On Thu, Feb 2, 2023 at 12:17 PM Gergely Nagy <gergely.nagy.alt_at_[hidden]> wrote:
>
> This, especially noreentry_this_object is too convoluted to be a core language feature.


Please argue as to why.


> Such a keyword would have to be generic, covering both single- and multithreaded cases, and would require some state, that you can easily implement yourself (just like you did, with the mutex).


I didn't use a mutex. Look again.


> void no_reentry_fn() {
> static std::mutex prevent;
> if (!prevent.try_lock()) return;
> std::scoped_lock prevent_l(prevent);
> ...
> }


Your code will dead-lock if the same thread tries to re-enter. The
Standard says that "mutex::try_lock" has undefined behaviour if the
current thread has already locked it.

I used an atomic_flag, not a mutex.