bulk_then_execute has unexpected return type/does not compile

[msimberg]

The following snippet of code does not do what I would expect it to do:

void fun1(int, shared_future<void>) {...}
int fun2(int, shared_future<void>) {...}
...
{
    shared_future<void> f = ...;
    std::vector<int> v(100);
    // tested with exec as pool_executor, thread_pool_executor or this_thread_executor
    bulk_then_execute(exec, &fun1, v, f); // Returns future<void>
    // bulk_then_execute(exec, &fun2, v, f); // Does not compile
}

Expected Behavior

• with fun1 I expect either that .get()ing the future<void> would block until all 100 invocations of fun1 have finished or that it returns a vector<future<void>> like bulk_async_execute
• with fun2 I expect it to compile and return a vector<future<int>>

Actual Behavior

• with fun1 get() does not wait for all invocations to finish
• with fun2 it fails to compile with the following error:

/home/simbergm/src/hpx-worktrees/fix-examples/hpx/parallel/executors/thread_execution.hpp:213:25: error: could not convert ‘hpx::traits::future_access<hpx::lcos::future<R>>::create(boost::intrusive_ptr<U>&&) [with SharedState = hpx::lcos::detail::future_data_base<std::vector<hpx::lcos::future<int>, std::allocator<hpx::lcos::future<int> > > >; R = std::vector<hpx::lcos::future<int>, std::allocator<hpx::lcos::future<int> > >]()’ from ‘hpx::lcos::future<std::vector<hpx::lcos::future<int>, std::allocator<hpx::lcos::future<int> > > >’ to ‘std::enable_if<true, hpx::lcos::future<std::vector<int> > >::type {aka hpx::lcos::future<std::vector<int> >}’
             std::move(p));
                         ^

Specifications

• HPX Version: 8b0f81c
• Platform (compiler, OS): gcc 6.3.0, Ubuntu 16.04