[Rcpp-devel] Rcpp::stop crashes RGui and RStudio under Windows

[JJ Allaire]

> // [[Rcpp::export]]
> int throwCpp(int nb) {
> BEGIN_RCPP
>   if (nb == 10)
>     Rcpp::stop("Unexpected condition occurred");
>   return nb*2; // Just for testing the normal case }
> END_RCPP
> }

This doesn't quite work for a couple of reasons (one small one larger):

(1) END_RCPP assumes an SEXP return type so you'd actually need to code it
like this:

// [[Rcpp::export]]
SEXP throwCpp(int nb) {
BEGIN_RCPP
   if (nb == 10)
      Rcpp::stop("Unexpected condition occurred");
   return Rcpp::wrap(nb*2);
END_RCPP
}

Or we could introduce a new variation of END_RCPP something like this:

// [[Rcpp::export]]
int throwCpp(int nb) {
BEGIN_RCPP
   if (nb == 10)
      Rcpp::stop("Unexpected condition occurred");
   return nb*2;
END_RCPP_(0)
}

(2) The more serious issue is that locating the END_RCPP inside the
function will result in an Rf_error that does a longjmp over internal Rcpp
code (bypassing C++ destructors in the process). The END_CPP construct
really needs to sit right at the extern "C" boundary to be fully safe.


As Romain said, our aspiration is to make it possible to write C++ code for
R without boilerplate scaffolding. We've got a couple of alternatives under
discussion and I'm sure we'll be able to get this to work one way or
another.

J.J.
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