https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104495
--- Comment #5 from Frank Heckenbach <f.heckenb...@fh-soft.de> ---
As I replacement, I'll use the following code. It's a simple double-checked
lock, probably not as efficient as the original, but seems to work.
Posted here as RFC and for anyone else who encounters the problem. Released
under CC0/public domain.
#include <mutex>
#include <atomic>
#include <functional>
class once_flag
{
std::atomic <bool> a { };
std::mutex m;
public:
once_flag () = default;
once_flag (once_flag &) = delete;
friend void call_once (once_flag &o, auto &&f, auto && ... args)
{
if (!o.a)
if (std::lock_guard g (o.m); !o.a)
{
std::invoke (std::forward <decltype (f)> (f), std::forward <decltype
(args)> (args) ...);
o.a = true;
}
}
};
