{-# LANGUAGE FlexibleContexts  #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE RankNTypes        #-}
{-# LANGUAGE TypeFamilies      #-}

module GHC.Tc.Gen.Export (rnExports, exports_from_avail) where

import GHC.Prelude

import GHC.Hs
import GHC.Types.FieldLabel
import GHC.Builtin.Names
import GHC.Tc.Utils.Monad
import GHC.Tc.Utils.Env
import GHC.Tc.Utils.TcType
import GHC.Rename.Names
import GHC.Rename.Env
import GHC.Rename.Unbound ( reportUnboundName )
import GHC.Utils.Error
import GHC.Unit.Module
import GHC.Unit.Module.Imported
import GHC.Core.TyCon
import GHC.Utils.Outputable
import GHC.Utils.Panic
import GHC.Core.ConLike
import GHC.Core.PatSyn
import GHC.Data.Maybe
import GHC.Utils.Misc (capitalise)
import GHC.Data.FastString (fsLit)
import GHC.Driver.Env

import GHC.Types.TyThing( tyThingCategory )
import GHC.Types.Unique.Set
import GHC.Types.SrcLoc as SrcLoc
import GHC.Types.Name
import GHC.Types.Name.Env
import GHC.Types.Name.Set
import GHC.Types.Avail
import GHC.Types.SourceFile
import GHC.Types.Id
import GHC.Types.Id.Info
import GHC.Types.Name.Reader

import Control.Monad
import GHC.Driver.Session
import GHC.Parser.PostProcess ( setRdrNameSpace )
import Data.Either            ( partitionEithers )

{-
************************************************************************
*                                                                      *
\subsection{Export list processing}
*                                                                      *
************************************************************************

Processing the export list.

You might think that we should record things that appear in the export
list as ``occurrences'' (using @addOccurrenceName@), but you'd be
wrong.  We do check (here) that they are in scope, but there is no
need to slurp in their actual declaration (which is what
@addOccurrenceName@ forces).

Indeed, doing so would big trouble when compiling @PrelBase@, because
it re-exports @GHC@, which includes @takeMVar#@, whose type includes
@ConcBase.StateAndSynchVar#@, and so on...

Note [Exports of data families]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Suppose you see (#5306)
        module M where
          import X( F )
          data instance F Int = FInt
What does M export?  AvailTC F [FInt]
                  or AvailTC F [F,FInt]?
The former is strictly right because F isn't defined in this module.
But then you can never do an explicit import of M, thus
    import M( F( FInt ) )
because F isn't exported by M.  Nor can you import FInt alone from here
    import M( FInt )
because we don't have syntax to support that.  (It looks like an import of
the type FInt.)

At one point I implemented a compromise:
  * When constructing exports with no export list, or with module M(
    module M ), we add the parent to the exports as well.
  * But not when you see module M( f ), even if f is a
    class method with a parent.
  * Nor when you see module M( module N ), with N /= M.

But the compromise seemed too much of a hack, so we backed it out.
You just have to use an explicit export list:
    module M( F(..) ) where ...

Note [Avails of associated data families]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Suppose you have (#16077)

    {-# LANGUAGE TypeFamilies #-}
    module A (module A) where

    class    C a  where { data T a }
    instance C () where { data T () = D }

Because @A@ is exported explicitly, GHC tries to produce an export list
from the @GlobalRdrEnv@. In this case, it pulls out the following:

    [ C defined at A.hs:4:1
    , T parent:C defined at A.hs:4:23
    , D parent:T defined at A.hs:5:35 ]

If map these directly into avails, (via 'availFromGRE'), we get
@[C{C;}, C{T;}, T{D;}]@, which eventually gets merged into @[C{C, T;}, T{D;}]@.
That's not right, because @T{D;}@ violates the AvailTC invariant: @T@ is
exported, but it isn't the first entry in the avail!

We work around this issue by expanding GREs where the parent and child
are both type constructors into two GRES.

    T parent:C defined at A.hs:4:23

      =>

    [ T parent:C defined at A.hs:4:23
    , T defined at A.hs:4:23 ]

Then, we get  @[C{C;}, C{T;}, T{T;}, T{D;}]@, which eventually gets merged
into @[C{C, T;}, T{T, D;}]@ (which satsifies the AvailTC invariant).
-}

data ExportAccum        -- The type of the accumulating parameter of
                        -- the main worker function in rnExports
     = ExportAccum
        ExportOccMap           --  Tracks exported occurrence names
        (UniqSet ModuleName)   --  Tracks (re-)exported module names

emptyExportAccum :: ExportAccum
emptyExportAccum :: ExportAccum
emptyExportAccum = ExportOccMap -> UniqSet ModuleName -> ExportAccum
ExportAccum forall a. OccEnv a
emptyOccEnv forall a. UniqSet a
emptyUniqSet

accumExports :: (ExportAccum -> x -> TcRn (Maybe (ExportAccum, y)))
             -> [x]
             -> TcRn [y]
accumExports :: forall x y.
(ExportAccum -> x -> TcRn (Maybe (ExportAccum, y)))
-> [x] -> TcRn [y]
accumExports ExportAccum -> x -> TcRn (Maybe (ExportAccum, y))
f = forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap (forall a. [Maybe a] -> [a]
catMaybes forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a b. (a, b) -> b
snd) forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall (m :: * -> *) acc x y.
Monad m =>
(acc -> x -> m (acc, y)) -> acc -> [x] -> m (acc, [y])
mapAccumLM ExportAccum
-> x -> IOEnv (Env TcGblEnv TcLclEnv) (ExportAccum, Maybe y)
f' ExportAccum
emptyExportAccum
  where f' :: ExportAccum
-> x -> IOEnv (Env TcGblEnv TcLclEnv) (ExportAccum, Maybe y)
f' ExportAccum
acc x
x = do
          Maybe (Maybe (ExportAccum, y))
m <- forall r. TcRn r -> TcRn (Maybe r)
attemptM (ExportAccum -> x -> TcRn (Maybe (ExportAccum, y))
f ExportAccum
acc x
x)
          forall (f :: * -> *) a. Applicative f => a -> f a
pure forall a b. (a -> b) -> a -> b
$ case Maybe (Maybe (ExportAccum, y))
m of
            Just (Just (ExportAccum
acc', y
y)) -> (ExportAccum
acc', forall a. a -> Maybe a
Just y
y)
            Maybe (Maybe (ExportAccum, y))
_                     -> (ExportAccum
acc, forall a. Maybe a
Nothing)

type ExportOccMap = OccEnv (GreName, IE GhcPs)
        -- Tracks what a particular exported OccName
        --   in an export list refers to, and which item
        --   it came from.  It's illegal to export two distinct things
        --   that have the same occurrence name

rnExports :: Bool       -- False => no 'module M(..) where' header at all
          -> Maybe (LocatedL [LIE GhcPs]) -- Nothing => no explicit export list
          -> RnM TcGblEnv

        -- Complains if two distinct exports have same OccName
        -- Warns about identical exports.
        -- Complains about exports items not in scope

rnExports :: Bool -> Maybe (LocatedL [LIE GhcPs]) -> RnM TcGblEnv
rnExports Bool
explicit_mod Maybe (LocatedL [LIE GhcPs])
exports
 = forall r. TcM r -> TcM r
checkNoErrs forall a b. (a -> b) -> a -> b
$   -- Fail if anything in rnExports finds
                   -- an error fails, to avoid error cascade
   forall gbl lcl a.
WarningFlag -> TcRnIf gbl lcl a -> TcRnIf gbl lcl a
unsetWOptM WarningFlag
Opt_WarnWarningsDeprecations forall a b. (a -> b) -> a -> b
$
       -- Do not report deprecations arising from the export
       -- list, to avoid bleating about re-exporting a deprecated
       -- thing (especially via 'module Foo' export item)
   do   { HscEnv
hsc_env <- forall gbl lcl. TcRnIf gbl lcl HscEnv
getTopEnv
        ; TcGblEnv
tcg_env <- forall gbl lcl. TcRnIf gbl lcl gbl
getGblEnv
        ; let dflags :: DynFlags
dflags = HscEnv -> DynFlags
hsc_dflags HscEnv
hsc_env
              TcGblEnv { tcg_mod :: TcGblEnv -> Module
tcg_mod     = Module
this_mod
                       , tcg_rdr_env :: TcGblEnv -> GlobalRdrEnv
tcg_rdr_env = GlobalRdrEnv
rdr_env
                       , tcg_imports :: TcGblEnv -> ImportAvails
tcg_imports = ImportAvails
imports
                       , tcg_src :: TcGblEnv -> HscSource
tcg_src     = HscSource
hsc_src } = TcGblEnv
tcg_env
              default_main :: RdrName
default_main | HscEnv -> Module
mainModIs HscEnv
hsc_env forall a. Eq a => a -> a -> Bool
== Module
this_mod
                           , Just String
main_fun <- DynFlags -> Maybe String
mainFunIs DynFlags
dflags
                           = NameSpace -> FastString -> RdrName
mkUnqual NameSpace
varName (String -> FastString
fsLit String
main_fun)
                           | Bool
otherwise
                           = RdrName
main_RDR_Unqual
        ; Bool
has_main <- (Bool -> Bool
not forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall (t :: * -> *) a. Foldable t => t a -> Bool
null) forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> RdrName -> RnM [Name]
lookupInfoOccRn RdrName
default_main -- #17832

