Revert to Cabal assuming signatures have object files.

GHC has been changed to guarantee producing valid object files for
signatures (they will usually be empty).
Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>

Cabal/Distribution/PackageDescription.hs

@@ -45,7 +45,6 @@ module Distribution.PackageDescription (
         withLib,
         hasLibs,
         libModules,
-        objectModules,
 
         -- ** Executables
         Executable(..),
@@ -418,12 +417,6 @@ libModules lib = exposedModules lib
               ++ exposedSignatures lib
               ++ requiredSignatures lib
 
--- | Get all the module names from the library which have OBJECT code.
--- This excludes signatures, which have interface files but no object code.
-objectModules :: Library -> [ModuleName]
-objectModules lib = exposedModules lib
-              ++ otherModules (libBuildInfo lib)
-
 -- -----------------------------------------------------------------------------
 -- Module re-exports
 

Cabal/Distribution/Simple/GHC.hs

@@ -51,7 +51,7 @@ import qualified Distribution.Simple.GHC.IPI641 as IPI641
 import qualified Distribution.Simple.GHC.IPI642 as IPI642
 import Distribution.PackageDescription as PD
          ( PackageDescription(..), BuildInfo(..), Executable(..)
-         , Library(..), libModules, objectModules, exeModules, hcOptions
+         , Library(..), libModules, exeModules, hcOptions
          , usedExtensions, allExtensions, ModuleRenaming, lookupRenaming )
 import Distribution.InstalledPackageInfo
          ( InstalledPackageInfo )
@@ -1136,7 +1136,7 @@ getHaskellObjects lib lbi pref wanted_obj_ext allow_split_objs
                           then "_split"
                           else "_" ++ wanted_obj_ext ++ "_split"
             dirs = [ pref </> (ModuleName.toFilePath x ++ splitSuffix)
-                   | x <- objectModules lib ]
+                   | x <- libModules lib ]
         objss <- mapM getDirectoryContents dirs
         let objs = [ dir </> obj
                    | (objs',dir) <- zip objss dirs, obj <- objs',
@@ -1145,7 +1145,7 @@ getHaskellObjects lib lbi pref wanted_obj_ext allow_split_objs
         return objs
   | otherwise  =
         return [ pref </> ModuleName.toFilePath x <.> wanted_obj_ext
-               | x <- objectModules lib ]
+               | x <- libModules lib ]
 
 -- | Extracts a String representing a hash of the ABI of a built
 -- library.  It can fail if the library has not yet been built.

Cabal/Distribution/Simple/Register.hs

@@ -60,7 +60,7 @@ import Distribution.Simple.Setup
          ( RegisterFlags(..), CopyDest(..)
          , fromFlag, fromFlagOrDefault, flagToMaybe )
 import Distribution.PackageDescription
-         ( PackageDescription(..), Library(..), BuildInfo(..) )
+         ( PackageDescription(..), Library(..), BuildInfo(..), libModules )
 import Distribution.Package
          ( Package(..), packageName, InstalledPackageId(..) )
 import Distribution.InstalledPackageInfo
@@ -305,8 +305,7 @@ generalInstalledPackageInfo adjustRelIncDirs pkg ipid lib lbi clbi installDirs =
   where
     bi = libBuildInfo lib
     (absinc, relinc) = partition isAbsolute (includeDirs bi)
-    hasModules = not $ null (exposedModules lib)
-                    && null (otherModules bi)
+    hasModules = not $ null (libModules lib)
     hasLibrary = hasModules || not (null (cSources bi))
     -- Since we currently don't decide the InstalledPackageId of our package
     -- until just before we register, we didn't have one for the re-exports