Function lazily_elaborate_sizedness_candidate

pub(crate) fn lazily_elaborate_sizedness_candidate<'tcx>(
    infcx: &InferCtxt<'tcx>,
    obligation: &PolyTraitObligation<'tcx>,
    candidate: PolyTraitPredicate<'tcx>,
) -> PolyTraitPredicate<'tcx>

To improve performance, sizedness traits are not elaborated and so special-casing is required in the trait solver to find a Sized candidate for a MetaSized obligation. Returns the predicate to used in the candidate for such a obligation, given a candidate.