        -- If a module has no explicit header, and it has one or more main
        -- functions in scope, then add a header like
        -- "module Main(main) where ..."                               #13839
        -- See Note [Modules without a module header]
        ; let real_exports :: Maybe (LocatedL [LIE GhcPs])
real_exports
                 | Bool
explicit_mod = Maybe (LocatedL [LIE GhcPs])
exports
                 | Bool
has_main
                          = forall a. a -> Maybe a
Just (forall a an. a -> LocatedAn an a
noLocA [forall a an. a -> LocatedAn an a
noLocA (forall pass. XIEVar pass -> LIEWrappedName (IdP pass) -> IE pass
IEVar NoExtField
noExtField
                                     (forall a an. a -> LocatedAn an a
noLocA (forall name. LocatedN name -> IEWrappedName name
IEName forall a b. (a -> b) -> a -> b
$ forall a an. a -> LocatedAn an a
noLocA RdrName
default_main)))])
                        -- ToDo: the 'noLoc' here is unhelpful if 'main'
                        --       turns out to be out of scope
                 | Bool
otherwise = forall a. Maybe a
Nothing

        -- Rename the export list
        ; let do_it :: RnM (Maybe [(LIE GhcRn, [AvailInfo])], [AvailInfo])
do_it = Maybe (LocatedL [LIE GhcPs])
-> GlobalRdrEnv
-> ImportAvails
-> Module
-> RnM (Maybe [(LIE GhcRn, [AvailInfo])], [AvailInfo])
exports_from_avail Maybe (LocatedL [LIE GhcPs])
real_exports GlobalRdrEnv
rdr_env ImportAvails
imports Module
this_mod
        ; (Maybe [(GenLocated SrcSpanAnnA (IE GhcRn), [AvailInfo])]
rn_exports, [AvailInfo]
final_avails)
            <- if HscSource
hsc_src forall a. Eq a => a -> a -> Bool
== HscSource
HsigFile
                then do (Maybe
  (Maybe [(GenLocated SrcSpanAnnA (IE GhcRn), [AvailInfo])],
   [AvailInfo])
mb_r, Messages DecoratedSDoc
msgs) <- forall a. TcRn a -> TcRn (Maybe a, Messages DecoratedSDoc)
tryTc RnM (Maybe [(LIE GhcRn, [AvailInfo])], [AvailInfo])
do_it
                        case Maybe
  (Maybe [(GenLocated SrcSpanAnnA (IE GhcRn), [AvailInfo])],
   [AvailInfo])
mb_r of
                            Just (Maybe [(GenLocated SrcSpanAnnA (IE GhcRn), [AvailInfo])],
 [AvailInfo])
r  -> forall (m :: * -> *) a. Monad m => a -> m a
return (Maybe [(GenLocated SrcSpanAnnA (IE GhcRn), [AvailInfo])],
 [AvailInfo])
r
                            Maybe
  (Maybe [(GenLocated SrcSpanAnnA (IE GhcRn), [AvailInfo])],
   [AvailInfo])
Nothing -> Messages DecoratedSDoc -> TcRn ()
addMessages Messages DecoratedSDoc
msgs forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> forall env a. IOEnv env a
failM
                else forall r. TcM r -> TcM r
checkNoErrs RnM (Maybe [(LIE GhcRn, [AvailInfo])], [AvailInfo])
do_it

        -- Final processing
        ; let final_ns :: NameSet
final_ns = [AvailInfo] -> NameSet
availsToNameSetWithSelectors [AvailInfo]
final_avails

        ; String -> SDoc -> TcRn ()
traceRn String
"rnExports: Exports:" (forall a. Outputable a => a -> SDoc
ppr [AvailInfo]
final_avails)

        ; forall (m :: * -> *) a. Monad m => a -> m a
return (TcGblEnv
tcg_env { tcg_exports :: [AvailInfo]
tcg_exports    = [AvailInfo]
final_avails
                          , tcg_rn_exports :: Maybe [(LIE GhcRn, [AvailInfo])]
tcg_rn_exports = case TcGblEnv -> Maybe [(LIE GhcRn, [AvailInfo])]
tcg_rn_exports TcGblEnv
tcg_env of
                                                Maybe [(LIE GhcRn, [AvailInfo])]
Nothing -> forall a. Maybe a
Nothing
                                                Just [(LIE GhcRn, [AvailInfo])]
_  -> Maybe [(GenLocated SrcSpanAnnA (IE GhcRn), [AvailInfo])]
rn_exports
                          , tcg_dus :: DefUses
tcg_dus = TcGblEnv -> DefUses
tcg_dus TcGblEnv
tcg_env DefUses -> DefUses -> DefUses
`plusDU`
                                      NameSet -> DefUses
usesOnly NameSet
final_ns }) }

exports_from_avail :: Maybe (LocatedL [LIE GhcPs])
                         -- ^ 'Nothing' means no explicit export list
                   -> GlobalRdrEnv
                   -> ImportAvails
                         -- ^ Imported modules; this is used to test if a
                         -- @module Foo@ export is valid (it's not valid
                         -- if we didn't import @Foo@!)
                   -> Module
                   -> RnM (Maybe [(LIE GhcRn, Avails)], Avails)
                         -- (Nothing, _) <=> no explicit export list
                         -- if explicit export list is present it contains
                         -- each renamed export item together with its exported
                         -- names.

exports_from_avail :: Maybe (LocatedL [LIE GhcPs])
-> GlobalRdrEnv
-> ImportAvails
-> Module
-> RnM (Maybe [(LIE GhcRn, [AvailInfo])], [AvailInfo])
exports_from_avail Maybe (LocatedL [LIE GhcPs])
Nothing GlobalRdrEnv
rdr_env ImportAvails
_imports Module
_this_mod
   -- The same as (module M) where M is the current module name,
   -- so that's how we handle it, except we also export the data family
   -- when a data instance is exported.
  = do {
    ; Bool
warnMissingExportList <- forall gbl lcl. WarningFlag -> TcRnIf gbl lcl Bool
woptM WarningFlag
Opt_WarnMissingExportList
    ; WarningFlag -> Bool -> SDoc -> TcRn ()
warnIfFlag WarningFlag
Opt_WarnMissingExportList
        Bool
warnMissingExportList
        (ModuleName -> SDoc
missingModuleExportWarn forall a b. (a -> b) -> a -> b
$ forall unit. GenModule unit -> ModuleName
moduleName Module
_this_mod)
    ; let avails :: [AvailInfo]
avails =
            forall a b. (a -> b) -> [a] -> [b]
map AvailInfo -> AvailInfo
fix_faminst forall b c a. (b -> c) -> (a -> b) -> a -> c
. [GlobalRdrElt] -> [AvailInfo]
gresToAvailInfo
              forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a. (a -> Bool) -> [a] -> [a]
filter GlobalRdrElt -> Bool
isLocalGRE forall b c a. (b -> c) -> (a -> b) -> a -> c
. GlobalRdrEnv -> [GlobalRdrElt]
globalRdrEnvElts forall a b. (a -> b) -> a -> b
$ GlobalRdrEnv
rdr_env
    ; forall (m :: * -> *) a. Monad m => a -> m a
return (forall a. Maybe a
Nothing, [AvailInfo]
avails) }
  where
    -- #11164: when we define a data instance
    -- but not data family, re-export the family
    -- Even though we don't check whether this is actually a data family
    -- only data families can locally define subordinate things (`ns` here)
    -- without locally defining (and instead importing) the parent (`n`)
    fix_faminst :: AvailInfo -> AvailInfo
fix_faminst avail :: AvailInfo
avail@(AvailTC Name
n [GreName]
ns)
      | AvailInfo -> Bool
availExportsDecl AvailInfo
avail = AvailInfo
avail
      | Bool
otherwise = Name -> [GreName] -> AvailInfo
AvailTC Name
n (Name -> GreName
NormalGreName Name
nforall a. a -> [a] -> [a]
:[GreName]
ns)
    fix_faminst AvailInfo
avail = AvailInfo
avail


exports_from_avail (Just (L SrcSpanAnnL
_ [LIE GhcPs]
rdr_items)) GlobalRdrEnv
rdr_env ImportAvails
imports Module
this_mod
  = do [(GenLocated SrcSpanAnnA (IE GhcRn), [AvailInfo])]
ie_avails <- forall x y.
(ExportAccum -> x -> TcRn (Maybe (ExportAccum, y)))
-> [x] -> TcRn [y]
accumExports ExportAccum
-> LIE GhcPs -> RnM (Maybe (ExportAccum, (LIE GhcRn, [AvailInfo])))
do_litem [LIE GhcPs]
rdr_items
       let final_exports :: [AvailInfo]
final_exports = [AvailInfo] -> [AvailInfo]
nubAvails (forall (t :: * -> *) a b. Foldable t => (a -> [b]) -> t a -> [b]
concatMap forall a b. (a, b) -> b
snd [(GenLocated SrcSpanAnnA (IE GhcRn), [AvailInfo])]
ie_avails) -- Combine families
       forall (m :: * -> *) a. Monad m => a -> m a
return (forall a. a -> Maybe a
Just [(GenLocated SrcSpanAnnA (IE GhcRn), [AvailInfo])]
ie_avails, [AvailInfo]
final_exports)
  where
    do_litem :: ExportAccum -> LIE GhcPs
             -> RnM (Maybe (ExportAccum, (LIE GhcRn, Avails)))
    do_litem :: ExportAccum
-> LIE GhcPs -> RnM (Maybe (ExportAccum, (LIE GhcRn, [AvailInfo])))
do_litem ExportAccum
acc LIE GhcPs
lie = forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan (forall a e. GenLocated (SrcSpanAnn' a) e -> SrcSpan
getLocA LIE GhcPs
lie) (ExportAccum
-> LIE GhcPs -> RnM (Maybe (ExportAccum, (LIE GhcRn, [AvailInfo])))
exports_from_item ExportAccum
acc LIE GhcPs
lie)

