Commit c82fa23e authored by simonpj's avatar simonpj
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[project @ 2005-01-05 17:49:38 by simonpj]

Add assert
parent 2b8e1af0
......@@ -322,7 +322,13 @@ lookup_inst_env env key_cls key_tys key_all_tvs
-- Does not match, so next check whether the things unify
-- [see notes about overlapping instances above]
-> case tcUnifyTys bind_fn tpl key_tys of
-> ASSERT2( not (tyVarsOfTypes key_tys `intersectsVarSet` tpl_tyvars),
(ppr key_cls <+> ppr key_tys <+> ppr key_all_tvs) $$
(ppr dfun_id <+> ppr tpl_tyvars <+> ppr tpl)
-- Unification will break badly if the variables overlap
-- They shouldn't because we allocate separate uniques for them
case tcUnifyTys bind_fn tpl key_tys of
Just _ -> find rest ms (dfun_id:us)
Nothing -> find rest ms us
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