return typecheck(ir.InitExpr(n.Init(), u), top) // typecheckargs can add to old.Init

		case ir.OCOMPLEX, ir.OCOPY, ir.OUNSAFEADD, ir.OUNSAFESLICE, ir.OUNSAFESTRING:
			typecheckargs(n)
			arg1, arg2, ok := needTwoArgs(n)
			if !ok {
				n.SetType(nil)
				return n
			}
			b := ir.NewBinaryExpr(n.Pos(), l.BuiltinOp, arg1, arg2)
			return typecheck(ir.InitExpr(n.Init(), b), top) // typecheckargs can add to old.Init
		}

	}

	if len(n.Args) > 1 {
		p := fmt.Sprintf(f, args...)
		base.Errorf("too many arguments to %s: %v", p, n)
		return n.Args[0], false
	}

	return n.Args[0], true
}

func needTwoArgs(n *ir.CallExpr) (ir.Node, ir.Node, bool) {
	if len(n.Args) != 2 {
		if len(n.Args) < 2 {
			base.Errorf("not enough arguments in call to %v", n)
		} else {
			base.Errorf("too many arguments in call to %v", n)
		}