    -- Maps a parent to its in-scope children
    kids_env :: NameEnv [GlobalRdrElt]
    kids_env :: NameEnv [GlobalRdrElt]
kids_env = [GlobalRdrElt] -> NameEnv [GlobalRdrElt]
mkChildEnv (GlobalRdrEnv -> [GlobalRdrElt]
globalRdrEnvElts GlobalRdrEnv
rdr_env)

    -- See Note [Avails of associated data families]
    expand_tyty_gre :: GlobalRdrElt -> [GlobalRdrElt]
    expand_tyty_gre :: GlobalRdrElt -> [GlobalRdrElt]
expand_tyty_gre (gre :: GlobalRdrElt
gre@GRE { gre_par :: GlobalRdrElt -> Parent
gre_par = ParentIs Name
p })
      | Name -> Bool
isTyConName Name
p, Name -> Bool
isTyConName (GlobalRdrElt -> Name
greMangledName GlobalRdrElt
gre) = [GlobalRdrElt
gre, GlobalRdrElt
gre{ gre_par :: Parent
gre_par = Parent
NoParent }]
    expand_tyty_gre GlobalRdrElt
gre = [GlobalRdrElt
gre]

    imported_modules :: [ModuleName]
imported_modules = [ ImportedModsVal -> ModuleName
imv_name ImportedModsVal
imv
                       | [ImportedBy]
xs <- forall a. ModuleEnv a -> [a]
moduleEnvElts forall a b. (a -> b) -> a -> b
$ ImportAvails -> ImportedMods
imp_mods ImportAvails
imports
                       , ImportedModsVal
imv <- [ImportedBy] -> [ImportedModsVal]
importedByUser [ImportedBy]
xs ]

    exports_from_item :: ExportAccum -> LIE GhcPs
                      -> RnM (Maybe (ExportAccum, (LIE GhcRn, Avails)))
    exports_from_item :: ExportAccum
-> LIE GhcPs -> RnM (Maybe (ExportAccum, (LIE GhcRn, [AvailInfo])))
exports_from_item (ExportAccum ExportOccMap
occs UniqSet ModuleName
earlier_mods)
                      (L SrcSpanAnnA
loc ie :: IE GhcPs
ie@(IEModuleContents XIEModuleContents GhcPs
_ lmod :: XRec GhcPs ModuleName
lmod@(L SrcSpanAnnA
_ ModuleName
mod)))
        | ModuleName
mod forall a. Uniquable a => a -> UniqSet a -> Bool
`elementOfUniqSet` UniqSet ModuleName
earlier_mods    -- Duplicate export of M
        = do { WarningFlag -> Bool -> SDoc -> TcRn ()
warnIfFlag WarningFlag
Opt_WarnDuplicateExports Bool
True
                          (ModuleName -> SDoc
dupModuleExport ModuleName
mod) ;
               forall (m :: * -> *) a. Monad m => a -> m a
return forall a. Maybe a
Nothing }

        | Bool
otherwise
        = do { let { exportValid :: Bool
exportValid = (ModuleName
mod forall (t :: * -> *) a. (Foldable t, Eq a) => a -> t a -> Bool
`elem` [ModuleName]
imported_modules)
                                Bool -> Bool -> Bool
|| (forall unit. GenModule unit -> ModuleName
moduleName Module
this_mod forall a. Eq a => a -> a -> Bool
== ModuleName
mod)
                   ; gre_prs :: [(GlobalRdrElt, GlobalRdrElt)]
gre_prs     = ModuleName -> [GlobalRdrElt] -> [(GlobalRdrElt, GlobalRdrElt)]
pickGREsModExp ModuleName
mod (GlobalRdrEnv -> [GlobalRdrElt]
globalRdrEnvElts GlobalRdrEnv
rdr_env)
                   ; new_exports :: [AvailInfo]
new_exports = [ GlobalRdrElt -> AvailInfo
availFromGRE GlobalRdrElt
gre'
                                   | (GlobalRdrElt
gre, GlobalRdrElt
_) <- [(GlobalRdrElt, GlobalRdrElt)]
gre_prs
                                   , GlobalRdrElt
gre' <- GlobalRdrElt -> [GlobalRdrElt]
expand_tyty_gre GlobalRdrElt
gre ]
                   ; all_gres :: [GlobalRdrElt]
all_gres    = forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr (\(GlobalRdrElt
gre1,GlobalRdrElt
gre2) [GlobalRdrElt]
gres -> GlobalRdrElt
gre1 forall a. a -> [a] -> [a]
: GlobalRdrElt
gre2 forall a. a -> [a] -> [a]
: [GlobalRdrElt]
gres) [] [(GlobalRdrElt, GlobalRdrElt)]
gre_prs
                   ; mods :: UniqSet ModuleName
mods        = forall a. Uniquable a => UniqSet a -> a -> UniqSet a
addOneToUniqSet UniqSet ModuleName
earlier_mods ModuleName
mod
                   }

             ; Bool -> SDoc -> TcRn ()
checkErr Bool
exportValid (ModuleName -> SDoc
moduleNotImported ModuleName
mod)
             ; WarningFlag -> Bool -> SDoc -> TcRn ()
warnIfFlag WarningFlag
Opt_WarnDodgyExports
                          (Bool
exportValid Bool -> Bool -> Bool
&& forall (t :: * -> *) a. Foldable t => t a -> Bool
null [(GlobalRdrElt, GlobalRdrElt)]
gre_prs)
                          (ModuleName -> SDoc
nullModuleExport ModuleName
mod)

             ; String -> SDoc -> TcRn ()
traceRn String
"efa" (forall a. Outputable a => a -> SDoc
ppr ModuleName
mod SDoc -> SDoc -> SDoc
$$ forall a. Outputable a => a -> SDoc
ppr [GlobalRdrElt]
all_gres)
             ; [GlobalRdrElt] -> TcRn ()
addUsedGREs [GlobalRdrElt]
all_gres

             ; ExportOccMap
occs' <- IE GhcPs -> ExportOccMap -> [AvailInfo] -> RnM ExportOccMap
check_occs IE GhcPs
ie ExportOccMap
occs [AvailInfo]
new_exports
                      -- This check_occs not only finds conflicts
                      -- between this item and others, but also
                      -- internally within this item.  That is, if
                      -- 'M.x' is in scope in several ways, we'll have
                      -- several members of mod_avails with the same
                      -- OccName.
             ; String -> SDoc -> TcRn ()
traceRn String
"export_mod"
                       ([SDoc] -> SDoc
vcat [ forall a. Outputable a => a -> SDoc
ppr ModuleName
mod
                             , forall a. Outputable a => a -> SDoc
ppr [AvailInfo]
new_exports ])

             ; forall (m :: * -> *) a. Monad m => a -> m a
return (forall a. a -> Maybe a
Just ( ExportOccMap -> UniqSet ModuleName -> ExportAccum
ExportAccum ExportOccMap
occs' UniqSet ModuleName
mods
                            , ( forall l e. l -> e -> GenLocated l e
L SrcSpanAnnA
loc (forall pass.
XIEModuleContents pass -> XRec pass ModuleName -> IE pass
IEModuleContents NoExtField
noExtField XRec GhcPs ModuleName
lmod)
                              , [AvailInfo]
new_exports))) }

    exports_from_item acc :: ExportAccum
acc@(ExportAccum ExportOccMap
occs UniqSet ModuleName
mods) (L SrcSpanAnnA
loc IE GhcPs
ie)
        | Just IE GhcRn
new_ie <- IE GhcPs -> Maybe (IE GhcRn)
lookup_doc_ie IE GhcPs
ie
        = forall (m :: * -> *) a. Monad m => a -> m a
return (forall a. a -> Maybe a
Just (ExportAccum
acc, (forall l e. l -> e -> GenLocated l e
L SrcSpanAnnA
loc IE GhcRn
new_ie, [])))

        | Bool
otherwise
        = do (IE GhcRn
new_ie, AvailInfo
avail) <- IE GhcPs -> RnM (IE GhcRn, AvailInfo)
lookup_ie IE GhcPs
ie
             if Name -> Bool
isUnboundName (forall (p :: Pass). IE (GhcPass p) -> IdP (GhcPass p)
ieName IE GhcRn
new_ie)
                  then forall (m :: * -> *) a. Monad m => a -> m a
return forall a. Maybe a
Nothing    -- Avoid error cascade
                  else do

