RnTypes.hs 67.8 KB
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{-
(c) The GRASP/AQUA Project, Glasgow University, 1992-1998

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\section[RnSource]{Main pass of renamer}
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-}
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{-# LANGUAGE ScopedTypeVariables #-}
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{-# LANGUAGE CPP #-}
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module RnTypes (
        -- Type related stuff
        rnHsType, rnLHsType, rnLHsTypes, rnContext,
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        rnHsKind, rnLHsKind, rnLHsMaybeKind,
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        rnHsSigType, rnHsWcType,
        rnHsSigWcType, rnHsSigWcTypeScoped,
        rnLHsInstType,
        newTyVarNameRn, collectAnonWildCards,
        rnConDeclFields,
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        rnLTyVar,
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        -- Precence related stuff
        mkOpAppRn, mkNegAppRn, mkOpFormRn, mkConOpPatRn,
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        checkPrecMatch, checkSectionPrec,
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        -- Binding related stuff
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        warnUnusedForAlls, bindLHsTyVarBndr,
        bindSigTyVarsFV, bindHsQTyVars, bindLRdrNames,
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        extractHsTyRdrTyVars, extractHsTysRdrTyVars,
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        extractHsTysRdrTyVarsDups, rmDupsInRdrTyVars,
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        extractRdrKindSigVars, extractDataDefnKindVars,
        freeKiTyVarsAllVars, freeKiTyVarsKindVars, freeKiTyVarsTypeVars
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  ) where
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import {-# SOURCE #-} RnSplice( rnSpliceType )
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import DynFlags
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import HsSyn
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import RnHsDoc          ( rnLHsDoc, rnMbLHsDoc )
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import RnEnv
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import TcRnMonad
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import RdrName
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import PrelNames
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import TysPrim          ( funTyConName )
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import TysWiredIn       ( starKindTyConName, unicodeStarKindTyConName )
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import Name
import SrcLoc
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import NameSet
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import FieldLabel
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import Util
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import BasicTypes       ( compareFixity, funTyFixity, negateFixity,
                          Fixity(..), FixityDirection(..) )
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import Outputable
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import FastString
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import Maybes
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import qualified GHC.LanguageExtensions as LangExt

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import Data.List        ( (\\), nubBy, partition )
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import Control.Monad    ( unless, when )
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#if __GLASGOW_HASKELL__ < 709
import Data.Monoid      ( mappend, mempty, mconcat )
#endif

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#include "HsVersions.h"

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{-
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These type renamers are in a separate module, rather than in (say) RnSource,
to break several loop.

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*********************************************************
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*                                                       *
           HsSigWcType (i.e with wildcards)
*                                                       *
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*********************************************************
-}
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rnHsSigWcType :: HsDocContext -> LHsSigWcType RdrName
            -> RnM (LHsSigWcType Name, FreeVars)
rnHsSigWcType doc sig_ty
  = rn_hs_sig_wc_type True doc sig_ty $ \sig_ty' ->
    return (sig_ty', emptyFVs)

rnHsSigWcTypeScoped :: HsDocContext -> LHsSigWcType RdrName
                    -> (LHsSigWcType Name -> RnM (a, FreeVars))
                    -> RnM (a, FreeVars)
-- Used for
--   - Signatures on binders in a RULE
--   - Pattern type signatures
-- Wildcards are allowed
rnHsSigWcTypeScoped ctx sig_ty thing_inside
  = rn_hs_sig_wc_type False ctx sig_ty thing_inside
    -- False: for pattern type sigs and rules we /do/ want
    --        to bring those type varibles into scope
    -- e.g  \ (x :: forall a. a-> b) -> e
    -- Here we do bring 'b' into scope

rn_hs_sig_wc_type :: Bool   -- see rnImplicitBndrs
                  -> HsDocContext
                  -> LHsSigWcType RdrName
                  -> (LHsSigWcType Name -> RnM (a, FreeVars))
                  -> RnM (a, FreeVars)
-- rn_hs_sig_wc_type is used for source-language type signatures
rn_hs_sig_wc_type no_implicit_if_forall ctxt
                  (HsIB { hsib_body = wc_ty }) thing_inside
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  = do { let hs_ty = hswc_body wc_ty
       ; free_vars <- extract_filtered_rdr_ty_vars hs_ty
       ; (free_vars', nwc_rdrs) <- partition_nwcs free_vars
       ; rnImplicitBndrs no_implicit_if_forall free_vars' hs_ty $ \ vars ->
    do { rn_hs_wc_type ctxt wc_ty nwc_rdrs $ \ wc_ty' ->
         thing_inside (HsIB { hsib_vars = vars
                            , hsib_body = wc_ty' }) } }
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rnHsWcType :: HsDocContext -> LHsWcType RdrName -> RnM (LHsWcType Name, FreeVars)
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rnHsWcType ctxt wc_ty@(HsWC { hswc_body = hs_ty })
  = do { free_vars <- extract_filtered_rdr_ty_vars hs_ty
       ; (_, nwc_rdrs) <- partition_nwcs free_vars
       ; rn_hs_wc_type ctxt wc_ty nwc_rdrs $ \ wc_ty' ->
         return (wc_ty', emptyFVs) }

