[commit: ghc] wip/tc/typeable-with-kinds: Always use a fresh wanted variable, as otherwise we could get into loops. (968ebd4)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : wip/tc/typeable-with-kinds
Link       : http://ghc.haskell.org/trac/ghc/changeset/968ebd4936121e139978d106b809b9f58df3d234/ghc

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

commit 968ebd4936121e139978d106b809b9f58df3d234
Author: Iavor S. Diatchki <diatchki at galois.com>
Date:   Fri Mar 6 11:33:31 2015 -0800

    Always use a fresh wanted variable, as otherwise we could get into loops.


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

968ebd4936121e139978d106b809b9f58df3d234
 compiler/typecheck/TcInteract.hs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/compiler/typecheck/TcInteract.hs b/compiler/typecheck/TcInteract.hs
index 716a8c1..8f85dd3 100644
--- a/compiler/typecheck/TcInteract.hs
+++ b/compiler/typecheck/TcInteract.hs
@@ -1889,7 +1889,7 @@ matchTypeableClass clas k t loc
 
   -- Emit a `Typeable` constraint for the given type.
   subGoal ty = do let goal = mkClassPred clas [ typeKind ty, ty ]
-                  (ev,_) <- newWantedEvVar loc goal
+                  ev <- newWantedEvVarNC loc goal
                   return ev