[Rcpp-devel] tracking volatile bug

Let try to stick with regular rcpp code
(file: matrix_norm.cpp):

//[[Rcpp::depends(RcppArmadillo)]]
#include <RcppArmadillo.h>
using namespace Rcpp;
using namespace arma;

// [[Rcpp::export]]
double nmat(mat A) {
   Function Matrix_norm_r_=Environment("package:Matrix")["norm"];
   double res=as<double>(Matrix_norm_r_(A, "1"));
   return res;
}

When called in R as:

library(Rcpp)
library(Matrix)
sourceCpp("matrix_norm.cpp")
gctorture(TRUE)
nmat(as.matrix(pi))

it gives an error:
Erreur : 'getCharCE' doit ?tre appel? sur un CHARSXP
(my English translation: Error: 'getCharCE' must be called on CHARSXP)

Something was irregular on my side here?
Serguei.