Function deeply_normalize_param_env_ignoring_regions 

pub fn deeply_normalize_param_env_ignoring_regions<'tcx>(
    tcx: TyCtxt<'tcx>,
    unnormalized_env: ParamEnv<'tcx>,
    cause: ObligationCause<'tcx>,
) -> ParamEnv<'tcx>

Deeply normalize the param env using the next solver ignoring region errors.

FIXME(-Zhigher-ranked-assumptions): this is a hack to work around the fact that we don’t support placeholder assumptions right now and is necessary for compare_method_predicate_entailment, see the use of this function for more info. We should remove this once we have proper support for implied bounds on binders.