildTvImplication in tc_lhs_sig_type.  See Note [Skolem
escape prevention] in GHC.Tc.Utils.TcType for why it is unsolvable
(the unification variable for b's kind is untouchable).

Then, in GHC.Tc.Solver.simplifyAndEmitFlatConstraints (called from tcHsSigType)
we'll try to float out the constraint, be unable to do so, and fail.
See GHC.Tc.Solver Note [Failure in local type signatures] for more
detail on this.

The separation between tcHsSigType and tc_lhs_sig_type is because
tcClassSigType wants to use the latter, but *not* fail fast, because
there are skolems from the class decl which are in scope; but it's fine
not to because tcClassDecl1 has a solveEqualities wrapped around all
the tcClassSigType calls.

That's why tcHsSigType does simplifyAndEmitFlatConstraints (which
fails fast) but tcClassSigType just does emitImplication (which does
not).  Ugh.

c.f. see also Note [Skolem escape and forall-types]. The difference
is that we don't need to simplify at a forall type, only at the
top level of a signature.
-}

-- Does validity checking and zonking.
tcStandaloneKindSig :: LStandaloneKindSig GhcRn -> TcM (Name, Kind)
tcStandaloneKindSig :: LStandaloneKindSig GhcRn -> TcM (Name, Type)
tcStandaloneKindSig (L SrcSpanAnnA
_ (StandaloneKindSig XStandaloneKindSig GhcRn
_ (L SrcSpanAnnN
_ Name
name) LHsSigType GhcRn
ksig))
  = UserTypeCtxt
-> GenLocated SrcSpanAnnA (HsSigType GhcRn)
-> TcM (Name, Type)
-> TcM (Name, Type)
forall hs_ty a.
Outputable hs_ty =>
UserTypeCtxt -> LocatedA hs_ty -> TcM a -> TcM a
addSigCtxt UserTypeCtxt
ctxt LHsSigType GhcRn
GenLocated SrcSpanAnnA (HsSigType GhcRn)
ksig (TcM (Name, Type) -> TcM (Name, Type))
-> TcM (Name, Type) -> TcM (Name, Type)
forall a b. (a -> b) -> a -> b
$
    do { Type
kind <- TypeOrKind -> UserTypeCtxt -> LHsSigType GhcRn -> TcM Type
tc_top_lhs_type TypeOrKind
KindLevel UserTypeCtxt
ctxt LHsSigType GhcRn
ksig
       ; UserTypeCtxt -> Type -> TcM ()
checkValidType UserTypeCtxt
ctxt Type
kind
       ; (Name, Type) -> TcM (Name, Type)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (Name
name, Type
kind) }
  where
   ctxt :: UserTypeCtxt
ctxt = Name -> UserTypeCtxt
StandaloneKindSigCtxt Name
name

tcTopLHsType :: UserTypeCtxt -> LHsSigType GhcRn -> TcM Type
tcTopLHsType :: UserTypeCtxt -> LHsSigType GhcRn -> TcM Type
tcTopLHsType UserTypeCtxt
ctxt LHsSigType GhcRn
lsig_ty
  = TcM Type -> TcM Type
forall r. TcM r -> TcM r
checkNoErrs (TcM Type -> TcM Type) -> TcM Type -> TcM Type
forall a b. (a -> b) -> a -> b
$  -- Fail eagerly to avoid follow-on errors.  We are at
                   -- top level so these constraints will never be solved later.
    TypeOrKind -> UserTypeCtxt -> LHsSigType GhcRn -> TcM Type
tc_top_lhs_type TypeOrKind
TypeLevel UserTypeCtxt
ctxt LHsSigType GhcRn
lsig_ty

tc_top_lhs_type :: TypeOrKind -> UserTypeCtxt -> LHsSigType GhcRn -> TcM Type
-- tc_top_lhs_type is used for kind-checking top-level LHsSigTypes where
--   we want to fully solve /all/ equalities, and report errors
-- Does zonking, but not validity checking because it's used
--   for things (like deriving and instances) that aren't
--   ordinary types
-- Used for both types and kinds
tc_top_lhs_type :: TypeOrKind -> UserTypeCtxt -> LHsSigType GhcRn -> TcM Type
tc_top_lhs_type TypeOrKind
tyki UserTypeCtxt
ctxt (L SrcSpanAnnA
loc sig_ty :: HsSigType GhcRn
sig_ty@(HsSig { sig_bndrs :: forall pass. HsSigType pass -> HsOuterSigTyVarBndrs pass
sig_bndrs = HsOuterSigTyVarBndrs GhcRn
hs_outer_bndrs
                                               , sig_body :: forall pass. HsSigType pass -> LHsType pass
sig_body = LHsType GhcRn
body }))
  = SrcSpanAnnA -> TcM Type -> TcM Type
forall ann a. SrcSpanAnn' ann -> TcRn a -> TcRn a
setSrcSpanA SrcSpanAnnA
loc (TcM Type -> TcM Type) -> TcM Type -> TcM Type
forall a b. (a -> b) -> a -> b
$
    do { String -> SDoc -> TcM ()
traceTc String
"tc_top_lhs_type {" (HsSigType GhcRn -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsSigType GhcRn
sig_ty)
       ; SkolemInfo
skol_info <- SkolemInfoAnon -> IOEnv (Env TcGblEnv TcLclEnv) SkolemInfo
forall (m :: * -> *). MonadIO m => SkolemInfoAnon -> m SkolemInfo
mkSkolemInfo SkolemInfoAnon
skol_info_anon
       ; (TcLevel
tclvl, WantedConstraints
wanted, (HsOuterTyVarBndrs Specificity GhcTc
outer_bndrs, Type
ty))
              <- String
-> TcM (HsOuterTyVarBndrs Specificity GhcTc, Type)
-> TcM
     (TcLevel, WantedConstraints,
      (HsOuterTyVarBndrs Specificity GhcTc, Type))
forall a. String -> TcM a -> TcM (TcLevel, WantedConstraints, a)
pushLevelAndSolveEqualitiesX String
"tc_top_lhs_type"    (TcM (HsOuterTyVarBndrs Specificity GhcTc, Type)
 -> TcM
      (TcLevel, WantedConstraints,
       (HsOuterTyVarBndrs Specificity GhcTc, Type)))
-> TcM (HsOuterTyVarBndrs Specificity GhcTc, Type)
-> TcM
     (TcLevel, WantedConstraints,
      (HsOuterTyVarBndrs Specificity GhcTc, Type))
forall a b. (a -> b) -> a -> b
$
                 SkolemInfo
-> HsOuterSigTyVarBndrs GhcRn
-> TcM Type
-> TcM (HsOuterTyVarBndrs Specificity GhcTc, Type)
forall flag a.
OutputableBndrFlag flag 'Renamed =>
SkolemInfo
-> HsOuterTyVarBndrs flag GhcRn
-> TcM a
-> TcM (HsOuterTyVarBndrs flag GhcTc, a)
tcOuterTKBndrs SkolemInfo
skol_info HsOuterSigTyVarBndrs GhcRn
hs_outer_bndrs (TcM Type -> TcM (HsOuterTyVarBndrs Specificity GhcTc, Type))
-> TcM Type -> TcM (HsOuterTyVarBndrs Specificity GhcTc, Type)
forall a b. (a -> b) -> a -> b
$
                 do { Type
kind <- ContextKind -> TcM Type
newExpectedKind (UserTypeCtxt -> ContextKind
expectedKindInCtxt UserTypeCtxt
ctxt)
                    ; TcTyMode -> LHsType GhcRn -> Type -> TcM Type
tc_lhs_type (TypeOrKind -> TcTyMode
mkMode TypeOrKind
tyki) LHsType GhcRn
body Type
kind }

       ; HsOuterTyVarBndrs Specificity GhcTc
outer_bndrs <- HsOuterTyVarBndrs Specificity GhcTc
-> TcM (HsOuterTyVarBndrs Specificity GhcTc)
forall flag.
HsOuterTyVarBndrs flag GhcTc -> TcM (HsOuterTyVarBndrs flag GhcTc)
scopedSortOuter HsOuterTyVarBndrs Specificity GhcTc
outer_bndrs
       ; let outer_tv_bndrs :: [VarBndr TyVar Specificity]
outer_tv_bndrs = HsOuterTyVarBndrs Specificity GhcTc -> [VarBndr TyVar Specificity]
outerTyVarBndrs HsOuterTyVarBndrs Specificity GhcTc
outer_bndrs
             ty1 :: Type
ty1 = [VarBndr TyVar Specificity] -> Type -> Type
mkInvisForAllTys [VarBndr TyVar Specificity]
outer_tv_bndrs Type
ty

       ; [TyVar]
kvs <- SkolemInfo -> Type -> TcM [TyVar]
kindGeneralizeAll SkolemInfo
skol_info Type
ty1  -- "All" because it's a top-level type
       ; SkolemInfo -> [TyVar] -> TcLevel -> WantedConstraints -> TcM ()
reportUnsolvedEqualities SkolemInfo
skol_info [TyVar]
kvs TcLevel
tclvl WantedConstraints
wanted

       ; ZonkEnv
ze       <- ZonkFlexi -> TcM ZonkEnv
mkEmptyZonkEnv ZonkFlexi
NoFlexi
       ; Type
final_ty <- ZonkEnv -> Type -> TcM Type
zonkTcTypeToTypeX ZonkEnv
ze ([TyVar] -> Type -> Type
mkInfForAllTys [TyVar]
kvs Type
ty1)
       ; String -> SDoc -> TcM ()
traceTc String
"tc_top_lhs_type }" ([SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat [HsSigType GhcRn -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsSigType GhcRn
sig_ty, Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
final_ty])
       ; Type -> TcM Type
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return Type
final_ty }
  where
    skol_info_anon :: SkolemInfoAnon
skol_info_anon = UserTypeCtxt -> SkolemInfoAnon
SigTypeSkol UserTypeCtxt
ctxt

-----------------
tcHsDeriv :: LHsSigType GhcRn -> TcM ([TyVar], Class, [Type], [Kind])
-- Like tcHsSigType, but for the ...deriving( C t1 ty2 ) clause
-- Returns the C, [ty1, ty2, and the kinds of C's remaining arguments
-- E.g.    class C (a::*) (b::k->k)
--         data T a b = ... deriving( C Int )
--    returns ([k], C, [k, Int], [k->k])
-- Return values are fully zonked
tcHsDeriv :: LHsSigType GhcRn -> TcM ([TyVar], Class, [Type], [Type])
tcHsDeriv LHsSigType GhcRn
hs_ty
  = do { Type
ty <- UserTypeCtxt -> LHsSigType GhcRn -> TcM Type
tcTopLHsType UserTypeCtxt
DerivClauseCtxt LHsSigType GhcRn
hs_ty
       ; let ([TyVar]
tvs, Type
pred)    = Type -> ([TyVar], Type)
splitForAllTyCoVars Type
ty
             ([Scaled Type]
kind_args, Type
_) = Type -> ([Scaled Type], Type)
splitFunTys ((() :: Constraint) => Type -> Type
Type -> Type
typeKind Type
pred)
       ; case Type -> Maybe (Class, [Type])
getClassPredTys_maybe Type
pred of
           Just (Class
cls, [Type]
tys) -> ([TyVar], Class, [Type], [Type])
-> TcM ([TyVar], Class, [Type], [Type])
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ([TyVar]
tvs, Class
cls, [Type]
tys, (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]
kind_args)
           Maybe (Class, [Type])
Nothing -> TcRnMessage -> TcM ([TyVar], Class, [Type], [Type])
forall a. TcRnMessage -> TcM a
failWithTc (TcRnMessage -> TcM ([TyVar], Class, [Type], [Type]))
-> TcRnMessage -> TcM ([TyVar], Class, [Type], [Type])
forall a b. (a -> b) -> a -> b
$ LHsSigType GhcRn -> TcRnMessage
TcRnIllegalDerivingItem LHsSigType GhcRn
hs_ty }

-- | Typecheck a deriving strategy. For most deriving strategies, this is a
-- no-op, but for the @via@ strategy, this requires typechecking the @via@ type.
tcDerivStrategy :: Maybe (LDerivStrategy GhcRn)
                   -- ^ The deriving strategy
                -> TcM (Maybe (LDerivStrategy GhcTc), [TcTyVar])
                   -- ^ The typechecked deriving strategy and the tyvars that it binds
                   -- (if using 'ViaStrategy').
tcDerivStrategy :: Maybe (LDerivStrategy GhcRn)
-> TcM (Maybe (LDerivStrategy GhcTc), [TyVar])
tcDerivStrategy Maybe (LDerivStrategy GhcRn)
mb_lds
  = case Maybe (LDerivStrategy GhcRn)
mb_lds of
      Maybe (LDerivStrategy GhcRn)
Nothing -> Maybe (GenLocated (SrcAnn NoEpAnns) (DerivStrategy GhcTc))
-> TcM
     (Maybe (GenLocated (SrcAnn NoEpAnns) (DerivStrategy GhcTc)),
      [TyVar])
forall ds a. ds -> TcM (ds, [a])
boring_case Maybe (GenLocated (SrcAnn NoEpAnns) (DerivStrategy GhcTc))
forall a. Maybe a
Nothing
      Just (L SrcAnn NoEpAnns
loc DerivStrategy GhcRn
ds) ->
        SrcAnn NoEpAnns
-> TcM (Maybe (LDerivStrategy GhcTc), [TyVar])
-> TcM (Maybe (LDerivStrategy GhcTc), [TyVar])
forall ann a. SrcSpanAnn' ann -> TcRn a -> TcRn a
setSrcSpanA SrcAnn NoEpAnns
loc (TcM (Maybe (LDerivStrategy GhcTc), [TyVar])
 -> TcM (Maybe (LDerivStrategy GhcTc), [TyVar]))
-> TcM (Maybe (LDerivStrategy GhcTc), [TyVar])
-> TcM (Maybe (LDerivStrategy GhcTc), [TyVar])
forall a b. (a -> b) -> a -> b
$ do
          (DerivStrategy GhcTc
ds', [TyVar]
tvs) <- DerivStrategy GhcRn -> TcM (DerivStrategy GhcTc, [TyVar])
tc_deriv_strategy DerivStrategy GhcRn
ds
          (Maybe (GenLocated (SrcAnn NoEpAnns) (DerivStrategy GhcTc)),
 [TyVar])
-> TcM
     (Maybe (GenLocated (SrcAnn NoEpAnns) (DerivStrategy GhcTc)),
      [TyVar])
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (f :: * -> *) a. Applicative f => a -> f a
pure (GenLocated (SrcAnn NoEpAnns) (DerivStrategy GhcTc)
-> Maybe (GenLocated (SrcAnn NoEpAnns) (DerivStrategy GhcTc))
forall a. a -> Maybe a
Just (SrcAnn NoEpAnns
-> DerivStrategy GhcTc
-> GenLocated (SrcAnn NoEpAnns) (DerivStrategy GhcTc)
forall l e. l -> e -> GenLocated l e
L SrcAnn NoEpAnns
loc DerivStrategy GhcTc
ds'), [TyVar]
tvs)
  where
    tc_deriv_strategy :: DerivStrategy GhcRn
                      -> TcM (DerivStrategy GhcTc, [TyVar])
    tc_deriv_strategy :: DerivStrategy GhcRn -> TcM (DerivStrategy GhcTc, [TyVar])
tc_deriv_strategy (StockStrategy    XStockStrategy GhcRn
_) = DerivStrategy GhcTc -> TcM (DerivStrategy GhcTc, [TyVar])
forall ds a. ds -> TcM (ds, [a])
boring_case (XStockStrategy GhcTc -> DerivStrategy GhcTc
forall pass. XStockStrategy pass -> DerivStrategy pass
StockStrategy    XStockStrategy GhcTc
NoExtField
noExtField)
    tc_deriv_strategy (AnyclassStrategy XAnyClassStrategy GhcRn
_) = DerivStrategy GhcTc -> TcM (DerivStrategy GhcTc, [TyVar])
forall ds a. ds -> TcM (ds, [a])
boring_case (XAnyClassStrategy GhcTc -> DerivStrategy GhcTc
forall pass. XAnyClassStrategy pass -> DerivStrategy pass
AnyclassStrategy XAnyClassStrategy GhcTc
NoExtField
noExtField)
    tc_deriv_strategy (NewtypeStrategy  XNewtypeStrategy GhcRn
_) = DerivStrategy GhcTc -> TcM (DerivStrategy GhcTc, [TyVar])
forall ds a. ds -> TcM (ds, [a])
boring_case (XNewtypeStrategy GhcTc -> DerivStrategy GhcTc
forall pass. XNewtypeStrategy pass -> DerivStrategy pass
NewtypeStrategy  XNewtypeStrategy GhcTc
NoExtField
noExtField)
    tc_deriv_strategy (ViaStrategy XViaStrategy GhcRn
hs_sig)
      = do { Type
ty <- UserTypeCtxt -> LHsSigType GhcRn -> TcM Type
tcTopLHsType UserTypeCtxt
DerivClauseCtxt XViaStrategy GhcRn
LHsSigType GhcRn
hs_sig
             -- rec {..}: see Note [Keeping SkolemInfo inside a SkolemTv]
             --           in GHC.Tc.Utils.TcType
           ; rec { ([TyVar]
via_tvs, Type
via_pred) <- SkolemInfoAnon -> Type -> TcM ([TyVar], Type)
tcSkolemiseInvisibleBndrs (Type -> SkolemInfoAnon
DerivSkol Type
via_pred) Type
ty }
           ; (DerivStrategy GhcTc, [TyVar])
-> TcM (DerivStrategy GhcTc, [TyVar])
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (f :: * -> *) a. Applicative f => a -> f a
pure (XViaStrategy GhcTc -> DerivStrategy GhcTc
forall pass. XViaStrategy pass -> DerivStrategy pass
ViaStrategy XViaStrategy GhcTc
Type
via_pred, [TyVar]
via_tvs) }

    boring_case :: ds -> TcM (ds, [a])
    boring_case :: forall ds a. ds -> TcM (ds, [a])
boring_case ds
ds = (ds, [a]) -> IOEnv (Env TcGblEnv TcLclEnv) (ds, [a])
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (f :: * -> *) a. Applicative f => a -> f a
pure (ds
ds, [])

tcHsClsInstType :: UserTypeCtxt    -- InstDeclCtxt or SpecInstCtxt
                -> LHsSigType GhcRn
                -> TcM Type
-- Like tcHsSigType, but for a class instance declaration
tcHsClsInstType :: UserTypeCtxt -> LHsSigType GhcRn -> TcM Type
tcHsClsInstType UserTypeCtxt
user_ctxt LHsSigType GhcRn
hs_inst_ty
  = SrcSpan -> TcM Type -> TcM Type
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan (GenLocated SrcSpanAnnA (HsSigType GhcRn) -> SrcSpan
forall a e. GenLocated (SrcSpanAnn' a) e -> SrcSpan
getLocA LHsSigType GhcRn
GenLocated SrcSpanAnnA (HsSigType GhcRn)
hs_inst_ty) (TcM Type -> TcM Type) -> TcM Type -> TcM Type
forall a b. (a -> b) -> a -> b
$
    do { Type
inst_ty <- UserTypeCtxt -> LHsSigType GhcRn -> TcM Type
tcTopLHsType UserTypeCtxt
user_ctxt LHsSigType GhcRn
hs_inst_ty
       ; UserTypeCtxt -> LHsSigType GhcRn -> Type -> TcM ()
checkValidInstance UserTypeCtxt
user_ctxt LHsSigType GhcRn
hs_inst_ty Type
inst_ty
       ; Type -> TcM Type
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return Type
inst_ty }

----------------------------------------------
-- | Type-check a visible type application
tcHsTypeApp :: LHsWcType GhcRn -> Kind -> TcM Type
-- See Note [Recipe for checking a signature] in GHC.Tc.Gen.HsType
tcHsTypeApp :: LHsWcType GhcRn -> Type -> TcM Type
tcHsTypeApp LHsWcType GhcRn
wc_ty Type
kind
  | HsWC { hswc_ext :: forall pass thing. HsWildCardBndrs pass thing -> XHsWC pass thing
hswc_ext = XHsWC GhcRn (LHsType GhcRn)
sig_wcs, hswc_body :: forall pass thing. HsWildCardBndrs pass thing -> thing
hswc_body = LHsType GhcRn
hs_ty } <- LHsWcType GhcRn
wc_ty
  = do { TcTyMode
mode <- TypeOrKind -> HoleMode -> TcM TcTyMode
mkHoleMode TypeOrKind
TypeLevel HoleMode
HM_VTA
                 -- HM_VTA: See Note [Wildcards in visible type application]
       ; Type
ty <- LHsType GhcRn -> TcM Type -> TcM Type
forall a. LHsType GhcRn -> TcM a -> TcM a
addTypeCtxt LHsType GhcRn
hs_ty                  (TcM Type -> TcM Type) -> TcM Type -> TcM Type
forall a b. (a -> b) -> a -> b
$
               String -> TcM Type -> TcM Type
forall a. String -> TcM a -> TcM a
solveEqualities String
"tcHsTypeApp" (TcM Type -> TcM Type) -> TcM Type -> TcM Type
forall a b. (a -> b) -> a -> b
$
               -- We are looking at a user-written type, very like a
               -- signature so we want to solve its equalities right now
               HsQTvsRn -> ([(Name, TyVar)] -> TcM Type) -> TcM Type
forall a. HsQTvsRn -> ([(Name, TyVar)] -> TcM a) -> TcM a
bindNamedWildCardBinders HsQTvsRn
XHsWC GhcRn (LHsType GhcRn)
sig_wcs (([(Name, TyVar)] -> TcM Type) -> TcM Type)
-> ([(Name, TyVar)] -> TcM Type) -> TcM Type
forall a b. (a -> b) -> a -> b
$ \ [(Name, TyVar)]
_ ->
               TcTyMode -> LHsType GhcRn -> Type -> TcM Type
tc_lhs_type TcTyMode
mode LHsType GhcRn
hs_ty Type
kind

       -- We do not kind-generalize type applications: we just
       -- instantiate with exactly what the user says.
       -- See Note [No generalization in type application]
       -- We still must call kindGeneralizeNone, though, according
       -- to Note [Recipe for checking a signature]
       ; Type -> TcM ()
kindGeneralizeNone Type
ty
       ; Type
ty <- Type -> TcM Type
zonkTcType Type
ty
       ; UserTypeCtxt -> Type -> TcM ()
checkValidType UserTypeCtxt
TypeAppCtxt Type
ty
       ; Type -> TcM Type
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return Type
ty }

{- Note [Wildcards in visible type application]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
A HsWildCardBndrs's hswc_ext now only includes /named/ wildcards, so
any unnamed wildcards stay unchanged in hswc_body.  When called in
tcHsTypeApp, tcCheckLHsType will call emitAnonTypeHole
on these anonymous wildcards. However, this would trigger
error/warning when an anonymous wildcard is passed in as a visible type
argument, which we do not want because users should be able to write
@_ to skip a instantiating a type variable variable without fuss. The
solution is to switch the PartialTypeSignatures flags here to let the
typechecker know that it's checking a '@_' and do not emit hole
constraints on it.  See related Note [Wildcards in visible kind
application] and Note [The wildcard story for types] in GHC.Hs.Type

Ugh!

Note [No generalization in type application]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We do not kind-generalize type applications. Imagine

  id @(Proxy Nothing)

If we kind-generalized, we would get

  id @(forall {k}. Proxy @(Maybe k) (Nothing @k))

which is very sneakily impredicative instantiation.

There is also the possibility of mentioning a wildcard
(`id @(Proxy _)`), which definitely should not be kind-generalized.

-}

tcFamTyPats :: TyCon
            -> HsTyPats GhcRn                -- Patterns
            -> TcM (TcType, TcKind)          -- (lhs_type, lhs_kind)
-- Check the LHS of a type/data family instance
-- e.g.   type instance F ty1 .. tyn = ...
-- Used for both type and data families
tcFamTyPats :: TyCon -> HsTyPats GhcRn -> TcM (Type, Type)
tcFamTyPats TyCon
fam_tc HsTyPats GhcRn
hs_pats
  = do { String -> SDoc -> TcM ()
traceTc String
"tcFamTyPats {" (SDoc -> TcM ()) -> SDoc -> TcM ()
forall a b. (a -> b) -> a -> b
$
         [SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat [ TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
fam_tc, String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"arity:" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Arity -> SDoc
forall a. Outputable a => a -> SDoc
ppr Arity
fam_arity ]

       ; TcTyMode
mode <- TypeOrKind -> HoleMode -> TcM TcTyMode
mkHoleMode TypeOrKind
TypeLevel HoleMode
HM_FamPat
                 -- HM_FamPat: See Note [Wildcards in family instances] in
                 -- GHC.Rename.Module
       ; let fun_ty :: Type
fun_ty = TyCon -> [Type] -> Type
mkTyConApp TyCon
fam_tc []
       ; (Type
fam_app, Type
res_kind) <- TcTyMode
-> LHsType GhcRn -> Type -> HsTyPats GhcRn -> TcM (Type, Type)
tcInferTyApps TcTyMode
mode LHsType GhcRn
GenLocated SrcSpanAnnA (HsType GhcRn)
lhs_fun Type
fun_ty HsTyPats GhcRn
hs_pats

       -- Hack alert: see Note [tcFamTyPats: zonking the result kind]
       ; Type
res_kind <- Type -> TcM Type
zonkTcType Type
res_kind

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

       ; (Type, Type) -> TcM (Type, Type)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (Type
fam_app, Type
res_kind) }
  where
    fam_name :: Name
fam_name  = TyCon -> Name
tyConName TyCon
fam_tc
    fam_arity :: Arity
fam_arity = TyCon -> Arity
tyConArity TyCon
fam_tc
    lhs_fun :: GenLocated SrcSpanAnnA (HsType GhcRn)
lhs_fun   = HsType GhcRn -> GenLocated SrcSpanAnnA (HsType GhcRn)
forall a an. a -> LocatedAn an a
noLocA (XTyVar GhcRn -> PromotionFlag -> LIdP GhcRn -> HsType GhcRn
forall pass.
XTyVar pass -> PromotionFlag -> LIdP pass -> HsType pass
HsTyVar XTyVar GhcRn
EpAnn [AddEpAnn]
forall a. EpAnn a
noAnn PromotionFlag
NotPromoted (Name -> GenLocated SrcSpanAnnN Name
forall a an. a -> LocatedAn an a
noLocA Name
fam_name))

{- Note [tcFamTyPats: zonking the result kind]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider (#19250)
    F :: forall k. k -> k
    type instance F (x :: Constraint) = ()

The tricky point is this:
  is that () an empty type tuple (() :: Type), or
  an empty constraint tuple (() :: Constraint)?
We work this out in a hacky way, by looking at the expected kind:
see Note [Inferring tuple kinds].

