l, r = defaultlit2(l, r, false)
	if l.Type() == nil || r.Type() == nil {
		return l, r, nil
	}
	t := l.Type()
	if t.Kind() == types.TIDEAL {
		t = r.Type()
	}
	aop := ir.OXXX
	if n.Op().IsCmp() && t.Kind() != types.TIDEAL && !types.Identical(l.Type(), r.Type()) {
		// comparison is okay as long as one side is
		// assignable to the other.  convert so they have
		// the same type.
		//

	// TODO(mdempsky): Handle all untyped types correctly.
	if src == types.UntypedBool && dst.Type().IsBoolean() {
		return
	}

	if op, why := assignOp(src, dst.Type()); op == ir.OXXX {
		base.Errorf("cannot assign %v to %L in multiple assignment%s", src, dst, why)
		return
	}
}

// The result of stringtoruneslit MUST be assigned back to n, e.g.
//