[commit: ghc] master: Refactor to avoid gratuitous DEBUG warning (04c9c3b)

[git at git.haskell.org]

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

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/04c9c3b23065916b7beb9cebc959a05786f01dbe/ghc

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

commit 04c9c3b23065916b7beb9cebc959a05786f01dbe
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Wed Aug 28 16:38:54 2013 +0100

    Refactor to avoid gratuitous DEBUG warning


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

04c9c3b23065916b7beb9cebc959a05786f01dbe
 compiler/coreSyn/CoreUtils.lhs |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/compiler/coreSyn/CoreUtils.lhs b/compiler/coreSyn/CoreUtils.lhs
index bdd048d..06f167c 100644
--- a/compiler/coreSyn/CoreUtils.lhs
+++ b/compiler/coreSyn/CoreUtils.lhs
@@ -1623,10 +1623,10 @@ tryEtaReduce bndrs body
     -- for why we have an accumulating coercion
     go [] fun co
       | ok_fun fun 
-      , let result = mkCast fun co
-      , not (any (`elemVarSet` exprFreeVars result) bndrs)
-      = Just result   -- Check for any of the binders free in the result
-                      -- including the accumulated coercion
+      , let used_vars = exprFreeVars fun `unionVarSet` tyCoVarsOfCo co
+      , not (any (`elemVarSet` used_vars) bndrs)
+      = Just (mkCast fun co)   -- Check for any of the binders free in the result
+                               -- including the accumulated coercion
 
     go (b : bs) (App fun arg) co
       | Just co' <- ok_arg b arg co