Checking multiple inheritance of S4 objects in Rcpp

Suppose I have the following two classes in R:

setClass("Person", representation(name = "character", age = "numeric"))
setClass("Employee", representation(boss = "Person"), contains = "Person")

I can easily check inheritance in base R:

employee <- new("Employee", name = "Jack", age = 25)

inherits(employee, "Employee")
#> [1] TRUE
inherits(employee, "Person")
#> [1] TRUE

I could not achieve the same in Rcpp:

Rcpp::cppFunction('
void check_class(Rcpp::S4 x) {
  Rcout << "Class: " << as<std::string>(x.attr("class")) << std::endl;
  Rcout << "x.inherits(\\"Employee\\")     : " << x.inherits("Employee") << std::endl;
  Rcout << "x.inherits(\\"Person\\")       : " << x.inherits("Person") << std::endl;
  Rcout << "Rf_inherits(x, \\"Employee\\") : " << Rf_inherits(x, "Employee") << std::endl;
  Rcout << "Rf_inherits(x, \\"Person\\")   : " << Rf_inherits(x, "Person") << std::endl;
  Rcout << "R_extends : " << R_extends(x, Rf_mkString("Person"), R_GlobalEnv) << std::endl;
}')

check_class(employee)
#> Class: Employee
#> x.inherits("Employee")     : 1
#> x.inherits("Person")       : 0
#> Rf_inherits(x, "Employee") : 1
#> Rf_inherits(x, "Person")   : 0
#> R_extends :
#> Error in extends(new("Employee", boss = new("Person", name = character(0), : 'class1' must be the name of a class or a class definition

I expected x.inherits("Person") to be true as well.

How can I check whether an object inherits from parent classes in Rcpp?