Function rustc_trait_selection::traits::coherence::negative_impl_exists

fn negative_impl_exists<'cx, 'tcx>(
    selcx: &SelectionContext<'cx, 'tcx>,
    param_env: ParamEnv<'tcx>,
    o: &PredicateObligation<'tcx>
) -> bool

Try to prove that a negative impl exist for the given obligation and its super predicates.