create-mrb-fiber-from-c.c

#include <mruby.h>
#include <mruby/compile.h>
#include <mruby/string.h>
#include <stdio.h>

mrb_state* mrb;

void p(mrb_value value) {
    printf("--> %s\n", mrb_str_to_cstr(mrb, mrb_inspect(mrb, value)));
}

int main() {
    mrb = mrb_open();

    mrb_value fiber_class = mrb_obj_value(mrb_class_get(mrb, "Fiber"));

    mrb_value proc = mrb_load_string(mrb, "proc { |a| a + 1 }");

    mrb_value fiber = mrb_funcall_with_block(mrb, fiber_class, mrb_intern_cstr(mrb, "new"), 0, NULL, proc);
    p(fiber);

    mrb_value start_arg = mrb_fixnum_value(123);
    mrb_value retn = mrb_fiber_resume(mrb, fiber, 1, &start_arg);
    p(retn);
}

// Expected output:
//
// --> #<Fiber:0x55ce69b1fd90>
// --> 124

// Actual output:
//
// --> #<Fiber:0x55ce69b1fd90>
// --> undefined method '+' (NoMethodError)