no-empty-paths.diff

diff --git a/Cabal/src/Distribution/FieldGrammar/Newtypes.hs b/Cabal/src/Distribution/FieldGrammar/Newtypes.hs
index 3f37b43eb..35a1e781c 100644
--- a/Cabal/src/Distribution/FieldGrammar/Newtypes.hs
+++ b/Cabal/src/Distribution/FieldGrammar/Newtypes.hs
@@ -250,7 +250,11 @@ newtype FilePathNT = FilePathNT { getFilePathNT :: String }
 instance Newtype String FilePathNT
 
 instance Parsec FilePathNT where
-    parsec = pack <$> parsecToken
+    parsec = do
+        token <- parsecToken
+        if null token
+        then P.unexpected "empty FilePath"
+        else return (FilePathNT token)
 
 instance Pretty FilePathNT where
     pretty = showFilePath . unpack