In this case, we kind-check the RHS using the kind gotten from the LHS:
see the call to tcCheckLHsType in tcTyFamInstEqnGuts in GHC.Tc.Tycl.

But we want the kind from the LHS to be /zonked/, so that when
kind-checking the RHS (tcCheckLHsType) we can "see" what we learned
from kind-checking the LHS (tcFamTyPats).  In our example above, the
type of the LHS is just `kappa` (by instantiating the forall k), but
then we learn (from x::Constraint) that kappa ~ Constraint.  We want
that info when kind-checking the RHS.

Easy solution: just zonk that return kind.  Of course this won't help
if there is lots of type-family reduction to do, but it works fine in
common cases.
-}


{-
************************************************************************
*                                                                      *
            The main kind checker: no validity checks here
*                                                                      *
************************************************************************
-}

---------------------------
tcHsOpenType, tcHsLiftedType,
  tcHsOpenTypeNC, tcHsLiftedTypeNC :: LHsType GhcRn -> TcM TcType
-- Used for type signatures
-- Do not do validity checking
tcHsOpenType :: LHsType GhcRn -> TcM Type
tcHsOpenType   LHsType GhcRn
hs_ty = LHsType GhcRn -> TcM Type -> TcM Type
forall a. LHsType GhcRn -> TcM a -> TcM a
addTypeCtxt LHsType GhcRn
hs_ty (TcM Type -> TcM Type) -> TcM Type -> TcM Type
forall a b. (a -> b) -> a -> b
$ LHsType GhcRn -> TcM Type
tcHsOpenTypeNC LHsType GhcRn
hs_ty
tcHsLiftedType :: LHsType GhcRn -> TcM Type
tcHsLiftedType LHsType GhcRn
hs_ty = LHsType GhcRn -> TcM Type -> TcM Type
forall a. LHsType GhcRn -> TcM a -> TcM a
addTypeCtxt LHsType GhcRn
hs_ty (TcM Type -> TcM Type) -> TcM Type -> TcM Type
forall a b. (a -> b) -> a -> b
$ LHsType GhcRn -> TcM Type
tcHsLiftedTypeNC LHsType GhcRn
hs_ty

tcHsOpenTypeNC :: LHsType GhcRn -> TcM Type
tcHsOpenTypeNC   LHsType GhcRn
hs_ty = do { Type
ek <- TcM Type
newOpenTypeKind; LHsType GhcRn -> Type -> TcM Type
tcLHsType LHsType GhcRn
hs_ty Type
ek }
tcHsLiftedTypeNC :: LHsType GhcRn -> TcM Type
tcHsLiftedTypeNC LHsType GhcRn
hs_ty = LHsType GhcRn -> Type -> TcM Type
tcLHsType LHsType GhcRn
hs_ty Type
liftedTypeKind

-- Like tcHsType, but takes an expected kind
tcCheckLHsType :: LHsType GhcRn -> ContextKind -> TcM TcType
tcCheckLHsType :: LHsType GhcRn -> ContextKind -> TcM Type
tcCheckLHsType LHsType GhcRn
hs_ty ContextKind
exp_kind
  = LHsType GhcRn -> TcM Type -> TcM Type
forall a. LHsType GhcRn -> TcM a -> TcM a
addTypeCtxt LHsType GhcRn
hs_ty (TcM Type -> TcM Type) -> TcM Type -> TcM Type
forall a b. (a -> b) -> a -> b
$
    do { Type
ek <- ContextKind -> TcM Type
newExpectedKind ContextKind
exp_kind
       ; LHsType GhcRn -> Type -> TcM Type
tcLHsType LHsType GhcRn
hs_ty Type
ek }

tcInferLHsType :: LHsType GhcRn -> TcM TcType
tcInferLHsType :: LHsType GhcRn -> TcM Type
tcInferLHsType LHsType GhcRn
hs_ty
  = do { (Type
ty,Type
_kind) <- LHsType GhcRn -> TcM (Type, Type)
tcInferLHsTypeKind LHsType GhcRn
hs_ty
       ; Type -> TcM Type
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return Type
ty }

tcInferLHsTypeKind :: LHsType GhcRn -> TcM (TcType, TcKind)
-- Called from outside: set the context
-- Eagerly instantiate any trailing invisible binders
tcInferLHsTypeKind :: LHsType GhcRn -> TcM (Type, Type)
tcInferLHsTypeKind lhs_ty :: LHsType GhcRn
lhs_ty@(L SrcSpanAnnA
loc HsType GhcRn
hs_ty)
  = LHsType GhcRn -> TcM (Type, Type) -> TcM (Type, Type)
forall a. LHsType GhcRn -> TcM a -> TcM a
addTypeCtxt LHsType GhcRn
lhs_ty (TcM (Type, Type) -> TcM (Type, Type))
-> TcM (Type, Type) -> TcM (Type, Type)
forall a b. (a -> b) -> a -> b
$
    SrcSpanAnnA -> TcM (Type, Type) -> TcM (Type, Type)
forall ann a. SrcSpanAnn' ann -> TcRn a -> TcRn a
setSrcSpanA SrcSpanAnnA
loc    (TcM (Type, Type) -> TcM (Type, Type))
-> TcM (Type, Type) -> TcM (Type, Type)
forall a b. (a -> b) -> a -> b
$  -- Cover the tcInstInvisibleTyBinders
    do { (Type
res_ty, Type
res_kind) <- TcTyMode -> HsType GhcRn -> TcM (Type, Type)
tc_infer_hs_type TcTyMode
typeLevelMode HsType GhcRn
hs_ty
       ; Type -> Type -> TcM (Type, Type)
tcInstInvisibleTyBinders Type
res_ty Type
res_kind }
  -- See Note [Do not always instantiate eagerly in types]

-- Used to check the argument of GHCi :kind
-- Allow and report wildcards, e.g. :kind T _
-- Do not saturate family applications: see Note [Dealing with :kind]
-- Does not instantiate eagerly; See Note [Do not always instantiate eagerly in types]
tcInferLHsTypeUnsaturated :: LHsType GhcRn -> TcM (TcType, TcKind)
tcInferLHsTypeUnsaturated :: LHsType GhcRn -> TcM (Type, Type)
tcInferLHsTypeUnsaturated LHsType GhcRn
hs_ty
  = LHsType GhcRn -> TcM (Type, Type) -> TcM (Type, Type)
forall a. LHsType GhcRn -> TcM a -> TcM a
addTypeCtxt LHsType GhcRn
hs_ty (TcM (Type, Type) -> TcM (Type, Type))
-> TcM (Type, Type) -> TcM (Type, Type)
forall a b. (a -> b) -> a -> b
$
    do { TcTyMode
mode <- TypeOrKind -> HoleMode -> TcM TcTyMode
mkHoleMode TypeOrKind
TypeLevel HoleMode
HM_Sig  -- Allow and report holes
       ; case HsType GhcRn -> Maybe (LHsType GhcRn, HsTyPats GhcRn)
splitHsAppTys (GenLocated SrcSpanAnnA (HsType GhcRn) -> HsType GhcRn
forall l e. GenLocated l e -> e
unLoc LHsType GhcRn
GenLocated SrcSpanAnnA (HsType GhcRn)
hs_ty) of
           Just (LHsType GhcRn
hs_fun_ty, HsTyPats GhcRn
hs_args)
              -> do { (Type
fun_ty, Type
_ki) <- TcTyMode -> LHsType GhcRn -> TcM (Type, Type)
tcInferTyAppHead TcTyMode
mode LHsType GhcRn
hs_fun_ty
                    ; TcTyMode
-> LHsType GhcRn -> Type -> HsTyPats GhcRn -> TcM (Type, Type)
tcInferTyApps_nosat TcTyMode
mode LHsType GhcRn
hs_fun_ty Type
fun_ty HsTyPats GhcRn
hs_args }
                      -- Notice the 'nosat'; do not instantiate trailing
                      -- invisible arguments of a type family.
                      -- See Note [Dealing with :kind]
           Maybe (LHsType GhcRn, HsTyPats GhcRn)
Nothing -> TcTyMode -> LHsType GhcRn -> TcM (Type, Type)
tc_infer_lhs_type TcTyMode
mode LHsType GhcRn
hs_ty }

{- Note [Dealing with :kind]
~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider this GHCi command
  ghci> type family F :: Either j k
  ghci> :kind F
  F :: forall {j,k}. Either j k

We will only get the 'forall' if we /refrain/ from saturating those
invisible binders. But generally we /do/ saturate those invisible
binders (see tcInferTyApps), and we want to do so for nested application
even in GHCi.  Consider for example (#16287)
  ghci> type family F :: k
  ghci> data T :: (forall k. k) -> Type
  ghci> :kind T F
We want to reject this. It's just at the very top level that we want
to switch off saturation.

So tcInferLHsTypeUnsaturated does a little special case for top level
applications.  Actually the common case is a bare variable, as above.

Note [Do not always instantiate eagerly in types]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Terms are eagerly instantiated. This means that if you say

  x = id

then `id` gets instantiated to have type alpha -> alpha. The variable
alpha is then unconstrained and regeneralized. But we cannot do this
in types, as we have no type-level lambda. So, when we are sure
that we will not want to regeneralize later -- because we are done
checking a type, for example -- we can instantiate. But we do not
instantiate at variables, nor do we in tcInferLHsTypeUnsaturated,
which is used by :kind in GHCi.

************************************************************************
*                                                                      *
      Type-checking modes
*                                                                      *
************************************************************************

The kind-checker is parameterised by a TcTyMode, which contains some
information about where we're checking a type.

The renamer issues errors about what it can. All errors issued here must
concern things that the renamer can't handle.

-}

tcMult :: HsArrow GhcRn -> TcM Mult
tcMult :: HsArrow GhcRn -> TcM Type
tcMult HsArrow GhcRn
hc = TcTyMode -> HsArrow GhcRn -> TcM Type
tc_mult TcTyMode
typeLevelMode HsArrow GhcRn
hc

-- | Info about the context in which we're checking a type. Currently,
-- differentiates only between types and kinds, but this will likely
-- grow, at least to include the distinction between patterns and
-- not-patterns.
--
-- To find out where the mode is used, search for 'mode_tyki'
--
-- This data type is purely local, not exported from this module
data TcTyMode
  = TcTyMode { TcTyMode -> TypeOrKind
mode_tyki :: TypeOrKind
             , TcTyMode -> HoleInfo
mode_holes :: HoleInfo   }

-- See Note [Levels for wildcards]
-- Nothing <=> no wildcards expected
type HoleInfo = Maybe (TcLevel, HoleMode)

-- HoleMode says how to treat the occurrences
-- of anonymous wildcards; see tcAnonWildCardOcc
data HoleMode = HM_Sig      -- Partial type signatures: f :: _ -> Int
              | HM_FamPat   -- Family instances: F _ Int = Bool
              | HM_VTA      -- Visible type and kind application:
                            --   f @(Maybe _)
                            --   Maybe @(_ -> _)
              | HM_TyAppPat -- Visible type applications in patterns:
                            --   foo (Con @_ @t x) = ...
                            --   case x of Con @_ @t v -> ...

mkMode :: TypeOrKind -> TcTyMode
mkMode :: TypeOrKind -> TcTyMode
mkMode TypeOrKind
tyki = TcTyMode { mode_tyki :: TypeOrKind
mode_tyki = TypeOrKind
tyki, mode_holes :: HoleInfo
mode_holes = HoleInfo
forall a. Maybe a
Nothing }

typeLevelMode, kindLevelMode :: TcTyMode
-- These modes expect no wildcards (holes) in the type
kindLevelMode :: TcTyMode
kindLevelMode = TypeOrKind -> TcTyMode
mkMode TypeOrKind
KindLevel
typeLevelMode :: TcTyMode
typeLevelMode = TypeOrKind -> TcTyMode
mkMode TypeOrKind
TypeLevel

mkHoleMode :: TypeOrKind -> HoleMode -> TcM TcTyMode
mkHoleMode :: TypeOrKind -> HoleMode -> TcM TcTyMode
mkHoleMode TypeOrKind
tyki HoleMode
hm
  = do { TcLevel
lvl <- TcM TcLevel
getTcLevel
       ; TcTyMode -> TcM TcTyMode
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (TcTyMode { mode_tyki :: TypeOrKind
mode_tyki  = TypeOrKind
tyki
                          , mode_holes :: HoleInfo
mode_holes = (TcLevel, HoleMode) -> HoleInfo
forall a. a -> Maybe a
Just (TcLevel
lvl,HoleMode
hm) }) }

instance Outputable HoleMode where
  ppr :: HoleMode -> SDoc
ppr HoleMode
HM_Sig      = String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"HM_Sig"
  ppr HoleMode
HM_FamPat   = String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"HM_FamPat"
  ppr HoleMode
HM_VTA      = String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"HM_VTA"
  ppr HoleMode
HM_TyAppPat = String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"HM_TyAppPat"

instance Outputable TcTyMode where
  ppr :: TcTyMode -> SDoc
ppr (TcTyMode { mode_tyki :: TcTyMode -> TypeOrKind
mode_tyki = TypeOrKind
tyki, mode_holes :: TcTyMode -> HoleInfo
mode_holes = HoleInfo
hm })
    = String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"TcTyMode" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc
braces ([SDoc] -> SDoc
forall doc. IsLine doc => [doc] -> doc
sep [ TypeOrKind -> SDoc
forall a. Outputable a => a -> SDoc
ppr TypeOrKind
tyki SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<> SDoc
forall doc. IsLine doc => doc
comma
                                      , HoleInfo -> SDoc
forall a. Outputable a => a -> SDoc
ppr HoleInfo
hm ])

{-
Note [Bidirectional type checking]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In expressions, whenever we see a polymorphic identifier, say `id`, we are
free to instantiate it with metavariables, knowing that we can always
re-generalize with type-lambdas when necessary. For example:

  rank2 :: (forall a. a -> a) -> ()
  x = rank2 id

When checking the body of `x`, we can instantiate `id` with a metavariable.
Then, when we're checking the application of `rank2`, we notice that we really
need a polymorphic `id`, and then re-generalize over the unconstrained
metavariable.

In types, however, we're not so lucky, because *we cannot re-generalize*!
There is no lambda. So, we must be careful only to instantiate at the last
possible moment, when we're sure we're never going to want the lost polymorphism
again. This is done in calls to tcInstInvisibleTyBinders.

To implement this behavior, we use bidirectional type checking, where we
explicitly think about whether we know the kind of the type we're checking
or not. Note that there is a difference between not knowing a kind and
knowing a metavariable kind: the metavariables are TauTvs, and cannot become
forall-quantified kinds. Previously (before dependent types), there were
no higher-rank kinds, and so we could instantiate early and be sure that
no types would have polymorphic kinds, and so we could always assume that
the kind of a type was a fresh metavariable. Not so anymore, thus the
need for two algorithms.

For HsType forms that can never be kind-polymorphic, we implement only the
"down" direction, where we safely assume a metavariable kind. For HsType forms
that *can* be kind-polymorphic, we implement just the "up" (functions with
"infer" in their name) version, as we gain nothing by also implementing the
"down" version.

Note [Future-proofing the type checker]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
As discussed in Note [Bidirectional type checking], each HsType form is
handled in *either* tc_infer_hs_type *or* tc_hs_type. These functions
are mutually recursive, so that either one can work for any type former.
But, we want to make sure that our pattern-matches are complete. So,
we have a bunch of repetitive code just so that we get warnings if we're
missing any patterns.

-}

------------------------------------------
-- | Check and desugar a type, returning the core type and its
-- possibly-polymorphic kind. Much like 'tcInferRho' at the expression
-- level.
tc_infer_lhs_type :: TcTyMode -> LHsType GhcRn -> TcM (TcType, TcKind)
tc_infer_lhs_type :: TcTyMode -> LHsType GhcRn -> TcM (Type, Type)
tc_infer_lhs_type TcTyMode
mode (L SrcSpanAnnA
span HsType GhcRn
ty)
  = SrcSpanAnnA -> TcM (Type, Type) -> TcM (Type, Type)
forall ann a. SrcSpanAnn' ann -> TcRn a -> TcRn a
setSrcSpanA SrcSpanAnnA
span (TcM (Type, Type) -> TcM (Type, Type))
-> TcM (Type, Type) -> TcM (Type, Type)
forall a b. (a -> b) -> a -> b
$
    TcTyMode -> HsType GhcRn -> TcM (Type, Type)
tc_infer_hs_type TcTyMode
mode HsType GhcRn
ty

---------------------------
-- | Call 'tc_infer_hs_type' and check its result against an expected kind.
tc_infer_hs_type_ek :: HasDebugCallStack => TcTyMode -> HsType GhcRn -> TcKind -> TcM TcType
tc_infer_hs_type_ek :: (() :: Constraint) => TcTyMode -> HsType GhcRn -> Type -> TcM Type
tc_infer_hs_type_ek TcTyMode
mode HsType GhcRn
hs_ty Type
ek
  = do { (Type
ty, Type
k) <- TcTyMode -> HsType GhcRn -> TcM (Type, Type)
tc_infer_hs_type TcTyMode
mode HsType GhcRn
hs_ty
       ; (() :: Constraint) =>
HsType GhcRn -> Type -> Type -> Type -> TcM Type
HsType GhcRn -> Type -> Type -> Type -> TcM Type
checkExpectedKind HsType GhcRn
hs_ty Type
ty Type
k Type
ek }

---------------------------
-- | Infer the kind of a type and desugar. This is the "up" type-checker,
-- as described in Note [Bidirectional type checking]
tc_infer_hs_type :: TcTyMode -> HsType GhcRn -> TcM (TcType, TcKind)

tc_infer_hs_type :: TcTyMode -> HsType GhcRn -> TcM (Type, Type)
tc_infer_hs_type TcTyMode
mode (HsParTy XParTy GhcRn
_ LHsType GhcRn
t)
  = TcTyMode -> LHsType GhcRn -> TcM (Type, Type)
tc_infer_lhs_type TcTyMode
mode LHsType GhcRn
t

tc_infer_hs_type TcTyMode
mode HsType GhcRn
ty
  | Just (LHsType GhcRn
hs_fun_ty, HsTyPats GhcRn
hs_args) <- HsType GhcRn -> Maybe (LHsType GhcRn, HsTyPats GhcRn)
splitHsAppTys HsType GhcRn
ty
  = do { (Type
fun_ty, Type
_ki) <- TcTyMode -> LHsType GhcRn -> TcM (Type, Type)
tcInferTyAppHead TcTyMode
mode LHsType GhcRn
hs_fun_ty
       ; TcTyMode
-> LHsType GhcRn -> Type -> HsTyPats GhcRn -> TcM (Type, Type)
tcInferTyApps TcTyMode
mode LHsType GhcRn
hs_fun_ty Type
fun_ty HsTyPats GhcRn
hs_args }

tc_infer_hs_type TcTyMode
mode (HsKindSig XKindSig GhcRn
_ LHsType GhcRn
ty LHsType GhcRn
sig)
  = do { let mode' :: TcTyMode
mode' = TcTyMode
mode { mode_tyki = KindLevel }
       ; Type
sig' <- TcTyMode -> UserTypeCtxt -> LHsType GhcRn -> TcM Type
tc_lhs_kind_sig TcTyMode
mode' UserTypeCtxt
KindSigCtxt LHsType GhcRn
sig
                 -- We must typecheck the kind signature, and solve all
                 -- its equalities etc; from this point on we may do
                 -- things like instantiate its foralls, so it needs
                 -- to be fully determined (#14904)
       ; String -> SDoc -> TcM ()
traceTc String
"tc_infer_hs_type:sig" (GenLocated SrcSpanAnnA (HsType GhcRn) -> SDoc
forall a. Outputable a => a -> SDoc
ppr LHsType GhcRn
GenLocated SrcSpanAnnA (HsType GhcRn)
ty SDoc -> SDoc -> SDoc
forall doc. IsDoc doc => doc -> doc -> doc
$$ Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
sig')
       ; Type
ty' <- TcTyMode -> LHsType GhcRn -> Type -> TcM Type
tc_lhs_type TcTyMode
mode LHsType GhcRn
ty Type
sig'
       ; (Type, Type) -> TcM (Type, Type)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (Type
ty', Type
sig') }

-- HsSpliced is an annotation produced by 'GHC.Rename.Splice.rnSpliceType' to communicate
-- the splice location to the typechecker. Here we skip over it in order to have
-- the same kind inferred for a given expression whether it was produced from
-- splices or not.
--
-- See Note [Delaying modFinalizers in untyped splices].
tc_infer_hs_type TcTyMode
mode (HsSpliceTy (HsUntypedSpliceTop ThModFinalizers
_ GenLocated SrcSpanAnnA (HsType GhcRn)
ty) HsUntypedSplice GhcRn
_)
  = TcTyMode -> LHsType GhcRn -> TcM (Type, Type)
tc_infer_lhs_type TcTyMode
mode LHsType GhcRn
GenLocated SrcSpanAnnA (HsType GhcRn)
ty

tc_infer_hs_type TcTyMode
_ (HsSpliceTy (HsUntypedSpliceNested Name
n) HsUntypedSplice GhcRn
s) = String -> SDoc -> TcM (Type, Type)
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"tc_infer_hs_type: invalid nested splice" (Bool -> Maybe Name -> HsUntypedSplice GhcRn -> SDoc
forall (p :: Pass).
OutputableBndrId p =>
Bool -> Maybe Name -> HsUntypedSplice (GhcPass p) -> SDoc
pprUntypedSplice Bool
True (Name -> Maybe Name
forall a. a -> Maybe a
Just Name
n) HsUntypedSplice GhcRn
s)

tc_infer_hs_type TcTyMode
mode (HsDocTy XDocTy GhcRn
_ LHsType GhcRn
ty LHsDoc GhcRn
_) = TcTyMode -> LHsType GhcRn -> TcM (Type, Type)
tc_infer_lhs_type TcTyMode
mode LHsType GhcRn
ty

-- See Note [Typechecking HsCoreTys]
tc_infer_hs_type TcTyMode
_ (XHsType XXType GhcRn
ty)
  = do TcLclEnv
env <- TcRnIf TcGblEnv TcLclEnv TcLclEnv
forall gbl lcl. TcRnIf gbl lcl lcl
getLclEnv
       -- Raw uniques since we go from NameEnv to TvSubstEnv.
       let subst_prs :: [(Unique, TcTyVar)]
           subst_prs :: [(Unique, TyVar)]
subst_prs = [ (Name -> Unique
forall a. Uniquable a => a -> Unique
getUnique Name
nm, TyVar
tv)
                       | ATyVar Name
nm TyVar
tv <- NameEnv TcTyThing -> [TcTyThing]
forall a. NameEnv a -> [a]
nonDetNameEnvElts (TcLclEnv -> NameEnv TcTyThing
tcl_env TcLclEnv
env) ]
           subst :: Subst
subst = InScopeSet -> TvSubstEnv -> Subst
mkTvSubst
                     ([TyVar] -> InScopeSet
mkInScopeSetList ([TyVar] -> InScopeSet) -> [TyVar] -> InScopeSet
forall a b. (a -> b) -> a -> b
$ ((Unique, TyVar) -> TyVar) -> [(Unique, TyVar)] -> [TyVar]
forall a b. (a -> b) -> [a] -> [b]
map (Unique, TyVar) -> TyVar
forall a b. (a, b) -> b
snd [(Unique, TyVar)]
subst_prs)
                     ([(Unique, Type)] -> TvSubstEnv
forall elt key. [(Unique, elt)] -> UniqFM key elt
listToUFM_Directly ([(Unique, Type)] -> TvSubstEnv) -> [(Unique, Type)] -> TvSubstEnv
forall a b. (a -> b) -> a -> b
$ ((Unique, TyVar) -> (Unique, Type))
-> [(Unique, TyVar)] -> [(Unique, Type)]
forall a b. (a -> b) -> [a] -> [b]
map ((TyVar -> Type) -> (Unique, TyVar) -> (Unique, Type)
forall a b. (a -> b) -> (Unique, a) -> (Unique, b)
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap TyVar -> Type
mkTyVarTy) [(Unique, TyVar)]
subst_prs)
           ty' :: Type
ty' = (() :: Constraint) => Subst -> Type -> Type
Subst -> Type -> Type
substTy Subst
subst XXType GhcRn
Type
ty
       (Type, Type) -> TcM (Type, Type)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (Type
ty', (() :: Constraint) => Type -> Type
Type -> Type
typeKind Type
ty')

tc_infer_hs_type TcTyMode
_ (HsExplicitListTy XExplicitListTy GhcRn
_ PromotionFlag
_ [LHsType GhcRn]
tys)
  | [GenLocated SrcSpanAnnA (HsType GhcRn)] -> Bool
forall a. [a] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [LHsType GhcRn]
[GenLocated SrcSpanAnnA (HsType GhcRn)]
tys  -- this is so that we can use visible kind application with '[]
              -- e.g ... '[] @Bool
  = (Type, Type) -> TcM (Type, Type)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (TyCon -> Type
mkTyConTy TyCon
promotedNilDataCon,
            [TyVar] -> Type -> Type
mkSpecForAllTys [TyVar
alphaTyVar] (Type -> Type) -> Type -> Type
forall a b. (a -> b) -> a -> b
$ Type -> Type
mkListTy Type
alphaTy)

tc_infer_hs_type TcTyMode
mode HsType GhcRn
other_ty
  = do { Type
kv <- TcM Type
newMetaKindVar
       ; Type
ty' <- TcTyMode -> HsType GhcRn -> Type -> TcM Type
tc_hs_type TcTyMode
mode HsType GhcRn
other_ty Type
kv
       ; (Type, Type) -> TcM (Type, Type)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (Type
ty', Type
kv) }

{-
Note [Typechecking HsCoreTys]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
HsCoreTy is an escape hatch that allows embedding Core Types in HsTypes.
As such, there's not much to be done in order to typecheck an HsCoreTy,
since it's already been typechecked to some extent. There is one thing that
we must do, however: we must substitute the type variables from the tcl_env.
To see why, consider GeneralizedNewtypeDeriving, which is one of the main
clients of HsCoreTy (example adapted from #14579):

  newtype T a = MkT a deriving newtype Eq

This will produce an InstInfo GhcPs that looks roughly like this:

  instance forall a_1. Eq a_1 => Eq (T a_1) where
    (==) = coerce @(  a_1 ->   a_1 -> Bool) -- The type within @(...) is an HsCoreTy
                  @(T a_1 -> T a_1 -> Bool) -- So is this
                  (==)

This is then fed into the renamer. Since all of the type variables in this
InstInfo use Exact RdrNames, the resulting InstInfo GhcRn looks basically
identical. Things get more interesting when the InstInfo is fed into the
typechecker, however. GHC will first generate fresh skolems to instantiate
the instance-bound type variables with. In the example above, we might generate
the skolem a_2 and use that to instantiate a_1, which extends the local type
environment (tcl_env) with [a_1 :-> a_2]. This gives us:

  instance forall a_2. Eq a_2 => Eq (T a_2) where ...

