Function rustc_trait_selection::traits::chalk_fulfill::in_environment

fn in_environment<'tcx>(
    infcx: &InferCtxt<'_, 'tcx>, 
    obligation: &PredicateObligation<'tcx>
) -> ChalkEnvironmentAndGoal<'tcx>

We need to wrap a ty::Predicate in an elaborated environment before we canonicalize. This is due to the fact that we insert extra clauses into the environment for all input types (FromEnv).