c++11 / unique_ptr with packaged_task

[Jonathan Wakely]

On 1 March 2013 06:21, NightStrike wrote:
> This code compiles with clang/libc++, but doesn't with gcc4.8/libstdc++:
>
> #include <functional>
> #include <future>
> #include <iostream>
> #include <memory>
> #include <ostream>
>
> struct S
> {
>         void f()
>         {
>                 std::cerr << "Meep meep\n";
>         }
> };
>
> int main()
> {
>         std::unique_ptr<S> sp(new S);
>         std::packaged_task<void ()> pt(std::bind(&S::f, std::move(sp)));
>         pt();
>         std::cerr << "sp is empty: " << std::boolalpha << !sp << std::endl;
> }
>
>
>
> Is that a bug in gcc?

The problem is that I implemented packaged_task using a std::function
to hold the stored task, and std::function requires a
CopyConstructible target object, but your function object is only
MoveConstructible.

This is a GCC bug, I think I can see an easy way to fix it, but it
will have to wait for 4.8.1 because it's not a regression.