To ensure that the body of this instance is well scoped, every occurrence of
the `a` type variable should refer to a_2, the new skolem. However, the
HsCoreTys mention a_1, not a_2. Luckily, the tcl_env provides exactly the
substitution we need ([a_1 :-> a_2]) to fix up the scoping. We apply this
substitution to each HsCoreTy and all is well:

  instance forall a_2. Eq a_2 => Eq (T a_2) where
    (==) = coerce @(  a_2 ->   a_2 -> Bool)
                  @(T a_2 -> T a_2 -> Bool)
                  (==)
-}

------------------------------------------
tcLHsType :: LHsType GhcRn -> TcKind -> TcM TcType
tcLHsType :: LHsType GhcRn -> Type -> TcM Type
tcLHsType LHsType GhcRn
hs_ty Type
exp_kind
  = TcTyMode -> LHsType GhcRn -> Type -> TcM Type
tc_lhs_type TcTyMode
typeLevelMode LHsType GhcRn
hs_ty Type
exp_kind

tc_lhs_type :: TcTyMode -> LHsType GhcRn -> TcKind -> TcM TcType
tc_lhs_type :: TcTyMode -> LHsType GhcRn -> Type -> TcM Type
tc_lhs_type TcTyMode
mode (L SrcSpanAnnA
span HsType GhcRn
ty) Type
exp_kind
  = SrcSpanAnnA -> TcM Type -> TcM Type
forall ann a. SrcSpanAnn' ann -> TcRn a -> TcRn a
setSrcSpanA SrcSpanAnnA
span (TcM Type -> TcM Type) -> TcM Type -> TcM Type
forall a b. (a -> b) -> a -> b
$
    TcTyMode -> HsType GhcRn -> Type -> TcM Type
tc_hs_type TcTyMode
mode HsType GhcRn
ty Type
exp_kind

tc_hs_type :: TcTyMode -> HsType GhcRn -> TcKind -> TcM TcType
-- See Note [Bidirectional type checking]

tc_hs_type :: TcTyMode -> HsType GhcRn -> Type -> TcM Type
tc_hs_type TcTyMode
mode (HsParTy XParTy GhcRn
_ LHsType GhcRn
ty)   Type
exp_kind = TcTyMode -> LHsType GhcRn -> Type -> TcM Type
tc_lhs_type TcTyMode
mode LHsType GhcRn
ty Type
exp_kind
tc_hs_type TcTyMode
mode (HsDocTy XDocTy GhcRn
_ LHsType GhcRn
ty LHsDoc GhcRn
_) Type
exp_kind = TcTyMode -> LHsType GhcRn -> Type -> TcM Type
tc_lhs_type TcTyMode
mode LHsType GhcRn
ty Type
exp_kind
tc_hs_type TcTyMode
_ ty :: HsType GhcRn
ty@(HsBangTy XBangTy GhcRn
_ HsSrcBang
bang LHsType GhcRn
_) Type
_
    -- While top-level bangs at this point are eliminated (eg !(Maybe Int)),
    -- other kinds of bangs are not (eg ((!Maybe) Int)). These kinds of
    -- bangs are invalid, so fail. (#7210, #14761)
    = TcRnMessage -> TcM Type
forall a. TcRnMessage -> TcM a
failWith (TcRnMessage -> TcM Type) -> TcRnMessage -> TcM Type
forall a b. (a -> b) -> a -> b
$ HsType GhcRn -> HsSrcBang -> TcRnMessage
TcRnUnexpectedAnnotation HsType GhcRn
ty HsSrcBang
bang
tc_hs_type TcTyMode
_ ty :: HsType GhcRn
ty@(HsRecTy {})      Type
_
      -- Record types (which only show up temporarily in constructor
      -- signatures) should have been removed by now
    = TcRnMessage -> TcM Type
forall a. TcRnMessage -> TcM a
failWithTc (TcRnMessage -> TcM Type) -> TcRnMessage -> TcM Type
forall a b. (a -> b) -> a -> b
$ HsType GhcRn -> TcRnMessage
TcRnIllegalRecordSyntax HsType GhcRn
ty

-- HsSpliced is an annotation produced by 'GHC.Rename.Splice.rnSpliceType'.
-- Here we get rid of it and add the finalizers to the global environment
-- while capturing the local environment.
--
-- See Note [Delaying modFinalizers in untyped splices].
tc_hs_type TcTyMode
mode (HsSpliceTy (HsUntypedSpliceTop ThModFinalizers
mod_finalizers GenLocated SrcSpanAnnA (HsType GhcRn)
ty) HsUntypedSplice GhcRn
_)
           Type
exp_kind
  = do ThModFinalizers -> TcM ()
addModFinalizersWithLclEnv ThModFinalizers
mod_finalizers
       TcTyMode -> LHsType GhcRn -> Type -> TcM Type
tc_lhs_type TcTyMode
mode LHsType GhcRn
GenLocated SrcSpanAnnA (HsType GhcRn)
ty Type
exp_kind

tc_hs_type TcTyMode
_ (HsSpliceTy (HsUntypedSpliceNested Name
n) HsUntypedSplice GhcRn
s) Type
_ = String -> SDoc -> TcM Type
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"tc_hs_type: invalid nested splice" (Bool -> Maybe Name -> HsUntypedSplice GhcRn -> SDoc
forall (p :: Pass).
OutputableBndrId p =>
Bool -> Maybe Name -> HsUntypedSplice (GhcPass p) -> SDoc
pprUntypedSplice Bool
True (Name -> Maybe Name
forall a. a -> Maybe a
Just Name
n) HsUntypedSplice GhcRn
s)

---------- Functions and applications
tc_hs_type TcTyMode
mode (HsFunTy XFunTy GhcRn
_ HsArrow GhcRn
mult LHsType GhcRn
ty1 LHsType GhcRn
ty2) Type
exp_kind
  = TcTyMode
-> HsArrow GhcRn
-> LHsType GhcRn
-> LHsType GhcRn
-> Type
-> TcM Type
tc_fun_type TcTyMode
mode HsArrow GhcRn
mult LHsType GhcRn
ty1 LHsType GhcRn
ty2 Type
exp_kind

tc_hs_type TcTyMode
mode (HsOpTy XOpTy GhcRn
_ PromotionFlag
_ LHsType GhcRn
ty1 (L SrcSpanAnnN
_ Name
op) LHsType GhcRn
ty2) Type
exp_kind
  | Name
op Name -> Unique -> Bool
forall a. Uniquable a => a -> Unique -> Bool
`hasKey` Unique
unrestrictedFunTyConKey
  = TcTyMode
-> HsArrow GhcRn
-> LHsType GhcRn
-> LHsType GhcRn
-> Type
-> TcM Type
tc_fun_type TcTyMode
mode (LHsUniToken "->" "\8594" GhcRn -> HsArrow GhcRn
forall pass. LHsUniToken "->" "\8594" pass -> HsArrow pass
HsUnrestrictedArrow LHsUniToken "->" "\8594" GhcRn
GenLocated TokenLocation (HsUniToken "->" "\8594")
forall (tok :: Symbol) (utok :: Symbol).
GenLocated TokenLocation (HsUniToken tok utok)
noHsUniTok) LHsType GhcRn
ty1 LHsType GhcRn
ty2 Type
exp_kind

--------- Foralls
tc_hs_type TcTyMode
mode (HsForAllTy { hst_tele :: forall pass. HsType pass -> HsForAllTelescope pass
hst_tele = HsForAllTelescope GhcRn
tele, hst_body :: forall pass. HsType pass -> LHsType pass
hst_body = LHsType GhcRn
ty }) Type
exp_kind
  = do { ([TcTyVarBinder]
tv_bndrs, Type
ty') <- TcTyMode
-> HsForAllTelescope GhcRn
-> TcM Type
-> TcM ([TcTyVarBinder], Type)
forall a.
TcTyMode
-> HsForAllTelescope GhcRn -> TcM a -> TcM ([TcTyVarBinder], a)
tcTKTelescope TcTyMode
mode HsForAllTelescope GhcRn
tele (TcM Type -> TcM ([TcTyVarBinder], Type))
-> TcM Type -> TcM ([TcTyVarBinder], Type)
forall a b. (a -> b) -> a -> b
$
                            TcTyMode -> LHsType GhcRn -> Type -> TcM Type
tc_lhs_type TcTyMode
mode LHsType GhcRn
ty Type
exp_kind
                 -- Pass on the mode from the type, to any wildcards
                 -- in kind signatures on the forall'd variables
                 -- e.g.      f :: _ -> Int -> forall (a :: _). blah
                 -- Why exp_kind?  See Note [Body kind of a HsForAllTy]

       -- Do not kind-generalise here!  See Note [Kind generalisation]

       ; Type -> TcM Type
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ([TcTyVarBinder] -> Type -> Type
mkForAllTys [TcTyVarBinder]
tv_bndrs Type
ty') }

tc_hs_type TcTyMode
mode (HsQualTy { hst_ctxt :: forall pass. HsType pass -> LHsContext pass
hst_ctxt = LHsContext GhcRn
ctxt, hst_body :: forall pass. HsType pass -> LHsType pass
hst_body = LHsType GhcRn
rn_ty }) Type
exp_kind
  | [GenLocated SrcSpanAnnA (HsType GhcRn)] -> Bool
forall a. [a] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null (GenLocated SrcSpanAnnC [GenLocated SrcSpanAnnA (HsType GhcRn)]
-> [GenLocated SrcSpanAnnA (HsType GhcRn)]
forall l e. GenLocated l e -> e
unLoc LHsContext GhcRn
GenLocated SrcSpanAnnC [GenLocated SrcSpanAnnA (HsType GhcRn)]
ctxt)
  = TcTyMode -> LHsType GhcRn -> Type -> TcM Type
tc_lhs_type TcTyMode
mode LHsType GhcRn
rn_ty Type
exp_kind

  -- See Note [Body kind of a HsQualTy]
  | Type -> Bool
isConstraintLikeKind Type
exp_kind
  = do { [Type]
ctxt' <- TcTyMode -> LHsContext GhcRn -> TcM [Type]
tc_hs_context TcTyMode
mode LHsContext GhcRn
ctxt
       ; Type
ty'   <- TcTyMode -> LHsType GhcRn -> Type -> TcM Type
tc_lhs_type TcTyMode
mode LHsType GhcRn
rn_ty Type
constraintKind
       ; Type -> TcM Type
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ([Type] -> Type -> Type
(() :: Constraint) => [Type] -> Type -> Type
tcMkDFunPhiTy [Type]
ctxt' Type
ty') }

  | Bool
otherwise
  = do { [Type]
ctxt' <- TcTyMode -> LHsContext GhcRn -> TcM [Type]
tc_hs_context TcTyMode
mode LHsContext GhcRn
ctxt

       ; Type
ek <- TcM Type
newOpenTypeKind  -- The body kind (result of the function) can
                                -- be TYPE r, for any r, hence newOpenTypeKind
       ; Type
ty' <- TcTyMode -> LHsType GhcRn -> Type -> TcM Type
tc_lhs_type TcTyMode
mode LHsType GhcRn
rn_ty Type
ek
       ; (() :: Constraint) =>
HsType GhcRn -> Type -> Type -> Type -> TcM Type
HsType GhcRn -> Type -> Type -> Type -> TcM Type
checkExpectedKind (GenLocated SrcSpanAnnA (HsType GhcRn) -> HsType GhcRn
forall l e. GenLocated l e -> e
unLoc LHsType GhcRn
GenLocated SrcSpanAnnA (HsType GhcRn)
rn_ty) ([Type] -> Type -> Type
(() :: Constraint) => [Type] -> Type -> Type
tcMkPhiTy [Type]
ctxt' Type
ty')
                           Type
liftedTypeKind Type
exp_kind }

--------- Lists, arrays, and tuples
tc_hs_type TcTyMode
mode rn_ty :: HsType GhcRn
rn_ty@(HsListTy XListTy GhcRn
_ LHsType GhcRn
elt_ty) Type
exp_kind
  = do { Type
tau_ty <- TcTyMode -> LHsType GhcRn -> Type -> TcM Type
tc_lhs_type TcTyMode
mode LHsType GhcRn
elt_ty Type
liftedTypeKind
       ; TyCon -> TcM ()
checkWiredInTyCon TyCon
listTyCon
       ; (() :: Constraint) =>
HsType GhcRn -> Type -> Type -> Type -> TcM Type
HsType GhcRn -> Type -> Type -> Type -> TcM Type
checkExpectedKind HsType GhcRn
rn_ty (Type -> Type
mkListTy Type
tau_ty) Type
liftedTypeKind Type
exp_kind }

-- See Note [Distinguishing tuple kinds] in GHC.Hs.Type
-- See Note [Inferring tuple kinds]
tc_hs_type TcTyMode
mode rn_ty :: HsType GhcRn
rn_ty@(HsTupleTy XTupleTy GhcRn
_ HsTupleSort
HsBoxedOrConstraintTuple [LHsType GhcRn]
hs_tys) Type
exp_kind
     -- (NB: not zonking before looking at exp_k, to avoid left-right bias)
  | Just TupleSort
tup_sort <- Type -> Maybe TupleSort
tupKindSort_maybe Type
exp_kind
  = String -> SDoc -> TcM ()
traceTc String
"tc_hs_type tuple" ([GenLocated SrcSpanAnnA (HsType GhcRn)] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [LHsType GhcRn]
[GenLocated SrcSpanAnnA (HsType GhcRn)]
hs_tys) TcM () -> TcM Type -> TcM Type
forall a b.
IOEnv (Env TcGblEnv TcLclEnv) a
-> IOEnv (Env TcGblEnv TcLclEnv) b
-> IOEnv (Env TcGblEnv TcLclEnv) b
forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>>
    HsType GhcRn
-> TcTyMode -> TupleSort -> [LHsType GhcRn] -> Type -> TcM Type
tc_tuple HsType GhcRn
rn_ty TcTyMode
mode TupleSort
tup_sort [LHsType GhcRn]
hs_tys Type
exp_kind
  | Bool
otherwise
  = do { String -> SDoc -> TcM ()
traceTc String
"tc_hs_type tuple 2" ([GenLocated SrcSpanAnnA (HsType GhcRn)] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [LHsType GhcRn]
[GenLocated SrcSpanAnnA (HsType GhcRn)]
hs_tys)
       ; ([Type]
tys, [Type]
kinds) <- (GenLocated SrcSpanAnnA (HsType GhcRn) -> TcM (Type, Type))
-> [GenLocated SrcSpanAnnA (HsType GhcRn)]
-> IOEnv (Env TcGblEnv TcLclEnv) ([Type], [Type])
forall (m :: * -> *) a b c.
Applicative m =>
(a -> m (b, c)) -> [a] -> m ([b], [c])
mapAndUnzipM (TcTyMode -> LHsType GhcRn -> TcM (Type, Type)
tc_infer_lhs_type TcTyMode
mode) [LHsType GhcRn]
[GenLocated SrcSpanAnnA (HsType GhcRn)]
hs_tys
       ; [Type]
kinds <- (Type -> TcM Type) -> [Type] -> TcM [Type]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
forall (m :: * -> *) a b. Monad m => (a -> m b) -> [a] -> m [b]
mapM Type -> TcM Type
zonkTcType [Type]
kinds
           -- Infer each arg type separately, because errors can be
           -- confusing if we give them a shared kind.  Eg #7410
           -- (Either Int, Int), we do not want to get an error saying
           -- "the second argument of a tuple should have kind *->*"

       ; let (Type
arg_kind, TupleSort
tup_sort)
               = case [ (Type
k,TupleSort
s) | Type
k <- [Type]
kinds
                              , Just TupleSort
s <- [Type -> Maybe TupleSort
tupKindSort_maybe Type
k] ] of
                    ((Type
k,TupleSort
s) : [(Type, TupleSort)]
_) -> (Type
k,TupleSort
s)
                    [] -> (Type
liftedTypeKind, TupleSort
BoxedTuple)
         -- In the [] case, it's not clear what the kind is, so guess *

       ; [Type]
tys' <- [TcM Type] -> TcM [Type]
forall (t :: * -> *) (m :: * -> *) a.
(Traversable t, Monad m) =>
t (m a) -> m (t a)
forall (m :: * -> *) a. Monad m => [m a] -> m [a]
sequence [ SrcSpanAnnA -> TcM Type -> TcM Type
forall ann a. SrcSpanAnn' ann -> TcRn a -> TcRn a
setSrcSpanA SrcSpanAnnA
loc (TcM Type -> TcM Type) -> TcM Type -> TcM Type
forall a b. (a -> b) -> a -> b
$
                            (() :: Constraint) =>
HsType GhcRn -> Type -> Type -> Type -> TcM Type
HsType GhcRn -> Type -> Type -> Type -> TcM Type
checkExpectedKind HsType GhcRn
hs_ty Type
ty Type
kind Type
arg_kind
                          | ((L SrcSpanAnnA
loc HsType GhcRn
hs_ty),Type
ty,Type
kind) <- [GenLocated SrcSpanAnnA (HsType GhcRn)]
-> [Type]
-> [Type]
-> [(GenLocated SrcSpanAnnA (HsType GhcRn), Type, Type)]
forall a b c. [a] -> [b] -> [c] -> [(a, b, c)]
zip3 [LHsType GhcRn]
[GenLocated SrcSpanAnnA (HsType GhcRn)]
hs_tys [Type]
tys [Type]
kinds ]

       ; HsType GhcRn -> TupleSort -> [Type] -> [Type] -> Type -> TcM Type
finish_tuple HsType GhcRn
rn_ty TupleSort
tup_sort [Type]
tys' ((Type -> Type) -> [Type] -> [Type]
forall a b. (a -> b) -> [a] -> [b]
map (Type -> Type -> Type
forall a b. a -> b -> a
const Type
arg_kind) [Type]
tys') Type
exp_kind }


tc_hs_type TcTyMode
mode rn_ty :: HsType GhcRn
rn_ty@(HsTupleTy XTupleTy GhcRn
_ HsTupleSort
HsUnboxedTuple [LHsType GhcRn]
tys) Type
exp_kind
  = HsType GhcRn
-> TcTyMode -> TupleSort -> [LHsType GhcRn] -> Type -> TcM Type
tc_tuple HsType GhcRn
rn_ty TcTyMode
mode TupleSort
UnboxedTuple [LHsType GhcRn]
tys Type
exp_kind

tc_hs_type TcTyMode
mode rn_ty :: HsType GhcRn
rn_ty@(HsSumTy XSumTy GhcRn
_ [LHsType GhcRn]
hs_tys) Type
exp_kind
  = do { let arity :: Arity
arity = [GenLocated SrcSpanAnnA (HsType GhcRn)] -> Arity
forall a. [a] -> Arity
forall (t :: * -> *) a. Foldable t => t a -> Arity
length [LHsType GhcRn]
[GenLocated SrcSpanAnnA (HsType GhcRn)]
hs_tys
       ; [Type]
arg_kinds <- (GenLocated SrcSpanAnnA (HsType GhcRn) -> TcM Type)
-> [GenLocated SrcSpanAnnA (HsType GhcRn)] -> TcM [Type]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
forall (m :: * -> *) a b. Monad m => (a -> m b) -> [a] -> m [b]
mapM (\GenLocated SrcSpanAnnA (HsType GhcRn)
_ -> TcM Type
newOpenTypeKind) [LHsType GhcRn]
[GenLocated SrcSpanAnnA (HsType GhcRn)]
hs_tys
       ; [Type]
tau_tys   <- (GenLocated SrcSpanAnnA (HsType GhcRn) -> Type -> TcM Type)
-> [GenLocated SrcSpanAnnA (HsType GhcRn)] -> [Type] -> TcM [Type]
forall (m :: * -> *) a b c.
Applicative m =>
(a -> b -> m c) -> [a] -> [b] -> m [c]
zipWithM (TcTyMode -> LHsType GhcRn -> Type -> TcM Type
tc_lhs_type TcTyMode
mode) [LHsType GhcRn]
[GenLocated SrcSpanAnnA (HsType GhcRn)]
hs_tys [Type]
arg_kinds
       ; let arg_reps :: [Type]
arg_reps = (Type -> Type) -> [Type] -> [Type]
forall a b. (a -> b) -> [a] -> [b]
map (() :: Constraint) => Type -> Type
Type -> Type
kindRep [Type]
arg_kinds
             arg_tys :: [Type]
arg_tys  = [Type]
arg_reps [Type] -> [Type] -> [Type]
forall a. [a] -> [a] -> [a]
++ [Type]
tau_tys
             sum_ty :: Type
sum_ty   = TyCon -> [Type] -> Type
mkTyConApp (Arity -> TyCon
sumTyCon Arity
arity) [Type]
arg_tys
             sum_kind :: Type
sum_kind = [Type] -> Type
unboxedSumKind [Type]
arg_reps
       ; (() :: Constraint) =>
HsType GhcRn -> Type -> Type -> Type -> TcM Type
HsType GhcRn -> Type -> Type -> Type -> TcM Type
checkExpectedKind HsType GhcRn
rn_ty Type
sum_ty Type
sum_kind Type
exp_kind
       }

--------- Promoted lists and tuples
tc_hs_type TcTyMode
mode rn_ty :: HsType GhcRn
rn_ty@(HsExplicitListTy XExplicitListTy GhcRn
_ PromotionFlag
_ [LHsType GhcRn]
tys) Type
exp_kind
  = do { [(Type, Type)]
tks <- (GenLocated SrcSpanAnnA (HsType GhcRn) -> TcM (Type, Type))
-> [GenLocated SrcSpanAnnA (HsType GhcRn)]
-> IOEnv (Env TcGblEnv TcLclEnv) [(Type, Type)]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
forall (m :: * -> *) a b. Monad m => (a -> m b) -> [a] -> m [b]
mapM (TcTyMode -> LHsType GhcRn -> TcM (Type, Type)
tc_infer_lhs_type TcTyMode
mode) [LHsType GhcRn]
[GenLocated SrcSpanAnnA (HsType GhcRn)]
tys
       ; ([Type]
taus', Type
kind) <- [LHsType GhcRn] -> [(Type, Type)] -> TcM ([Type], Type)
unifyKinds [LHsType GhcRn]
tys [(Type, Type)]
tks
       ; let ty :: Type
ty = ((Type -> Type -> Type) -> Type -> [Type] -> Type
forall a b. (a -> b -> b) -> b -> [a] -> b
forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr (Type -> Type -> Type -> Type
mk_cons Type
kind) (Type -> Type
mk_nil Type
kind) [Type]
taus')
       ; (() :: Constraint) =>
HsType GhcRn -> Type -> Type -> Type -> TcM Type
HsType GhcRn -> Type -> Type -> Type -> TcM Type
checkExpectedKind HsType GhcRn
rn_ty Type
ty (Type -> Type
mkListTy Type
kind) Type
exp_kind }
  where
    mk_cons :: Type -> Type -> Type -> Type
mk_cons Type
k Type
a Type
b = TyCon -> [Type] -> Type
mkTyConApp (DataCon -> TyCon
promoteDataCon DataCon
consDataCon) [Type
k, Type
a, Type
b]
    mk_nil :: Type -> Type
mk_nil  Type
k     = TyCon -> [Type] -> Type
mkTyConApp (DataCon -> TyCon
promoteDataCon DataCon
nilDataCon) [Type
k]

tc_hs_type TcTyMode
mode rn_ty :: HsType GhcRn
rn_ty@(HsExplicitTupleTy XExplicitTupleTy GhcRn
_ [LHsType GhcRn]
tys) Type
exp_kind
  -- using newMetaKindVar means that we force instantiations of any polykinded
  -- types. At first, I just used tc_infer_lhs_type, but that led to #11255.
  = do { [Type]
ks   <- Arity -> TcM Type -> TcM [Type]
forall (m :: * -> *) a. Applicative m => Arity -> m a -> m [a]
replicateM Arity
arity TcM Type
newMetaKindVar
       ; [Type]
taus <- (GenLocated SrcSpanAnnA (HsType GhcRn) -> Type -> TcM Type)
-> [GenLocated SrcSpanAnnA (HsType GhcRn)] -> [Type] -> TcM [Type]
forall (m :: * -> *) a b c.
Applicative m =>
(a -> b -> m c) -> [a] -> [b] -> m [c]
zipWithM (TcTyMode -> LHsType GhcRn -> Type -> TcM Type
tc_lhs_type TcTyMode
mode) [LHsType GhcRn]
[GenLocated SrcSpanAnnA (HsType GhcRn)]
tys [Type]
ks
       ; let kind_con :: TyCon
kind_con   = Boxity -> Arity -> TyCon
tupleTyCon           Boxity
Boxed Arity
arity
             ty_con :: TyCon
ty_con     = Boxity -> Arity -> TyCon
promotedTupleDataCon Boxity
Boxed Arity
arity
             tup_k :: Type
tup_k      = TyCon -> [Type] -> Type
mkTyConApp TyCon
kind_con [Type]
ks
       ; Arity -> TcM ()
checkTupSize Arity
arity
       ; (() :: Constraint) =>
HsType GhcRn -> Type -> Type -> Type -> TcM Type
HsType GhcRn -> Type -> Type -> Type -> TcM Type
checkExpectedKind HsType GhcRn
rn_ty (TyCon -> [Type] -> Type
mkTyConApp TyCon
ty_con ([Type]
ks [Type] -> [Type] -> [Type]
forall a. [a] -> [a] -> [a]
++ [Type]
taus)) Type
tup_k Type
exp_kind }
  where
    arity :: Arity
arity = [GenLocated SrcSpanAnnA (HsType GhcRn)] -> Arity
forall a. [a] -> Arity
forall (t :: * -> *) a. Foldable t => t a -> Arity
length [LHsType GhcRn]
[GenLocated SrcSpanAnnA (HsType GhcRn)]
tys

