The following gives a segfault:

#include <stdio.h>
#include <math.h>
#include <gsl/gsl_errno.h>
#include <gsl/gsl_sf_hyperg.h>

int main (void)
{
  gsl_sf_result result;
  gsl_set_error_handler_off();
  int status = gsl_sf_hyperg_1F1_e(1.0,NAN,-1.0, &result);
  if (status == GSL_SUCCESS) {
    printf ("success: %.18e\n", result.val);
  } else {
    printf ("failure");
  } 
  return 0;
}

From my understanding of the error handling, the _e functions should return an invalid error code instead of crashing in such cases.

Downstream issue: https://github.com/JuliaMath/GSL.jl/issues/96