-- | Renames a type with wild card binders.
-- Expects a list of names of type variables that should be replaced with
-- named wild cards. (See Note [Renaming named wild cards])
-- Although the parser does not create named wild cards, it is possible to find
-- them in declaration splices, so the function tries to collect them.
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rn_hs_wc_type :: HsDocContext -> LHsWcType RdrName
              -> [Located RdrName]  -- Named wildcards
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              -> (LHsWcType Name -> RnM (a, FreeVars))
              -> RnM (a, FreeVars)
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rn_hs_wc_type ctxt (HsWC { hswc_body = hs_ty }) nwc_rdrs thing_inside
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  = do { nwcs <- mapM newLocalBndrRn nwc_rdrs
       ; bindLocalNamesFV nwcs $
    do { let env = RTKE { rtke_level = TypeLevel
                        , rtke_what  = RnTypeBody
                        , rtke_nwcs  = mkNameSet nwcs
                        , rtke_ctxt  = ctxt }
       ; (wc_ty, fvs1) <- rnWcSigTy env hs_ty
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       ; let wc_ty' :: HsWildCardBndrs Name (LHsType Name)
             wc_ty' = wc_ty { hswc_wcs = nwcs ++ hswc_wcs wc_ty }
       ; (res, fvs2) <- thing_inside wc_ty'
       ; return (res, fvs1 `plusFV` fvs2) } }
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rnWcSigTy :: RnTyKiEnv -> LHsType RdrName
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          -> RnM (LHsWcType Name, FreeVars)
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-- ^ Renames just the top level of a type signature
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-- It's exactly like rnHsTyKi, except that it uses rnWcSigContext
-- on a qualified type, and return info on any extra-constraints
-- wildcard.  Some code duplication, but no big deal.
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rnWcSigTy env (L loc hs_ty@(HsForAllTy { hst_bndrs = tvs, hst_body = hs_tau }))
  = bindLHsTyVarBndrs (rtke_ctxt env) Nothing [] tvs $ \ _ tvs' ->
    do { (hs_tau', fvs) <- rnWcSigTy env hs_tau
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       ; warnUnusedForAlls (inTypeDoc hs_ty) tvs' fvs
       ; let hs_ty' = HsForAllTy { hst_bndrs = tvs', hst_body = hswc_body hs_tau' }
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       ; return ( hs_tau' { hswc_body = L loc hs_ty' }, fvs) }
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rnWcSigTy env (L loc (HsQualTy { hst_ctxt = hs_ctxt, hst_body = tau }))
  = do { (hs_ctxt', fvs1) <- rnWcSigContext env hs_ctxt
       ; (tau',     fvs2) <- rnLHsTyKi env tau
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       ; let awcs_tau = collectAnonWildCards tau'
             hs_ty'   = HsQualTy { hst_ctxt = hswc_body hs_ctxt'
                                 , hst_body = tau' }
       ; return ( HsWC { hswc_wcs = hswc_wcs hs_ctxt' ++ awcs_tau
                       , hswc_ctx = hswc_ctx hs_ctxt'
                       , hswc_body = L loc hs_ty' }
                , fvs1 `plusFV` fvs2) }

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rnWcSigTy env hs_ty
  = do { (hs_ty', fvs) <- rnLHsTyKi env hs_ty
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       ; return (HsWC { hswc_wcs = collectAnonWildCards hs_ty'
                      , hswc_ctx = Nothing
                      , hswc_body = hs_ty' }
                , fvs) }

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rnWcSigContext :: RnTyKiEnv -> LHsContext RdrName
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               -> RnM (HsWildCardBndrs Name (LHsContext Name), FreeVars)
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rnWcSigContext env (L loc hs_ctxt)
  | Just (hs_ctxt1, hs_ctxt_last) <- snocView hs_ctxt
  , L lx (HsWildCardTy wc) <- ignoreParens hs_ctxt_last
  = do { (hs_ctxt1', fvs) <- mapFvRn rn_top_constraint hs_ctxt1
       ; setSrcSpan lx $ checkExtraConstraintWildCard env wc
       ; wc' <- rnAnonWildCard wc
       ; let hs_ctxt' = hs_ctxt1' ++ [L lx (HsWildCardTy wc')]
             awcs     = concatMap collectAnonWildCards hs_ctxt1'
             -- NB: *not* including the extra-constraint wildcard
       ; return ( HsWC { hswc_wcs = awcs
                       , hswc_ctx = Just lx
                       , hswc_body = L loc hs_ctxt' }
                , fvs ) }
  | otherwise
  = do { (hs_ctxt', fvs) <- mapFvRn rn_top_constraint hs_ctxt
       ; return (HsWC { hswc_wcs = concatMap collectAnonWildCards hs_ctxt'
                      , hswc_ctx = Nothing
                      , hswc_body = L loc hs_ctxt' }, fvs) }
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  where
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    rn_top_constraint = rnLHsTyKi (env { rtke_what = RnTopConstraint })
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-- | extract_filtered finds free type and kind variables in a type,
--     without duplicates, and
--     without variables that are already in scope in LocalRdrEnv
--   NB: this includes named wildcards, which look like perfectly
--       ordinary type variables at this point
extract_filtered_rdr_ty_vars :: LHsType RdrName -> RnM FreeKiTyVars
extract_filtered_rdr_ty_vars hs_ty
  = do { rdr_env <- getLocalRdrEnv
       ; filterInScope rdr_env <$> extractHsTyRdrTyVars hs_ty }

-- | When the NamedWildCards extension is enabled, partition_nwcs
-- removes type variables that start with an underscore from the
-- FreeKiTyVars in the argument and returns them in a separate list.
-- When the extension is disabled, the function returns the argument
-- and empty list.  See Note [Renaming named wild cards]
partition_nwcs :: FreeKiTyVars -> RnM (FreeKiTyVars, [Located RdrName])
partition_nwcs free_vars@(FKTV { fktv_tys = tys, fktv_all = all })
  = do { wildcards_enabled <- fmap (xopt LangExt.NamedWildCards) getDynFlags
       ; let (nwcs, no_nwcs) | wildcards_enabled = partition is_wildcard tys
                             | otherwise         = ([], tys)
             free_vars' = free_vars { fktv_tys = no_nwcs
                                    , fktv_all = all \\ nwcs }
       ; return (free_vars', nwcs) }
  where
     is_wildcard :: Located RdrName -> Bool
     is_wildcard rdr = startsWithUnderscore (rdrNameOcc (unLoc rdr))

{- Note [Renaming named wild cards]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Identifiers starting with an underscore are always parsed as type variables.
It is only here in the renamer that we give the special treatment.
See Note [The wildcard story for types] in HsTypes.

It's easy!  When we collect the implicitly bound type variables, ready
to bring them into scope, and NamedWildCards is on, we partition the
variables into the ones that start with an underscore (the named
wildcards) and the rest. Then we just add them to the hswc_wcs field
of the HsWildCardBndrs structure, and we are done.