--------- Constraint types
tc_hs_type TcTyMode
mode rn_ty :: HsType GhcRn
rn_ty@(HsIParamTy XIParamTy GhcRn
_ (L SrcAnn NoEpAnns
_ HsIPName
n) LHsType GhcRn
ty) Type
exp_kind
  = do { Bool -> TcM ()
forall (m :: * -> *). (HasCallStack, Applicative m) => Bool -> m ()
massert (TypeOrKind -> Bool
isTypeLevel (TcTyMode -> TypeOrKind
mode_tyki TcTyMode
mode))
       ; Type
ty' <- TcTyMode -> LHsType GhcRn -> Type -> TcM Type
tc_lhs_type TcTyMode
mode LHsType GhcRn
ty Type
liftedTypeKind
       ; let n' :: Type
n' = FastString -> Type
mkStrLitTy (FastString -> Type) -> FastString -> Type
forall a b. (a -> b) -> a -> b
$ HsIPName -> FastString
hsIPNameFS HsIPName
n
       ; Class
ipClass <- Name -> TcM Class
tcLookupClass Name
ipClassName
       ; (() :: Constraint) =>
HsType GhcRn -> Type -> Type -> Type -> TcM Type
HsType GhcRn -> Type -> Type -> Type -> TcM Type
checkExpectedKind HsType GhcRn
rn_ty (Class -> [Type] -> Type
mkClassPred Class
ipClass [Type
n',Type
ty'])
                           Type
constraintKind Type
exp_kind }

tc_hs_type TcTyMode
_ rn_ty :: HsType GhcRn
rn_ty@(HsStarTy XStarTy GhcRn
_ Bool
_) Type
exp_kind
  -- Desugaring 'HsStarTy' to 'Data.Kind.Type' here means that we don't
  -- have to handle it in 'coreView'
  = (() :: Constraint) =>
HsType GhcRn -> Type -> Type -> Type -> TcM Type
HsType GhcRn -> Type -> Type -> Type -> TcM Type
checkExpectedKind HsType GhcRn
rn_ty Type
liftedTypeKind Type
liftedTypeKind Type
exp_kind

--------- Literals
tc_hs_type TcTyMode
_ rn_ty :: HsType GhcRn
rn_ty@(HsTyLit XTyLit GhcRn
_ (HsNumTy XNumTy GhcRn
_ Integer
n)) Type
exp_kind
  = do { TyCon -> TcM ()
checkWiredInTyCon TyCon
naturalTyCon
       ; (() :: Constraint) =>
HsType GhcRn -> Type -> Type -> Type -> TcM Type
HsType GhcRn -> Type -> Type -> Type -> TcM Type
checkExpectedKind HsType GhcRn
rn_ty (Integer -> Type
mkNumLitTy Integer
n) Type
naturalTy Type
exp_kind }

tc_hs_type TcTyMode
_ rn_ty :: HsType GhcRn
rn_ty@(HsTyLit XTyLit GhcRn
_ (HsStrTy XStrTy GhcRn
_ FastString
s)) Type
exp_kind
  = do { TyCon -> TcM ()
checkWiredInTyCon TyCon
typeSymbolKindCon
       ; (() :: Constraint) =>
HsType GhcRn -> Type -> Type -> Type -> TcM Type
HsType GhcRn -> Type -> Type -> Type -> TcM Type
checkExpectedKind HsType GhcRn
rn_ty (FastString -> Type
mkStrLitTy FastString
s) Type
typeSymbolKind Type
exp_kind }
tc_hs_type TcTyMode
_ rn_ty :: HsType GhcRn
rn_ty@(HsTyLit XTyLit GhcRn
_ (HsCharTy XCharTy GhcRn
_ Char
c)) Type
exp_kind
  = do { TyCon -> TcM ()
checkWiredInTyCon TyCon
charTyCon
       ; (() :: Constraint) =>
HsType GhcRn -> Type -> Type -> Type -> TcM Type
HsType GhcRn -> Type -> Type -> Type -> TcM Type
checkExpectedKind HsType GhcRn
rn_ty (Char -> Type
mkCharLitTy Char
c) Type
charTy Type
exp_kind }

--------- Wildcards

tc_hs_type TcTyMode
mode ty :: HsType GhcRn
ty@(HsWildCardTy XWildCardTy GhcRn
_)        Type
ek
  = IsExtraConstraint -> TcTyMode -> HsType GhcRn -> Type -> TcM Type
tcAnonWildCardOcc IsExtraConstraint
NoExtraConstraint TcTyMode
mode HsType GhcRn
ty Type
ek

--------- Potentially kind-polymorphic types: call the "up" checker
-- See Note [Future-proofing the type checker]
tc_hs_type TcTyMode
mode ty :: HsType GhcRn
ty@(HsTyVar {})            Type
ek = (() :: Constraint) => TcTyMode -> HsType GhcRn -> Type -> TcM Type
TcTyMode -> HsType GhcRn -> Type -> TcM Type
tc_infer_hs_type_ek TcTyMode
mode HsType GhcRn
ty Type
ek
tc_hs_type TcTyMode
mode ty :: HsType GhcRn
ty@(HsAppTy {})            Type
ek = (() :: Constraint) => TcTyMode -> HsType GhcRn -> Type -> TcM Type
TcTyMode -> HsType GhcRn -> Type -> TcM Type
tc_infer_hs_type_ek TcTyMode
mode HsType GhcRn
ty Type
ek
tc_hs_type TcTyMode
mode ty :: HsType GhcRn
ty@(HsAppKindTy{})         Type
ek = (() :: Constraint) => TcTyMode -> HsType GhcRn -> Type -> TcM Type
TcTyMode -> HsType GhcRn -> Type -> TcM Type
tc_infer_hs_type_ek TcTyMode
mode HsType GhcRn
ty Type
ek
tc_hs_type TcTyMode
mode ty :: HsType GhcRn
ty@(HsOpTy {})             Type
ek = (() :: Constraint) => TcTyMode -> HsType GhcRn -> Type -> TcM Type
TcTyMode -> HsType GhcRn -> Type -> TcM Type
tc_infer_hs_type_ek TcTyMode
mode HsType GhcRn
ty Type
ek
tc_hs_type TcTyMode
mode ty :: HsType GhcRn
ty@(HsKindSig {})          Type
ek = (() :: Constraint) => TcTyMode -> HsType GhcRn -> Type -> TcM Type
TcTyMode -> HsType GhcRn -> Type -> TcM Type
tc_infer_hs_type_ek TcTyMode
mode HsType GhcRn
ty Type
ek
tc_hs_type TcTyMode
mode ty :: HsType GhcRn
ty@(XHsType {})            Type
ek = (() :: Constraint) => TcTyMode -> HsType GhcRn -> Type -> TcM Type
TcTyMode -> HsType GhcRn -> Type -> TcM Type
tc_infer_hs_type_ek TcTyMode
mode HsType GhcRn
ty Type
ek

{-
Note [Variable Specificity and Forall Visibility]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
A HsForAllTy contains an HsForAllTelescope to denote the visibility of the forall
binder. Furthermore, each invisible type variable binder also has a
Specificity. Together, these determine the variable binders (ForAllTyFlag) for each
variable in the generated ForAllTy type.

This table summarises this relation:
----------------------------------------------------------------------------
| User-written type         HsForAllTelescope   Specificity        ForAllTyFlag
|---------------------------------------------------------------------------
| f :: forall a. type       HsForAllInvis       SpecifiedSpec      Specified
| f :: forall {a}. type     HsForAllInvis       InferredSpec       Inferred
| f :: forall a -> type     HsForAllVis         SpecifiedSpec      Required
| f :: forall {a} -> type   HsForAllVis         InferredSpec       /
|   This last form is nonsensical and is thus rejected.
----------------------------------------------------------------------------

For more information regarding the interpretation of the resulting ForAllTyFlag, see
Note [VarBndrs, ForAllTyBinders, TyConBinders, and visibility] in "GHC.Core.TyCo.Rep".
-}

------------------------------------------
tc_mult :: TcTyMode -> HsArrow GhcRn -> TcM Mult
tc_mult :: TcTyMode -> HsArrow GhcRn -> TcM Type
tc_mult TcTyMode
mode HsArrow GhcRn
ty = TcTyMode -> LHsType GhcRn -> Type -> TcM Type
tc_lhs_type TcTyMode
mode (HsArrow GhcRn -> LHsType GhcRn
arrowToHsType HsArrow GhcRn
ty) Type
multiplicityTy
------------------------------------------
tc_fun_type :: TcTyMode -> HsArrow GhcRn -> LHsType GhcRn -> LHsType GhcRn -> TcKind
            -> TcM TcType
tc_fun_type :: TcTyMode
-> HsArrow GhcRn
-> LHsType GhcRn
-> LHsType GhcRn
-> Type
-> TcM Type
tc_fun_type TcTyMode
mode HsArrow GhcRn
mult LHsType GhcRn
ty1 LHsType GhcRn
ty2 Type
exp_kind = case TcTyMode -> TypeOrKind
mode_tyki TcTyMode
mode of
  TypeOrKind
TypeLevel ->
    do { String -> SDoc -> TcM ()
traceTc String
"tc_fun_type" (GenLocated SrcSpanAnnA (HsType GhcRn) -> SDoc
forall a. Outputable a => a -> SDoc
ppr LHsType GhcRn
GenLocated SrcSpanAnnA (HsType GhcRn)
ty1 SDoc -> SDoc -> SDoc
forall doc. IsDoc doc => doc -> doc -> doc
$$ GenLocated SrcSpanAnnA (HsType GhcRn) -> SDoc
forall a. Outputable a => a -> SDoc
ppr LHsType GhcRn
GenLocated SrcSpanAnnA (HsType GhcRn)
ty2)
       ; Type
arg_k <- TcM Type
newOpenTypeKind
       ; Type
res_k <- TcM Type
newOpenTypeKind
       ; Type
ty1'  <- TcTyMode -> LHsType GhcRn -> Type -> TcM Type
tc_lhs_type TcTyMode
mode LHsType GhcRn
ty1 Type
arg_k
       ; Type
ty2'  <- TcTyMode -> LHsType GhcRn -> Type -> TcM Type
tc_lhs_type TcTyMode
mode LHsType GhcRn
ty2 Type
res_k
       ; Type
mult' <- TcTyMode -> HsArrow GhcRn -> TcM Type
tc_mult TcTyMode
mode HsArrow GhcRn
mult
       ; (() :: Constraint) =>
HsType GhcRn -> Type -> Type -> Type -> TcM Type
HsType GhcRn -> Type -> Type -> Type -> TcM Type
checkExpectedKind (XFunTy GhcRn
-> HsArrow GhcRn -> LHsType GhcRn -> LHsType GhcRn -> HsType GhcRn
forall pass.
XFunTy pass
-> HsArrow pass -> LHsType pass -> LHsType pass -> HsType pass
HsFunTy XFunTy GhcRn
EpAnn NoEpAnns
forall a. EpAnn a
noAnn HsArrow GhcRn
mult LHsType GhcRn
ty1 LHsType GhcRn
ty2)
                           (Type -> Type -> Type -> Type
tcMkVisFunTy Type
mult' Type
ty1' Type
ty2')
                           Type
liftedTypeKind Type
exp_kind }
  TypeOrKind
KindLevel ->  -- no representation polymorphism in kinds. yet.
    do { Type
ty1'  <- TcTyMode -> LHsType GhcRn -> Type -> TcM Type
tc_lhs_type TcTyMode
mode LHsType GhcRn
ty1 Type
liftedTypeKind
       ; Type
ty2'  <- TcTyMode -> LHsType GhcRn -> Type -> TcM Type
tc_lhs_type TcTyMode
mode LHsType GhcRn
ty2 Type
liftedTypeKind
       ; Type
mult' <- TcTyMode -> HsArrow GhcRn -> TcM Type
tc_mult TcTyMode
mode HsArrow GhcRn
mult
       ; (() :: Constraint) =>
HsType GhcRn -> Type -> Type -> Type -> TcM Type
HsType GhcRn -> Type -> Type -> Type -> TcM Type
checkExpectedKind (XFunTy GhcRn
-> HsArrow GhcRn -> LHsType GhcRn -> LHsType GhcRn -> HsType GhcRn
forall pass.
XFunTy pass
-> HsArrow pass -> LHsType pass -> LHsType pass -> HsType pass
HsFunTy XFunTy GhcRn
EpAnn NoEpAnns
forall a. EpAnn a
noAnn HsArrow GhcRn
mult LHsType GhcRn
ty1 LHsType GhcRn
ty2)
                           (Type -> Type -> Type -> Type
tcMkVisFunTy Type
mult' Type
ty1' Type
ty2')
                           Type
liftedTypeKind Type
exp_kind }

{- Note [Skolem escape and forall-types]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
See also Note [Checking telescopes].

Consider
  f :: forall a. (forall kb (b :: kb). Proxy '[a, b]) -> ()

The Proxy '[a,b] forces a and b to have the same kind.  But a's
kind must be bound outside the 'forall a', and hence escapes.
We discover this by building an implication constraint for
each forall.  So the inner implication constraint will look like
    forall kb (b::kb).  kb ~ ka
where ka is a's kind.  We can't unify these two, /even/ if ka is
unification variable, because it would be untouchable inside
this inner implication.

That's what the pushLevelAndCaptureConstraints, plus subsequent
buildTvImplication/emitImplication is all about, when kind-checking
HsForAllTy.

Note that

* We don't need to /simplify/ the constraints here
  because we aren't generalising. We just capture them.

* We can't use emitResidualTvConstraint, because that has a fast-path
  for empty constraints.  We can't take that fast path here, because
  we must do the bad-telescope check even if there are no inner wanted
  constraints. See Note [Checking telescopes] in
  GHC.Tc.Types.Constraint.  Lacking this check led to #16247.
-}

{- *********************************************************************
*                                                                      *
                Tuples
*                                                                      *
********************************************************************* -}

---------------------------
tupKindSort_maybe :: TcKind -> Maybe TupleSort
tupKindSort_maybe :: Type -> Maybe TupleSort
tupKindSort_maybe Type
k
  | Just (Type
k', Coercion
_) <- Type -> Maybe (Type, Coercion)
splitCastTy_maybe Type
k = Type -> Maybe TupleSort
tupKindSort_maybe Type
k'
  | Just Type
k'      <- Type -> Maybe Type
coreView Type
k          = Type -> Maybe TupleSort
tupKindSort_maybe Type
k'
  | Type -> Bool
isConstraintKind Type
k                  = TupleSort -> Maybe TupleSort
forall a. a -> Maybe a
Just TupleSort
ConstraintTuple
  | Type -> Bool
tcIsLiftedTypeKind Type
k                = TupleSort -> Maybe TupleSort
forall a. a -> Maybe a
Just TupleSort
BoxedTuple
  | Bool
otherwise                           = Maybe TupleSort
forall a. Maybe a
Nothing

tc_tuple :: HsType GhcRn -> TcTyMode -> TupleSort -> [LHsType GhcRn] -> TcKind -> TcM TcType
tc_tuple :: HsType GhcRn
-> TcTyMode -> TupleSort -> [LHsType GhcRn] -> Type -> TcM Type
tc_tuple HsType GhcRn
rn_ty TcTyMode
mode TupleSort
tup_sort [LHsType GhcRn]
tys Type
exp_kind
  = do { [Type]
arg_kinds <- case TupleSort
tup_sort of
           TupleSort
BoxedTuple      -> [Type] -> TcM [Type]
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (Arity -> Type -> [Type]
forall a. Arity -> a -> [a]
replicate Arity
arity Type
liftedTypeKind)
           TupleSort
UnboxedTuple    -> Arity -> TcM Type -> TcM [Type]
forall (m :: * -> *) a. Applicative m => Arity -> m a -> m [a]
replicateM Arity
arity TcM Type
newOpenTypeKind
           TupleSort
ConstraintTuple -> [Type] -> TcM [Type]
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (Arity -> Type -> [Type]
forall a. Arity -> a -> [a]
replicate Arity
arity Type
constraintKind)
       ; [Type]
tau_tys <- (GenLocated SrcSpanAnnA (HsType GhcRn) -> Type -> TcM Type)
-> [GenLocated SrcSpanAnnA (HsType GhcRn)] -> [Type] -> TcM [Type]
forall (m :: * -> *) a b c.
Applicative m =>
(a -> b -> m c) -> [a] -> [b] -> m [c]
zipWithM (TcTyMode -> LHsType GhcRn -> Type -> TcM Type
tc_lhs_type TcTyMode
mode) [LHsType GhcRn]
[GenLocated SrcSpanAnnA (HsType GhcRn)]
tys [Type]
arg_kinds
       ; HsType GhcRn -> TupleSort -> [Type] -> [Type] -> Type -> TcM Type
finish_tuple HsType GhcRn
rn_ty TupleSort
tup_sort [Type]
tau_tys [Type]
arg_kinds Type
exp_kind }
  where
    arity :: Arity
arity   = [GenLocated SrcSpanAnnA (HsType GhcRn)] -> Arity
forall a. [a] -> Arity
forall (t :: * -> *) a. Foldable t => t a -> Arity
length [LHsType GhcRn]
[GenLocated SrcSpanAnnA (HsType GhcRn)]
tys

finish_tuple :: HsType GhcRn
             -> TupleSort
             -> [TcType]    -- ^ argument types
             -> [TcKind]    -- ^ of these kinds
             -> TcKind      -- ^ expected kind of the whole tuple
             -> TcM TcType
finish_tuple :: HsType GhcRn -> TupleSort -> [Type] -> [Type] -> Type -> TcM Type
finish_tuple HsType GhcRn
rn_ty TupleSort
tup_sort [Type]
tau_tys [Type]
tau_kinds Type
exp_kind = do
  String -> SDoc -> TcM ()
traceTc String
"finish_tuple" (TupleSort -> SDoc
forall a. Outputable a => a -> SDoc
ppr TupleSort
tup_sort SDoc -> SDoc -> SDoc
forall doc. IsDoc doc => doc -> doc -> doc
$$ [Type] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Type]
tau_kinds SDoc -> SDoc -> SDoc
forall doc. IsDoc doc => doc -> doc -> doc
$$ Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
exp_kind)
  case TupleSort
tup_sort of
    TupleSort
ConstraintTuple
      |  [Type
tau_ty] <- [Type]
tau_tys
         -- Drop any uses of 1-tuple constraints here.
         -- See Note [Ignore unary constraint tuples]
      -> Type -> Type -> TcM Type
check_expected_kind Type
tau_ty Type
constraintKind
      |  Bool
otherwise
      -> do let tycon :: TyCon
tycon = Arity -> TyCon
cTupleTyCon Arity
arity
            Arity -> TcM ()
checkCTupSize Arity
arity
            Type -> Type -> TcM Type
check_expected_kind (TyCon -> [Type] -> Type
mkTyConApp TyCon
tycon [Type]
tau_tys) Type
constraintKind
    TupleSort
BoxedTuple -> do
      let tycon :: TyCon
tycon = Boxity -> Arity -> TyCon
tupleTyCon Boxity
Boxed Arity
arity
      Arity -> TcM ()
checkTupSize Arity
arity
      TyCon -> TcM ()
checkWiredInTyCon TyCon
tycon
      Type -> Type -> TcM Type
check_expected_kind (TyCon -> [Type] -> Type
mkTyConApp TyCon
tycon [Type]
tau_tys) Type
liftedTypeKind
    TupleSort
UnboxedTuple -> do
      let tycon :: TyCon
tycon    = Boxity -> Arity -> TyCon
tupleTyCon Boxity
Unboxed Arity
arity
          tau_reps :: [Type]
tau_reps = (Type -> Type) -> [Type] -> [Type]
forall a b. (a -> b) -> [a] -> [b]
map (() :: Constraint) => Type -> Type
Type -> Type
kindRep [Type]
tau_kinds
          -- See also Note [Unboxed tuple RuntimeRep vars] in GHC.Core.TyCon
          arg_tys :: [Type]
arg_tys  = [Type]
tau_reps [Type] -> [Type] -> [Type]
forall a. [a] -> [a] -> [a]
++ [Type]
tau_tys
          res_kind :: Type
res_kind = [Type] -> Type
unboxedTupleKind [Type]
tau_reps
      Arity -> TcM ()
checkTupSize Arity
arity
      Type -> Type -> TcM Type
check_expected_kind (TyCon -> [Type] -> Type
mkTyConApp TyCon
tycon [Type]
arg_tys) Type
res_kind
  where
    arity :: Arity
arity = [Type] -> Arity
forall a. [a] -> Arity
forall (t :: * -> *) a. Foldable t => t a -> Arity
length [Type]
tau_tys
    check_expected_kind :: Type -> Type -> TcM Type
check_expected_kind Type
ty Type
act_kind =
      (() :: Constraint) =>
HsType GhcRn -> Type -> Type -> Type -> TcM Type
HsType GhcRn -> Type -> Type -> Type -> TcM Type
checkExpectedKind HsType GhcRn
rn_ty Type
ty Type
act_kind Type
exp_kind

{-
Note [Ignore unary constraint tuples]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
GHC provides unary tuples and unboxed tuples (see Note [One-tuples] in
GHC.Builtin.Types) but does *not* provide unary constraint tuples. Why? First,
recall the definition of a unary tuple data type:

  data Solo a = Solo a

Note that `Solo a` is *not* the same thing as `a`, since Solo is boxed and
lazy. Therefore, the presence of `Solo` matters semantically. On the other
hand, suppose we had a unary constraint tuple:

  class a => Solo% a

This compiles down a newtype (i.e., a cast) in Core, so `Solo% a` is
semantically equivalent to `a`. Therefore, a 1-tuple constraint would have
no user-visible impact, nor would it allow you to express anything that
you couldn't otherwise.

We could simply add Solo% for consistency with tuples (Solo) and unboxed
tuples (Solo#), but that would require even more magic to wire in another
magical class, so we opt not to do so. We must be careful, however, since
one can try to sneak in uses of unary constraint tuples through Template
Haskell, such as in this program (from #17511):

  f :: $(pure (ForallT [] [TupleT 1 `AppT` (ConT ''Show `AppT` ConT ''Int)]
                       (ConT ''String)))
  -- f :: Solo% (Show Int) => String
  f = "abc"

This use of `TupleT 1` will produce an HsBoxedOrConstraintTuple of arity 1,
and since it is used in a Constraint position, GHC will attempt to treat
it as thought it were a constraint tuple, which can potentially lead to
trouble if one attempts to look up the name of a constraint tuple of arity
1 (as it won't exist). To avoid this trouble, we simply take any unary
constraint tuples discovered when typechecking and drop them—i.e., treat
"Solo% a" as though the user had written "a". This is always safe to do
since the two constraints should be semantically equivalent.
-}

{- *********************************************************************
*                                                                      *
                Type applications
*                                                                      *
********************************************************************* -}

splitHsAppTys :: HsType GhcRn -> Maybe (LHsType GhcRn, [LHsTypeArg GhcRn])
splitHsAppTys :: HsType GhcRn -> Maybe (LHsType GhcRn, HsTyPats GhcRn)
splitHsAppTys HsType GhcRn
hs_ty
  | HsType GhcRn -> Bool
is_app HsType GhcRn
hs_ty = (GenLocated SrcSpanAnnA (HsType GhcRn),
 [HsArg
    (GenLocated SrcSpanAnnA (HsType GhcRn))
    (GenLocated SrcSpanAnnA (HsType GhcRn))])
-> Maybe
     (GenLocated SrcSpanAnnA (HsType GhcRn),
      [HsArg
         (GenLocated SrcSpanAnnA (HsType GhcRn))
         (GenLocated SrcSpanAnnA (HsType GhcRn))])
forall a. a -> Maybe a
Just (LHsType GhcRn -> HsTyPats GhcRn -> (LHsType GhcRn, HsTyPats GhcRn)
go (HsType GhcRn -> GenLocated SrcSpanAnnA (HsType GhcRn)
forall a an. a -> LocatedAn an a
noLocA HsType GhcRn
hs_ty) [])
  | Bool
otherwise    = Maybe (LHsType GhcRn, HsTyPats GhcRn)
Maybe
  (GenLocated SrcSpanAnnA (HsType GhcRn),
   [HsArg
      (GenLocated SrcSpanAnnA (HsType GhcRn))
      (GenLocated SrcSpanAnnA (HsType GhcRn))])
forall a. Maybe a
Nothing
  where
    is_app :: HsType GhcRn -> Bool
    is_app :: HsType GhcRn -> Bool
is_app (HsAppKindTy {})        = Bool
True
    is_app (HsAppTy {})            = Bool
True
    is_app (HsOpTy XOpTy GhcRn
_ PromotionFlag
_ LHsType GhcRn
_ (L SrcSpanAnnN
_ Name
op) LHsType GhcRn
_) = Bool -> Bool
not (Name
op Name -> Unique -> Bool
forall a. Uniquable a => a -> Unique -> Bool
`hasKey` Unique
unrestrictedFunTyConKey)
      -- I'm not sure why this funTyConKey test is necessary
      -- Can it even happen?  Perhaps for   t1 `(->)` t2
      -- but then maybe it's ok to treat that like a normal
      -- application rather than using the special rule for HsFunTy
    is_app (HsTyVar {})            = Bool
True
    is_app (HsParTy XParTy GhcRn
_ (L SrcSpanAnnA
_ HsType GhcRn
ty))    = HsType GhcRn -> Bool
is_app HsType GhcRn
ty
    is_app HsType GhcRn
_                       = Bool
False

