dummy.cpp

#include <stdexcept>
#include <iostream>

void maybe_throw(int should_throw) {
  if (should_throw)
    throw std::domain_error("exception in C++: dummy");
}

extern "C" int some_fn(int should_throw) {
  try {
    maybe_throw(should_throw);
  } catch (const std::exception& e) {
    std::cerr << e.what() << '\n';
    return 1;
  }
  return 0;
}

dummy.jl

run(`g++ dummy.cpp -shared -fPIC -o dummy.so`)

dummy = Libc.Libdl.dlopen("./dummy.so")

println(ccall(Libc.Libdl.dlsym(dummy, "some_fn"), Cint, (Cint,), 0))
println(ccall(Libc.Libdl.dlsym(dummy, "some_fn"), Cint, (Cint,), 1))