[commit: ghc] master: Do not promote data families (a3f68ca)

[Simon Peyton Jones]

Repository : ssh://darcs.haskell.org//srv/darcs/ghc

On branch  : master

http://hackage.haskell.org/trac/ghc/changeset/a3f68cac382083d50f02616f3af7bfb47e79d50d

>---------------------------------------------------------------

commit a3f68cac382083d50f02616f3af7bfb47e79d50d
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Thu Jun 7 09:48:19 2012 +0100

    Do not promote data families

>---------------------------------------------------------------

 compiler/basicTypes/DataCon.lhs |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/compiler/basicTypes/DataCon.lhs b/compiler/basicTypes/DataCon.lhs
index 2fbedd6..aabc5d0 100644
--- a/compiler/basicTypes/DataCon.lhs
+++ b/compiler/basicTypes/DataCon.lhs
@@ -1029,7 +1029,9 @@ isPromotableType ty
 -- If tc's kind is [ *^n -> * ] returns [ Just n ], else returns [ Nothing ]
 isPromotableTyCon :: TyCon -> Maybe Int
 isPromotableTyCon tc
-  | all isLiftedTypeKind (res:args) = Just $ length args
+  | isDataTyCon tc  -- Only *data* types can be promoted, not newtypes
+    		    -- not synonyms, not type families
+  , all isLiftedTypeKind (res:args) = Just $ length args
   | otherwise                       = Nothing
   where
     (args, res) = splitKindFunTys (tyConKind tc)