    go :: LHsType GhcRn
       -> [HsArg (LHsType GhcRn) (LHsKind GhcRn)]
       -> (LHsType GhcRn,
           [HsArg (LHsType GhcRn) (LHsKind GhcRn)]) -- AZ temp
    go :: LHsType GhcRn -> HsTyPats GhcRn -> (LHsType GhcRn, HsTyPats GhcRn)
go (L SrcSpanAnnA
_  (HsAppTy XAppTy GhcRn
_ LHsType GhcRn
f LHsType GhcRn
a))      HsTyPats GhcRn
as = LHsType GhcRn -> HsTyPats GhcRn -> (LHsType GhcRn, HsTyPats GhcRn)
go LHsType GhcRn
f (GenLocated SrcSpanAnnA (HsType GhcRn)
-> HsArg
     (GenLocated SrcSpanAnnA (HsType GhcRn))
     (GenLocated SrcSpanAnnA (HsType GhcRn))
forall tm ty. tm -> HsArg tm ty
HsValArg LHsType GhcRn
GenLocated SrcSpanAnnA (HsType GhcRn)
a HsArg
  (GenLocated SrcSpanAnnA (HsType GhcRn))
  (GenLocated SrcSpanAnnA (HsType GhcRn))
-> [HsArg
      (GenLocated SrcSpanAnnA (HsType GhcRn))
      (GenLocated SrcSpanAnnA (HsType GhcRn))]
-> [HsArg
      (GenLocated SrcSpanAnnA (HsType GhcRn))
      (GenLocated SrcSpanAnnA (HsType GhcRn))]
forall a. a -> [a] -> [a]
: HsTyPats GhcRn
[HsArg
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
as)
    go (L SrcSpanAnnA
_  (HsAppKindTy XAppKindTy GhcRn
l LHsType GhcRn
ty LHsType GhcRn
k)) HsTyPats GhcRn
as = LHsType GhcRn -> HsTyPats GhcRn -> (LHsType GhcRn, HsTyPats GhcRn)
go LHsType GhcRn
ty (SrcSpan
-> GenLocated SrcSpanAnnA (HsType GhcRn)
-> HsArg
     (GenLocated SrcSpanAnnA (HsType GhcRn))
     (GenLocated SrcSpanAnnA (HsType GhcRn))
forall tm ty. SrcSpan -> ty -> HsArg tm ty
HsTypeArg XAppKindTy GhcRn
SrcSpan
l LHsType GhcRn
GenLocated SrcSpanAnnA (HsType GhcRn)
k HsArg
  (GenLocated SrcSpanAnnA (HsType GhcRn))
  (GenLocated SrcSpanAnnA (HsType GhcRn))
-> [HsArg
      (GenLocated SrcSpanAnnA (HsType GhcRn))
      (GenLocated SrcSpanAnnA (HsType GhcRn))]
-> [HsArg
      (GenLocated SrcSpanAnnA (HsType GhcRn))
      (GenLocated SrcSpanAnnA (HsType GhcRn))]
forall a. a -> [a] -> [a]
: HsTyPats GhcRn
[HsArg
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
as)
    go (L SrcSpanAnnA
sp (HsParTy XParTy GhcRn
_ LHsType GhcRn
f))        HsTyPats GhcRn
as = LHsType GhcRn -> HsTyPats GhcRn -> (LHsType GhcRn, HsTyPats GhcRn)
go LHsType GhcRn
f (SrcSpan
-> HsArg
     (GenLocated SrcSpanAnnA (HsType GhcRn))
     (GenLocated SrcSpanAnnA (HsType GhcRn))
forall tm ty. SrcSpan -> HsArg tm ty
HsArgPar (SrcSpanAnnA -> SrcSpan
forall a. SrcSpanAnn' a -> SrcSpan
locA SrcSpanAnnA
sp) HsArg
  (GenLocated SrcSpanAnnA (HsType GhcRn))
  (GenLocated SrcSpanAnnA (HsType GhcRn))
-> [HsArg
      (GenLocated SrcSpanAnnA (HsType GhcRn))
      (GenLocated SrcSpanAnnA (HsType GhcRn))]
-> [HsArg
      (GenLocated SrcSpanAnnA (HsType GhcRn))
      (GenLocated SrcSpanAnnA (HsType GhcRn))]
forall a. a -> [a] -> [a]
: HsTyPats GhcRn
[HsArg
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
as)
    go (L SrcSpanAnnA
_  (HsOpTy XOpTy GhcRn
_ PromotionFlag
prom LHsType GhcRn
l op :: LIdP GhcRn
op@(L SrcSpanAnnN
sp Name
_) LHsType GhcRn
r)) HsTyPats GhcRn
as
      = ( SrcSpanAnnA
-> HsType GhcRn -> GenLocated SrcSpanAnnA (HsType GhcRn)
forall l e. l -> e -> GenLocated l e
L (SrcSpanAnnN -> SrcSpanAnnA
forall a ann. SrcSpanAnn' a -> SrcAnn ann
na2la SrcSpanAnnN
sp) (XTyVar GhcRn -> PromotionFlag -> LIdP GhcRn -> HsType GhcRn
forall pass.
XTyVar pass -> PromotionFlag -> LIdP pass -> HsType pass
HsTyVar XTyVar GhcRn
EpAnn [AddEpAnn]
forall a. EpAnn a
noAnn PromotionFlag
prom LIdP GhcRn
op)
        , GenLocated SrcSpanAnnA (HsType GhcRn)
-> HsArg
     (GenLocated SrcSpanAnnA (HsType GhcRn))
     (GenLocated SrcSpanAnnA (HsType GhcRn))
forall tm ty. tm -> HsArg tm ty
HsValArg LHsType GhcRn
GenLocated SrcSpanAnnA (HsType GhcRn)
l HsArg
  (GenLocated SrcSpanAnnA (HsType GhcRn))
  (GenLocated SrcSpanAnnA (HsType GhcRn))
-> [HsArg
      (GenLocated SrcSpanAnnA (HsType GhcRn))
      (GenLocated SrcSpanAnnA (HsType GhcRn))]
-> [HsArg
      (GenLocated SrcSpanAnnA (HsType GhcRn))
      (GenLocated SrcSpanAnnA (HsType GhcRn))]
forall a. a -> [a] -> [a]
: GenLocated SrcSpanAnnA (HsType GhcRn)
-> HsArg
     (GenLocated SrcSpanAnnA (HsType GhcRn))
     (GenLocated SrcSpanAnnA (HsType GhcRn))
forall tm ty. tm -> HsArg tm ty
HsValArg LHsType GhcRn
GenLocated SrcSpanAnnA (HsType GhcRn)
r HsArg
  (GenLocated SrcSpanAnnA (HsType GhcRn))
  (GenLocated SrcSpanAnnA (HsType GhcRn))
-> [HsArg
      (GenLocated SrcSpanAnnA (HsType GhcRn))
      (GenLocated SrcSpanAnnA (HsType GhcRn))]
-> [HsArg
      (GenLocated SrcSpanAnnA (HsType GhcRn))
      (GenLocated SrcSpanAnnA (HsType GhcRn))]
forall a. a -> [a] -> [a]
: HsTyPats GhcRn
[HsArg
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
as )
    go LHsType GhcRn
f HsTyPats GhcRn
as = (LHsType GhcRn
f, HsTyPats GhcRn
as)

---------------------------
tcInferTyAppHead :: TcTyMode -> LHsType GhcRn -> TcM (TcType, TcKind)
-- Version of tc_infer_lhs_type specialised for the head of an
-- application. In particular, for a HsTyVar (which includes type
-- constructors, it does not zoom off into tcInferTyApps and family
-- saturation
tcInferTyAppHead :: TcTyMode -> LHsType GhcRn -> TcM (Type, Type)
tcInferTyAppHead TcTyMode
_ (L SrcSpanAnnA
_ (HsTyVar XTyVar GhcRn
_ PromotionFlag
_ (L SrcSpanAnnN
_ Name
tv)))
  = Name -> TcM (Type, Type)
tcTyVar Name
tv
tcInferTyAppHead TcTyMode
mode LHsType GhcRn
ty
  = TcTyMode -> LHsType GhcRn -> TcM (Type, Type)
tc_infer_lhs_type TcTyMode
mode LHsType GhcRn
ty

---------------------------
-- | Apply a type of a given kind to a list of arguments. This instantiates
-- invisible parameters as necessary. Always consumes all the arguments,
-- using matchExpectedFunKind as necessary.
-- This takes an optional @VarEnv Kind@ which maps kind variables to kinds.-
-- These kinds should be used to instantiate invisible kind variables;
-- they come from an enclosing class for an associated type/data family.
--
-- tcInferTyApps also arranges to saturate any trailing invisible arguments
--   of a type-family application, which is usually the right thing to do
-- tcInferTyApps_nosat does not do this saturation; it is used only
--   by ":kind" in GHCi
tcInferTyApps, tcInferTyApps_nosat
    :: TcTyMode
    -> LHsType GhcRn        -- ^ Function (for printing only)
    -> TcType               -- ^ Function
    -> [LHsTypeArg GhcRn]   -- ^ Args
    -> TcM (TcType, TcKind) -- ^ (f args, result kind)
tcInferTyApps :: TcTyMode
-> LHsType GhcRn -> Type -> HsTyPats GhcRn -> TcM (Type, Type)
tcInferTyApps TcTyMode
mode LHsType GhcRn
hs_ty Type
fun HsTyPats GhcRn
hs_args
  = do { (Type
f_args, Type
res_k) <- TcTyMode
-> LHsType GhcRn -> Type -> HsTyPats GhcRn -> TcM (Type, Type)
tcInferTyApps_nosat TcTyMode
mode LHsType GhcRn
hs_ty Type
fun HsTyPats GhcRn
hs_args
       ; Type -> Type -> TcM (Type, Type)
saturateFamApp Type
f_args Type
res_k }

tcInferTyApps_nosat :: TcTyMode
-> LHsType GhcRn -> Type -> HsTyPats GhcRn -> TcM (Type, Type)
tcInferTyApps_nosat TcTyMode
mode LHsType GhcRn
orig_hs_ty Type
fun HsTyPats GhcRn
orig_hs_args
  = do { String -> SDoc -> TcM ()
traceTc String
"tcInferTyApps {" (GenLocated SrcSpanAnnA (HsType GhcRn) -> SDoc
forall a. Outputable a => a -> SDoc
ppr LHsType GhcRn
GenLocated SrcSpanAnnA (HsType GhcRn)
orig_hs_ty SDoc -> SDoc -> SDoc
forall doc. IsDoc doc => doc -> doc -> doc
$$ [HsArg
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
-> SDoc
forall a. Outputable a => a -> SDoc
ppr HsTyPats GhcRn
[HsArg
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
orig_hs_args)
       ; (Type
f_args, Type
res_k) <- Arity
-> Type
-> [HsArg
      (GenLocated SrcSpanAnnA (HsType GhcRn))
      (GenLocated SrcSpanAnnA (HsType GhcRn))]
-> TcM (Type, Type)
go_init Arity
1 Type
fun HsTyPats GhcRn
[HsArg
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
orig_hs_args
       ; String -> SDoc -> TcM ()
traceTc String
"tcInferTyApps }" (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
f_args SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
res_k)
       ; (Type, Type) -> TcM (Type, Type)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (Type
f_args, Type
res_k) }
  where

    -- go_init just initialises the auxiliary
    -- arguments of the 'go' loop
    go_init :: Arity
-> Type
-> [HsArg
      (GenLocated SrcSpanAnnA (HsType GhcRn))
      (GenLocated SrcSpanAnnA (HsType GhcRn))]
-> TcM (Type, Type)
go_init Arity
n Type
fun [HsArg
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
all_args
      = Arity
-> Type -> Subst -> Type -> HsTyPats GhcRn -> TcM (Type, Type)
go Arity
n Type
fun Subst
empty_subst Type
fun_ki HsTyPats GhcRn
[HsArg
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
all_args
      where
        fun_ki :: Type
fun_ki = (() :: Constraint) => Type -> Type
Type -> Type
typeKind Type
fun
           -- We do (typeKind fun) here, even though the caller
           -- knows the function kind, to absolutely guarantee
           -- INVARIANT for 'go'
           -- Note that in a typical application (F t1 t2 t3),
           -- the 'fun' is just a TyCon, so typeKind is fast

        empty_subst :: Subst
empty_subst = InScopeSet -> Subst
mkEmptySubst (InScopeSet -> Subst) -> InScopeSet -> Subst
forall a b. (a -> b) -> a -> b
$ TyVarSet -> InScopeSet
mkInScopeSet (TyVarSet -> InScopeSet) -> TyVarSet -> InScopeSet
forall a b. (a -> b) -> a -> b
$
                      Type -> TyVarSet
tyCoVarsOfType Type
fun_ki

    go :: Int             -- The # of the next argument
       -> TcType          -- Function applied to some args
       -> Subst        -- Applies to function kind
       -> TcKind          -- Function kind
       -> [LHsTypeArg GhcRn]    -- Un-type-checked args
       -> TcM (TcType, TcKind)  -- Result type and its kind
    -- INVARIANT: in any call (go n fun subst fun_ki args)
    --               typeKind fun  =  subst(fun_ki)
    -- So the 'subst' and 'fun_ki' arguments are simply
    -- there to avoid repeatedly calling typeKind.
    --
    -- Reason for INVARIANT: to support the Purely Kinded Type Invariant
    -- it's important that if fun_ki has a forall, then so does
    -- (typeKind fun), because the next thing we are going to do
    -- is apply 'fun' to an argument type.

    -- Dispatch on all_args first, for performance reasons
    go :: Arity
-> Type -> Subst -> Type -> HsTyPats GhcRn -> TcM (Type, Type)
go Arity
n Type
fun Subst
subst Type
fun_ki HsTyPats GhcRn
all_args = case (HsTyPats GhcRn
[HsArg
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
all_args, Type -> Maybe (PiTyBinder, Type)
tcSplitPiTy_maybe Type
fun_ki) of

      ---------------- No user-written args left. We're done!
      ([], Maybe (PiTyBinder, Type)
_) -> (Type, Type) -> TcM (Type, Type)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (Type
fun, (() :: Constraint) => Subst -> Type -> Type
Subst -> Type -> Type
substTy Subst
subst Type
fun_ki)

      ---------------- HsArgPar: We don't care about parens here
      (HsArgPar SrcSpan
_ : [HsArg
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
args, Maybe (PiTyBinder, Type)
_) -> Arity
-> Type -> Subst -> Type -> HsTyPats GhcRn -> TcM (Type, Type)
go Arity
n Type
fun Subst
subst Type
fun_ki HsTyPats GhcRn
[HsArg
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
args

      ---------------- HsTypeArg: a kind application (fun @ki)
      (HsTypeArg SrcSpan
_ GenLocated SrcSpanAnnA (HsType GhcRn)
hs_ki_arg : [HsArg
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
hs_args, Just (PiTyBinder
ki_binder, Type
inner_ki)) ->
        case PiTyBinder
ki_binder of

        -- FunTy with PredTy on LHS, or ForAllTy with Inferred
        Named (Bndr TyVar
_ ForAllTyFlag
Inferred)          -> PiTyBinder -> Type -> TcM (Type, Type)
instantiate PiTyBinder
ki_binder Type
inner_ki
        Anon Scaled Type
_ FunTyFlag
af | FunTyFlag -> Bool
isInvisibleFunArg FunTyFlag
af -> PiTyBinder -> Type -> TcM (Type, Type)
instantiate PiTyBinder
ki_binder Type
inner_ki

        Named (Bndr TyVar
_ ForAllTyFlag
Specified) ->  -- Visible kind application
          do { String -> SDoc -> TcM ()
traceTc String
"tcInferTyApps (vis kind app)"
                       ([SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat [ PiTyBinder -> SDoc
forall a. Outputable a => a -> SDoc
ppr PiTyBinder
ki_binder, GenLocated SrcSpanAnnA (HsType GhcRn) -> SDoc
forall a. Outputable a => a -> SDoc
ppr GenLocated SrcSpanAnnA (HsType GhcRn)
hs_ki_arg
                             , Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr (PiTyBinder -> Type
piTyBinderType PiTyBinder
ki_binder)
                             , Subst -> SDoc
forall a. Outputable a => a -> SDoc
ppr Subst
subst ])

             ; let exp_kind :: Type
exp_kind = (() :: Constraint) => Subst -> Type -> Type
Subst -> Type -> Type
substTy Subst
subst (Type -> Type) -> Type -> Type
forall a b. (a -> b) -> a -> b
$ PiTyBinder -> Type
piTyBinderType PiTyBinder
ki_binder
             ; TcTyMode
arg_mode <- TypeOrKind -> HoleMode -> TcM TcTyMode
mkHoleMode TypeOrKind
KindLevel HoleMode
HM_VTA
                   -- HM_VKA: see Note [Wildcards in visible kind application]
             ; Type
ki_arg <- SDoc -> TcM Type -> TcM Type
forall a. SDoc -> TcM a -> TcM a
addErrCtxt (GenLocated SrcSpanAnnA (HsType GhcRn)
-> GenLocated SrcSpanAnnA (HsType GhcRn) -> Arity -> SDoc
forall fun arg.
(Outputable fun, Outputable arg) =>
fun -> arg -> Arity -> SDoc
funAppCtxt LHsType GhcRn
GenLocated SrcSpanAnnA (HsType GhcRn)
orig_hs_ty GenLocated SrcSpanAnnA (HsType GhcRn)
hs_ki_arg Arity
n) (TcM Type -> TcM Type) -> TcM Type -> TcM Type
forall a b. (a -> b) -> a -> b
$
                         TcTyMode -> LHsType GhcRn -> Type -> TcM Type
tc_lhs_type TcTyMode
arg_mode LHsType GhcRn
GenLocated SrcSpanAnnA (HsType GhcRn)
hs_ki_arg Type
exp_kind

             ; String -> SDoc -> TcM ()
traceTc String
"tcInferTyApps (vis kind app)" (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
exp_kind)
             ; (Subst
subst', Type
fun') <- Subst -> Type -> PiTyBinder -> Type -> TcM (Subst, Type)
mkAppTyM Subst
subst Type
fun PiTyBinder
ki_binder Type
ki_arg
             ; Arity
-> Type -> Subst -> Type -> HsTyPats GhcRn -> TcM (Type, Type)
go (Arity
nArity -> Arity -> Arity
forall a. Num a => a -> a -> a
+Arity
1) Type
fun' Subst
subst' Type
inner_ki HsTyPats GhcRn
[HsArg
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
hs_args }

        -- Attempted visible kind application (fun @ki), but fun_ki is
        --   forall k -> blah   or   k1 -> k2
        -- So we need a normal application.  Error.
        PiTyBinder
_ -> GenLocated SrcSpanAnnA (HsType GhcRn) -> Type -> TcM (Type, Type)
forall {a}. GenLocated SrcSpanAnnA (HsType GhcRn) -> Type -> TcRn a
ty_app_err GenLocated SrcSpanAnnA (HsType GhcRn)
hs_ki_arg (Type -> TcM (Type, Type)) -> Type -> TcM (Type, Type)
forall a b. (a -> b) -> a -> b
$ (() :: Constraint) => Subst -> Type -> Type
Subst -> Type -> Type
substTy Subst
subst Type
fun_ki

      -- No binder; try applying the substitution, or fail if that's not possible
      (HsTypeArg SrcSpan
_ GenLocated SrcSpanAnnA (HsType GhcRn)
ki_arg : [HsArg
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
_, Maybe (PiTyBinder, Type)
Nothing) -> TcM (Type, Type) -> TcM (Type, Type)
try_again_after_substing_or (TcM (Type, Type) -> TcM (Type, Type))
-> TcM (Type, Type) -> TcM (Type, Type)
forall a b. (a -> b) -> a -> b
$
                                           GenLocated SrcSpanAnnA (HsType GhcRn) -> Type -> TcM (Type, Type)
forall {a}. GenLocated SrcSpanAnnA (HsType GhcRn) -> Type -> TcRn a
ty_app_err GenLocated SrcSpanAnnA (HsType GhcRn)
ki_arg Type
substed_fun_ki

      ---------------- HsValArg: a normal argument (fun ty)
      (HsValArg GenLocated SrcSpanAnnA (HsType GhcRn)
arg : [HsArg
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
args, Just (PiTyBinder
ki_binder, Type
inner_ki))
        -- next binder is invisible; need to instantiate it
        | PiTyBinder -> Bool
isInvisiblePiTyBinder PiTyBinder
ki_binder   -- FunTy with constraint on LHS;
                                            -- or ForAllTy with Inferred or Specified
         -> PiTyBinder -> Type -> TcM (Type, Type)
instantiate PiTyBinder
ki_binder Type
inner_ki

        -- "normal" case
        | Bool
otherwise
         -> do { String -> SDoc -> TcM ()
traceTc String
"tcInferTyApps (vis normal app)"
                          ([SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat [ PiTyBinder -> SDoc
forall a. Outputable a => a -> SDoc
ppr PiTyBinder
ki_binder
                                , GenLocated SrcSpanAnnA (HsType GhcRn) -> SDoc
forall a. Outputable a => a -> SDoc
ppr GenLocated SrcSpanAnnA (HsType GhcRn)
arg
                                , Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr (PiTyBinder -> Type
piTyBinderType PiTyBinder
ki_binder)
                                , Subst -> SDoc
forall a. Outputable a => a -> SDoc
ppr Subst
subst ])
                ; let exp_kind :: Type
exp_kind = (() :: Constraint) => Subst -> Type -> Type
Subst -> Type -> Type
substTy Subst
subst (Type -> Type) -> Type -> Type
forall a b. (a -> b) -> a -> b
$ PiTyBinder -> Type
piTyBinderType PiTyBinder
ki_binder
                ; Type
arg' <- SDoc -> TcM Type -> TcM Type
forall a. SDoc -> TcM a -> TcM a
addErrCtxt (GenLocated SrcSpanAnnA (HsType GhcRn)
-> GenLocated SrcSpanAnnA (HsType GhcRn) -> Arity -> SDoc
forall fun arg.
(Outputable fun, Outputable arg) =>
fun -> arg -> Arity -> SDoc
funAppCtxt LHsType GhcRn
GenLocated SrcSpanAnnA (HsType GhcRn)
orig_hs_ty GenLocated SrcSpanAnnA (HsType GhcRn)
arg Arity
n) (TcM Type -> TcM Type) -> TcM Type -> TcM Type
forall a b. (a -> b) -> a -> b
$
                          TcTyMode -> LHsType GhcRn -> Type -> TcM Type
tc_lhs_type TcTyMode
mode LHsType GhcRn
GenLocated SrcSpanAnnA (HsType GhcRn)
arg Type
exp_kind
                ; String -> SDoc -> TcM ()
traceTc String
"tcInferTyApps (vis normal app) 2" (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
exp_kind)
                ; (Subst
subst', Type
fun') <- Subst -> Type -> PiTyBinder -> Type -> TcM (Subst, Type)
mkAppTyM Subst
subst Type
fun PiTyBinder
ki_binder Type
arg'
                ; Arity
-> Type -> Subst -> Type -> HsTyPats GhcRn -> TcM (Type, Type)
go (Arity
nArity -> Arity -> Arity
forall a. Num a => a -> a -> a
+Arity
1) Type
fun' Subst
subst' Type
inner_ki HsTyPats GhcRn
[HsArg
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
args }

          -- no binder; try applying the substitution, or infer another arrow in fun kind
      (HsValArg GenLocated SrcSpanAnnA (HsType GhcRn)
_ : [HsArg
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
_, Maybe (PiTyBinder, Type)
Nothing)
        -> TcM (Type, Type) -> TcM (Type, Type)
try_again_after_substing_or (TcM (Type, Type) -> TcM (Type, Type))
-> TcM (Type, Type) -> TcM (Type, Type)
forall a b. (a -> b) -> a -> b
$
           do { let arrows_needed :: Arity
arrows_needed = [HsArg
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
-> Arity
forall tm ty. [HsArg tm ty] -> Arity
n_initial_val_args HsTyPats GhcRn
[HsArg
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
all_args
              ; Coercion
co <- TypedThing -> Arity -> Type -> TcM Coercion
matchExpectedFunKind (HsType GhcRn -> TypedThing
HsTypeRnThing (HsType GhcRn -> TypedThing) -> HsType GhcRn -> TypedThing
forall a b. (a -> b) -> a -> b
$ GenLocated SrcSpanAnnA (HsType GhcRn) -> HsType GhcRn
forall l e. GenLocated l e -> e
unLoc LHsType GhcRn
GenLocated SrcSpanAnnA (HsType GhcRn)
hs_ty) Arity
arrows_needed Type
substed_fun_ki

              ; Type
fun' <- Type -> TcM Type
zonkTcType (Type
fun Type -> Coercion -> Type
`mkCastTy` Coercion
co)
                     -- This zonk is essential, to expose the fruits
                     -- of matchExpectedFunKind to the 'go' loop

              ; String -> SDoc -> TcM ()
traceTc String
"tcInferTyApps (no binder)" (SDoc -> TcM ()) -> SDoc -> TcM ()
forall a b. (a -> b) -> a -> b
$
                   [SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat [ Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
fun SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
fun_ki
                        , Arity -> SDoc
forall a. Outputable a => a -> SDoc
ppr Arity
arrows_needed
                        , Coercion -> SDoc
forall a. Outputable a => a -> SDoc
ppr Coercion
co
                        , Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
fun' SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr ((() :: Constraint) => Type -> Type
Type -> Type
typeKind Type
fun')]
              ; Arity
-> Type
-> [HsArg
      (GenLocated SrcSpanAnnA (HsType GhcRn))
      (GenLocated SrcSpanAnnA (HsType GhcRn))]
-> TcM (Type, Type)
go_init Arity
n Type
fun' HsTyPats GhcRn
[HsArg
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
all_args }
                -- Use go_init to establish go's INVARIANT
      where
        instantiate :: PiTyBinder -> Type -> TcM (Type, Type)
instantiate PiTyBinder
ki_binder Type
inner_ki
          = do { String -> SDoc -> TcM ()
traceTc String
"tcInferTyApps (need to instantiate)"
                         ([SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat [ PiTyBinder -> SDoc
forall a. Outputable a => a -> SDoc
ppr PiTyBinder
ki_binder, Subst -> SDoc
forall a. Outputable a => a -> SDoc
ppr Subst
subst])
               ; (Subst
subst', Type
arg') <- Subst -> PiTyBinder -> TcM (Subst, Type)
tcInstInvisibleTyBinder Subst
subst PiTyBinder
ki_binder
               ; Arity
-> Type -> Subst -> Type -> HsTyPats GhcRn -> TcM (Type, Type)
go Arity
n (Type -> Type -> Type
mkAppTy Type
fun Type
arg') Subst
subst' Type
inner_ki HsTyPats GhcRn
all_args }
                 -- Because tcInvisibleTyBinder instantiate ki_binder,
                 -- the kind of arg' will have the same shape as the kind
                 -- of ki_binder.  So we don't need mkAppTyM here.