*********************************************************
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*                                                       *
           HsSigtype (i.e. no wildcards)
*                                                       *
****************************************************** -}

rnHsSigType :: HsDocContext -> LHsSigType RdrName
            -> RnM (LHsSigType Name, FreeVars)
-- Used for source-language type signatures
-- that cannot have wildcards
rnHsSigType ctx (HsIB { hsib_body = hs_ty })
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  = do { vars <- extract_filtered_rdr_ty_vars hs_ty
       ; rnImplicitBndrs True vars hs_ty $ \ vars ->
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    do { (body', fvs) <- rnLHsType ctx hs_ty
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       ; return (HsIB { hsib_vars = vars
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                      , hsib_body = body' }, fvs) } }
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rnImplicitBndrs :: Bool    -- True <=> no implicit quantification
                           --          if type is headed by a forall
                           -- E.g.  f :: forall a. a->b
                           -- Do not quantify over 'b' too.
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                -> FreeKiTyVars
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                -> LHsType RdrName
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                -> ([Name] -> RnM (a, FreeVars))
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                -> RnM (a, FreeVars)
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rnImplicitBndrs no_implicit_if_forall free_vars hs_ty@(L loc _) thing_inside
  = do { let real_tv_rdrs  -- Implicit quantification only if
                           -- there is no explicit forall
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               | no_implicit_if_forall
               , L _ (HsForAllTy {}) <- hs_ty = []
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               | otherwise                    = freeKiTyVarsTypeVars free_vars
             real_rdrs = freeKiTyVarsKindVars free_vars ++ real_tv_rdrs
       ; traceRn (text "rnSigType" <+> (ppr hs_ty $$ ppr free_vars $$
                                        ppr real_rdrs))
       ; vars <- mapM (newLocalBndrRn . L loc . unLoc) real_rdrs
       ; bindLocalNamesFV vars $
         thing_inside vars }
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rnLHsInstType :: SDoc -> LHsSigType RdrName -> RnM (LHsSigType Name, FreeVars)
-- Rename the type in an instance or standalone deriving decl
-- The 'doc_str' is "an instance declaration" or "a VECTORISE pragma"
rnLHsInstType doc_str inst_ty
  | Just cls <- getLHsInstDeclClass_maybe inst_ty
  , isTcOcc (rdrNameOcc (unLoc cls))
         -- The guards check that the instance type looks like
         --   blah => C ty1 .. tyn
  = do { let full_doc = doc_str <+> ptext (sLit "for") <+> quotes (ppr cls)
       ; rnHsSigType (GenericCtx full_doc) inst_ty }

  | otherwise  -- The instance is malformed, but we'd still like
               -- to make progress rather than failing outright, so
               -- we report more errors.  So we rename it anyway.
  = do { addErrAt (getLoc (hsSigType inst_ty)) $
         ptext (sLit "Malformed instance:") <+> ppr inst_ty
       ; rnHsSigType (GenericCtx doc_str) inst_ty }


{- ******************************************************
*                                                       *
           LHsType and HsType
*                                                       *
****************************************************** -}
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{-
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rnHsType is here because we call it from loadInstDecl, and I didn't
want a gratuitous knot.

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Note [Context quantification]
-----------------------------
Variables in type signatures are implicitly quantified
when (1) they are in a type signature not beginning
with "forall" or (2) in any qualified type T => R.
We are phasing out (2) since it leads to inconsistencies
(Trac #4426):

data A = A (a -> a)           is an error
data A = A (Eq a => a -> a)   binds "a"
data A = A (Eq a => a -> b)   binds "a" and "b"
data A = A (() => a -> b)     binds "a" and "b"
f :: forall a. a -> b         is an error
f :: forall a. () => a -> b   is an error
f :: forall a. a -> (() => b) binds "a" and "b"

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This situation is now considered to be an error. See rnHsTyKi for case
HsForAllTy Qualified.
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Note [Dealing with *]
~~~~~~~~~~~~~~~~~~~~~
As a legacy from the days when types and kinds were different, we use
the type * to mean what we now call GHC.Types.Type. The problem is that
* should associate just like an identifier, *not* a symbol.
Running example: the user has written

  T (Int, Bool) b + c * d

At this point, we have a bunch of stretches of types

  [[T, (Int, Bool), b], [c], [d]]

these are the [[LHsType Name]] and a bunch of operators

  [GHC.TypeLits.+, GHC.Types.*]

Note that the * is GHC.Types.*. So, we want to rearrange to have

  [[T, (Int, Bool), b], [c, *, d]]

and

  [GHC.TypeLits.+]

as our lists. We can then do normal fixity resolution on these. The fixities
must come along for the ride just so that the list stays in sync with the
operators.
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Note [QualTy in kinds]
~~~~~~~~~~~~~~~~~~~~~~
I was wondering whether QualTy could occur only at TypeLevel.  But no,
we can have a qualified type in a kind too. Here is an example:

  type family F a where
    F Bool = Nat
    F Nat  = Type

  type family G a where
    G Type = Type -> Type
    G ()   = Nat

  data X :: forall k1 k2. (F k1 ~ G k2) => k1 -> k2 -> Type where
    MkX :: X 'True '()

See that k1 becomes Bool and k2 becomes (), so the equality is
satisfied. If I write MkX :: X 'True 'False, compilation fails with a
suitable message:

  MkX :: X 'True '()
    • Couldn't match kind ‘G Bool’ with ‘Nat’
      Expected kind: G Bool
        Actual kind: F Bool

However: in a kind, the constraints in the QualTy must all be
equalities; or at least, any kinds with a class constraint are
uninhabited.
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-}
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data RnTyKiEnv
  = RTKE { rtke_ctxt  :: HsDocContext
         , rtke_level :: TypeOrKind  -- Am I renaming a type or a kind?
         , rtke_what  :: RnTyKiWhat  -- And within that what am I renaming?
         , rtke_nwcs  :: NameSet     -- These are the in-scope named wildcards
    }
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data RnTyKiWhat = RnTypeBody
                | RnTopConstraint   -- Top-level context of HsSigWcTypes
                | RnConstraint      -- All other constraints
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instance Outputable RnTyKiEnv where
  ppr (RTKE { rtke_level = lev, rtke_what = what
            , rtke_nwcs = wcs, rtke_ctxt = ctxt })
    = ptext (sLit "RTKE")
      <+> braces (sep [ ppr lev, ppr what, ppr wcs
                      , pprHsDocContext ctxt ])
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instance Outputable RnTyKiWhat where
  ppr RnTypeBody      = text "RnTypeBody"
  ppr RnTopConstraint = text "RnTopConstraint"
  ppr RnConstraint    = text "RnConstraint"
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mkTyKiEnv :: HsDocContext -> TypeOrKind -> RnTyKiWhat -> RnTyKiEnv
mkTyKiEnv cxt level what
 = RTKE { rtke_level = level, rtke_nwcs = emptyNameSet
        , rtke_what = what, rtke_ctxt = cxt }
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isRnKindLevel :: RnTyKiEnv -> Bool
isRnKindLevel (RTKE { rtke_level = KindLevel }) = True
isRnKindLevel _                                 = False
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--------------
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rnLHsType  :: HsDocContext -> LHsType RdrName -> RnM (LHsType Name, FreeVars)
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rnLHsType ctxt ty = rnLHsTyKi (mkTyKiEnv ctxt TypeLevel RnTypeBody) ty
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rnLHsTypes :: HsDocContext -> [LHsType RdrName] -> RnM ([LHsType Name], FreeVars)
rnLHsTypes doc tys = mapFvRn (rnLHsType doc) tys