                    ExportOccMap
occs' <- IE GhcPs -> ExportOccMap -> [AvailInfo] -> RnM ExportOccMap
check_occs IE GhcPs
ie ExportOccMap
occs [AvailInfo
avail]

                    forall (m :: * -> *) a. Monad m => a -> m a
return (forall a. a -> Maybe a
Just ( ExportOccMap -> UniqSet ModuleName -> ExportAccum
ExportAccum ExportOccMap
occs' UniqSet ModuleName
mods
                                 , (forall l e. l -> e -> GenLocated l e
L SrcSpanAnnA
loc IE GhcRn
new_ie, [AvailInfo
avail])))

    -------------
    lookup_ie :: IE GhcPs -> RnM (IE GhcRn, AvailInfo)
    lookup_ie :: IE GhcPs -> RnM (IE GhcRn, AvailInfo)
lookup_ie (IEVar XIEVar GhcPs
_ (L SrcSpanAnnA
l IEWrappedName (IdP GhcPs)
rdr))
        = do (Name
name, AvailInfo
avail) <- RdrName -> RnM (Name, AvailInfo)
lookupGreAvailRn forall a b. (a -> b) -> a -> b
$ forall name. IEWrappedName name -> name
ieWrappedName IEWrappedName (IdP GhcPs)
rdr
             forall (m :: * -> *) a. Monad m => a -> m a
return (forall pass. XIEVar pass -> LIEWrappedName (IdP pass) -> IE pass
IEVar NoExtField
noExtField (forall l e. l -> e -> GenLocated l e
L SrcSpanAnnA
l (forall name1 name2.
IEWrappedName name1 -> name2 -> IEWrappedName name2
replaceWrappedName IEWrappedName (IdP GhcPs)
rdr Name
name)), AvailInfo
avail)

    lookup_ie (IEThingAbs XIEThingAbs GhcPs
_ (L SrcSpanAnnA
l IEWrappedName (IdP GhcPs)
rdr))
        = do (Name
name, AvailInfo
avail) <- RdrName -> RnM (Name, AvailInfo)
lookupGreAvailRn forall a b. (a -> b) -> a -> b
$ forall name. IEWrappedName name -> name
ieWrappedName IEWrappedName (IdP GhcPs)
rdr
             forall (m :: * -> *) a. Monad m => a -> m a
return (forall pass.
XIEThingAbs pass -> LIEWrappedName (IdP pass) -> IE pass
IEThingAbs forall a. EpAnn a
noAnn (forall l e. l -> e -> GenLocated l e
L SrcSpanAnnA
l (forall name1 name2.
IEWrappedName name1 -> name2 -> IEWrappedName name2
replaceWrappedName IEWrappedName (IdP GhcPs)
rdr Name
name))
                    , AvailInfo
avail)

    lookup_ie ie :: IE GhcPs
ie@(IEThingAll XIEThingAll GhcPs
_ GenLocated SrcSpanAnnA (IEWrappedName (IdP GhcPs))
n')
        = do
            (Located Name
n, [Name]
avail, [FieldLabel]
flds) <- IE GhcPs
-> LIEWrappedName RdrName
-> RnM (Located Name, [Name], [FieldLabel])
lookup_ie_all IE GhcPs
ie GenLocated SrcSpanAnnA (IEWrappedName (IdP GhcPs))
n'
            let name :: Name
name = forall l e. GenLocated l e -> e
unLoc Located Name
n
            forall (m :: * -> *) a. Monad m => a -> m a
return (forall pass.
XIEThingAll pass -> LIEWrappedName (IdP pass) -> IE pass
IEThingAll forall a. EpAnn a
noAnn (forall name1 name2.
LIEWrappedName name1 -> name2 -> LIEWrappedName name2
replaceLWrappedName GenLocated SrcSpanAnnA (IEWrappedName (IdP GhcPs))
n' (forall l e. GenLocated l e -> e
unLoc Located Name
n))
                   , Name -> [Name] -> [FieldLabel] -> AvailInfo
availTC Name
name (Name
nameforall a. a -> [a] -> [a]
:[Name]
avail) [FieldLabel]
flds)


    lookup_ie ie :: IE GhcPs
ie@(IEThingWith XIEThingWith GhcPs
_ GenLocated SrcSpanAnnA (IEWrappedName (IdP GhcPs))
l IEWildcard
wc [GenLocated SrcSpanAnnA (IEWrappedName (IdP GhcPs))]
sub_rdrs)
        = do
            (Located Name
lname, [LIEWrappedName Name]
subs, [Name]
avails, [Located FieldLabel]
flds)
              <- forall (p :: Pass) a.
OutputableBndrId p =>
IE (GhcPass p) -> TcM a -> TcM a
addExportErrCtxt IE GhcPs
ie forall a b. (a -> b) -> a -> b
$ LIEWrappedName RdrName
-> [LIEWrappedName RdrName]
-> TcM
     (Located Name, [LIEWrappedName Name], [Name], [Located FieldLabel])
lookup_ie_with GenLocated SrcSpanAnnA (IEWrappedName (IdP GhcPs))
l [GenLocated SrcSpanAnnA (IEWrappedName (IdP GhcPs))]
sub_rdrs
            (Located Name
_, [Name]
all_avail, [FieldLabel]
all_flds) <-
              case IEWildcard
wc of
                IEWildcard
NoIEWildcard -> forall (m :: * -> *) a. Monad m => a -> m a
return (Located Name
lname, [], [])
                IEWildcard Int
_ -> IE GhcPs
-> LIEWrappedName RdrName
-> RnM (Located Name, [Name], [FieldLabel])
lookup_ie_all IE GhcPs
ie GenLocated SrcSpanAnnA (IEWrappedName (IdP GhcPs))
l
            let name :: Name
name = forall l e. GenLocated l e -> e
unLoc Located Name
lname
            let flds' :: [Located FieldLabel]
flds' = [Located FieldLabel]
flds forall a. [a] -> [a] -> [a]
++ (forall a b. (a -> b) -> [a] -> [b]
map forall e. e -> Located e
noLoc [FieldLabel]
all_flds)
            forall (m :: * -> *) a. Monad m => a -> m a
return (forall pass.
XIEThingWith pass
-> LIEWrappedName (IdP pass)
-> IEWildcard
-> [LIEWrappedName (IdP pass)]
-> IE pass
IEThingWith [Located FieldLabel]
flds' (forall name1 name2.
LIEWrappedName name1 -> name2 -> LIEWrappedName name2
replaceLWrappedName GenLocated SrcSpanAnnA (IEWrappedName (IdP GhcPs))
l Name
name) IEWildcard
wc [LIEWrappedName Name]
subs,
                    Name -> [Name] -> [FieldLabel] -> AvailInfo
availTC Name
name (Name
name forall a. a -> [a] -> [a]
: [Name]
avails forall a. [a] -> [a] -> [a]
++ [Name]
all_avail)
                                 (forall a b. (a -> b) -> [a] -> [b]
map forall l e. GenLocated l e -> e
unLoc [Located FieldLabel]
flds forall a. [a] -> [a] -> [a]
++ [FieldLabel]
all_flds))


    lookup_ie IE GhcPs
_ = forall a. String -> a
panic String
"lookup_ie"    -- Other cases covered earlier


    lookup_ie_with :: LIEWrappedName RdrName -> [LIEWrappedName RdrName]
                   -> RnM (Located Name, [LIEWrappedName Name], [Name],
                           [Located FieldLabel])
    lookup_ie_with :: LIEWrappedName RdrName
-> [LIEWrappedName RdrName]
-> TcM
     (Located Name, [LIEWrappedName Name], [Name], [Located FieldLabel])
lookup_ie_with (L SrcSpanAnnA
l IEWrappedName RdrName
rdr) [LIEWrappedName RdrName]
sub_rdrs
        = do Name
name <- RdrName -> RnM Name
lookupGlobalOccRn forall a b. (a -> b) -> a -> b
$ forall name. IEWrappedName name -> name
ieWrappedName IEWrappedName RdrName
rdr
             ([LIEWrappedName Name]
non_flds, [Located FieldLabel]
flds) <- Name
-> [LIEWrappedName RdrName]
-> RnM ([LIEWrappedName Name], [Located FieldLabel])
lookupChildrenExport Name
name [LIEWrappedName RdrName]
sub_rdrs
             if Name -> Bool
isUnboundName Name
name
                then forall (m :: * -> *) a. Monad m => a -> m a
return (forall l e. l -> e -> GenLocated l e
L (forall a. SrcSpanAnn' a -> SrcSpan
locA SrcSpanAnnA
l) Name
name, [], [Name
name], [])
                else forall (m :: * -> *) a. Monad m => a -> m a
return (forall l e. l -> e -> GenLocated l e
L (forall a. SrcSpanAnn' a -> SrcSpan
locA SrcSpanAnnA
l) Name
name, [LIEWrappedName Name]
non_flds
                            , forall a b. (a -> b) -> [a] -> [b]
map (forall name. IEWrappedName name -> name
ieWrappedName forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall l e. GenLocated l e -> e
unLoc) [LIEWrappedName Name]
non_flds
                            , [Located FieldLabel]
flds)