        try_again_after_substing_or :: TcM (Type, Type) -> TcM (Type, Type)
try_again_after_substing_or TcM (Type, Type)
fallthrough
          | Bool -> Bool
not (Subst -> Bool
isEmptyTCvSubst Subst
subst)
          = Arity
-> Type -> Subst -> Type -> HsTyPats GhcRn -> TcM (Type, Type)
go Arity
n Type
fun Subst
zapped_subst Type
substed_fun_ki HsTyPats GhcRn
all_args
          | Bool
otherwise
          = TcM (Type, Type)
fallthrough

        zapped_subst :: Subst
zapped_subst   = Subst -> Subst
zapSubst Subst
subst
        substed_fun_ki :: Type
substed_fun_ki = (() :: Constraint) => Subst -> Type -> Type
Subst -> Type -> Type
substTy Subst
subst Type
fun_ki
        hs_ty :: LHsType GhcRn
hs_ty          = LHsType GhcRn -> HsTyPats GhcRn -> LHsType GhcRn
appTypeToArg LHsType GhcRn
orig_hs_ty (Arity
-> [HsArg
      (GenLocated SrcSpanAnnA (HsType GhcRn))
      (GenLocated SrcSpanAnnA (HsType GhcRn))]
-> [HsArg
      (GenLocated SrcSpanAnnA (HsType GhcRn))
      (GenLocated SrcSpanAnnA (HsType GhcRn))]
forall a. Arity -> [a] -> [a]
take (Arity
nArity -> Arity -> Arity
forall a. Num a => a -> a -> a
-Arity
1) HsTyPats GhcRn
[HsArg
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
orig_hs_args)

    n_initial_val_args :: [HsArg tm ty] -> Arity
    -- Count how many leading HsValArgs we have
    n_initial_val_args :: forall tm ty. [HsArg tm ty] -> Arity
n_initial_val_args (HsValArg {} : [HsArg tm ty]
args) = Arity
1 Arity -> Arity -> Arity
forall a. Num a => a -> a -> a
+ [HsArg tm ty] -> Arity
forall tm ty. [HsArg tm ty] -> Arity
n_initial_val_args [HsArg tm ty]
args
    n_initial_val_args (HsArgPar {} : [HsArg tm ty]
args) = [HsArg tm ty] -> Arity
forall tm ty. [HsArg tm ty] -> Arity
n_initial_val_args [HsArg tm ty]
args
    n_initial_val_args [HsArg tm ty]
_                    = Arity
0

    ty_app_err :: GenLocated SrcSpanAnnA (HsType GhcRn) -> Type -> TcRn a
ty_app_err GenLocated SrcSpanAnnA (HsType GhcRn)
arg Type
ty
      = TcRnMessage -> TcRn a
forall a. TcRnMessage -> TcM a
failWith (TcRnMessage -> TcRn a) -> TcRnMessage -> TcRn a
forall a b. (a -> b) -> a -> b
$ LHsType GhcRn -> Type -> TcRnMessage
TcRnInvalidVisibleKindArgument LHsType GhcRn
GenLocated SrcSpanAnnA (HsType GhcRn)
arg Type
ty

mkAppTyM :: Subst
         -> TcType -> PiTyBinder    -- fun, plus its top-level binder
         -> TcType                  -- arg
         -> TcM (Subst, TcType)  -- Extended subst, plus (fun arg)
-- Precondition: the application (fun arg) is well-kinded after zonking
--               That is, the application makes sense
--
-- Precondition: for (mkAppTyM subst fun bndr arg)
--       typeKind fun  =  Pi bndr. body
--  That is, fun always has a ForAllTy or FunTy at the top
--           and 'bndr' is fun's pi-binder
--
-- Postcondition: if fun and arg satisfy (PKTI), the purely-kinded type
--                invariant, then so does the result type (fun arg)
--
-- We do not require that
--    typeKind arg = tyVarKind (binderVar bndr)
-- This must be true after zonking (precondition 1), but it's not
-- required for the (PKTI).
mkAppTyM :: Subst -> Type -> PiTyBinder -> Type -> TcM (Subst, Type)
mkAppTyM Subst
subst Type
fun PiTyBinder
ki_binder Type
arg
  | -- See Note [mkAppTyM]: Nasty case 2
    TyConApp TyCon
tc [Type]
args <- Type
fun
  , TyCon -> Bool
isTypeSynonymTyCon TyCon
tc
  , [Type]
args [Type] -> Arity -> Bool
forall a. [a] -> Arity -> Bool
`lengthIs` (TyCon -> Arity
tyConArity TyCon
tc Arity -> Arity -> Arity
forall a. Num a => a -> a -> a
- Arity
1)
  , (TyVar -> Bool) -> [TyVar] -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
any TyVar -> Bool
isTrickyTvBinder (TyCon -> [TyVar]
tyConTyVars TyCon
tc) -- We could cache this in the synonym
  = do { Type
arg'  <- Type -> TcM Type
zonkTcType  Type
arg
       ; [Type]
args' <- [Type] -> TcM [Type]
zonkTcTypes [Type]
args
       ; let subst' :: Subst
subst' = case PiTyBinder
ki_binder of
                        Anon {}           -> Subst
subst
                        Named (Bndr TyVar
tv ForAllTyFlag
_) -> Subst -> TyVar -> Type -> Subst
extendTvSubstAndInScope Subst
subst TyVar
tv Type
arg'
       ; (Subst, Type) -> TcM (Subst, Type)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (Subst
subst', TyCon -> [Type] -> Type
mkTyConApp TyCon
tc ([Type]
args' [Type] -> [Type] -> [Type]
forall a. [a] -> [a] -> [a]
++ [Type
arg'])) }


mkAppTyM Subst
subst Type
fun (Anon {}) Type
arg
   = (Subst, Type) -> TcM (Subst, Type)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (Subst
subst, Type -> Type -> Type
mk_app_ty Type
fun Type
arg)

mkAppTyM Subst
subst Type
fun (Named (Bndr TyVar
tv ForAllTyFlag
_)) Type
arg
  = do { Type
arg' <- if TyVar -> Bool
isTrickyTvBinder TyVar
tv
                 then -- See Note [mkAppTyM]: Nasty case 1
                      Type -> TcM Type
zonkTcType Type
arg
                 else Type -> TcM Type
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return     Type
arg
       ; (Subst, Type) -> TcM (Subst, Type)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ( Subst -> TyVar -> Type -> Subst
extendTvSubstAndInScope Subst
subst TyVar
tv Type
arg'
                , Type -> Type -> Type
mk_app_ty Type
fun Type
arg' ) }

mk_app_ty :: TcType -> TcType -> TcType
-- This function just adds an ASSERT for mkAppTyM's precondition
mk_app_ty :: Type -> Type -> Type
mk_app_ty Type
fun Type
arg
  = Bool -> SDoc -> Type -> Type
forall a. HasCallStack => Bool -> SDoc -> a -> a
assertPpr (Type -> Bool
isPiTy Type
fun_kind)
              (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
fun SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
fun_kind SDoc -> SDoc -> SDoc
forall doc. IsDoc doc => doc -> doc -> doc
$$ Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
arg) (Type -> Type) -> Type -> Type
forall a b. (a -> b) -> a -> b
$
    Type -> Type -> Type
mkAppTy Type
fun Type
arg
  where
    fun_kind :: Type
fun_kind = (() :: Constraint) => Type -> Type
Type -> Type
typeKind Type
fun

isTrickyTvBinder :: TcTyVar -> Bool
-- NB: isTrickyTvBinder is just an optimisation
-- It would be absolutely sound to return True always
isTrickyTvBinder :: TyVar -> Bool
isTrickyTvBinder TyVar
tv = Type -> Bool
isPiTy (TyVar -> Type
tyVarKind TyVar
tv)

{- Note [The Purely Kinded Type Invariant (PKTI)]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
During type inference, we maintain this invariant

 (PKTI) It is legal to call 'typeKind' on any Type ty,
        on any sub-term of ty, /without/ zonking ty

        Moreover, any such returned kind
        will itself satisfy (PKTI)

By "legal to call typeKind" we mean "typeKind will not crash".
The way in which typeKind can crash is in applications
    (a t1 t2 .. tn)
if 'a' is a type variable whose kind doesn't have enough arrows
or foralls.  (The crash is in piResultTys.)

The loop in tcInferTyApps has to be very careful to maintain the (PKTI).
For example, suppose
    kappa is a unification variable
    We have already unified kappa := Type
      yielding    co :: Refl (Type -> Type)
    a :: kappa
then consider the type
    (a Int)
If we call typeKind on that, we'll crash, because the (un-zonked)
kind of 'a' is just kappa, not an arrow kind.  So we must zonk first.

So the type inference engine is very careful when building applications.
This happens in tcInferTyApps. Suppose we are kind-checking the type (a Int),
where (a :: kappa).  Then in tcInferApps we'll run out of binders on
a's kind, so we'll call matchExpectedFunKind, and unify
   kappa := kappa1 -> kappa2,  with evidence co :: kappa ~ (kappa1 ~ kappa2)
At this point we must zonk the function type to expose the arrrow, so
that (a Int) will satisfy (PKTI).

The absence of this caused #14174 and #14520.

The calls to mkAppTyM is the other place we are very careful; see Note [mkAppTyM].

Wrinkle around FunTy:
Note that the PKTI does *not* guarantee anything about the shape of FunTys.
Specifically, when we have (FunTy vis mult arg res), it should be the case
that arg :: TYPE rr1 and res :: TYPE rr2, for some rr1 and rr2. However, we
might not have this. Example: if the user writes (a -> b), then we might
invent a :: kappa1 and b :: kappa2. We soon will check whether kappa1 ~ TYPE rho1
(for some rho1), and that will lead to kappa1 := TYPE rho1 (ditto for kappa2).
However, when we build the FunTy, we might not have zonked `a`, and so the
FunTy will be built without being able to purely extract the RuntimeReps.

Because the PKTI does not guarantee that the RuntimeReps are available in a FunTy,
we must be aware of this when splitting: splitTyConApp and splitAppTy will *not*
split a FunTy if the RuntimeReps are not available. See also Note [Decomposing FunTy]
in GHC.Tc.Solver.Canonical.

Note [mkAppTyM]
~~~~~~~~~~~~~~~
mkAppTyM is trying to guarantee the Purely Kinded Type Invariant
(PKTI) for its result type (fun arg).  There are two ways it can go wrong:

* Nasty case 1: forall types (polykinds/T14174a)
    T :: forall (p :: *->*). p Int -> p Bool
  Now kind-check (T x), where x::kappa.
  Well, T and x both satisfy the PKTI, but
     T x :: x Int -> x Bool
  and (x Int) does /not/ satisfy the PKTI.

* Nasty case 2: type synonyms
    type S f a = f a
  Even though (S ff aa) would satisfy the (PKTI) if S was a data type
  (i.e. nasty case 1 is dealt with), it might still not satisfy (PKTI)
  if S is a type synonym, because the /expansion/ of (S ff aa) is
  (ff aa), and /that/ does not satisfy (PKTI).  E.g. perhaps
  (ff :: kappa), where 'kappa' has already been unified with (*->*).

  We check for nasty case 2 on the final argument of a type synonym.

Notice that in both cases the trickiness only happens if the
bound variable has a pi-type.  Hence isTrickyTvBinder.
-}


saturateFamApp :: TcType -> TcKind -> TcM (TcType, TcKind)
-- Precondition for (saturateFamApp ty kind):
--     typeKind ty = kind
--
-- If 'ty' is an unsaturated family application with trailing
-- invisible arguments, instantiate them.
-- See Note [saturateFamApp]

saturateFamApp :: Type -> Type -> TcM (Type, Type)
saturateFamApp Type
ty Type
kind
  | Just (TyCon
tc, [Type]
args) <- HasCallStack => Type -> Maybe (TyCon, [Type])
Type -> Maybe (TyCon, [Type])
tcSplitTyConApp_maybe Type
ty
  , TyCon -> Bool
tyConMustBeSaturated TyCon
tc
  , let n_to_inst :: Arity
n_to_inst = TyCon -> Arity
tyConArity TyCon
tc Arity -> Arity -> Arity
forall a. Num a => a -> a -> a
- [Type] -> Arity
forall a. [a] -> Arity
forall (t :: * -> *) a. Foldable t => t a -> Arity
length [Type]
args
  = do { ([Type]
extra_args, Type
ki') <- Arity -> Type -> TcM ([Type], Type)
tcInstInvisibleTyBindersN Arity
n_to_inst Type
kind
       ; (Type, Type) -> TcM (Type, Type)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (Type
ty Type -> [Type] -> Type
`mkAppTys` [Type]
extra_args, Type
ki') }
  | Bool
otherwise
  = (Type, Type) -> TcM (Type, Type)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (Type
ty, Type
kind)

{- Note [saturateFamApp]
~~~~~~~~~~~~~~~~~~~~~~~~
Consider
   type family F :: Either j k
   type instance F @Type = Right Maybe
   type instance F @Type = Right Either```

Then F :: forall {j,k}. Either j k

The two type instances do a visible kind application that instantiates
'j' but not 'k'.  But we want to end up with instances that look like
  type instance F @Type @(*->*) = Right @Type @(*->*) Maybe

so that F has arity 2.  We must instantiate that trailing invisible
binder. In general, Invisible binders precede Specified and Required,
so this is only going to bite for apparently-nullary families.

Note that
  type family F2 :: forall k. k -> *
is quite different and really does have arity 0.

It's not just type instances where we need to saturate those
unsaturated arguments: see #11246.  Hence doing this in tcInferApps.
-}

appTypeToArg :: LHsType GhcRn -> [LHsTypeArg GhcRn] -> LHsType GhcRn
appTypeToArg :: LHsType GhcRn -> HsTyPats GhcRn -> LHsType GhcRn
appTypeToArg LHsType GhcRn
f []                       = LHsType GhcRn
f
appTypeToArg LHsType GhcRn
f (HsValArg LHsType GhcRn
arg    : HsTyPats GhcRn
args) = LHsType GhcRn -> HsTyPats GhcRn -> LHsType GhcRn
appTypeToArg (LHsType GhcRn -> LHsType GhcRn -> LHsType GhcRn
forall (p :: Pass).
LHsType (GhcPass p) -> LHsType (GhcPass p) -> LHsType (GhcPass p)
mkHsAppTy LHsType GhcRn
f LHsType GhcRn
arg) HsTyPats GhcRn
args
appTypeToArg LHsType GhcRn
f (HsArgPar SrcSpan
_      : HsTyPats GhcRn
args) = LHsType GhcRn -> HsTyPats GhcRn -> LHsType GhcRn
appTypeToArg LHsType GhcRn
f                 HsTyPats GhcRn
args
appTypeToArg LHsType GhcRn
f (HsTypeArg SrcSpan
l LHsType GhcRn
arg : HsTyPats GhcRn
args)
  = LHsType GhcRn -> HsTyPats GhcRn -> LHsType GhcRn
appTypeToArg (XAppKindTy GhcRn -> LHsType GhcRn -> LHsType GhcRn -> LHsType GhcRn
forall (p :: Pass).
XAppKindTy (GhcPass p)
-> LHsType (GhcPass p)
-> LHsType (GhcPass p)
-> LHsType (GhcPass p)
mkHsAppKindTy XAppKindTy GhcRn
SrcSpan
l LHsType GhcRn
f LHsType GhcRn
arg) HsTyPats GhcRn
args


{- *********************************************************************
*                                                                      *
                checkExpectedKind
*                                                                      *
********************************************************************* -}

-- | This instantiates invisible arguments for the type being checked if it must
-- be saturated and is not yet saturated. It then calls and uses the result
-- from checkExpectedKindX to build the final type
checkExpectedKind :: HasDebugCallStack
                  => HsType GhcRn       -- ^ type we're checking (for printing)
                  -> TcType             -- ^ type we're checking
                  -> TcKind             -- ^ the known kind of that type
                  -> TcKind             -- ^ the expected kind
                  -> TcM TcType
-- Just a convenience wrapper to save calls to 'ppr'
checkExpectedKind :: (() :: Constraint) =>
HsType GhcRn -> Type -> Type -> Type -> TcM Type
checkExpectedKind HsType GhcRn
hs_ty Type
ty Type
act_kind Type
exp_kind
  = do { String -> SDoc -> TcM ()
traceTc String
"checkExpectedKind" (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
ty SDoc -> SDoc -> SDoc
forall doc. IsDoc doc => doc -> doc -> doc
$$ Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
act_kind)

       ; ([Type]
new_args, Type
act_kind') <- Arity -> Type -> TcM ([Type], Type)
tcInstInvisibleTyBindersN Arity
n_to_inst Type
act_kind

       ; let origin :: CtOrigin
origin = TypeEqOrigin { uo_actual :: Type
uo_actual   = Type
act_kind'
                                   , uo_expected :: Type
uo_expected = Type
exp_kind
                                   , uo_thing :: Maybe TypedThing
uo_thing    = TypedThing -> Maybe TypedThing
forall a. a -> Maybe a
Just (HsType GhcRn -> TypedThing
HsTypeRnThing HsType GhcRn
hs_ty)
                                   , uo_visible :: Bool
uo_visible  = Bool
True } -- the hs_ty is visible

       ; String -> SDoc -> TcM ()
traceTc String
"checkExpectedKindX" (SDoc -> TcM ()) -> SDoc -> TcM ()
forall a b. (a -> b) -> a -> b
$
         [SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat [ HsType GhcRn -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsType GhcRn
hs_ty
              , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"act_kind':" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
act_kind'
              , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"exp_kind:" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
exp_kind ]

       ; let res_ty :: Type
res_ty = Type
ty Type -> [Type] -> Type
`mkAppTys` [Type]
new_args

       ; if Type
act_kind' (() :: Constraint) => Type -> Type -> Bool
Type -> Type -> Bool
`tcEqType` Type
exp_kind
         then Type -> TcM Type
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return Type
res_ty  -- This is very common
         else do { Coercion
co_k <- TypeOrKind -> CtOrigin -> Type -> Type -> TcM Coercion
uType TypeOrKind
KindLevel CtOrigin
origin Type
act_kind' Type
exp_kind
                 ; String -> SDoc -> TcM ()
traceTc String
"checkExpectedKind" ([SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat [ Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
act_kind
                                                     , Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
exp_kind
                                                     , Coercion -> SDoc
forall a. Outputable a => a -> SDoc
ppr Coercion
co_k ])
                ; Type -> TcM Type
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (Type
res_ty Type -> Coercion -> Type
`mkCastTy` Coercion
co_k) } }
    where
      -- We need to make sure that both kinds have the same number of implicit
      -- foralls out front. If the actual kind has more, instantiate accordingly.
      -- Otherwise, just pass the type & kind through: the errors are caught
      -- in unifyType.
      n_exp_invis_bndrs :: Arity
n_exp_invis_bndrs = Type -> Arity
invisibleTyBndrCount Type
exp_kind
      n_act_invis_bndrs :: Arity
n_act_invis_bndrs = Type -> Arity
invisibleTyBndrCount Type
act_kind
      n_to_inst :: Arity
n_to_inst         = Arity
n_act_invis_bndrs Arity -> Arity -> Arity
forall a. Num a => a -> a -> a
- Arity
n_exp_invis_bndrs

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

tcHsContext :: Maybe (LHsContext GhcRn) -> TcM [PredType]
tcHsContext :: Maybe (LHsContext GhcRn) -> TcM [Type]
tcHsContext Maybe (LHsContext GhcRn)
Nothing    = [Type] -> TcM [Type]
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return []
tcHsContext (Just LHsContext GhcRn
cxt) = TcTyMode -> LHsContext GhcRn -> TcM [Type]
tc_hs_context TcTyMode
typeLevelMode LHsContext GhcRn
cxt

tcLHsPredType :: LHsType GhcRn -> TcM PredType
tcLHsPredType :: LHsType GhcRn -> TcM Type
tcLHsPredType LHsType GhcRn
pred = TcTyMode -> LHsType GhcRn -> TcM Type
tc_lhs_pred TcTyMode
typeLevelMode LHsType GhcRn
pred

tc_hs_context :: TcTyMode -> LHsContext GhcRn -> TcM [PredType]
tc_hs_context :: TcTyMode -> LHsContext GhcRn -> TcM [Type]
tc_hs_context TcTyMode
mode LHsContext GhcRn
ctxt = (GenLocated SrcSpanAnnA (HsType GhcRn) -> TcM Type)
-> [GenLocated SrcSpanAnnA (HsType GhcRn)] -> TcM [Type]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
forall (m :: * -> *) a b. Monad m => (a -> m b) -> [a] -> m [b]
mapM (TcTyMode -> LHsType GhcRn -> TcM Type
tc_lhs_pred TcTyMode
mode) (GenLocated SrcSpanAnnC [GenLocated SrcSpanAnnA (HsType GhcRn)]
-> [GenLocated SrcSpanAnnA (HsType GhcRn)]
forall l e. GenLocated l e -> e
unLoc LHsContext GhcRn
GenLocated SrcSpanAnnC [GenLocated SrcSpanAnnA (HsType GhcRn)]
ctxt)

tc_lhs_pred :: TcTyMode -> LHsType GhcRn -> TcM PredType
tc_lhs_pred :: TcTyMode -> LHsType GhcRn -> TcM Type
tc_lhs_pred TcTyMode
mode LHsType GhcRn
pred = TcTyMode -> LHsType GhcRn -> Type -> TcM Type
tc_lhs_type TcTyMode
mode LHsType GhcRn
pred Type
constraintKind

---------------------------
tcTyVar :: Name -> TcM (TcType, TcKind)
-- See Note [Type checking recursive type and class declarations]
-- in GHC.Tc.TyCl
-- This does not instantiate. See Note [Do not always instantiate eagerly in types]
tcTyVar :: Name -> TcM (Type, Type)
tcTyVar Name
name         -- Could be a tyvar, a tycon, or a datacon
  = do { String -> SDoc -> TcM ()
traceTc String
"lk1" (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
name)
       ; TcTyThing
thing <- Name -> TcM TcTyThing
tcLookup Name
name
       ; case TcTyThing
thing of
           ATyVar Name
_ TyVar
tv -> (Type, Type) -> TcM (Type, Type)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (TyVar -> Type
mkTyVarTy TyVar
tv, TyVar -> Type
tyVarKind TyVar
tv)

           -- See Note [Recursion through the kinds]
           (TcTyThing -> Maybe TyCon
tcTyThingTyCon_maybe -> Just TyCon
tc) -- TyCon or TcTyCon
             -> (Type, Type) -> TcM (Type, Type)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (TyCon -> Type
mkTyConTy TyCon
tc, TyCon -> Type
tyConKind TyCon
tc)

           AGlobal (AConLike (RealDataCon DataCon
dc))
             -> do { Bool
data_kinds <- Extension -> TcRnIf TcGblEnv TcLclEnv Bool
forall gbl lcl. Extension -> TcRnIf gbl lcl Bool
xoptM Extension
LangExt.DataKinds
                   ; Bool -> TcM () -> TcM ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
unless (Bool
data_kinds Bool -> Bool -> Bool
|| DataCon -> Bool
specialPromotedDc DataCon
dc) (TcM () -> TcM ()) -> TcM () -> TcM ()
forall a b. (a -> b) -> a -> b
$
                       Name -> PromotionErr -> TcM ()
forall a. Name -> PromotionErr -> TcM a
promotionErr Name
name PromotionErr
NoDataKindsDC
                   ; Bool -> TcM () -> TcM ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
when (TyCon -> Bool
isFamInstTyCon (DataCon -> TyCon
dataConTyCon DataCon
dc)) (TcM () -> TcM ()) -> TcM () -> TcM ()
forall a b. (a -> b) -> a -> b
$
                       -- see #15245
                       Name -> PromotionErr -> TcM ()
forall a. Name -> PromotionErr -> TcM a
promotionErr Name
name PromotionErr
FamDataConPE
                   ; let ([TyVar]
_, [TyVar]
_, [EqSpec]
_, [Type]
theta, [Scaled Type]
_, Type
_) = DataCon
-> ([TyVar], [TyVar], [EqSpec], [Type], [Scaled Type], Type)
dataConFullSig DataCon
dc
                   ; String -> SDoc -> TcM ()
traceTc String
"tcTyVar" (DataCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr DataCon
dc SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [Type] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Type]
theta SDoc -> SDoc -> SDoc
forall doc. IsDoc doc => doc -> doc -> doc
$$ Maybe Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr ([Type] -> Maybe Type
dc_theta_illegal_constraint [Type]
theta))
                   ; case [Type] -> Maybe Type
dc_theta_illegal_constraint [Type]
theta of
                       Just Type
pred -> Name -> PromotionErr -> TcM ()
forall a. Name -> PromotionErr -> TcM a
promotionErr Name
name (PromotionErr -> TcM ()) -> PromotionErr -> TcM ()
forall a b. (a -> b) -> a -> b
$
                                    Type -> PromotionErr
ConstrainedDataConPE Type
pred
                       Maybe Type
Nothing   -> () -> TcM ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (f :: * -> *) a. Applicative f => a -> f a
pure ()
                   ; let tc :: TyCon
tc = DataCon -> TyCon
promoteDataCon DataCon
dc
                   ; (Type, Type) -> TcM (Type, Type)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (TyCon -> [Type] -> Type
mkTyConApp TyCon
tc [], TyCon -> Type
tyConKind TyCon
tc) }

           APromotionErr PromotionErr
err -> Name -> PromotionErr -> TcM (Type, Type)
forall a. Name -> PromotionErr -> TcM a
promotionErr Name
name PromotionErr
err

           TcTyThing
_  -> String -> TcTyThing -> Name -> TcM (Type, Type)
forall a. String -> TcTyThing -> Name -> TcM a
wrongThingErr String
"type" TcTyThing
thing Name
name }
  where
    -- We cannot promote a data constructor with a context that contains
    -- constraints other than equalities, so error if we find one.
    -- See Note [Constraints in kinds] in GHC.Core.TyCo.Rep
    dc_theta_illegal_constraint :: ThetaType -> Maybe PredType
    dc_theta_illegal_constraint :: [Type] -> Maybe Type
dc_theta_illegal_constraint = (Type -> Bool) -> [Type] -> Maybe Type
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Maybe a
find (Bool -> Bool
not (Bool -> Bool) -> (Type -> Bool) -> Type -> Bool
forall b c a. (b -> c) -> (a -> b) -> a -> c
. Type -> Bool
isEqPred)

{-
Note [Recursion through the kinds]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider these examples

Ticket #11554:
  data P (x :: k) = Q
  data A :: Type where
    MkA :: forall (a :: A). P a -> A

Ticket #12174
  data V a
  data T = forall (a :: T). MkT (V a)

The type is recursive (which is fine) but it is recursive /through the
kinds/.  In earlier versions of GHC this caused a loop in the compiler
(to do with knot-tying) but there is nothing fundamentally wrong with
the code (kinds are types, and the recursive declarations are OK). But
it's hard to distinguish "recursion through the kinds" from "recursion
through the types". Consider this (also #11554):

  data PB k (x :: k) = Q
  data B :: Type where
    MkB :: P B a -> B

Here the occurrence of B is not obviously in a kind position.

So now GHC allows all these programs.  #12081 and #15942 are other
examples.

Note [Body kind of a HsForAllTy]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The body of a forall is usually a type, but in principle
there's no reason to prohibit *unlifted* types.
In fact, GHC can itself construct a function with an
unboxed tuple inside a for-all (via CPR analysis; see
typecheck/should_compile/tc170).

Moreover in instance heads we get forall-types with
kind Constraint.

It's tempting to check that the body kind is either * or #. But this is
wrong. For example:

  class C a b
  newtype N = Mk Foo deriving (C a)

We're doing newtype-deriving for C. But notice how `a` isn't in scope in
the predicate `C a`. So we quantify, yielding `forall a. C a` even though
`C a` has kind `* -> Constraint`. The `forall a. C a` is a bit cheeky, but
convenient. Bottom line: don't check for * or # here.