rnHsType  :: HsDocContext -> HsType RdrName -> RnM (HsType Name, FreeVars)
rnHsType ctxt ty = rnHsTyKi (mkTyKiEnv ctxt TypeLevel RnTypeBody) ty
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rnLHsKind  :: HsDocContext -> LHsKind RdrName -> RnM (LHsKind Name, FreeVars)
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rnLHsKind ctxt kind = rnLHsTyKi (mkTyKiEnv ctxt KindLevel RnTypeBody) kind

rnHsKind  :: HsDocContext -> HsKind RdrName -> RnM (HsKind Name, FreeVars)
rnHsKind ctxt kind = rnHsTyKi  (mkTyKiEnv ctxt KindLevel RnTypeBody) kind
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rnLHsMaybeKind  :: HsDocContext -> Maybe (LHsKind RdrName)
                -> RnM (Maybe (LHsKind Name), FreeVars)
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rnLHsMaybeKind _ Nothing
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  = return (Nothing, emptyFVs)
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rnLHsMaybeKind doc (Just kind)
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  = do { (kind', fvs) <- rnLHsKind doc kind
       ; return (Just kind', fvs) }
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--------------
rnTyKiContext :: RnTyKiEnv -> LHsContext RdrName -> RnM (LHsContext Name, FreeVars)
rnTyKiContext env (L loc cxt)
  = do { traceRn (text "rncontext" <+> ppr cxt)
       ; let env' = env { rtke_what = RnConstraint }
       ; (cxt', fvs) <- mapFvRn (rnLHsTyKi env') cxt
       ; return (L loc cxt', fvs) }
  where
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rnContext :: HsDocContext -> LHsContext RdrName -> RnM (LHsContext Name, FreeVars)
rnContext doc theta = rnTyKiContext (mkTyKiEnv doc TypeLevel RnConstraint) theta
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--------------
rnLHsTyKi  :: RnTyKiEnv -> LHsType RdrName -> RnM (LHsType Name, FreeVars)
rnLHsTyKi env (L loc ty)
  = setSrcSpan loc $
    do { (ty', fvs) <- rnHsTyKi env ty
       ; return (L loc ty', fvs) }
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rnHsTyKi :: RnTyKiEnv -> HsType RdrName -> RnM (HsType Name, FreeVars)

rnHsTyKi env ty@(HsForAllTy { hst_bndrs = tyvars, hst_body  = tau })
  = do { checkTypeInType env ty
       ; bindLHsTyVarBndrs (rtke_ctxt env) Nothing [] tyvars $ \ _ tyvars' ->
    do { (tau',  fvs) <- rnLHsTyKi env tau
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       ; warnUnusedForAlls (inTypeDoc ty) tyvars' fvs
       ; return ( HsForAllTy { hst_bndrs = tyvars', hst_body =  tau' }
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                , fvs) } }
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rnHsTyKi env ty@(HsQualTy { hst_ctxt = lctxt, hst_body = tau })
  = do { checkTypeInType env ty  -- See Note [QualTy in kinds]
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       ; (ctxt', fvs1) <- rnTyKiContext env lctxt
       ; (tau',  fvs2) <- rnLHsTyKi env tau
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       ; return (HsQualTy { hst_ctxt = ctxt', hst_body =  tau' }
                , fvs1 `plusFV` fvs2) }

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rnHsTyKi env (HsTyVar (L loc rdr_name))
  = do { name <- rnTyVar env rdr_name
       ; return (HsTyVar (L loc name), unitFV name) }
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rnHsTyKi env ty@(HsOpTy ty1 l_op ty2)
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  = setSrcSpan (getLoc l_op) $
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    do  { (l_op', fvs1) <- rnHsTyOp env ty l_op
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        ; fix   <- lookupTyFixityRn l_op'
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        ; (ty1', fvs2) <- rnLHsTyKi env ty1
        ; (ty2', fvs3) <- rnLHsTyKi env ty2
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        ; res_ty <- mkHsOpTyRn (\t1 t2 -> HsOpTy t1 l_op' t2)
                               (unLoc l_op') fix ty1' ty2'
        ; return (res_ty, plusFVs [fvs1, fvs2, fvs3]) }
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rnHsTyKi env (HsParTy ty)
  = do { (ty', fvs) <- rnLHsTyKi env ty
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       ; return (HsParTy ty', fvs) }
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rnHsTyKi env (HsBangTy b ty)
  = do { (ty', fvs) <- rnLHsTyKi env ty
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       ; return (HsBangTy b ty', fvs) }
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rnHsTyKi env ty@(HsRecTy flds)
  = do { let ctxt = rtke_ctxt env
       ; fls          <- get_fields ctxt
       ; (flds', fvs) <- rnConDeclFields ctxt fls flds
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       ; return (HsRecTy flds', fvs) }
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  where
    get_fields (ConDeclCtx names)
      = concatMapM (lookupConstructorFields . unLoc) names
    get_fields _
      = do { addErr (hang (ptext (sLit "Record syntax is illegal here:"))
                                   2 (ppr ty))
           ; return [] }

