// in that case, do not call typecheck back, or it will cycle.
	// if the variable has a type (ntype) then typechecking
	// will not look at defn, so it is okay (and desirable,
	// so that the conversion below happens).

	checkLHS := func(i int, typ *types.Type) {
		if n := lhs[i]; typ != nil && ir.DeclaredBy(n, stmt) && n.Type() == nil {
			base.Assertf(typ.Kind() == types.TNIL, "unexpected untyped nil")
			n.SetType(defaultType(typ))
		}