Remove unused field from 'ExposedModule' which GHC does not use.

Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>

Cabal/Distribution/InstalledPackageInfo.hs

@@ -161,8 +161,7 @@ data OriginalModule
 data ExposedModule
    = ExposedModule {
        exposedName      :: ModuleName,
-       exposedReexport  :: Maybe OriginalModule,
-       exposedSignature :: Maybe OriginalModule -- This field is unused for now.
+       exposedReexport  :: Maybe OriginalModule
      }
   deriving (Eq, Generic, Read, Show)
 
@@ -176,14 +175,11 @@ instance Text OriginalModule where
         return (OriginalModule ipi m)
 
 instance Text ExposedModule where
-    disp (ExposedModule m reexport signature) =
+    disp (ExposedModule m reexport) =
         Disp.sep [ disp m
                  , case reexport of
                     Just m' -> Disp.sep [Disp.text "from", disp m']
                     Nothing -> Disp.empty
-                 , case signature of
-                    Just m' -> Disp.sep [Disp.text "is", disp m']
-                    Nothing -> Disp.empty
                  ]
     parse = do
         m <- parseModuleNameQ
@@ -192,12 +188,7 @@ instance Text ExposedModule where
             _ <- Parse.string "from"
             Parse.skipSpaces
             fmap Just parse
-        Parse.skipSpaces
-        signature <- Parse.option Nothing $ do
-            _ <- Parse.string "is"
-            Parse.skipSpaces
-            fmap Just parse
-        return (ExposedModule m reexport signature)
+        return (ExposedModule m reexport)
 
 
 instance Binary OriginalModule
@@ -213,7 +204,7 @@ showExposedModules :: [ExposedModule] -> Disp.Doc
 showExposedModules xs
     | all isExposedModule xs = fsep (map disp xs)
     | otherwise = fsep (Disp.punctuate comma (map disp xs))
-    where isExposedModule (ExposedModule _ Nothing Nothing) = True
+    where isExposedModule (ExposedModule _ Nothing) = True
           isExposedModule _ = False
 
 parseExposedModules :: Parse.ReadP r [ExposedModule]

Cabal/Distribution/Simple/Build.hs

@@ -393,7 +393,7 @@ testSuiteLibV09AsLibAndExe pkg_descr
                 , componentPackageRenaming = componentPackageRenaming clbi
                 , componentId = cid
                 , componentCompatPackageKey = compat_key
-                , componentExposedModules = [IPI.ExposedModule m Nothing Nothing]
+                , componentExposedModules = [IPI.ExposedModule m Nothing]
                 }
     pkg = pkg_descr {
             package      = (package pkg_descr) { pkgName = pkg_name }

Cabal/Distribution/Simple/Configure.hs

@@ -1544,7 +1544,7 @@ mkComponentsLocalBuildInfo cfg comp installedPackages pkg_descr
     componentLocalBuildInfo cid compat_key component =
       case component of
       CLib lib -> do
-        let exports = map (\n -> Installed.ExposedModule n Nothing Nothing)
+        let exports = map (\n -> Installed.ExposedModule n Nothing)
                           (PD.exposedModules lib)
         let mb_reexports = resolveModuleReexports installedPackages
                                                   (packageId pkg_descr)
@@ -1649,7 +1649,6 @@ resolveModuleReexports installedPackages srcpkgid key externalPkgDeps lib =
                                                         definingModuleName
               exposedModule  = Installed.ExposedModule visibleModuleName
                                                        (Just originalModule)
-                                                             Nothing
         ]
 
     -- All the modules exported from this package and their defining name and

Cabal/Distribution/Simple/GHC/IPI642.hs

@@ -67,7 +67,7 @@ mkComponentId = Current.ComponentId . display
 toCurrent :: InstalledPackageInfo -> Current.InstalledPackageInfo
 toCurrent ipi@InstalledPackageInfo{} =
   let pid = convertPackageId (package ipi)
-      mkExposedModule m = Current.ExposedModule m Nothing Nothing
+      mkExposedModule m = Current.ExposedModule m Nothing
   in Current.InstalledPackageInfo {
     Current.sourcePackageId    = pid,
     Current.installedComponentId         = mkComponentId pid,

Cabal/Distribution/Simple/GHCJS.hs

@@ -18,7 +18,6 @@ import Distribution.Simple.GHC.ImplInfo
 import qualified Distribution.Simple.GHC.Internal as Internal
 import Distribution.PackageDescription as PD
 import Distribution.InstalledPackageInfo
-import qualified Distribution.InstalledPackageInfo as InstalledPackageInfo
 import Distribution.Package
 import Distribution.Simple.PackageIndex ( InstalledPackageIndex )
 import qualified Distribution.Simple.PackageIndex as PackageIndex

Cabal/Distribution/Simple/LocalBuildInfo.hs

@@ -63,13 +63,11 @@ import Distribution.Simple.InstallDirs hiding (absoluteInstallDirs,
                                                substPathTemplate, )
 import qualified Distribution.Simple.InstallDirs as InstallDirs
 import Distribution.Simple.Program
-import Distribution.InstalledPackageInfo
 import Distribution.PackageDescription
 import qualified Distribution.InstalledPackageInfo as Installed
 import Distribution.Package
 import Distribution.Simple.Compiler
 import Distribution.Simple.PackageIndex
-import Distribution.ModuleName
 import Distribution.Simple.Setup
 import Distribution.Simple.Utils
 import Distribution.Text

Cabal/Distribution/Simple/PackageIndex.hs

@@ -595,7 +595,7 @@ moduleNameIndex :: InstalledPackageIndex -> Map ModuleName [IPI.InstalledPackage
 moduleNameIndex index =
   Map.fromListWith (++) $ do
     pkg <- allPackages index
-    IPI.ExposedModule m reexport _ <- IPI.exposedModules pkg
+    IPI.ExposedModule m reexport <- IPI.exposedModules pkg
     case reexport of
         Nothing -> return (m, [pkg])
         Just (IPI.OriginalModule _ m') | m == m'   -> []

Cabal/Distribution/Simple/Program/GHC.hs

@@ -27,7 +27,6 @@ import Distribution.Utils.NubList
 import Language.Haskell.Extension
 
 import qualified Data.Map as M
-import Data.List ( intercalate )
 
 -- | A structured set of GHC options/flags
 --

Cabal/Distribution/Simple/Setup.hs

@@ -71,7 +71,6 @@ import Distribution.ReadE
 import Distribution.Text
 import qualified Distribution.Compat.ReadP as Parse
 import qualified Text.PrettyPrint as Disp
-import Distribution.ModuleName
 import Distribution.Package
 import Distribution.PackageDescription hiding (Flag)
 import Distribution.Simple.Command hiding (boolOpt, boolOpt')