rnHsTyKi env (HsFunTy ty1 ty2)
  = do { (ty1', fvs1) <- rnLHsTyKi env ty1
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        -- Might find a for-all as the arg of a function type
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       ; (ty2', fvs2) <- rnLHsTyKi env ty2
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        -- Or as the result.  This happens when reading Prelude.hi
        -- when we find return :: forall m. Monad m -> forall a. a -> m a
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        -- Check for fixity rearrangements
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       ; res_ty <- mkHsOpTyRn HsFunTy funTyConName funTyFixity ty1' ty2'
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       ; return (res_ty, fvs1 `plusFV` fvs2) }
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rnHsTyKi env listTy@(HsListTy ty)
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  = do { data_kinds <- xoptM LangExt.DataKinds
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       ; when (not data_kinds && isRnKindLevel env)
              (addErr (dataKindsErr env listTy))
       ; (ty', fvs) <- rnLHsTyKi env ty
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       ; return (HsListTy ty', fvs) }
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rnHsTyKi env t@(HsKindSig ty k)
  = do { checkTypeInType env t
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       ; kind_sigs_ok <- xoptM LangExt.KindSignatures
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       ; unless kind_sigs_ok (badKindSigErr (rtke_ctxt env) ty)
       ; (ty', fvs1) <- rnLHsTyKi env ty
       ; (k', fvs2)  <- rnLHsTyKi (env { rtke_level = KindLevel }) k
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       ; return (HsKindSig ty' k', fvs1 `plusFV` fvs2) }
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rnHsTyKi env t@(HsPArrTy ty)
  = do { notInKinds env t
       ; (ty', fvs) <- rnLHsTyKi env ty
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       ; return (HsPArrTy ty', fvs) }
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-- Unboxed tuples are allowed to have poly-typed arguments.  These
-- sometimes crop up as a result of CPR worker-wrappering dictionaries.
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rnHsTyKi env tupleTy@(HsTupleTy tup_con tys)
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  = do { data_kinds <- xoptM LangExt.DataKinds
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       ; when (not data_kinds && isRnKindLevel env)
              (addErr (dataKindsErr env tupleTy))
       ; (tys', fvs) <- mapFvRn (rnLHsTyKi env) tys
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       ; return (HsTupleTy tup_con tys', fvs) }

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-- Ensure that a type-level integer is nonnegative (#8306, #8412)
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rnHsTyKi env tyLit@(HsTyLit t)
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  = do { data_kinds <- xoptM LangExt.DataKinds
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       ; unless data_kinds (addErr (dataKindsErr env tyLit))
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       ; when (negLit t) (addErr negLitErr)
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       ; checkTypeInType env tyLit
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       ; return (HsTyLit t, emptyFVs) }
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  where
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    negLit (HsStrTy _ _) = False
    negLit (HsNumTy _ i) = i < 0
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    negLitErr = ptext (sLit "Illegal literal in type (type literals must not be negative):") <+> ppr tyLit
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rnHsTyKi env overall_ty@(HsAppsTy tys)
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  = do { -- Step 1: Break up the HsAppsTy into symbols and non-symbol regions
         let (non_syms, syms) = splitHsAppsTy tys

             -- Step 2: rename the pieces
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       ; (syms1, fvs1)      <- mapFvRn (rnHsTyOp env overall_ty) syms
       ; (non_syms1, fvs2)  <- (mapFvRn . mapFvRn) (rnLHsTyKi env) non_syms
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             -- Step 3: deal with *. See Note [Dealing with *]
       ; let (non_syms2, syms2) = deal_with_star [] [] non_syms1 syms1

             -- Step 4: collapse the non-symbol regions with HsAppTy
       ; non_syms3 <- mapM deal_with_non_syms non_syms2

             -- Step 5: assemble the pieces, using mkHsOpTyRn
       ; L _ res_ty <- build_res_ty non_syms3 syms2

        -- all done. Phew.
       ; return (res_ty, fvs1 `plusFV` fvs2) }
  where
    -- See Note [Dealing with *]
    deal_with_star :: [[LHsType Name]] -> [Located Name]
                   -> [[LHsType Name]] -> [Located Name]
                   -> ([[LHsType Name]], [Located Name])
    deal_with_star acc1 acc2
                   (non_syms1 : non_syms2 : non_syms) (L loc star : ops)
      | star `hasKey` starKindTyConKey || star `hasKey` unicodeStarKindTyConKey
      = deal_with_star acc1 acc2
                       ((non_syms1 ++ L loc (HsTyVar (L loc star)) : non_syms2) : non_syms)
                       ops
    deal_with_star acc1 acc2 (non_syms1 : non_syms) (op1 : ops)
      = deal_with_star (non_syms1 : acc1) (op1 : acc2) non_syms ops
    deal_with_star acc1 acc2 [non_syms] []
      = (reverse (non_syms : acc1), reverse acc2)
    deal_with_star _ _ _ _
      = pprPanic "deal_with_star" (ppr overall_ty)

    -- collapse [LHsType Name] to LHsType Name by making applications
    -- monadic only for failure
    deal_with_non_syms :: [LHsType Name] -> RnM (LHsType Name)
    deal_with_non_syms (non_sym : non_syms) = return $ mkHsAppTys non_sym non_syms
    deal_with_non_syms []                   = failWith (emptyNonSymsErr overall_ty)

    -- assemble a right-biased OpTy for use in mkHsOpTyRn
    build_res_ty :: [LHsType Name] -> [Located Name] -> RnM (LHsType Name)
    build_res_ty (arg1 : args) (op1 : ops)
      = do { rhs <- build_res_ty args ops
           ; fix <- lookupTyFixityRn op1
           ; res <-
               mkHsOpTyRn (\t1 t2 -> HsOpTy t1 op1 t2) (unLoc op1) fix arg1 rhs
           ; let loc = combineSrcSpans (getLoc arg1) (getLoc rhs)
           ; return (L loc res)
           }
    build_res_ty [arg] [] = return arg
    build_res_ty _ _ = pprPanic "build_op_ty" (ppr overall_ty)

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rnHsTyKi env (HsAppTy ty1 ty2)
  = do { (ty1', fvs1) <- rnLHsTyKi env ty1
       ; (ty2', fvs2) <- rnLHsTyKi env ty2
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       ; return (HsAppTy ty1' ty2', fvs1 `plusFV` fvs2) }

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rnHsTyKi env t@(HsIParamTy n ty)
  = do { notInKinds env t
       ; (ty', fvs) <- rnLHsTyKi env ty
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       ; return (HsIParamTy n ty', fvs) }
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rnHsTyKi env t@(HsEqTy ty1 ty2)
  = do { checkTypeInType env t
       ; (ty1', fvs1) <- rnLHsTyKi env ty1
       ; (ty2', fvs2) <- rnLHsTyKi env ty2
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       ; return (HsEqTy ty1' ty2', fvs1 `plusFV` fvs2) }
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rnHsTyKi _ (HsSpliceTy sp k)
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  = rnSpliceType sp k
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rnHsTyKi env (HsDocTy ty haddock_doc)
  = do { (ty', fvs) <- rnLHsTyKi env ty
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       ; haddock_doc' <- rnLHsDoc haddock_doc
       ; return (HsDocTy ty' haddock_doc', fvs) }
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rnHsTyKi _ (HsCoreTy ty)
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  = return (HsCoreTy ty, emptyFVs)
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    -- The emptyFVs probably isn't quite right
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    -- but I don't think it matters