Note [Body kind of a HsQualTy]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If ctxt is non-empty, the HsQualTy really is a /function/, so the
kind of the result really is '*', and in that case the kind of the
body-type can be lifted or unlifted.

However, consider
    instance Eq a => Eq [a] where ...
or
    f :: (Eq a => Eq [a]) => blah
Here both body-kind of the HsQualTy is Constraint rather than *.
Rather crudely we tell the difference by looking at exp_kind. It's
very convenient to typecheck instance types like any other HsSigType.

Admittedly the '(Eq a => Eq [a]) => blah' case is erroneous, but it's
better to reject in checkValidType.  If we say that the body kind
should be '*' we risk getting TWO error messages, one saying that Eq
[a] doesn't have kind '*', and one saying that we need a Constraint to
the left of the outer (=>).

How do we figure out the right body kind?  Well, it's a bit of a
kludge: I just look at the expected kind.  If it's Constraint, we
must be in this instance situation context. It's a kludge because it
wouldn't work if any unification was involved to compute that result
kind -- but it isn't.  (The true way might be to use the 'mode'
parameter, but that seemed like a sledgehammer to crack a nut.)

Note [Inferring tuple kinds]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Give a tuple type (a,b,c), which the parser labels as HsBoxedOrConstraintTuple,
we try to figure out whether it's a tuple of kind * or Constraint.
  Step 1: look at the expected kind
  Step 2: infer argument kinds

If after Step 2 it's not clear from the arguments that it's
Constraint, then it must be *.  Once having decided that we re-check
the arguments to give good error messages in
  e.g.  (Maybe, Maybe)

Note that we will still fail to infer the correct kind in this case:

  type T a = ((a,a), D a)
  type family D :: Constraint -> Constraint

While kind checking T, we do not yet know the kind of D, so we will default the
kind of T to * -> *. It works if we annotate `a` with kind `Constraint`.

Note [Desugaring types]
~~~~~~~~~~~~~~~~~~~~~~~
The type desugarer is phase 2 of dealing with HsTypes.  Specifically:

  * It transforms from HsType to Type

  * It zonks any kinds.  The returned type should have no mutable kind
    or type variables (hence returning Type not TcType):
      - any unconstrained kind variables are defaulted to (Any *) just
        as in GHC.Tc.Utils.Zonk.
      - there are no mutable type variables because we are
        kind-checking a type
    Reason: the returned type may be put in a TyCon or DataCon where
    it will never subsequently be zonked.

You might worry about nested scopes:
        ..a:kappa in scope..
            let f :: forall b. T '[a,b] -> Int
In this case, f's type could have a mutable kind variable kappa in it;
and we might then default it to (Any *) when dealing with f's type
signature.  But we don't expect this to happen because we can't get a
lexically scoped type variable with a mutable kind variable in it.  A
delicate point, this.  If it becomes an issue we might need to
distinguish top-level from nested uses.

Moreover
  * it cannot fail,
  * it does no unifications
  * it does no validity checking, except for structural matters, such as
        (a) spurious ! annotations.
        (b) a class used as a type

Note [Kind of a type splice]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider these terms, each with TH type splice inside:
     [| e1 :: Maybe $(..blah..) |]
     [| e2 :: $(..blah..) |]
When kind-checking the type signature, we'll kind-check the splice
$(..blah..); we want to give it a kind that can fit in any context,
as if $(..blah..) :: forall k. k.

In the e1 example, the context of the splice fixes kappa to *.  But
in the e2 example, we'll desugar the type, zonking the kind unification
variables as we go.  When we encounter the unconstrained kappa, we
want to default it to '*', not to (Any *).

-}

addTypeCtxt :: LHsType GhcRn -> TcM a -> TcM a
        -- Wrap a context around only if we want to show that contexts.
        -- Omit invisible ones and ones user's won't grok
addTypeCtxt :: forall a. LHsType GhcRn -> TcM a -> TcM a
addTypeCtxt (L SrcSpanAnnA
_ (HsWildCardTy XWildCardTy GhcRn
_)) TcM a
thing = TcM a
thing   -- "In the type '_'" just isn't helpful.
addTypeCtxt (L SrcSpanAnnA
_ HsType GhcRn
ty) TcM a
thing
  = SDoc -> TcM a -> TcM a
forall a. SDoc -> TcM a -> TcM a
addErrCtxt SDoc
doc TcM a
thing
  where
    doc :: SDoc
doc = String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"In the type" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> SDoc -> SDoc
quotes (HsType GhcRn -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsType GhcRn
ty)


{- *********************************************************************
*                                                                      *
                Type-variable binders
*                                                                      *
********************************************************************* -}

bindNamedWildCardBinders :: [Name]
                         -> ([(Name, TcTyVar)] -> TcM a)
                         -> TcM a
-- Bring into scope the /named/ wildcard binders.  Remember that
-- plain wildcards _ are anonymous and dealt with by HsWildCardTy
-- Soe Note [The wildcard story for types] in GHC.Hs.Type
bindNamedWildCardBinders :: forall a. HsQTvsRn -> ([(Name, TyVar)] -> TcM a) -> TcM a
bindNamedWildCardBinders HsQTvsRn
wc_names [(Name, TyVar)] -> TcM a
thing_inside
  = do { [TyVar]
wcs <- (Name -> IOEnv (Env TcGblEnv TcLclEnv) TyVar)
-> HsQTvsRn -> TcM [TyVar]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
forall (m :: * -> *) a b. Monad m => (a -> m b) -> [a] -> m [b]
mapM Name -> IOEnv (Env TcGblEnv TcLclEnv) TyVar
newNamedWildTyVar HsQTvsRn
wc_names
       ; let wc_prs :: [(Name, TyVar)]
wc_prs = HsQTvsRn
wc_names HsQTvsRn -> [TyVar] -> [(Name, TyVar)]
forall a b. [a] -> [b] -> [(a, b)]
`zip` [TyVar]
wcs
       ; [(Name, TyVar)] -> TcM a -> TcM a
forall r. [(Name, TyVar)] -> TcM r -> TcM r
tcExtendNameTyVarEnv [(Name, TyVar)]
wc_prs (TcM a -> TcM a) -> TcM a -> TcM a
forall a b. (a -> b) -> a -> b
$
         [(Name, TyVar)] -> TcM a
thing_inside [(Name, TyVar)]
wc_prs }

newNamedWildTyVar :: Name -> TcM TcTyVar
-- ^ New unification variable '_' for a wildcard
newNamedWildTyVar :: Name -> IOEnv (Env TcGblEnv TcLclEnv) TyVar
newNamedWildTyVar Name
_name   -- Currently ignoring the "_x" wildcard name used in the type
  = do { Type
kind <- TcM Type
newMetaKindVar
       ; TcTyVarDetails
details <- MetaInfo -> TcM TcTyVarDetails
newMetaDetails MetaInfo
TauTv
       ; Name
wc_name <- FastString -> TcM Name
newMetaTyVarName (String -> FastString
fsLit String
"w")   -- See Note [Wildcard names]
       ; let tyvar :: TyVar
tyvar = Name -> Type -> TcTyVarDetails -> TyVar
mkTcTyVar Name
wc_name Type
kind TcTyVarDetails
details
       ; String -> SDoc -> TcM ()
traceTc String
"newWildTyVar" (TyVar -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyVar
tyvar)
       ; TyVar -> IOEnv (Env TcGblEnv TcLclEnv) TyVar
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return TyVar
tyvar }

---------------------------
tcAnonWildCardOcc :: IsExtraConstraint
                  -> TcTyMode -> HsType GhcRn -> Kind -> TcM TcType
tcAnonWildCardOcc :: IsExtraConstraint -> TcTyMode -> HsType GhcRn -> Type -> TcM Type
tcAnonWildCardOcc IsExtraConstraint
is_extra (TcTyMode { mode_holes :: TcTyMode -> HoleInfo
mode_holes = Just (TcLevel
hole_lvl, HoleMode
hole_mode) })
                  HsType GhcRn
ty Type
exp_kind
    -- hole_lvl: see Note [Checking partial type signatures]
    --           esp the bullet on nested forall types
  = do { TcTyVarDetails
kv_details <- TcLevel -> TcM TcTyVarDetails
newTauTvDetailsAtLevel TcLevel
hole_lvl
       ; Name
kv_name    <- FastString -> TcM Name
newMetaTyVarName (String -> FastString
fsLit String
"k")
       ; TcTyVarDetails
wc_details <- TcLevel -> TcM TcTyVarDetails
newTauTvDetailsAtLevel TcLevel
hole_lvl
       ; Name
wc_name    <- FastString -> TcM Name
newMetaTyVarName (String -> FastString
fsLit String
wc_nm)
       ; let kv :: TyVar
kv      = Name -> Type -> TcTyVarDetails -> TyVar
mkTcTyVar Name
kv_name Type
liftedTypeKind TcTyVarDetails
kv_details
             wc_kind :: Type
wc_kind = TyVar -> Type
mkTyVarTy TyVar
kv
             wc_tv :: TyVar
wc_tv   = Name -> Type -> TcTyVarDetails -> TyVar
mkTcTyVar Name
wc_name Type
wc_kind TcTyVarDetails
wc_details

       ; String -> SDoc -> TcM ()
traceTc String
"tcAnonWildCardOcc" (TcLevel -> SDoc
forall a. Outputable a => a -> SDoc
ppr TcLevel
hole_lvl SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Bool -> SDoc
forall a. Outputable a => a -> SDoc
ppr Bool
emit_holes)
       ; Bool -> TcM () -> TcM ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
when Bool
emit_holes (TcM () -> TcM ()) -> TcM () -> TcM ()
forall a b. (a -> b) -> a -> b
$
         IsExtraConstraint -> TyVar -> TcM ()
emitAnonTypeHole IsExtraConstraint
is_extra TyVar
wc_tv
         -- Why the 'when' guard?
         -- See Note [Wildcards in visible kind application]

       -- You might think that this would always just unify
       -- wc_kind with exp_kind, so we could avoid even creating kv
       -- But the level numbers might not allow that unification,
       -- so we have to do it properly (T14140a)
       ; (() :: Constraint) =>
HsType GhcRn -> Type -> Type -> Type -> TcM Type
HsType GhcRn -> Type -> Type -> Type -> TcM Type
checkExpectedKind HsType GhcRn
ty (TyVar -> Type
mkTyVarTy TyVar
wc_tv) Type
wc_kind Type
exp_kind }
  where
     -- See Note [Wildcard names]
     wc_nm :: String
wc_nm = case HoleMode
hole_mode of
               HoleMode
HM_Sig      -> String
"w"
               HoleMode
HM_FamPat   -> String
"_"
               HoleMode
HM_VTA      -> String
"w"
               HoleMode
HM_TyAppPat -> String
"_"

     emit_holes :: Bool
emit_holes = case HoleMode
hole_mode of
                     HoleMode
HM_Sig     -> Bool
True
                     HoleMode
HM_FamPat  -> Bool
False
                     HoleMode
HM_VTA     -> Bool
False
                     HoleMode
HM_TyAppPat -> Bool
False

tcAnonWildCardOcc IsExtraConstraint
is_extra TcTyMode
_ HsType GhcRn
_ Type
_
-- mode_holes is Nothing. This means we have an anonymous wildcard
-- in an unexpected place. The renamer rejects these wildcards in 'checkAnonWildcard',
-- but it is possible for a wildcard to be introduced by a Template Haskell splice,
-- as per #15433. To account for this, we throw a generic catch-all error message.
  = TcRnMessage -> TcM Type
forall a. TcRnMessage -> TcM a
failWith (TcRnMessage -> TcM Type) -> TcRnMessage -> TcM Type
forall a b. (a -> b) -> a -> b
$ Maybe Name -> BadAnonWildcardContext -> TcRnMessage
TcRnIllegalWildcardInType Maybe Name
forall a. Maybe a
Nothing BadAnonWildcardContext
reason
    where
      reason :: BadAnonWildcardContext
reason =
        case IsExtraConstraint
is_extra of
          IsExtraConstraint
YesExtraConstraint ->
            SoleExtraConstraintWildcardAllowed -> BadAnonWildcardContext
ExtraConstraintWildcardNotAllowed
              SoleExtraConstraintWildcardAllowed
SoleExtraConstraintWildcardNotAllowed
          IsExtraConstraint
NoExtraConstraint  ->
            BadAnonWildcardContext
WildcardsNotAllowedAtAll

{- Note [Wildcard names]
~~~~~~~~~~~~~~~~~~~~~~~~
So we hackily use the mode_holes flag to control the name used
for wildcards:

* For proper holes (whether in a visible type application (VTA) or no),
  we rename the '_' to 'w'. This is so that we see variables like 'w0'
  or 'w1' in error messages, a vast improvement upon '_0' and '_1'. For
  example, we prefer
       Found type wildcard ‘_’ standing for ‘w0’
  over
       Found type wildcard ‘_’ standing for ‘_1’

  Even in the VTA case, where we do not emit an error to be printed, we
  want to do the renaming, as the variables may appear in other,
  non-wildcard error messages.

* However, holes in the left-hand sides of type families ("type
  patterns") stand for type variables which we do not care to name --
  much like the use of an underscore in an ordinary term-level
  pattern. When we spot these, we neither wish to generate an error
  message nor to rename the variable.  We don't rename the variable so
  that we can pretty-print a type family LHS as, e.g.,
    F _ Int _ = ...
  and not
     F w1 Int w2 = ...

  See also Note [Wildcards in family instances] in
  GHC.Rename.Module. The choice of HM_FamPat is made in
  tcFamTyPats. There is also some unsavory magic, relying on that
  underscore, in GHC.Core.Coercion.tidyCoAxBndrsForUser.

Note [Wildcards in visible kind application]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
There are cases where users might want to pass in a wildcard as a visible kind
argument, for instance:

data T :: forall k1 k2. k1 → k2 → Type where
  MkT :: T a b
x :: T @_ @Nat False n
x = MkT

So we should allow '@_' without emitting any hole constraints, and
regardless of whether PartialTypeSignatures is enabled or not. But how
would the typechecker know which '_' is being used in VKA and which is
not when it calls emitNamedTypeHole in
tcHsPartialSigType on all HsWildCardBndrs?  The solution is to neither
rename nor include unnamed wildcards in HsWildCardBndrs, but instead
give every anonymous wildcard a fresh wild tyvar in tcAnonWildCardOcc.

And whenever we see a '@', we set mode_holes to HM_VKA, so that
we do not call emitAnonTypeHole in tcAnonWildCardOcc.
See related Note [Wildcards in visible type application] here and
Note [The wildcard story for types] in GHC.Hs.Type
-}

{- *********************************************************************
*                                                                      *
             Kind inference for type declarations
*                                                                      *
********************************************************************* -}

-- See Note [kcCheckDeclHeader vs kcInferDeclHeader]
data InitialKindStrategy
  = InitialKindCheck SAKS_or_CUSK
  | InitialKindInfer

-- Does the declaration have a standalone kind signature (SAKS) or a complete
-- user-specified kind (CUSK)?
data SAKS_or_CUSK
  = SAKS Kind  -- Standalone kind signature, fully zonked! (zonkTcTypeToType)
  | CUSK       -- Complete user-specified kind (CUSK)

instance Outputable SAKS_or_CUSK where
  ppr :: SAKS_or_CUSK -> SDoc
ppr (SAKS Type
k) = String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"SAKS" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
k
  ppr SAKS_or_CUSK
CUSK = String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"CUSK"

-- See Note [kcCheckDeclHeader vs kcInferDeclHeader]
kcDeclHeader
  :: InitialKindStrategy
  -> Name              -- ^ of the thing being checked
  -> TyConFlavour      -- ^ What sort of 'TyCon' is being checked
  -> LHsQTyVars GhcRn  -- ^ Binders in the header
  -> TcM ContextKind   -- ^ The result kind
  -> TcM TcTyCon       -- ^ A suitably-kinded TcTyCon
kcDeclHeader :: InitialKindStrategy
-> Name
-> TyConFlavour
-> LHsQTyVars GhcRn
-> TcM ContextKind
-> TcM TyCon
kcDeclHeader (InitialKindCheck SAKS_or_CUSK
msig) = SAKS_or_CUSK
-> Name
-> TyConFlavour
-> LHsQTyVars GhcRn
-> TcM ContextKind
-> TcM TyCon
kcCheckDeclHeader SAKS_or_CUSK
msig
kcDeclHeader InitialKindStrategy
InitialKindInfer = Name
-> TyConFlavour -> LHsQTyVars GhcRn -> TcM ContextKind -> TcM TyCon
kcInferDeclHeader

{- Note [kcCheckDeclHeader vs kcInferDeclHeader]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kcCheckDeclHeader and kcInferDeclHeader are responsible for getting the initial kind
of a type constructor.

* kcCheckDeclHeader: the TyCon has a standalone kind signature or a CUSK. In that
  case, find the full, final, poly-kinded kind of the TyCon.  It's very like a
  term-level binding where we have a complete type signature for the function.

* kcInferDeclHeader: the TyCon has neither a standalone kind signature nor a
  CUSK. Find a monomorphic kind, with unification variables in it; they will be
  generalised later.  It's very like a term-level binding where we do not have a
  type signature (or, more accurately, where we have a partial type signature),
  so we infer the type and generalise.
-}

------------------------------
kcCheckDeclHeader
  :: SAKS_or_CUSK
  -> Name              -- ^ of the thing being checked
  -> TyConFlavour      -- ^ What sort of 'TyCon' is being checked
  -> LHsQTyVars GhcRn  -- ^ Binders in the header
  -> TcM ContextKind   -- ^ The result kind. AnyKind == no result signature
  -> TcM PolyTcTyCon   -- ^ A suitably-kinded generalized TcTyCon
kcCheckDeclHeader :: SAKS_or_CUSK
-> Name
-> TyConFlavour
-> LHsQTyVars GhcRn
-> TcM ContextKind
-> TcM TyCon
kcCheckDeclHeader (SAKS Type
sig) = Type
-> Name
-> TyConFlavour
-> LHsQTyVars GhcRn
-> TcM ContextKind
-> TcM TyCon
kcCheckDeclHeader_sig Type
sig
kcCheckDeclHeader SAKS_or_CUSK
CUSK       = Name
-> TyConFlavour -> LHsQTyVars GhcRn -> TcM ContextKind -> TcM TyCon
kcCheckDeclHeader_cusk

kcCheckDeclHeader_cusk
  :: Name              -- ^ of the thing being checked
  -> TyConFlavour      -- ^ What sort of 'TyCon' is being checked
  -> LHsQTyVars GhcRn  -- ^ Binders in the header
  -> TcM ContextKind   -- ^ The result kind
  -> TcM PolyTcTyCon   -- ^ A suitably-kinded generalized TcTyCon
kcCheckDeclHeader_cusk :: Name
-> TyConFlavour -> LHsQTyVars GhcRn -> TcM ContextKind -> TcM TyCon
kcCheckDeclHeader_cusk Name
name TyConFlavour
flav
              (HsQTvs { hsq_ext :: forall pass. LHsQTyVars pass -> XHsQTvs pass
hsq_ext = XHsQTvs GhcRn
kv_ns
                      , hsq_explicit :: forall pass. LHsQTyVars pass -> [LHsTyVarBndr () pass]
hsq_explicit = [LHsTyVarBndr () GhcRn]
hs_tvs }) TcM ContextKind
kc_res_ki
  -- CUSK case
  -- See Note [Required, Specified, and Inferred for types] in GHC.Tc.TyCl
  = Name -> TyConFlavour -> TcM TyCon -> TcM TyCon
forall a. Name -> TyConFlavour -> TcM a -> TcM a
addTyConFlavCtxt Name
name TyConFlavour
flav (TcM TyCon -> TcM TyCon) -> TcM TyCon -> TcM TyCon
forall a b. (a -> b) -> a -> b
$
    do { SkolemInfo
skol_info <- SkolemInfoAnon -> IOEnv (Env TcGblEnv TcLclEnv) SkolemInfo
forall (m :: * -> *). MonadIO m => SkolemInfoAnon -> m SkolemInfo
mkSkolemInfo SkolemInfoAnon
skol_info_anon
       ; (TcLevel
tclvl, WantedConstraints
wanted, ([TyVar]
scoped_kvs, ([TyVar]
tc_tvs, Type
res_kind)))
           <- String
-> TcM ([TyVar], ([TyVar], Type))
-> TcM (TcLevel, WantedConstraints, ([TyVar], ([TyVar], Type)))
forall a. String -> TcM a -> TcM (TcLevel, WantedConstraints, a)
pushLevelAndSolveEqualitiesX String
"kcCheckDeclHeader_cusk" (TcM ([TyVar], ([TyVar], Type))
 -> TcM (TcLevel, WantedConstraints, ([TyVar], ([TyVar], Type))))
-> TcM ([TyVar], ([TyVar], Type))
-> TcM (TcLevel, WantedConstraints, ([TyVar], ([TyVar], Type)))
forall a b. (a -> b) -> a -> b
$
              SkolemInfo
-> HsQTvsRn
-> TcM ([TyVar], Type)
-> TcM ([TyVar], ([TyVar], Type))
forall a. SkolemInfo -> HsQTvsRn -> TcM a -> TcM ([TyVar], a)
bindImplicitTKBndrs_Q_Skol SkolemInfo
skol_info HsQTvsRn
XHsQTvs GhcRn
kv_ns                      (TcM ([TyVar], Type) -> TcM ([TyVar], ([TyVar], Type)))
-> TcM ([TyVar], Type) -> TcM ([TyVar], ([TyVar], Type))
forall a b. (a -> b) -> a -> b
$
              SkolemInfo
-> ContextKind
-> [LHsTyVarBndr () GhcRn]
-> TcM Type
-> TcM ([TyVar], Type)
forall a.
SkolemInfo
-> ContextKind
-> [LHsTyVarBndr () GhcRn]
-> TcM a
-> TcM ([TyVar], a)
bindExplicitTKBndrs_Q_Skol SkolemInfo
skol_info ContextKind
ctxt_kind [LHsTyVarBndr () GhcRn]
hs_tvs           (TcM Type -> TcM ([TyVar], Type))
-> TcM Type -> TcM ([TyVar], Type)
forall a b. (a -> b) -> a -> b
$
              ContextKind -> TcM Type
newExpectedKind (ContextKind -> TcM Type) -> TcM ContextKind -> TcM Type
forall (m :: * -> *) a b. Monad m => (a -> m b) -> m a -> m b
=<< TcM ContextKind
kc_res_ki

           -- Now, because we're in a CUSK,
           -- we quantify over the mentioned kind vars
       ; let spec_req_tkvs :: [TyVar]
spec_req_tkvs = [TyVar]
scoped_kvs [TyVar] -> [TyVar] -> [TyVar]
forall a. [a] -> [a] -> [a]
++ [TyVar]
tc_tvs
             all_kinds :: [Type]
all_kinds     = Type
res_kind Type -> [Type] -> [Type]
forall a. a -> [a] -> [a]
: (TyVar -> Type) -> [TyVar] -> [Type]
forall a b. (a -> b) -> [a] -> [b]
map TyVar -> Type
tyVarKind [TyVar]
spec_req_tkvs

       ; CandidatesQTvs
candidates <- [Type] -> TcM CandidatesQTvs
candidateQTyVarsOfKinds [Type]
all_kinds
             -- 'candidates' are all the variables that we are going to
             -- skolemise and then quantify over.  We do not include spec_req_tvs
             -- because they are /already/ skolems

       ; [TyVar]
inferred <- SkolemInfo
-> NonStandardDefaultingStrategy -> CandidatesQTvs -> TcM [TyVar]
quantifyTyVars SkolemInfo
skol_info NonStandardDefaultingStrategy
DefaultNonStandardTyVars (CandidatesQTvs -> TcM [TyVar]) -> CandidatesQTvs -> TcM [TyVar]
forall a b. (a -> b) -> a -> b
$
                     CandidatesQTvs
candidates CandidatesQTvs -> [TyVar] -> CandidatesQTvs
`delCandidates` [TyVar]
spec_req_tkvs
                     -- NB: 'inferred' comes back sorted in dependency order

       ; [TyVar]
scoped_kvs <- (TyVar -> IOEnv (Env TcGblEnv TcLclEnv) TyVar)
-> [TyVar] -> TcM [TyVar]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
forall (m :: * -> *) a b. Monad m => (a -> m b) -> [a] -> m [b]
mapM TyVar -> IOEnv (Env TcGblEnv TcLclEnv) TyVar
zonkTyCoVarKind [TyVar]
scoped_kvs  -- scoped_kvs and tc_tvs are skolems,
       ; [TyVar]
tc_tvs     <- (TyVar -> IOEnv (Env TcGblEnv TcLclEnv) TyVar)
-> [TyVar] -> TcM [TyVar]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
forall (m :: * -> *) a b. Monad m => (a -> m b) -> [a] -> m [b]
mapM TyVar -> IOEnv (Env TcGblEnv TcLclEnv) TyVar
zonkTyCoVarKind [TyVar]
tc_tvs      -- so zonkTyCoVarKind suffices
       ; Type
res_kind   <- Type -> TcM Type
zonkTcType           Type
res_kind

       ; let mentioned_kv_set :: TyVarSet
mentioned_kv_set = CandidatesQTvs -> TyVarSet
candidateKindVars CandidatesQTvs
candidates
             specified :: [TyVar]
specified        = [TyVar] -> [TyVar]
scopedSort [TyVar]
scoped_kvs
                                -- NB: maintain the L-R order of scoped_kvs

             all_tcbs :: [TyConBinder]
all_tcbs =  ForAllTyFlag -> [TyVar] -> [TyConBinder]
mkNamedTyConBinders ForAllTyFlag
Inferred  [TyVar]
inferred
                      [TyConBinder] -> [TyConBinder] -> [TyConBinder]
forall a. [a] -> [a] -> [a]
++ ForAllTyFlag -> [TyVar] -> [TyConBinder]
mkNamedTyConBinders ForAllTyFlag
Specified [TyVar]
specified
                      [TyConBinder] -> [TyConBinder] -> [TyConBinder]
forall a. [a] -> [a] -> [a]
++ (TyVar -> TyConBinder) -> [TyVar] -> [TyConBinder]
forall a b. (a -> b) -> [a] -> [b]
map (TyVarSet -> TyVar -> TyConBinder
mkRequiredTyConBinder TyVarSet
mentioned_kv_set) [TyVar]
tc_tvs

       -- Eta expand if necessary; we are building a PolyTyCon
       ; ([TyConBinder]
eta_tcbs, Type
res_kind) <- TyConFlavour
-> SkolemInfo -> [TyConBinder] -> Type -> TcM ([TyConBinder], Type)
etaExpandAlgTyCon TyConFlavour
flav SkolemInfo
skol_info [TyConBinder]
all_tcbs Type
res_kind