    lookup_ie_all :: IE GhcPs -> LIEWrappedName RdrName
                  -> RnM (Located Name, [Name], [FieldLabel])
    lookup_ie_all :: IE GhcPs
-> LIEWrappedName RdrName
-> RnM (Located Name, [Name], [FieldLabel])
lookup_ie_all IE GhcPs
ie (L SrcSpanAnnA
l IEWrappedName RdrName
rdr) =
          do Name
name <- RdrName -> RnM Name
lookupGlobalOccRn forall a b. (a -> b) -> a -> b
$ forall name. IEWrappedName name -> name
ieWrappedName IEWrappedName RdrName
rdr
             let gres :: [GlobalRdrElt]
gres = forall a. NameEnv [a] -> Name -> [a]
findChildren NameEnv [GlobalRdrElt]
kids_env Name
name
                 ([Name]
non_flds, [FieldLabel]
flds) = [GlobalRdrElt] -> ([Name], [FieldLabel])
classifyGREs [GlobalRdrElt]
gres
             RdrName -> [GlobalRdrElt] -> TcRn ()
addUsedKids (forall name. IEWrappedName name -> name
ieWrappedName IEWrappedName RdrName
rdr) [GlobalRdrElt]
gres
             Bool
warnDodgyExports <- forall gbl lcl. WarningFlag -> TcRnIf gbl lcl Bool
woptM WarningFlag
Opt_WarnDodgyExports
             forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
when (forall (t :: * -> *) a. Foldable t => t a -> Bool
null [GlobalRdrElt]
gres) forall a b. (a -> b) -> a -> b
$
                  if Name -> Bool
isTyConName Name
name
                  then forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
when Bool
warnDodgyExports forall a b. (a -> b) -> a -> b
$
                           WarnReason -> SDoc -> TcRn ()
addWarn (WarningFlag -> WarnReason
Reason WarningFlag
Opt_WarnDodgyExports)
                                   (Name -> SDoc
dodgyExportWarn Name
name)
                  else -- This occurs when you export T(..), but
                       -- only import T abstractly, or T is a synonym.
                       SDoc -> TcRn ()
addErr (IE GhcPs -> SDoc
exportItemErr IE GhcPs
ie)
             forall (m :: * -> *) a. Monad m => a -> m a
return (forall l e. l -> e -> GenLocated l e
L (forall a. SrcSpanAnn' a -> SrcSpan
locA SrcSpanAnnA
l) Name
name, [Name]
non_flds, [FieldLabel]
flds)

    -------------
    lookup_doc_ie :: IE GhcPs -> Maybe (IE GhcRn)
    lookup_doc_ie :: IE GhcPs -> Maybe (IE GhcRn)
lookup_doc_ie (IEGroup XIEGroup GhcPs
_ Int
lev HsDocString
doc) = forall a. a -> Maybe a
Just (forall pass. XIEGroup pass -> Int -> HsDocString -> IE pass
IEGroup NoExtField
noExtField Int
lev HsDocString
doc)
    lookup_doc_ie (IEDoc XIEDoc GhcPs
_ HsDocString
doc)       = forall a. a -> Maybe a
Just (forall pass. XIEDoc pass -> HsDocString -> IE pass
IEDoc NoExtField
noExtField HsDocString
doc)
    lookup_doc_ie (IEDocNamed XIEDocNamed GhcPs
_ String
str)  = forall a. a -> Maybe a
Just (forall pass. XIEDocNamed pass -> String -> IE pass
IEDocNamed NoExtField
noExtField String
str)
    lookup_doc_ie IE GhcPs
_ = forall a. Maybe a
Nothing

    -- In an export item M.T(A,B,C), we want to treat the uses of
    -- A,B,C as if they were M.A, M.B, M.C
    -- Happily pickGREs does just the right thing
    addUsedKids :: RdrName -> [GlobalRdrElt] -> RnM ()
    addUsedKids :: RdrName -> [GlobalRdrElt] -> TcRn ()
addUsedKids RdrName
parent_rdr [GlobalRdrElt]
kid_gres = [GlobalRdrElt] -> TcRn ()
addUsedGREs (RdrName -> [GlobalRdrElt] -> [GlobalRdrElt]
pickGREs RdrName
parent_rdr [GlobalRdrElt]
kid_gres)

classifyGREs :: [GlobalRdrElt] -> ([Name], [FieldLabel])
classifyGREs :: [GlobalRdrElt] -> ([Name], [FieldLabel])
classifyGREs = [GreName] -> ([Name], [FieldLabel])
partitionGreNames forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a b. (a -> b) -> [a] -> [b]
map GlobalRdrElt -> GreName
gre_name

-- Renaming and typechecking of exports happens after everything else has
-- been typechecked.

{-
Note [Modules without a module header]
--------------------------------------------------

The Haskell 2010 report says in section 5.1:

>> An abbreviated form of module, consisting only of the module body, is
>> permitted. If this is used, the header is assumed to be
>> ‘module Main(main) where’.

For modules without a module header, this is implemented the
following way:

If the module has a main function in scope:
   Then create a module header and export the main function,
   as if a module header like ‘module Main(main) where...’ would exist.
   This has the effect to mark the main function and all top level
   functions called directly or indirectly via main as 'used',
   and later on, unused top-level functions can be reported correctly.
   There is no distinction between GHC and GHCi.
If the module has several main functions in scope:
   Then generate a header as above. The ambiguity is reported later in
   module  `GHC.Tc.Module` function `check_main`.
If the module has NO main function:
   Then export all top-level functions. This marks all top level
   functions as 'used'.
   In GHCi this has the effect, that we don't get any 'non-used' warnings.
   In GHC, however, the 'has-main-module' check in GHC.Tc.Module.checkMain
   fires, and we get the error:
      The IO action ‘main’ is not defined in module ‘Main’
-}


-- Renaming exports lists is a minefield. Five different things can appear in
-- children export lists ( T(A, B, C) ).
-- 1. Record selectors
-- 2. Type constructors
-- 3. Data constructors
-- 4. Pattern Synonyms
-- 5. Pattern Synonym Selectors
--
-- However, things get put into weird name spaces.
-- 1. Some type constructors are parsed as variables (-.->) for example.
-- 2. All data constructors are parsed as type constructors
-- 3. When there is ambiguity, we default type constructors to data
-- constructors and require the explicit `type` keyword for type
-- constructors.
--
-- This function first establishes the possible namespaces that an
-- identifier might be in (`choosePossibleNameSpaces`).
--
-- Then for each namespace in turn, tries to find the correct identifier
-- there returning the first positive result or the first terminating
-- error.
--



lookupChildrenExport :: Name -> [LIEWrappedName RdrName]
                     -> RnM ([LIEWrappedName Name], [Located FieldLabel])
lookupChildrenExport :: Name
-> [LIEWrappedName RdrName]
-> RnM ([LIEWrappedName Name], [Located FieldLabel])
lookupChildrenExport Name
spec_parent [LIEWrappedName RdrName]
rdr_items =
  do
    [Either (LIEWrappedName Name) (Located FieldLabel)]
xs <- forall a b. (a -> TcRn b) -> [a] -> TcRn [b]
mapAndReportM LIEWrappedName RdrName
-> RnM (Either (LIEWrappedName Name) (Located FieldLabel))
doOne [LIEWrappedName RdrName]
rdr_items
    forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall a b. [Either a b] -> ([a], [b])
partitionEithers [Either (LIEWrappedName Name) (Located FieldLabel)]
xs
    where
        -- Pick out the possible namespaces in order of priority
        -- This is a consequence of how the parser parses all
        -- data constructors as type constructors.
        choosePossibleNamespaces :: NameSpace -> [NameSpace]
        choosePossibleNamespaces :: NameSpace -> [NameSpace]
choosePossibleNamespaces NameSpace
ns
          | NameSpace
ns forall a. Eq a => a -> a -> Bool
== NameSpace
varName = [NameSpace
varName, NameSpace
tcName]
          | NameSpace
ns forall a. Eq a => a -> a -> Bool
== NameSpace
tcName  = [NameSpace
dataName, NameSpace
tcName]
          | Bool
otherwise = [NameSpace
ns]
        -- Process an individual child
        doOne :: LIEWrappedName RdrName
              -> RnM (Either (LIEWrappedName Name) (Located FieldLabel))
        doOne :: LIEWrappedName RdrName
-> RnM (Either (LIEWrappedName Name) (Located FieldLabel))
doOne LIEWrappedName RdrName
n = do

          let bareName :: RdrName
bareName = (forall name. IEWrappedName name -> name
ieWrappedName forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall l e. GenLocated l e -> e
unLoc) LIEWrappedName RdrName
n
              lkup :: NameSpace -> RnM ChildLookupResult
lkup NameSpace
v = Bool -> Bool -> Name -> RdrName -> RnM ChildLookupResult
lookupSubBndrOcc_helper Bool
False Bool
True
                        Name
spec_parent (RdrName -> NameSpace -> RdrName
setRdrNameSpace RdrName
bareName NameSpace
v)

