Fix Trac #3017: ensure that we quantify over enough type variables when equalities...

[ghc-hetmet.git] / compiler / typecheck / TcSimplify.lhs

diff --git a/compiler/typecheck/TcSimplify.lhs b/compiler/typecheck/TcSimplify.lhs
index 071d4c0..0e1e5b0 100644 (file)
--- a/compiler/typecheck/TcSimplify.lhs
+++ b/compiler/typecheck/TcSimplify.lhs
@@ -659,7 +659,7 @@ tcSimplifyInfer doc tau_tvs wanted
        ; gbl_tvs  <- tcGetGlobalTyVars
        ; let preds1   = fdPredsOfInsts wanted'
              gbl_tvs1 = oclose preds1 gbl_tvs
-             qtvs     = grow preds1 tau_tvs1 `minusVarSet` gbl_tvs1
+             qtvs     = growInstsTyVars wanted' tau_tvs1 `minusVarSet` gbl_tvs1
                        -- See Note [Choosing which variables to quantify]
 
                -- To maximise sharing, remove from consideration any 
@@ -668,7 +668,7 @@ tcSimplifyInfer doc tau_tvs wanted
        ; extendLIEs free
 
                -- To make types simple, reduce as much as possible
-       ; traceTc (text "infer" <+> (ppr preds1 $$ ppr (grow preds1 tau_tvs1) $$ ppr gbl_tvs $$ 
+       ; traceTc (text "infer" <+> (ppr preds1 $$ ppr (growInstsTyVars wanted' tau_tvs1) $$ ppr gbl_tvs $$ 
                   ppr gbl_tvs1 $$ ppr free $$ ppr bound))
        ; (irreds1, binds1) <- tryHardCheckLoop doc bound
 
@@ -709,7 +709,7 @@ tcSimplifyInfer doc tau_tvs wanted
                -- Then b is fixed by gbl_tvs, so (C a b) will be in free, and
                -- irreds2 will be empty.  But we don't want to generalise over b!
        ; let preds2 = fdPredsOfInsts irreds2   -- irreds2 is zonked
-             qtvs   = grow preds2 tau_tvs2 `minusVarSet` oclose preds2 gbl_tvs2
+             qtvs   = growInstsTyVars irreds2 tau_tvs2 `minusVarSet` oclose preds2 gbl_tvs2
        ; let (free, irreds3) = partition (isFreeWhenInferring qtvs) irreds2
        ; extendLIEs free