       ; let all_tv_prs :: [(Name, TyVar)]
all_tv_prs = [TyVar] -> [(Name, TyVar)]
mkTyVarNamePairs ([TyVar]
scoped_kvs [TyVar] -> [TyVar] -> [TyVar]
forall a. [a] -> [a] -> [a]
++ [TyVar]
tc_tvs)
             final_tcbs :: [TyConBinder]
final_tcbs = [TyConBinder]
all_tcbs [TyConBinder] -> [TyConBinder] -> [TyConBinder]
forall a. [a] -> [a] -> [a]
`chkAppend` [TyConBinder]
eta_tcbs
             tycon :: TyCon
tycon = Name
-> [TyConBinder]
-> Type
-> [(Name, TyVar)]
-> Bool
-> TyConFlavour
-> TyCon
mkTcTyCon Name
name [TyConBinder]
final_tcbs Type
res_kind [(Name, TyVar)]
all_tv_prs
                               Bool
True -- it is generalised
                               TyConFlavour
flav

       ; SkolemInfo -> [TyVar] -> TcLevel -> WantedConstraints -> TcM ()
reportUnsolvedEqualities SkolemInfo
skol_info ([TyConBinder] -> [TyVar]
forall tv argf. [VarBndr tv argf] -> [tv]
binderVars [TyConBinder]
final_tcbs)
                                  TcLevel
tclvl WantedConstraints
wanted

         -- If the ordering from
         -- Note [Required, Specified, and Inferred for types] in GHC.Tc.TyCl
         -- doesn't work, we catch it here, before an error cascade
       ; TyCon -> TcM ()
checkTyConTelescope TyCon
tycon

       ; String -> SDoc -> TcM ()
traceTc String
"kcCheckDeclHeader_cusk " (SDoc -> TcM ()) -> SDoc -> TcM ()
forall a b. (a -> b) -> a -> b
$
         [SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat [ String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"name" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
name
              , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"candidates" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> CandidatesQTvs -> SDoc
forall a. Outputable a => a -> SDoc
ppr CandidatesQTvs
candidates
              , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"mentioned_kv_set" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> TyVarSet -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyVarSet
mentioned_kv_set
              , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"kv_ns" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> HsQTvsRn -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsQTvsRn
XHsQTvs GhcRn
kv_ns
              , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"hs_tvs" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [GenLocated SrcSpanAnnA (HsTyVarBndr () GhcRn)] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [LHsTyVarBndr () GhcRn]
[GenLocated SrcSpanAnnA (HsTyVarBndr () GhcRn)]
hs_tvs
              , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"scoped_kvs" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [TyVar] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TyVar]
scoped_kvs
              , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"spec_req_tvs" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [TyVar] -> SDoc
pprTyVars [TyVar]
spec_req_tkvs
              , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"all_kinds" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [Type] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Type]
all_kinds
              , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"tc_tvs" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [TyVar] -> SDoc
pprTyVars [TyVar]
tc_tvs
              , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"res_kind" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
res_kind
              , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"inferred" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [TyVar] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TyVar]
inferred
              , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"specified" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [TyVar] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TyVar]
specified
              , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"final_tcbs" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [TyConBinder] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TyConBinder]
final_tcbs
              , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"mkTyConKind final_tc_bndrs res_kind"
                SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr ([TyConBinder] -> Type -> Type
mkTyConKind [TyConBinder]
final_tcbs Type
res_kind)
              , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"all_tv_prs" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [(Name, TyVar)] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [(Name, TyVar)]
all_tv_prs ]

       ; TyCon -> TcM TyCon
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return TyCon
tycon }
  where
    skol_info_anon :: SkolemInfoAnon
skol_info_anon = TyConFlavour -> Name -> SkolemInfoAnon
TyConSkol TyConFlavour
flav Name
name
    ctxt_kind :: ContextKind
ctxt_kind | TyConFlavour -> Bool
tcFlavourIsOpen TyConFlavour
flav = Type -> ContextKind
TheKind Type
liftedTypeKind
              | Bool
otherwise            = ContextKind
AnyKind

-- | Kind-check a 'LHsQTyVars'. Used in 'inferInitialKind' (for tycon kinds and
-- other kinds).
--
-- This function does not do telescope checking.
kcInferDeclHeader
  :: Name              -- ^ of the thing being checked
  -> TyConFlavour      -- ^ What sort of 'TyCon' is being checked
  -> LHsQTyVars GhcRn
  -> TcM ContextKind   -- ^ The result kind
  -> TcM MonoTcTyCon   -- ^ A suitably-kinded non-generalized TcTyCon
kcInferDeclHeader :: Name
-> TyConFlavour -> LHsQTyVars GhcRn -> TcM ContextKind -> TcM TyCon
kcInferDeclHeader Name
name TyConFlavour
flav
              (HsQTvs { hsq_ext :: forall pass. LHsQTyVars pass -> XHsQTvs pass
hsq_ext = XHsQTvs GhcRn
kv_ns
                      , hsq_explicit :: forall pass. LHsQTyVars pass -> [LHsTyVarBndr () pass]
hsq_explicit = [LHsTyVarBndr () GhcRn]
hs_tvs }) TcM ContextKind
kc_res_ki
  -- No standalone kind signature and no CUSK.
  -- See Note [Required, Specified, and Inferred for types] in GHC.Tc.TyCl
  = Name -> TyConFlavour -> TcM TyCon -> TcM TyCon
forall a. Name -> TyConFlavour -> TcM a -> TcM a
addTyConFlavCtxt Name
name TyConFlavour
flav (TcM TyCon -> TcM TyCon) -> TcM TyCon -> TcM TyCon
forall a b. (a -> b) -> a -> b
$
    do { ([TyVar]
scoped_kvs, ([TyVar]
tc_tvs, Type
res_kind))
           -- Why bindImplicitTKBndrs_Q_Tv which uses newTyVarTyVar?
           -- See Note [Inferring kinds for type declarations] in GHC.Tc.TyCl
           <- HsQTvsRn -> TcM ([TyVar], Type) -> TcM ([TyVar], ([TyVar], Type))
forall a. HsQTvsRn -> TcM a -> TcM ([TyVar], a)
bindImplicitTKBndrs_Q_Tv HsQTvsRn
XHsQTvs GhcRn
kv_ns            (TcM ([TyVar], Type) -> TcM ([TyVar], ([TyVar], Type)))
-> TcM ([TyVar], Type) -> TcM ([TyVar], ([TyVar], Type))
forall a b. (a -> b) -> a -> b
$
              ContextKind
-> [LHsTyVarBndr () GhcRn] -> TcM Type -> TcM ([TyVar], Type)
forall a.
ContextKind -> [LHsTyVarBndr () GhcRn] -> TcM a -> TcM ([TyVar], a)
bindExplicitTKBndrs_Q_Tv ContextKind
ctxt_kind [LHsTyVarBndr () GhcRn]
hs_tvs (TcM Type -> TcM ([TyVar], Type))
-> TcM Type -> TcM ([TyVar], Type)
forall a b. (a -> b) -> a -> b
$
              ContextKind -> TcM Type
newExpectedKind (ContextKind -> TcM Type) -> TcM ContextKind -> TcM Type
forall (m :: * -> *) a b. Monad m => (a -> m b) -> m a -> m b
=<< TcM ContextKind
kc_res_ki
              -- Why "_Tv" not "_Skol"? See third wrinkle in
              -- Note [Inferring kinds for type declarations] in GHC.Tc.TyCl,

       ; let   -- NB: Don't add scoped_kvs to tyConTyVars, because they
               -- might unify with kind vars in other types in a mutually
               -- recursive group.
               -- See Note [Inferring kinds for type declarations] in GHC.Tc.TyCl

             tc_binders :: [TyConBinder]
tc_binders = [TyVar] -> [TyConBinder]
mkAnonTyConBinders [TyVar]
tc_tvs
               -- Also, note that tc_binders has the tyvars from only the
               -- user-written tyvarbinders. See S1 in Note [How TcTyCons work]
               -- in GHC.Tc.TyCl
               --
               -- mkAnonTyConBinder: see Note [No polymorphic recursion]

             all_tv_prs :: [(Name, TyVar)]
all_tv_prs = [TyVar] -> [(Name, TyVar)]
mkTyVarNamePairs ([TyVar]
scoped_kvs [TyVar] -> [TyVar] -> [TyVar]
forall a. [a] -> [a] -> [a]
++ [TyVar]
tc_tvs)
               -- NB: bindExplicitTKBndrs_Q_Tv does not clone;
               --     ditto Implicit
               -- See Note [Cloning for type variable binders]

             tycon :: TyCon
tycon = Name
-> [TyConBinder]
-> Type
-> [(Name, TyVar)]
-> Bool
-> TyConFlavour
-> TyCon
mkTcTyCon Name
name [TyConBinder]
tc_binders Type
res_kind [(Name, TyVar)]
all_tv_prs
                               Bool
False -- not yet generalised
                               TyConFlavour
flav

       ; String -> SDoc -> TcM ()
traceTc String
"kcInferDeclHeader: not-cusk" (SDoc -> TcM ()) -> SDoc -> TcM ()
forall a b. (a -> b) -> a -> b
$
         [SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat [ Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
name, HsQTvsRn -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsQTvsRn
XHsQTvs GhcRn
kv_ns, [GenLocated SrcSpanAnnA (HsTyVarBndr () GhcRn)] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [LHsTyVarBndr () GhcRn]
[GenLocated SrcSpanAnnA (HsTyVarBndr () GhcRn)]
hs_tvs
              , [TyVar] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TyVar]
scoped_kvs
              , [TyVar] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TyVar]
tc_tvs, Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr ([TyConBinder] -> Type -> Type
mkTyConKind [TyConBinder]
tc_binders Type
res_kind) ]
       ; TyCon -> TcM TyCon
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return TyCon
tycon }
  where
    ctxt_kind :: ContextKind
ctxt_kind | TyConFlavour -> Bool
tcFlavourIsOpen TyConFlavour
flav = Type -> ContextKind
TheKind Type
liftedTypeKind
              | Bool
otherwise            = ContextKind
AnyKind

-- | Kind-check a declaration header against a standalone kind signature.
-- See Note [kcCheckDeclHeader_sig]
kcCheckDeclHeader_sig
  :: Kind              -- ^ Standalone kind signature, fully zonked! (zonkTcTypeToType)
  -> Name              -- ^ of the thing being checked
  -> TyConFlavour      -- ^ What sort of 'TyCon' is being checked
  -> LHsQTyVars GhcRn  -- ^ Binders in the header
  -> TcM ContextKind   -- ^ The result kind. AnyKind == no result signature
  -> TcM PolyTcTyCon   -- ^ A suitably-kinded, fully generalised TcTyCon
-- Postcondition to (kcCheckDeclHeader_sig sig_kind n f hs_tvs kc_res_ki):
--   kind(returned PolyTcTyCon) = sig_kind
--
kcCheckDeclHeader_sig :: Type
-> Name
-> TyConFlavour
-> LHsQTyVars GhcRn
-> TcM ContextKind
-> TcM TyCon
kcCheckDeclHeader_sig Type
sig_kind Name
name TyConFlavour
flav
          (HsQTvs { hsq_ext :: forall pass. LHsQTyVars pass -> XHsQTvs pass
hsq_ext      = XHsQTvs GhcRn
implicit_nms
                  , hsq_explicit :: forall pass. LHsQTyVars pass -> [LHsTyVarBndr () pass]
hsq_explicit = [LHsTyVarBndr () GhcRn]
hs_tv_bndrs }) TcM ContextKind
kc_res_ki
  = Name -> TyConFlavour -> TcM TyCon -> TcM TyCon
forall a. Name -> TyConFlavour -> TcM a -> TcM a
addTyConFlavCtxt Name
name TyConFlavour
flav (TcM TyCon -> TcM TyCon) -> TcM TyCon -> TcM TyCon
forall a b. (a -> b) -> a -> b
$
    do { SkolemInfo
skol_info <- SkolemInfoAnon -> IOEnv (Env TcGblEnv TcLclEnv) SkolemInfo
forall (m :: * -> *). MonadIO m => SkolemInfoAnon -> m SkolemInfo
mkSkolemInfo (TyConFlavour -> Name -> SkolemInfoAnon
TyConSkol TyConFlavour
flav Name
name)
       ; ([TyConBinder]
sig_tcbs :: [TcTyConBinder], Type
sig_res_kind :: Kind)
             <- SkolemInfo
-> InScopeSet -> [OccName] -> Type -> TcM ([TyConBinder], Type)
splitTyConKind SkolemInfo
skol_info InScopeSet
emptyInScopeSet
                               ((GenLocated SrcSpanAnnA (HsTyVarBndr () GhcRn) -> OccName)
-> [GenLocated SrcSpanAnnA (HsTyVarBndr () GhcRn)] -> [OccName]
forall a b. (a -> b) -> [a] -> [b]
map GenLocated SrcSpanAnnA (HsTyVarBndr () GhcRn) -> OccName
forall a. NamedThing a => a -> OccName
getOccName [LHsTyVarBndr () GhcRn]
[GenLocated SrcSpanAnnA (HsTyVarBndr () GhcRn)]
hs_tv_bndrs) Type
sig_kind

       ; String -> SDoc -> TcM ()
traceTc String
"kcCheckDeclHeader_sig {" (SDoc -> TcM ()) -> SDoc -> TcM ()
forall a b. (a -> b) -> a -> b
$
           [SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat [ String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"sig_kind:" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
sig_kind
                , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"sig_tcbs:" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [TyConBinder] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TyConBinder]
sig_tcbs
                , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"sig_res_kind:" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
sig_res_kind ]

       ; (TcLevel
tclvl, WantedConstraints
wanted, ([TyVar]
implicit_tvs, ([TyConBinder]
skol_tcbs, ([TyConBinder]
extra_tcbs, Type
tycon_res_kind))))
           <- String
-> TcM ([TyVar], ([TyConBinder], ([TyConBinder], Type)))
-> TcM
     (TcLevel, WantedConstraints,
      ([TyVar], ([TyConBinder], ([TyConBinder], Type))))
forall a. String -> TcM a -> TcM (TcLevel, WantedConstraints, a)
pushLevelAndSolveEqualitiesX String
"kcCheckDeclHeader_sig" (TcM ([TyVar], ([TyConBinder], ([TyConBinder], Type)))
 -> TcM
      (TcLevel, WantedConstraints,
       ([TyVar], ([TyConBinder], ([TyConBinder], Type)))))
-> TcM ([TyVar], ([TyConBinder], ([TyConBinder], Type)))
-> TcM
     (TcLevel, WantedConstraints,
      ([TyVar], ([TyConBinder], ([TyConBinder], Type))))
forall a b. (a -> b) -> a -> b
$  -- #16687
              HsQTvsRn
-> TcM ([TyConBinder], ([TyConBinder], Type))
-> TcM ([TyVar], ([TyConBinder], ([TyConBinder], Type)))
forall a. HsQTvsRn -> TcM a -> TcM ([TyVar], a)
bindImplicitTKBndrs_Q_Tv HsQTvsRn
XHsQTvs GhcRn
implicit_nms                (TcM ([TyConBinder], ([TyConBinder], Type))
 -> TcM ([TyVar], ([TyConBinder], ([TyConBinder], Type))))
-> TcM ([TyConBinder], ([TyConBinder], Type))
-> TcM ([TyVar], ([TyConBinder], ([TyConBinder], Type)))
forall a b. (a -> b) -> a -> b
$  -- Q means don't clone
              [TyConBinder]
-> Type
-> [LHsTyVarBndr () GhcRn]
-> ([TyConBinder] -> Type -> TcM ([TyConBinder], Type))
-> TcM ([TyConBinder], ([TyConBinder], Type))
forall a.
[TyConBinder]
-> Type
-> [LHsTyVarBndr () GhcRn]
-> ([TyConBinder] -> Type -> TcM a)
-> TcM ([TyConBinder], a)
matchUpSigWithDecl [TyConBinder]
sig_tcbs Type
sig_res_kind [LHsTyVarBndr () GhcRn]
hs_tv_bndrs (([TyConBinder] -> Type -> TcM ([TyConBinder], Type))
 -> TcM ([TyConBinder], ([TyConBinder], Type)))
-> ([TyConBinder] -> Type -> TcM ([TyConBinder], Type))
-> TcM ([TyConBinder], ([TyConBinder], Type))
forall a b. (a -> b) -> a -> b
$ \ [TyConBinder]
excess_sig_tcbs Type
sig_res_kind ->
              do { -- Kind-check the result kind annotation, if present:
                   --    data T a b :: res_ki where ...
                   --               ^^^^^^^^^
                   -- We do it here because at this point the environment has been
                   -- extended with both 'implicit_tcv_prs' and 'explicit_tv_prs'.
                 ; ContextKind
ctx_k <- TcM ContextKind
kc_res_ki

                 -- Work out extra_arity, the number of extra invisible binders from
                 -- the kind signature that should be part of the TyCon's arity.
                 -- See Note [Arity inference in kcCheckDeclHeader_sig]
                 ; let n_invis_tcbs :: Arity
n_invis_tcbs = (TyConBinder -> Bool) -> [TyConBinder] -> Arity
forall a. (a -> Bool) -> [a] -> Arity
countWhile TyConBinder -> Bool
forall tv. VarBndr tv TyConBndrVis -> Bool
isInvisibleTyConBinder [TyConBinder]
excess_sig_tcbs
                       invis_arity :: Arity
invis_arity = case ContextKind
ctx_k of
                          ContextKind
AnyKind    -> Arity
n_invis_tcbs -- No kind signature, so make all the invisible binders
                                                     -- the signature into part of the arity of the TyCon
                          ContextKind
OpenKind   -> Arity
n_invis_tcbs -- Result kind is (TYPE rr), so again make all the
                                                     -- invisible binders part of the arity of the TyCon
                          TheKind Type
ki -> Arity
0 Arity -> Arity -> Arity
forall a. Ord a => a -> a -> a
`max` (Arity
n_invis_tcbs Arity -> Arity -> Arity
forall a. Num a => a -> a -> a
- Type -> Arity
invisibleTyBndrCount Type
ki)

                 ; let ([TyConBinder]
invis_tcbs, [TyConBinder]
resid_tcbs) = Arity -> [TyConBinder] -> ([TyConBinder], [TyConBinder])
forall a. Arity -> [a] -> ([a], [a])
splitAt Arity
invis_arity [TyConBinder]
excess_sig_tcbs
                 ; let sig_res_kind' :: Type
sig_res_kind' = [TyConBinder] -> Type -> Type
mkTyConKind [TyConBinder]
resid_tcbs Type
sig_res_kind

                 ; String -> SDoc -> TcM ()
traceTc String
"kcCheckDeclHeader_sig 2" (SDoc -> TcM ()) -> SDoc -> TcM ()
forall a b. (a -> b) -> a -> b
$ [SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat [ [TyConBinder] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TyConBinder]
excess_sig_tcbs
                                                            , Arity -> SDoc
forall a. Outputable a => a -> SDoc
ppr Arity
invis_arity, [TyConBinder] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TyConBinder]
invis_tcbs
                                                            , Arity -> SDoc
forall a. Outputable a => a -> SDoc
ppr Arity
n_invis_tcbs ]

                 -- Unify res_ki (from the type declaration) with the residual kind from
                 -- the kind signature. Don't forget to apply the skolemising 'subst' first.
                 ; case ContextKind
ctx_k of
                      ContextKind
AnyKind -> () -> TcM ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ()   -- No signature
                      ContextKind
_ -> do { Type
res_ki <- ContextKind -> TcM Type
newExpectedKind ContextKind
ctx_k
                              ; TcM Coercion -> TcM ()
forall a. TcM a -> TcM ()
discardResult (Maybe TypedThing -> Type -> Type -> TcM Coercion
unifyKind Maybe TypedThing
forall a. Maybe a
Nothing Type
sig_res_kind' Type
res_ki) }

                 -- Add more binders for data/newtype, so the result kind has no arrows
                 -- See Note [Datatype return kinds]
                 ; if [TyConBinder] -> Bool
forall a. [a] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [TyConBinder]
resid_tcbs Bool -> Bool -> Bool
|| Bool -> Bool
not (TyConFlavour -> Bool
needsEtaExpansion TyConFlavour
flav)
                   then ([TyConBinder], Type) -> TcM ([TyConBinder], Type)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ([TyConBinder]
invis_tcbs,      Type
sig_res_kind')
                   else ([TyConBinder], Type) -> TcM ([TyConBinder], Type)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ([TyConBinder]
excess_sig_tcbs, Type
sig_res_kind)
          }


        -- Check that there are no unsolved equalities
        ; let all_tcbs :: [TyConBinder]
all_tcbs = [TyConBinder]
skol_tcbs [TyConBinder] -> [TyConBinder] -> [TyConBinder]
forall a. [a] -> [a] -> [a]
++ [TyConBinder]
extra_tcbs
        ; SkolemInfo -> [TyVar] -> TcLevel -> WantedConstraints -> TcM ()
reportUnsolvedEqualities SkolemInfo
skol_info ([TyConBinder] -> [TyVar]
forall tv argf. [VarBndr tv argf] -> [tv]
binderVars [TyConBinder]
all_tcbs) TcLevel
tclvl WantedConstraints
wanted

        -- Check that distinct binders map to distinct tyvars (see #20916). For example
        --    type T :: k -> k -> Type
        --    data T (a::p) (b::q) = ...
        -- Here p and q both map to the same kind variable k.  We don't allow this
        -- so we must check that they are distinct.  A similar thing happens
        -- in GHC.Tc.TyCl.swizzleTcTyConBinders during inference.
        ; [TyVar]
implicit_tvs <- [TyVar] -> TcM [TyVar]
(() :: Constraint) => [TyVar] -> TcM [TyVar]
zonkTcTyVarsToTcTyVars [TyVar]
implicit_tvs
        ; let implicit_prs :: [(Name, TyVar)]
implicit_prs = HsQTvsRn
XHsQTvs GhcRn
implicit_nms HsQTvsRn -> [TyVar] -> [(Name, TyVar)]
forall a b. [a] -> [b] -> [(a, b)]
`zip` [TyVar]
implicit_tvs
        ; [(Name, TyVar)] -> TcM ()
checkForDuplicateScopedTyVars [(Name, TyVar)]
implicit_prs

        -- Swizzle the Names so that the TyCon uses the user-declared implicit names
        -- E.g  type T :: k -> Type
        --      data T (a :: j) = ....
        -- We want the TyConBinders of T to be [j, a::j], not [k, a::k]
        -- Why? So that the TyConBinders of the TyCon will lexically scope over the
        -- associated types and methods of a class.
        ; let swizzle_env :: VarEnv Name
swizzle_env = [(TyVar, Name)] -> VarEnv Name
forall a. [(TyVar, a)] -> VarEnv a
mkVarEnv (((Name, TyVar) -> (TyVar, Name))
-> [(Name, TyVar)] -> [(TyVar, Name)]
forall a b. (a -> b) -> [a] -> [b]
map (Name, TyVar) -> (TyVar, Name)
forall a b. (a, b) -> (b, a)
swap [(Name, TyVar)]
implicit_prs)
              (Subst
subst, [TyConBinder]
swizzled_tcbs) = (Subst -> TyConBinder -> (Subst, TyConBinder))
-> Subst -> [TyConBinder] -> (Subst, [TyConBinder])
forall (t :: * -> *) s a b.
Traversable t =>
(s -> a -> (s, b)) -> s -> t a -> (s, t b)
mapAccumL (VarEnv Name -> Subst -> TyConBinder -> (Subst, TyConBinder)
swizzleTcb VarEnv Name
swizzle_env) Subst
emptySubst [TyConBinder]
all_tcbs
              swizzled_kind :: Type
swizzled_kind          = (() :: Constraint) => Subst -> Type -> Type
Subst -> Type -> Type
substTy Subst
subst Type
tycon_res_kind
              all_tv_prs :: [(Name, TyVar)]
all_tv_prs             = [TyVar] -> [(Name, TyVar)]
mkTyVarNamePairs ([TyConBinder] -> [TyVar]
forall tv argf. [VarBndr tv argf] -> [tv]
binderVars [TyConBinder]
swizzled_tcbs)

        ; String -> SDoc -> TcM ()
traceTc String
"kcCheckDeclHeader swizzle" (SDoc -> TcM ()) -> SDoc -> TcM ()
forall a b. (a -> b) -> a -> b
$ [SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat
          [ String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"implicit_prs = "  SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [(Name, TyVar)] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [(Name, TyVar)]
implicit_prs
          , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"implicit_nms = "  SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> HsQTvsRn -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsQTvsRn
XHsQTvs GhcRn
implicit_nms
          , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"hs_tv_bndrs = "  SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [GenLocated SrcSpanAnnA (HsTyVarBndr () GhcRn)] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [LHsTyVarBndr () GhcRn]
[GenLocated SrcSpanAnnA (HsTyVarBndr () GhcRn)]
hs_tv_bndrs
          , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"all_tcbs = "      SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [TyVar] -> SDoc
pprTyVars ([TyConBinder] -> [TyVar]
forall tv argf. [VarBndr tv argf] -> [tv]
binderVars [TyConBinder]
all_tcbs)
          , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"swizzled_tcbs = " SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [TyVar] -> SDoc
pprTyVars ([TyConBinder] -> [TyVar]
forall tv argf. [VarBndr tv argf] -> [tv]
binderVars [TyConBinder]
swizzled_tcbs)
          , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"tycon_res_kind =" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
tycon_res_kind
          , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"swizzled_kind ="  SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
swizzled_kind ]

        -- Build the final, generalized PolyTcTyCon
        -- NB: all_tcbs must bind the tyvars in the range of all_tv_prs
        --     because the tv_prs is used when (say) typechecking the RHS of
        --     a type synonym.
        ; let tc :: TyCon
tc = Name
-> [TyConBinder]
-> Type
-> [(Name, TyVar)]
-> Bool
-> TyConFlavour
-> TyCon
mkTcTyCon Name
name [TyConBinder]
swizzled_tcbs Type
swizzled_kind [(Name, TyVar)]
all_tv_prs Bool
True TyConFlavour
flav

        ; String -> SDoc -> TcM ()
traceTc String
"kcCheckDeclHeader_sig }" (SDoc -> TcM ()) -> SDoc -> TcM ()
forall a b. (a -> b) -> a -> b
$ [SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat
          [ String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"tyConName = " SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyCon -> Name
tyConName TyCon
tc)
          , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"sig_kind =" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Type -> SDoc
debugPprType Type