          ChildLookupResult
name <-  [RnM ChildLookupResult] -> RnM ChildLookupResult
combineChildLookupResult forall a b. (a -> b) -> a -> b
$ forall a b. (a -> b) -> [a] -> [b]
map NameSpace -> RnM ChildLookupResult
lkup forall a b. (a -> b) -> a -> b
$
                   NameSpace -> [NameSpace]
choosePossibleNamespaces (RdrName -> NameSpace
rdrNameSpace RdrName
bareName)
          String -> SDoc -> TcRn ()
traceRn String
"lookupChildrenExport" (forall a. Outputable a => a -> SDoc
ppr ChildLookupResult
name)
          -- Default to data constructors for slightly better error
          -- messages
          let unboundName :: RdrName
              unboundName :: RdrName
unboundName = if RdrName -> NameSpace
rdrNameSpace RdrName
bareName forall a. Eq a => a -> a -> Bool
== NameSpace
varName
                                then RdrName
bareName
                                else RdrName -> NameSpace -> RdrName
setRdrNameSpace RdrName
bareName NameSpace
dataName

          case ChildLookupResult
name of
            ChildLookupResult
NameNotFound -> do { Name
ub <- RdrName -> RnM Name
reportUnboundName RdrName
unboundName
                               ; let l :: SrcSpanAnnA
l = forall l e. GenLocated l e -> l
getLoc LIEWrappedName RdrName
n
                               ; forall (m :: * -> *) a. Monad m => a -> m a
return (forall a b. a -> Either a b
Left (forall l e. l -> e -> GenLocated l e
L SrcSpanAnnA
l (forall name. LocatedN name -> IEWrappedName name
IEName (forall l e. l -> e -> GenLocated l e
L (forall a. SrcSpanAnn' a -> SrcSpanAnnN
la2na SrcSpanAnnA
l) Name
ub))))}
            FoundChild Parent
par GreName
child -> do { Name -> Parent -> GreName -> TcRn ()
checkPatSynParent Name
spec_parent Parent
par GreName
child
                                       ; forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ case GreName
child of
                                           FieldGreName FieldLabel
fl   -> forall a b. b -> Either a b
Right (forall l e. l -> e -> GenLocated l e
L (forall a e. GenLocated (SrcSpanAnn' a) e -> SrcSpan
getLocA LIEWrappedName RdrName
n) FieldLabel
fl)
                                           NormalGreName  Name
name -> forall a b. a -> Either a b
Left (forall name1 name2.
LIEWrappedName name1 -> name2 -> LIEWrappedName name2
replaceLWrappedName LIEWrappedName RdrName
n Name
name)
                                       }
            IncorrectParent Name
p GreName
c [Name]
gs -> forall a. Name -> GreName -> [Name] -> TcM a
failWithDcErr Name
p GreName
c [Name]
gs


-- Note: [Typing Pattern Synonym Exports]
-- It proved quite a challenge to precisely specify which pattern synonyms
-- should be allowed to be bundled with which type constructors.
-- In the end it was decided to be quite liberal in what we allow. Below is
-- how Simon described the implementation.
--
-- "Personally I think we should Keep It Simple.  All this talk of
--  satisfiability makes me shiver.  I suggest this: allow T( P ) in all
--   situations except where `P`'s type is ''visibly incompatible'' with
--   `T`.
--
--    What does "visibly incompatible" mean?  `P` is visibly incompatible
--    with
--     `T` if
--       * `P`'s type is of form `... -> S t1 t2`
--       * `S` is a data/newtype constructor distinct from `T`
--
--  Nothing harmful happens if we allow `P` to be exported with
--  a type it can't possibly be useful for, but specifying a tighter
--  relationship is very awkward as you have discovered."
--
-- Note that this allows *any* pattern synonym to be bundled with any
-- datatype type constructor. For example, the following pattern `P` can be
-- bundled with any type.
--
-- ```
-- pattern P :: (A ~ f) => f
-- ```
--
-- So we provide basic type checking in order to help the user out, most
-- pattern synonyms are defined with definite type constructors, but don't
-- actually prevent a library author completely confusing their users if
-- they want to.
--
-- So, we check for exactly four things
-- 1. The name arises from a pattern synonym definition. (Either a pattern
--    synonym constructor or a pattern synonym selector)
-- 2. The pattern synonym is only bundled with a datatype or newtype.
-- 3. Check that the head of the result type constructor is an actual type
--    constructor and not a type variable. (See above example)
-- 4. Is so, check that this type constructor is the same as the parent
--    type constructor.
--
--
-- Note: [Types of TyCon]
--
-- This check appears to be overly complicated, Richard asked why it
-- is not simply just `isAlgTyCon`. The answer for this is that
-- a classTyCon is also an `AlgTyCon` which we explicitly want to disallow.
-- (It is either a newtype or data depending on the number of methods)
--

-- | Given a resolved name in the children export list and a parent. Decide
-- whether we are allowed to export the child with the parent.
-- Invariant: gre_par == NoParent
-- See note [Typing Pattern Synonym Exports]
checkPatSynParent :: Name    -- ^ Alleged parent type constructor
                             -- User wrote T( P, Q )
                  -> Parent  -- The parent of P we discovered
                  -> GreName   -- ^ Either a
                             --   a) Pattern Synonym Constructor
                             --   b) A pattern synonym selector
                  -> TcM ()  -- Fails if wrong parent
checkPatSynParent :: Name -> Parent -> GreName -> TcRn ()
checkPatSynParent Name
_ (ParentIs {}) GreName
_
  = forall (m :: * -> *) a. Monad m => a -> m a
return ()

checkPatSynParent Name
parent Parent
NoParent GreName
gname
  | Name -> Bool
isUnboundName Name
parent -- Avoid an error cascade
  = forall (m :: * -> *) a. Monad m => a -> m a
return ()

  | Bool
otherwise
  = do { TyCon
parent_ty_con  <- Name -> TcM TyCon
tcLookupTyCon Name
parent
       ; TyThing
mpat_syn_thing <- Name -> TcM TyThing
tcLookupGlobal (GreName -> Name
greNameMangledName GreName
gname)

        -- 1. Check that the Id was actually from a thing associated with patsyns
       ; case TyThing
mpat_syn_thing of
            AnId Id
i | Id -> Bool
isId Id
i
                   , RecSelId { sel_tycon :: IdDetails -> RecSelParent
sel_tycon = RecSelPatSyn PatSyn
p } <- Id -> IdDetails
idDetails Id
i
                   -> SDoc -> TyCon -> PatSyn -> TcRn ()
handle_pat_syn (GreName -> SDoc
selErr GreName
gname) TyCon
parent_ty_con PatSyn
p

            AConLike (PatSynCon PatSyn
p) -> SDoc -> TyCon -> PatSyn -> TcRn ()
handle_pat_syn (PatSyn -> SDoc
psErr PatSyn
p) TyCon
parent_ty_con PatSyn
p

            TyThing
_ -> forall a. Name -> GreName -> [Name] -> TcM a
failWithDcErr Name
parent GreName
gname [] }
  where
    psErr :: PatSyn -> SDoc
psErr  = forall o. Outputable o => String -> o -> SDoc
exportErrCtxt String
"pattern synonym"
    selErr :: GreName -> SDoc
selErr = forall o. Outputable o => String -> o -> SDoc
exportErrCtxt String
"pattern synonym record selector"

    assocClassErr :: SDoc
    assocClassErr :: SDoc
assocClassErr = String -> SDoc
text String
"Pattern synonyms can be bundled only with datatypes."

    handle_pat_syn :: SDoc
                   -> TyCon      -- ^ Parent TyCon
                   -> PatSyn     -- ^ Corresponding bundled PatSyn
                                 --   and pretty printed origin
                   -> TcM ()
    handle_pat_syn :: SDoc -> TyCon -> PatSyn -> TcRn ()
handle_pat_syn SDoc
doc TyCon
ty_con PatSyn
pat_syn

      -- 2. See note [Types of TyCon]
      | Bool -> Bool
not forall a b. (a -> b) -> a -> b
$ TyCon -> Bool
isTyConWithSrcDataCons TyCon
ty_con
      = forall a. SDoc -> TcM a -> TcM a
addErrCtxt SDoc
doc forall a b. (a -> b) -> a -> b
$ forall a. SDoc -> TcM a
failWithTc SDoc
assocClassErr

      -- 3. Is the head a type variable?
      | Maybe TyCon
Nothing <- Maybe TyCon
mtycon
      = forall (m :: * -> *) a. Monad m => a -> m a
return ()
      -- 4. Ok. Check they are actually the same type constructor.

      | Just TyCon
p_ty_con <- Maybe TyCon
mtycon, TyCon
p_ty_con forall a. Eq a => a -> a -> Bool
/= TyCon
ty_con
      = forall a. SDoc -> TcM a -> TcM a
addErrCtxt SDoc
doc forall a b. (a -> b) -> a -> b
$ forall a. SDoc -> TcM a
failWithTc SDoc
typeMismatchError

      -- 5. We passed!
      | Bool
otherwise
      = forall (m :: * -> *) a. Monad m => a -> m a
return ()

      where
        expected_res_ty :: Type
expected_res_ty = TyCon -> [Type] -> Type
mkTyConApp TyCon
ty_con ([Id] -> [Type]
mkTyVarTys (TyCon -> [Id]
tyConTyVars TyCon
ty_con))
        ([Id]
_, [Type]
_, [Id]
_, [Type]
_, [Scaled Type]
_, Type
res_ty) = PatSyn -> ([Id], [Type], [Id], [Type], [Scaled Type], Type)
patSynSig PatSyn
pat_syn
        mtycon :: Maybe TyCon
mtycon = forall a b. (a, b) -> a
fst forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> HasCallStack => Type -> Maybe (TyCon, [Type])
tcSplitTyConApp_maybe Type
res_ty
        typeMismatchError :: SDoc
        typeMismatchError :: SDoc
typeMismatchError =
          String -> SDoc
text String
"Pattern synonyms can only be bundled with matching type constructors"
              SDoc -> SDoc -> SDoc
$$ String -> SDoc
text String
"Couldn't match expected type of"
              SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (forall a. Outputable a => a -> SDoc
ppr Type
expected_res_ty)
              SDoc -> SDoc -> SDoc
<+> String -> SDoc
text String
"with actual type of"
              SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (forall a. Outputable a => a -> SDoc
ppr Type
res_ty)


