Multiple task_system and system_timer are being created

[aaronalbers]

The function operators for default_executor_type and system_timer_type are templated and therefore will have unique static local variables depending on the number of different parameter types used in the target application.

Simple example that illustrates the problem:
http://cpp.sh/6vpmi

A potential fix is to use the polymorphic task that is already available rather than templates.

void operator()(task<void()>&& f) const {
        static task_system only_task_system;
        only_task_system(std::forward<task<void()>>(f));
}

That polymorphic task could also be propagated to the underlying task_system and system_timer function operators as to better indicate that only one type will be passed rather than any supported type.

[FelixPetriconi]

Thanks for reporting, I will look into this.

[FelixPetriconi]

Fixed in 1.3.1