Fix a pair of classic, but tricky, bugs in the type matcher; exposed by a program...

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

diff --git a/compiler/types/Unify.lhs b/compiler/types/Unify.lhs
index 5a1dbbc..34993ad 100644 (file)
--- a/compiler/types/Unify.lhs
+++ b/compiler/types/Unify.lhs
@@ -123,7 +123,7 @@ match menv subst ty1 ty2 | Just ty1' <- tcView ty1 = match menv subst ty1' ty2
                          | Just ty2' <- tcView ty2 = match menv subst ty1 ty2'
 
 match menv subst (TyVarTy tv1) ty2
-  | tv1 `elemVarSet` me_tmpls menv
+  | tv1' `elemVarSet` me_tmpls menv
   = case lookupVarEnv subst tv1' of
        Nothing         -- No existing binding
            | any (inRnEnvR rn_env) (varSetElems (tyVarsOfType ty2))
@@ -131,7 +131,7 @@ match menv subst (TyVarTy tv1) ty2
            | not (typeKind ty2 `isSubKind` tyVarKind tv1)
            -> Nothing  -- Kind mis-match
            | otherwise
-           -> Just (extendVarEnv subst tv1 ty2)
+           -> Just (extendVarEnv subst tv1' ty2)
 
        Just ty1'       -- There is an existing binding; check whether ty2 matches it
            | tcEqTypeX (nukeRnEnvL rn_env) ty1' ty2