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rnHsTyKi env ty@(HsExplicitListTy k tys)
  = do { checkTypeInType env ty
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       ; data_kinds <- xoptM LangExt.DataKinds
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       ; unless data_kinds (addErr (dataKindsErr env ty))
       ; (tys', fvs) <- mapFvRn (rnLHsTyKi env) tys
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       ; return (HsExplicitListTy k tys', fvs) }

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rnHsTyKi env ty@(HsExplicitTupleTy kis tys)
  = do { checkTypeInType env ty
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       ; data_kinds <- xoptM LangExt.DataKinds
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       ; unless data_kinds (addErr (dataKindsErr env ty))
       ; (tys', fvs) <- mapFvRn (rnLHsTyKi env) tys
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       ; return (HsExplicitTupleTy kis tys', fvs) }

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rnHsTyKi env (HsWildCardTy wc)
  = do { checkAnonWildCard env wc
       ; wc' <- rnAnonWildCard wc
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       ; return (HsWildCardTy wc', emptyFVs) }
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         -- emptyFVs: this occurrence does not refer to a
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         --           user-written binding site, so don't treat
         --           it as a free variable
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--------------
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rnTyVar :: RnTyKiEnv -> RdrName -> RnM Name
rnTyVar env rdr_name
  = do { name <- if   isRnKindLevel env
                 then lookupKindOccRn rdr_name
                 else lookupTypeOccRn rdr_name
       ; checkNamedWildCard env name
       ; return name }
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rnLTyVar :: Located RdrName -> RnM (Located Name)
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-- Called externally; does not deal with wildards
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rnLTyVar (L loc rdr_name)
  = do { tyvar <- lookupTypeOccRn rdr_name
       ; return (L loc tyvar) }
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--------------
rnHsTyOp :: Outputable a
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         => RnTyKiEnv -> a -> Located RdrName -> RnM (Located Name, FreeVars)
rnHsTyOp env overall_ty (L loc op)
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  = do { ops_ok <- xoptM LangExt.TypeOperators
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       ; op' <- rnTyVar env op
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       ; unless (ops_ok
                 || op' == starKindTyConName
                 || op' == unicodeStarKindTyConName
                 || op' `hasKey` eqTyConKey) $
           addErr (opTyErr op overall_ty)
       ; let l_op' = L loc op'
       ; return (l_op', unitFV op') }

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--------------
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notAllowed :: SDoc -> SDoc
notAllowed doc
  = ptext (sLit "Wildcard") <+> quotes doc <+> ptext (sLit "not allowed")

checkWildCard :: RnTyKiEnv -> Maybe SDoc -> RnM ()
checkWildCard env (Just doc)
  = addErr $ vcat [doc, nest 2 (ptext (sLit "in") <+> pprHsDocContext (rtke_ctxt env))]
checkWildCard _ Nothing
  = return ()
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checkAnonWildCard :: RnTyKiEnv -> HsWildCardInfo RdrName -> RnM ()
-- Report an error if an anonymoous wildcard is illegal here
checkAnonWildCard env wc
  = checkWildCard env mb_bad
  where
    mb_bad :: Maybe SDoc
    mb_bad | not (wildCardsAllowed env)
           = Just (notAllowed (ppr wc))
           | otherwise
           = case rtke_what env of
               RnTypeBody      -> Nothing
               RnConstraint    -> Just constraint_msg
               RnTopConstraint -> Just constraint_msg

    constraint_msg = hang (notAllowed (ppr wc) <+> ptext (sLit "in a constraint"))
                        2 hint_msg
    hint_msg = vcat [ ptext (sLit "except as the last top-level constraint of a type signature")
                    , nest 2 (ptext (sLit "e.g  f :: (Eq a, _) => blah")) ]

checkNamedWildCard :: RnTyKiEnv -> Name -> RnM ()
-- Report an error if a named wildcard is illegal here
checkNamedWildCard env name
  = checkWildCard env mb_bad
  where
    mb_bad | not (name `elemNameSet` rtke_nwcs env)
           = Nothing  -- Not a wildcard
           | not (wildCardsAllowed env)
           = Just (notAllowed (ppr name))
           | otherwise
           = case rtke_what env of
               RnTypeBody      -> Nothing   -- Allowed
               RnTopConstraint -> Nothing   -- Allowed
               RnConstraint    -> Just constraint_msg
    constraint_msg = notAllowed (ppr name) <+> ptext (sLit "in a constraint")

checkExtraConstraintWildCard :: RnTyKiEnv -> HsWildCardInfo RdrName
                             -> RnM ()
-- Rename the extra-constraint spot in a type signature
--    (blah, _) => type
-- Check that extra-constraints are allowed at all, and
-- if so that it's an anonymous wildcard
checkExtraConstraintWildCard env wc
  = checkWildCard env mb_bad
  where
    mb_bad | not (extraConstraintWildCardsAllowed env)
           = Just (ptext (sLit "Extra-contraint wildcard") <+> quotes (ppr wc)
                   <+> ptext (sLit "not allowed"))
           | otherwise
           = Nothing

extraConstraintWildCardsAllowed :: RnTyKiEnv -> Bool
extraConstraintWildCardsAllowed env
  = case rtke_ctxt env of
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      TypeSigCtx {}       -> True
      _                   -> False

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wildCardsAllowed :: RnTyKiEnv -> Bool
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-- ^ In what contexts are wildcards permitted
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wildCardsAllowed env
   = case rtke_ctxt env of
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       TypeSigCtx {}       -> True
       TypBrCtx {}         -> True   -- Template Haskell quoted type
       SpliceTypeCtx {}    -> True   -- Result of a Template Haskell splice
       ExprWithTySigCtx {} -> True
       PatCtx {}           -> True
       RuleCtx {}          -> True
       FamPatCtx {}        -> True   -- Not named wildcards though
       GHCiCtx {}          -> True
       _                   -> False

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rnAnonWildCard :: HsWildCardInfo RdrName -> RnM (HsWildCardInfo Name)
rnAnonWildCard (AnonWildCard _)
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  = do { loc <- getSrcSpanM
       ; uniq <- newUnique
       ; let name = mkInternalName uniq (mkTyVarOcc "_") loc
       ; return (AnonWildCard (L loc name)) }

