John Torjo <john.lists@torjo.com> wrote:
Ben Hutchings wrote: <snip>
expired() may read the count as still being 1 and so return false, but I believe the wnd_shared_ptr constructor will catch the fact that the pointer really has expired. Unfortunately I can't yet see the code to confirm this!
By looking at the code, I would think not. But I may be wrong. Anyway, I've posted the code in my other post.
Thanks for that. Supposing that expired() wrongly returns false because use_count is really 0 but it gets an old non-zero value. Then lock() attempts to construct a shared_ptr: calls shared_ptr<T>::shared_ptr<T>(weak_ptr<T> const &) calls detail::shared_count::shared_count(weak_count const &) calls detail::sp_counted_base::add_ref_lock() calls detail::atomic_conditional_increment( long volatile &) either reads the count as 0 or calls _InterlockedCompareExchange fails and returns 0 then loops around and reads the count as 0 returns 0 throws bad_weak_ptr catches bad_weak_ptr returns 0 OK?