Function region_outlives_implied 

pub(crate) fn region_outlives_implied<'tcx>(
    tcx: TyCtxt<'tcx>,
    src_region: Region<'tcx>,
    self_ty: Ty<'tcx>,
) -> bool

Whether src_region provably outlives the reference region of self_ty via the type’s own well-formedness. A reference parameter &'r SliceHost<'s> requires its pointee’s regions to outlive 'r ('s: 'r), which the where-clause-only region_outlives cannot see. Complements it with the implied outlives components of self_ty.