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---------------
-- | Ensures either that we're in a type or that -XTypeInType is set
checkTypeInType :: Outputable ty
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                => RnTyKiEnv
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                -> ty      -- ^ type
                -> RnM ()
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checkTypeInType env ty
  | isRnKindLevel env
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  = do { type_in_type <- xoptM LangExt.TypeInType
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       ; unless type_in_type $
         addErr (text "Illegal kind:" <+> ppr ty $$
                 text "Did you mean to enable TypeInType?") }
checkTypeInType _ _ = return ()

notInKinds :: Outputable ty
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           => RnTyKiEnv
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           -> ty
           -> RnM ()
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notInKinds env ty
  | isRnKindLevel env
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  = addErr (text "Illegal kind (even with TypeInType enabled):" <+> ppr ty)
notInKinds _ _ = return ()

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{- *****************************************************
*                                                      *
          Binding type variables
*                                                      *
***************************************************** -}

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bindSigTyVarsFV :: [Name]
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                -> RnM (a, FreeVars)
                -> RnM (a, FreeVars)
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-- Used just before renaming the defn of a function
-- with a separate type signature, to bring its tyvars into scope
-- With no -XScopedTypeVariables, this is a no-op
bindSigTyVarsFV tvs thing_inside
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  = do  { scoped_tyvars <- xoptM LangExt.ScopedTypeVariables
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        ; if not scoped_tyvars then
                thing_inside
          else
                bindLocalNamesFV tvs thing_inside }
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-- | Simply bring a bunch of RdrNames into scope. No checking for
-- validity, at all. The binding location is taken from the location
-- on each name.
bindLRdrNames :: [Located RdrName]
              -> ([Name] -> RnM (a, FreeVars))
              -> RnM (a, FreeVars)
bindLRdrNames rdrs thing_inside
  = do { var_names <- mapM (newTyVarNameRn Nothing) rdrs
       ; bindLocalNamesFV var_names $
         thing_inside var_names }

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---------------
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bindHsQTyVars :: forall a b.
                 HsDocContext
              -> Maybe a                 -- Just _  => an associated type decl
              -> [Located RdrName]       -- Kind variables from scope, in l-to-r
                                         -- order, but not from ...
              -> (LHsQTyVars RdrName)     -- ... these user-written tyvars
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              -> (LHsQTyVars Name -> RnM (b, FreeVars))
              -> RnM (b, FreeVars)
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-- (a) Bring kind variables into scope
--     both (i)  passed in (kv_bndrs)
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--     and  (ii) mentioned in the kinds of tv_bndrs
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-- (b) Bring type variables into scope
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bindHsQTyVars doc mb_assoc kv_bndrs tv_bndrs thing_inside
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  = do { bindLHsTyVarBndrs doc mb_assoc kv_bndrs (hsQTvExplicit tv_bndrs) $
         \ rn_kvs rn_bndrs ->
         thing_inside (HsQTvs { hsq_implicit = rn_kvs
                              , hsq_explicit = rn_bndrs }) }

bindLHsTyVarBndrs :: forall a b.
                     HsDocContext
                  -> Maybe a            -- Just _  => an associated type decl
                  -> [Located RdrName]  -- Unbound kind variables from scope,
                                        -- in l-to-r order, but not from ...
                  -> [LHsTyVarBndr RdrName]  -- ... these user-written tyvars
                  -> (   [Name]  -- all kv names
                      -> [LHsTyVarBndr Name]
                      -> RnM (b, FreeVars))
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                  -> RnM (b, FreeVars)
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bindLHsTyVarBndrs doc mb_assoc kv_bndrs tv_bndrs thing_inside
  = do { when (isNothing mb_assoc) (checkShadowedRdrNames tv_names_w_loc)
       ; go [] [] emptyNameSet emptyNameSet tv_bndrs }
  where
    tv_names_w_loc = map hsLTyVarLocName tv_bndrs

    go :: [Name]                 -- kind-vars found (in reverse order)
       -> [LHsTyVarBndr Name]    -- already renamed (in reverse order)
       -> NameSet                -- kind vars already in scope (for dup checking)
       -> NameSet                -- type vars already in scope (for dup checking)
       -> [LHsTyVarBndr RdrName] -- still to be renamed, scoped
       -> RnM (b, FreeVars)
    go rn_kvs rn_tvs kv_names tv_names (tv_bndr : tv_bndrs)
      = bindLHsTyVarBndr doc mb_assoc kv_names tv_names tv_bndr $
        \ kv_nms tv_bndr' -> go (reverse kv_nms ++ rn_kvs)
                                (tv_bndr' : rn_tvs)
                                (kv_names `extendNameSetList` kv_nms)
                                (tv_names `extendNameSet` hsLTyVarName tv_bndr')
                                tv_bndrs

    go rn_kvs rn_tvs _kv_names tv_names []
      = -- still need to deal with the kv_bndrs passed in originally
        bindImplicitKvs doc mb_assoc kv_bndrs tv_names $ \ kv_nms ->
        do { let all_rn_kvs = reverse (reverse kv_nms ++ rn_kvs)
                 all_rn_tvs = reverse rn_tvs
           ; env <- getLocalRdrEnv
           ; traceRn (text "bindHsTyVars" <+> (ppr env $$
                                               ppr all_rn_kvs $$
                                               ppr all_rn_tvs))
           ; thing_inside all_rn_kvs all_rn_tvs }

bindLHsTyVarBndr :: HsDocContext
                 -> Maybe a   -- associated class
                 -> NameSet   -- kind vars already in scope
                 -> NameSet   -- type vars already in scope
                 -> LHsTyVarBndr RdrName
                 -> ([Name] -> LHsTyVarBndr Name -> RnM (b, FreeVars))
                   -- passed the newly-bound implicitly-declared kind vars,
                   -- and the renamed LHsTyVarBndr
                 -> RnM (b, FreeVars)
bindLHsTyVarBndr doc mb_assoc kv_names tv_names hs_tv_bndr thing_inside
  = case hs_tv_bndr of
      L loc (UserTyVar lrdr@(L lv rdr)) ->
        do { check_dup loc rdr
           ; nm <- newTyVarNameRn mb_assoc lrdr
           ; bindLocalNamesFV [nm] $
             thing_inside [] (L loc (UserTyVar (L lv nm))) }
      L loc (KindedTyVar lrdr@(L lv rdr) kind) ->
        do { check_dup lv rdr