{-===========================================================================-}
check_occs :: IE GhcPs -> ExportOccMap -> [AvailInfo]
           -> RnM ExportOccMap
check_occs :: IE GhcPs -> ExportOccMap -> [AvailInfo] -> RnM ExportOccMap
check_occs IE GhcPs
ie ExportOccMap
occs [AvailInfo]
avails
  -- 'avails' are the entities specified by 'ie'
  = forall (t :: * -> *) (m :: * -> *) b a.
(Foldable t, Monad m) =>
(b -> a -> m b) -> b -> t a -> m b
foldlM ExportOccMap -> GreName -> RnM ExportOccMap
check ExportOccMap
occs [GreName]
children
  where
    children :: [GreName]
children = forall (t :: * -> *) a b. Foldable t => (a -> [b]) -> t a -> [b]
concatMap AvailInfo -> [GreName]
availGreNames [AvailInfo]
avails

    -- Check for distinct children exported with the same OccName (an error) or
    -- for duplicate exports of the same child (a warning).
    check :: ExportOccMap -> GreName -> RnM ExportOccMap
    check :: ExportOccMap -> GreName -> RnM ExportOccMap
check ExportOccMap
occs GreName
child
      = case ExportOccMap -> GreName -> Either (GreName, IE GhcPs) ExportOccMap
try_insert ExportOccMap
occs GreName
child of
          Right ExportOccMap
occs' -> forall (m :: * -> *) a. Monad m => a -> m a
return ExportOccMap
occs'

          Left (GreName
child', IE GhcPs
ie')
            | GreName -> Name
greNameMangledName GreName
child forall a. Eq a => a -> a -> Bool
== GreName -> Name
greNameMangledName GreName
child'   -- Duplicate export
            -- But we don't want to warn if the same thing is exported
            -- by two different module exports. See ticket #4478.
            -> do { WarningFlag -> Bool -> SDoc -> TcRn ()
warnIfFlag WarningFlag
Opt_WarnDuplicateExports
                               (Bool -> Bool
not (GreName -> IE GhcPs -> IE GhcPs -> Bool
dupExport_ok GreName
child IE GhcPs
ie IE GhcPs
ie'))
                               (GreName -> IE GhcPs -> IE GhcPs -> SDoc
dupExportWarn GreName
child IE GhcPs
ie IE GhcPs
ie')
                  ; forall (m :: * -> *) a. Monad m => a -> m a
return ExportOccMap
occs }

            | Bool
otherwise    -- Same occ name but different names: an error
            ->  do { GlobalRdrEnv
global_env <- TcRn GlobalRdrEnv
getGlobalRdrEnv ;
                     SDoc -> TcRn ()
addErr (GlobalRdrEnv -> GreName -> GreName -> IE GhcPs -> IE GhcPs -> SDoc
exportClashErr GlobalRdrEnv
global_env GreName
child' GreName
child IE GhcPs
ie' IE GhcPs
ie) ;
                     forall (m :: * -> *) a. Monad m => a -> m a
return ExportOccMap
occs }

    -- Try to insert a child into the map, returning Left if there is something
    -- already exported with the same OccName
    try_insert :: ExportOccMap -> GreName -> Either (GreName, IE GhcPs) ExportOccMap
    try_insert :: ExportOccMap -> GreName -> Either (GreName, IE GhcPs) ExportOccMap
try_insert ExportOccMap
occs GreName
child
      = case forall a. OccEnv a -> OccName -> Maybe a
lookupOccEnv ExportOccMap
occs OccName
name_occ of
          Maybe (GreName, IE GhcPs)
Nothing -> forall a b. b -> Either a b
Right (forall a. OccEnv a -> OccName -> a -> OccEnv a
extendOccEnv ExportOccMap
occs OccName
name_occ (GreName
child, IE GhcPs
ie))
          Just (GreName, IE GhcPs)
x  -> forall a b. a -> Either a b
Left (GreName, IE GhcPs)
x
      where
        -- For fields, we check for export clashes using the (OccName of the)
        -- selector Name
        name_occ :: OccName
name_occ = Name -> OccName
nameOccName (GreName -> Name
greNameMangledName GreName
child)


dupExport_ok :: GreName -> IE GhcPs -> IE GhcPs -> Bool
-- The GreName is exported by both IEs. Is that ok?
-- "No"  iff the name is mentioned explicitly in both IEs
--        or one of the IEs mentions the name *alone*
-- "Yes" otherwise
--
-- Examples of "no":  module M( f, f )
--                    module M( fmap, Functor(..) )
--                    module M( module Data.List, head )
--
-- Example of "yes"
--    module M( module A, module B ) where
--        import A( f )
--        import B( f )
--
-- Example of "yes" (#2436)
--    module M( C(..), T(..) ) where
--         class C a where { data T a }
--         instance C Int where { data T Int = TInt }
--
-- Example of "yes" (#2436)
--    module Foo ( T ) where
--      data family T a
--    module Bar ( T(..), module Foo ) where
--        import Foo
--        data instance T Int = TInt

dupExport_ok :: GreName -> IE GhcPs -> IE GhcPs -> Bool
dupExport_ok GreName
child IE GhcPs
ie1 IE GhcPs
ie2
  = Bool -> Bool
not (  forall {pass}. IE pass -> Bool
single IE GhcPs
ie1 Bool -> Bool -> Bool
|| forall {pass}. IE pass -> Bool
single IE GhcPs
ie2
        Bool -> Bool -> Bool
|| (IE GhcPs -> Bool
explicit_in IE GhcPs
ie1 Bool -> Bool -> Bool
&& IE GhcPs -> Bool
explicit_in IE GhcPs
ie2) )
  where
    explicit_in :: IE GhcPs -> Bool
explicit_in (IEModuleContents {}) = Bool
False                   -- module M
    explicit_in (IEThingAll XIEThingAll GhcPs
_ GenLocated SrcSpanAnnA (IEWrappedName (IdP GhcPs))
r)
      = forall name. HasOccName name => name -> OccName
occName GreName
child forall a. Eq a => a -> a -> Bool
== RdrName -> OccName
rdrNameOcc (forall name. IEWrappedName name -> name
ieWrappedName forall a b. (a -> b) -> a -> b
$ forall l e. GenLocated l e -> e
unLoc GenLocated SrcSpanAnnA (IEWrappedName (IdP GhcPs))
r)  -- T(..)
    explicit_in IE GhcPs
_              = Bool
True

    single :: IE pass -> Bool
single IEVar {}      = Bool
True
    single IEThingAbs {} = Bool
True
    single IE pass
_               = Bool
False


dupModuleExport :: ModuleName -> SDoc
dupModuleExport :: ModuleName -> SDoc
dupModuleExport ModuleName
mod
  = [SDoc] -> SDoc
hsep [String -> SDoc
text String
"Duplicate",
          SDoc -> SDoc
quotes (String -> SDoc
text String
"Module" SDoc -> SDoc -> SDoc
<+> forall a. Outputable a => a -> SDoc
ppr ModuleName
mod),
          String -> SDoc
text String
"in export list"]

moduleNotImported :: ModuleName -> SDoc
moduleNotImported :: ModuleName -> SDoc
moduleNotImported ModuleName
mod
  = [SDoc] -> SDoc
hsep [String -> SDoc
text String
"The export item",
          SDoc -> SDoc
quotes (String -> SDoc
text String
"module" SDoc -> SDoc -> SDoc
<+> forall a. Outputable a => a -> SDoc
ppr ModuleName
mod),
          String -> SDoc
text String
"is not imported"]

nullModuleExport :: ModuleName -> SDoc
nullModuleExport :: ModuleName -> SDoc
nullModuleExport ModuleName
mod
  = [SDoc] -> SDoc
hsep [String -> SDoc
text String
"The export item",
          SDoc -> SDoc
quotes (String -> SDoc
text String
"module" SDoc -> SDoc -> SDoc
<+> forall a. Outputable a => a -> SDoc
ppr ModuleName
mod),
          String -> SDoc
text String
"exports nothing"]

missingModuleExportWarn :: ModuleName -> SDoc
missingModuleExportWarn :: ModuleName -> SDoc
missingModuleExportWarn ModuleName
mod
  = [SDoc] -> SDoc
hsep [String -> SDoc
text String
"The export item",
          SDoc -> SDoc
quotes (String -> SDoc
text String
"module" SDoc -> SDoc -> SDoc
<+> forall a. Outputable a => a -> SDoc
ppr ModuleName
mod),
          String -> SDoc
text String
"is missing an export list"]


dodgyExportWarn :: Name -> SDoc
dodgyExportWarn :: Name -> SDoc
dodgyExportWarn Name
item
  = forall a b. (Outputable a, Outputable b) => SDoc -> a -> b -> SDoc
dodgyMsg (String -> SDoc
text String
"export") Name
item (forall (p :: Pass). IdP (GhcPass p) -> IE (GhcPass p)
dodgyMsgInsert Name
item :: IE GhcRn)

