X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcMType.lhs;h=f01d69db55cdbcf129ee6e18ac21ea54b60d2de5;hb=a346683b2ba5cc87a0db27eb1422158611327c54;hp=4542a34a0afc543a29916b65d2eafeba78b1e6b4;hpb=3e83dfb21b2f2220dce97427fff5c19459ae68d1;p=ghc-hetmet.git

diff --git a/compiler/typecheck/TcMType.lhs b/compiler/typecheck/TcMType.lhs
index 4542a34..f01d69d 100644
--- a/compiler/typecheck/TcMType.lhs
+++ b/compiler/typecheck/TcMType.lhs
@@ -107,6 +107,7 @@ import Outputable
 
 import Control.Monad	( when )
 import Data.List	( (\\) )
+
 \end{code}
 
 
@@ -367,7 +368,8 @@ data LookupTyVarResult	-- The result of a lookupTcTyVar call
 
 lookupTcTyVar :: TcTyVar -> TcM LookupTyVarResult
 lookupTcTyVar tyvar 
-  = case details of
+  = ASSERT( isTcTyVar tyvar )
+    case details of
       SkolemTv _   -> return (DoneTv details)
       MetaTv _ ref -> do { meta_details <- readMutVar ref
 			 ; case meta_details of