             -- check for -XKindSignatures
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           ; sig_ok <- xoptM LangExt.KindSignatures
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           ; unless sig_ok (badKindSigErr doc kind)

             -- deal with kind vars in the user-written kind
           ; free_kvs <- freeKiTyVarsAllVars <$> extractHsTyRdrTyVars kind
           ; bindImplicitKvs doc mb_assoc free_kvs tv_names $ \ kv_nms ->
             do { (kind', fvs1) <- rnLHsKind doc kind
                ; tv_nm  <- newTyVarNameRn mb_assoc lrdr
                ; (b, fvs2) <- bindLocalNamesFV [tv_nm] $
                               thing_inside kv_nms
                                 (L loc (KindedTyVar (L lv tv_nm) kind'))
                ; return (b, fvs1 `plusFV` fvs2) }}
  where
      -- make sure that the RdrName isn't in the sets of
      -- names. We can't just check that it's not in scope at all
      -- because we might be inside an associated class.
    check_dup :: SrcSpan -> RdrName -> RnM ()
    check_dup loc rdr
      = do { m_name <- lookupLocalOccRn_maybe rdr
           ; whenIsJust m_name $ \name ->
        do { when (name `elemNameSet` kv_names) $
             addErrAt loc (vcat [ ki_ty_err_msg name
                                , pprHsDocContext doc ])
           ; when (name `elemNameSet` tv_names) $
             dupNamesErr getLoc [L loc name, L (nameSrcSpan name) name] }}

    ki_ty_err_msg n = text "Variable" <+> quotes (ppr n) <+>
                      text "used as a kind variable before being bound" $$
                      text "as a type variable. Perhaps reorder your variables?"


bindImplicitKvs :: HsDocContext
                -> Maybe a
                -> [Located RdrName]  -- ^ kind var *occurrences*, from which
                                      -- intent to bind is inferred
                -> NameSet            -- ^ *type* variables, for type/kind
                                      -- misuse check for -XNoTypeInType
                -> ([Name] -> RnM (b, FreeVars)) -- ^ passed new kv_names
                -> RnM (b, FreeVars)
bindImplicitKvs _   _        []       _        thing_inside = thing_inside []
bindImplicitKvs doc mb_assoc free_kvs tv_names thing_inside
  = do { rdr_env <- getLocalRdrEnv
       ; let part_kvs lrdr@(L loc kv_rdr)
               = case lookupLocalRdrEnv rdr_env kv_rdr of
                   Just kv_name -> Left (L loc kv_name)
                   _            -> Right lrdr
             (bound_kvs, new_kvs) = partitionWith part_kvs free_kvs

          -- check whether we're mixing types & kinds illegally
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       ; type_in_type <- xoptM LangExt.TypeInType
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       ; unless type_in_type $
         mapM_ (check_tv_used_in_kind tv_names) bound_kvs

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       ; poly_kinds <- xoptM LangExt.PolyKinds
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       ; unless poly_kinds $
         addErr (badKindBndrs doc new_kvs)

          -- bind the vars and move on
       ; kv_nms <- mapM (newTyVarNameRn mb_assoc) new_kvs
       ; bindLocalNamesFV kv_nms $
         thing_inside kv_nms }
  where
      -- check to see if the variables free in a kind are bound as type
      -- variables. Assume -XNoTypeInType.
    check_tv_used_in_kind :: NameSet       -- ^ *type* variables
                          -> Located Name  -- ^ renamed var used in kind
                          -> RnM ()
    check_tv_used_in_kind tv_names (L loc kv_name)
      = when (kv_name `elemNameSet` tv_names) $
        addErrAt loc (vcat [ text "Type variable" <+> quotes (ppr kv_name) <+>
                             text "used in a kind." $$
                             text "Did you mean to use TypeInType?"
                           , pprHsDocContext doc ])


newTyVarNameRn :: Maybe a -> Located RdrName -> RnM Name
newTyVarNameRn mb_assoc (L loc rdr)
  = do { rdr_env <- getLocalRdrEnv
       ; case (mb_assoc, lookupLocalRdrEnv rdr_env rdr) of
           (Just _, Just n) -> return n
              -- Use the same Name as the parent class decl
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           _                -> newLocalBndrRn (L loc rdr) }
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---------------------
collectAnonWildCards :: LHsType Name -> [Name]
-- | Extract all wild cards from a type.
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collectAnonWildCards lty = go lty
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  where
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    go (L _ ty) = case ty of
      HsWildCardTy (AnonWildCard (L _ wc)) -> [wc]
      HsAppsTy tys                 -> gos (mapMaybe (prefix_types_only . unLoc) tys)
      HsAppTy ty1 ty2              -> go ty1 `mappend` go ty2
      HsFunTy ty1 ty2              -> go ty1 `mappend` go ty2
      HsListTy ty                  -> go ty
      HsPArrTy ty                  -> go ty
      HsTupleTy _ tys              -> gos tys
      HsOpTy ty1 _ ty2             -> go ty1 `mappend` go ty2
      HsParTy ty                   -> go ty
      HsIParamTy _ ty              -> go ty
      HsEqTy ty1 ty2               -> go ty1 `mappend` go ty2
      HsKindSig ty kind            -> go ty `mappend` go kind
      HsDocTy ty _                 -> go ty
      HsBangTy _ ty                -> go ty
      HsRecTy flds                 -> gos $ map (cd_fld_type . unLoc) flds
      HsExplicitListTy _ tys       -> gos tys
      HsExplicitTupleTy _ tys      -> gos tys
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      HsForAllTy { hst_body = ty } -> go ty
      HsQualTy { hst_ctxt = L _ ctxt
               , hst_body = ty }  -> gos ctxt `mappend` go ty
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      -- HsQuasiQuoteTy, HsSpliceTy, HsCoreTy, HsTyLit
      _ -> mempty

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    gos = mconcat . map go
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    prefix_types_only (HsAppPrefix ty) = Just ty
    prefix_types_only (HsAppInfix _)   = Nothing

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{-
*********************************************************
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*                                                       *
        ConDeclField
*                                                       *
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*********************************************************
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When renaming a ConDeclField, we have to find the FieldLabel
associated with each field.  But we already have all the FieldLabels
available (since they were brought into scope by
RnNames.getLocalNonValBinders), so we just take the list as an
argument, build a map and look them up.
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-}
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