exportErrCtxt :: Outputable o => String -> o -> SDoc
exportErrCtxt :: forall o. Outputable o => String -> o -> SDoc
exportErrCtxt String
herald o
exp =
  String -> SDoc
text String
"In the" SDoc -> SDoc -> SDoc
<+> String -> SDoc
text (String
herald forall a. [a] -> [a] -> [a]
++ String
":") SDoc -> SDoc -> SDoc
<+> forall a. Outputable a => a -> SDoc
ppr o
exp


addExportErrCtxt :: (OutputableBndrId p)
                 => IE (GhcPass p) -> TcM a -> TcM a
addExportErrCtxt :: forall (p :: Pass) a.
OutputableBndrId p =>
IE (GhcPass p) -> TcM a -> TcM a
addExportErrCtxt IE (GhcPass p)
ie = forall a. SDoc -> TcM a -> TcM a
addErrCtxt SDoc
exportCtxt
  where
    exportCtxt :: SDoc
exportCtxt = String -> SDoc
text String
"In the export:" SDoc -> SDoc -> SDoc
<+> forall a. Outputable a => a -> SDoc
ppr IE (GhcPass p)
ie

exportItemErr :: IE GhcPs -> SDoc
exportItemErr :: IE GhcPs -> SDoc
exportItemErr IE GhcPs
export_item
  = [SDoc] -> SDoc
sep [ String -> SDoc
text String
"The export item" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (forall a. Outputable a => a -> SDoc
ppr IE GhcPs
export_item),
          String -> SDoc
text String
"attempts to export constructors or class methods that are not visible here" ]


dupExportWarn :: GreName -> IE GhcPs -> IE GhcPs -> SDoc
dupExportWarn :: GreName -> IE GhcPs -> IE GhcPs -> SDoc
dupExportWarn GreName
child IE GhcPs
ie1 IE GhcPs
ie2
  = [SDoc] -> SDoc
hsep [SDoc -> SDoc
quotes (forall a. Outputable a => a -> SDoc
ppr GreName
child),
          String -> SDoc
text String
"is exported by", SDoc -> SDoc
quotes (forall a. Outputable a => a -> SDoc
ppr IE GhcPs
ie1),
          String -> SDoc
text String
"and",            SDoc -> SDoc
quotes (forall a. Outputable a => a -> SDoc
ppr IE GhcPs
ie2)]

dcErrMsg :: Name -> String -> SDoc -> [SDoc] -> SDoc
dcErrMsg :: Name -> String -> SDoc -> [SDoc] -> SDoc
dcErrMsg Name
ty_con String
what_is SDoc
thing [SDoc]
parents =
          String -> SDoc
text String
"The type constructor" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (forall a. Outputable a => a -> SDoc
ppr Name
ty_con)
                SDoc -> SDoc -> SDoc
<+> String -> SDoc
text String
"is not the parent of the" SDoc -> SDoc -> SDoc
<+> String -> SDoc
text String
what_is
                SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes SDoc
thing SDoc -> SDoc -> SDoc
<> Char -> SDoc
char Char
'.'
                SDoc -> SDoc -> SDoc
$$ String -> SDoc
text (String -> String
capitalise String
what_is)
                   SDoc -> SDoc -> SDoc
<> String -> SDoc
text String
"s can only be exported with their parent type constructor."
                SDoc -> SDoc -> SDoc
$$ (case [SDoc]
parents of
                      [] -> SDoc
empty
                      [SDoc
_] -> String -> SDoc
text String
"Parent:"
                      [SDoc]
_  -> String -> SDoc
text String
"Parents:") SDoc -> SDoc -> SDoc
<+> [SDoc] -> SDoc
fsep (SDoc -> [SDoc] -> [SDoc]
punctuate SDoc
comma [SDoc]
parents)

failWithDcErr :: Name -> GreName -> [Name] -> TcM a
failWithDcErr :: forall a. Name -> GreName -> [Name] -> TcM a
failWithDcErr Name
parent GreName
child [Name]
parents = do
  TyThing
ty_thing <- Name -> TcM TyThing
tcLookupGlobal (GreName -> Name
greNameMangledName GreName
child)
  forall a. SDoc -> TcM a
failWithTc forall a b. (a -> b) -> a -> b
$ Name -> String -> SDoc -> [SDoc] -> SDoc
dcErrMsg Name
parent (TyThing -> String
pp_category TyThing
ty_thing)
                        (forall a. Outputable a => a -> SDoc
ppr GreName
child) (forall a b. (a -> b) -> [a] -> [b]
map forall a. Outputable a => a -> SDoc
ppr [Name]
parents)
  where
    pp_category :: TyThing -> String
    pp_category :: TyThing -> String
pp_category (AnId Id
i)
      | Id -> Bool
isRecordSelector Id
i = String
"record selector"
    pp_category TyThing
i = TyThing -> String
tyThingCategory TyThing
i


exportClashErr :: GlobalRdrEnv
               -> GreName -> GreName
               -> IE GhcPs -> IE GhcPs
               -> SDoc
exportClashErr :: GlobalRdrEnv -> GreName -> GreName -> IE GhcPs -> IE GhcPs -> SDoc
exportClashErr GlobalRdrEnv
global_env GreName
child1 GreName
child2 IE GhcPs
ie1 IE GhcPs
ie2
  = [SDoc] -> SDoc
vcat [ String -> SDoc
text String
"Conflicting exports for" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (forall a. Outputable a => a -> SDoc
ppr OccName
occ) SDoc -> SDoc -> SDoc
<> SDoc
colon
         , forall {a}. Outputable a => GreName -> GlobalRdrElt -> a -> SDoc
ppr_export GreName
child1' GlobalRdrElt
gre1' IE GhcPs
ie1'
         , forall {a}. Outputable a => GreName -> GlobalRdrElt -> a -> SDoc
ppr_export GreName
child2' GlobalRdrElt
gre2' IE GhcPs
ie2'
         ]
  where
    occ :: OccName
occ = forall name. HasOccName name => name -> OccName
occName GreName
child1

    ppr_export :: GreName -> GlobalRdrElt -> a -> SDoc
ppr_export GreName
child GlobalRdrElt
gre a
ie = Int -> SDoc -> SDoc
nest Int
3 (SDoc -> Int -> SDoc -> SDoc
hang (SDoc -> SDoc
quotes (forall a. Outputable a => a -> SDoc
ppr a
ie) SDoc -> SDoc -> SDoc
<+> String -> SDoc
text String
"exports" SDoc -> SDoc -> SDoc
<+>
                                            SDoc -> SDoc
quotes (GreName -> SDoc
ppr_name GreName
child))
                                        Int
2 (GlobalRdrElt -> SDoc
pprNameProvenance GlobalRdrElt
gre))

    -- DuplicateRecordFields means that nameOccName might be a mangled
    -- $sel-prefixed thing, in which case show the correct OccName alone
    -- (but otherwise show the Name so it will have a module qualifier)
    ppr_name :: GreName -> SDoc
ppr_name (FieldGreName FieldLabel
fl) | FieldLabel -> Bool
flIsOverloaded FieldLabel
fl = forall a. Outputable a => a -> SDoc
ppr FieldLabel
fl
                               | Bool
otherwise         = forall a. Outputable a => a -> SDoc
ppr (FieldLabel -> Name
flSelector FieldLabel
fl)
    ppr_name (NormalGreName Name
name) = forall a. Outputable a => a -> SDoc
ppr Name
name

    -- get_gre finds a GRE for the Name, so that we can show its provenance
    gre1 :: GlobalRdrElt
gre1 = GreName -> GlobalRdrElt
get_gre GreName
child1
    gre2 :: GlobalRdrElt
gre2 = GreName -> GlobalRdrElt
get_gre GreName
child2
    get_gre :: GreName -> GlobalRdrElt
get_gre GreName
child
        = forall a. a -> Maybe a -> a
fromMaybe (forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"exportClashErr" (forall a. Outputable a => a -> SDoc
ppr GreName
child))
                    (GlobalRdrEnv -> GreName -> Maybe GlobalRdrElt
lookupGRE_GreName GlobalRdrEnv
global_env GreName
child)
    (GreName
child1', GlobalRdrElt
gre1', IE GhcPs
ie1', GreName
child2', GlobalRdrElt
gre2', IE GhcPs
ie2') =
      case SrcSpan -> SrcSpan -> Ordering
SrcLoc.leftmost_smallest (GlobalRdrElt -> SrcSpan
greSrcSpan GlobalRdrElt
gre1) (GlobalRdrElt -> SrcSpan
greSrcSpan GlobalRdrElt
gre2) of
        Ordering
LT -> (GreName
child1, GlobalRdrElt
gre1, IE GhcPs
ie1, GreName
child2, GlobalRdrElt
gre2, IE GhcPs
ie2)
        Ordering
GT -> (GreName
child2, GlobalRdrElt
gre2, IE GhcPs
ie2, GreName
child1, GlobalRdrElt
gre1, IE GhcPs
ie1)
        Ordering
EQ -> forall a. String -> a
panic String
"exportClashErr: clashing exports have idential location"