pointer used after 'void operator delete(void*, std::size_t)' in simple_state.hpp

[ocroquette]

Switching recently from GCC 11 to 12 (MinGW), we encountered the following new warning:

inlined from 'boost::statechart::detail::reaction_result boost::statechart::simple_state<MostDerived, Context, InnerInitial, historyMode>::react_impl(const event_base_type&, typename Context::inner_context_type::rtti_policy_type::id_type) [with MostDerived = ourstuff::{anonymous}::OurStuff Context = ourstuff::{anonymous}::OurStuff; InnerInitial = boost::mpl::list<mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na>; boost::statechart::history_mode historyMode = boost::statechart::has_no_history]' at C:/.../boost-1_80/boost/statechart/simple_state.hpp:489:37:

C:/.../boost-1_80/boost/statechart/detail/counted_base.hpp:80:27: error: pointer used after 'void operator delete(void*, std::size_t)' [-Werror=use-after-free]

   80 |       return --base_type::count_ == 0;

This happens only in the "RelWithDebInfo" CMake configuration.

As a workaround, we patched this file to disable the warning using a #pragma, since warnings are considered as errors in this project.

This is the code producing the warning in context, for reference:

    bool release() const
    {
      BOOST_ASSERT( base_type::count_ > 0 );
      return --base_type::count_ == 0;
    }

[mclow]

The cause of that warning is not obvious to me.
The (long) error message refers to stuff named OurStuff, which is not anywhere in the boost sources.

[ocroquette]

OurStuff belongs to the application code. I do not know how to reproduce the issue without it, unfortunately.

[mclow]

In that case, why do you think that this is a bug in Boost.Statechart, and not in your application?

[ocroquette]

I do not know indeed, the only understandable and traceable hint I have is the error message pointing to counted_base.hpp:80
If you do not know what is causing this either, you can close the ticket. Our workaround is good enough for us.

[mclow]

If there's a problem in the Boost.Statechart code, I'd like to find it and fix it.
However, I don't think there's enough information in what you've posted for me to tell if that's the case.

[mclow]

Error message formatted:

inlined from 
boost::statechart::detail::reaction_result
   boost::statechart::simple_state<MostDerived, Context, InnerInitial, historyMode>::react_impl(
     const event_base_type&, typename Context::inner_context_type::rtti_policy_type::id_type) [
        with MostDerived = ourstuff::{anonymous}::OurStuff Context = ourstuff::{anonymous}::OurStuff; 
             InnerInitial = boost::mpl::list<mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na>;
             boost::statechart::history_mode historyMode = boost::statechart::has_no_history]
at C:/.../boost-1_80/boost/statechart/simple_state.hpp:489:37:

C:/.../boost-1_80/boost/statechart/detail/counted_base.hpp:80:27:
    error: pointer used after 'void operator delete(void*, std::size_t)' [-Werror=use-after-free]