mruby-eval/eval.c (f_instance_eval): skip mrb_value to get singleton
Use mrb_singleton_class_ptr() instead of mrb_instance_class(), because
the former returns NULL, when the latter raises error for immediate
objects.
```
1.instance_eval <<END
def foo
:foo
end
END
```
MODIFY
mrbgems/mruby-eval/src/eval.c
mrbgems/mruby-eval/src/eval.c
@@ -177,15 +177,15 @@ f_instance_eval(mrb_state *mrb, mrb_value self)
mrb_int len;
const char *file = NULL;
mrb_int line = 1;
- mrb_value cv;
+ struct RClass *c;
struct RProc *proc;
mrb_get_args(mrb, "s|zi", &s, &len, &file, &line);
- cv = mrb_singleton_class(mrb, self);
+ c = mrb_singleton_class_ptr(mrb, self);
proc = create_proc_from_string(mrb, s, len, mrb_nil_value(), file, line);
- MRB_PROC_SET_TARGET_CLASS(proc, mrb_class_ptr(cv));
+ MRB_PROC_SET_TARGET_CLASS(proc, c);
mrb_assert(!MRB_PROC_CFUNC_P(proc));
- mrb_vm_ci_target_class_set(mrb->c->ci, mrb_class_ptr(cv));
+ mrb_vm_ci_target_class_set(mrb->c->ci, c);
return exec_irep(mrb, self, proc);
}
else {

mruby-eval/eval.c (f_instance_eval): skip mrb_value to get singleton

Use mrb_singleton_class_ptr() instead of mrb_instance_class(), because
the former returns NULL, when the latter raises error for immediate
objects.

```
1.instance_eval <<END
  def foo
    :foo
  end
END
```