Fix scoped type variables for expression type signatures

[ghc-hetmet.git] / compiler / types / InstEnv.lhs

diff --git a/compiler/types/InstEnv.lhs b/compiler/types/InstEnv.lhs
index 7aaf6dd..f4559e7 100644 (file)
--- a/compiler/types/InstEnv.lhs
+++ b/compiler/types/InstEnv.lhs
@@ -475,9 +475,9 @@ lookupInstEnv (pkg_ie, home_ie) cls tys
       = find ms us rest
 
       | otherwise
-      = ASSERT2( not (tyVarsOfTypes tys `intersectsVarSet` tpl_tvs),
-                      (ppr cls <+> ppr tys <+> ppr all_tvs) $$
-                      (ppr dfun <+> ppr tpl_tvs <+> ppr tpl_tys)
+      = ASSERT2( tyVarsOfTypes tys `disjointVarSet` tpl_tvs,
+                (ppr cls <+> ppr tys <+> ppr all_tvs) $$
+                (ppr dfun <+> ppr tpl_tvs <+> ppr tpl_tys)
                )
                -- Unification will break badly if the variables overlap
                -- They shouldn't because we allocate separate uniques for them