rclcpp_minimal_action_client not building

Bug report`

Required Info:

• Operating System:
  Ubuntu-MATE 20.04
• Installation type:
  binaries

Steps to reproduce issue

I've had a problem getting the examples to build for a while. I first thought something had gotten out of sync so I got around to creating a new virtualbox with Windows10 host and Ubuntu-MATE 20.04 client and pristine install of the Foxy binaries. rclcpp_minimal_action_client fails to build. Below is the output from the compiler.

Starting >>> examples_rclcpp_minimal_action_client
--- stderr: examples_rclcpp_minimal_action_client                             
/home/brutus/ros2/examples_ws/src/examples/rclcpp/actions/minimal_action_client/member_functions.cpp: In member function ‘void MinimalActionClient::send_goal()’:
/home/brutus/ros2/examples_ws/src/examples/rclcpp/actions/minimal_action_client/member_functions.cpp:78:71: error: no match for ‘operator=’ (operand types are ‘rclcpp_action::Client<example_interfaces::action::Fibonacci>::GoalResponseCallback’ {aka ‘std::function<void(std::shared_future<std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> > >)>’} and ‘std::_Bind_helper<false, void (MinimalActionClient::*)(std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> >), MinimalActionClient*, const std::_Placeholder<1>&>::type’ {aka ‘std::_Bind<void (MinimalActionClient::*(MinimalActionClient*, std::_Placeholder<1>))(std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> >)>’})
   78 |       std::bind(&MinimalActionClient::goal_response_callback, this, _1);
      | 
                                                                            ^
In file included from /usr/include/c++/9/functional:59,
                 from /home/brutus/ros2/examples_ws/src/examples/rclcpp/actions/minimal_action_client/member_functions.cpp:17:
/usr/include/c++/9/bits/std_function.h:462:7: note: candidate: ‘std::function<_Res(_ArgTypes ...)>& std::function<_Res(_ArgTypes ...)>::operator=(const std::function<_Res(_ArgTypes ...)>&) [with _Res = void; _ArgTypes = {std::shared_future<std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> > >}]’
  462 |       operator=(const function& __x)
      |       ^~~~~~~~
      
/usr/include/c++/9/bits/std_function.h:462:33: note:   no known conversion for argument 1 from ‘std::_Bind_helper<false, void (MinimalActionClient::*)(std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> >), MinimalActionClient*, const std::_Placeholder<1>&>::type’ {aka ‘std::_Bind<void (MinimalActionClient::*(MinimalActionClient*, std::_Placeholder<1>))(std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> >)>’} to ‘const std::function<void(std::shared_future<std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> > >)>&’
  462 |       operator=(const function& __x)
      |                 ~~~~~~~~~~~~~~~~^~~
      
/usr/include/c++/9/bits/std_function.h:480:7: note: candidate: ‘std::function<_Res(_ArgTypes ...)>& std::function<_Res(_ArgTypes ...)>::operator=(std::function<_Res(_ArgTypes ...)>&&) [with _Res = void; _ArgTypes = {std::shared_future<std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> > >}]’
  480 |       operator=(function&& __x) noexcept
      |       ^~~~~~~~
      
/usr/include/c++/9/bits/std_function.h:480:28: note:   no known conversion for argument 1 from ‘std::_Bind_helper<false, void (MinimalActionClient::*)(std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> >), MinimalActionClient*, const std::_Placeholder<1>&>::type’ {aka ‘std::_Bind<void (MinimalActionClient::*(MinimalActionClient*, std::_Placeholder<1>))(std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> >)>’} to ‘std::function<void(std::shared_future<std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> > >)>&&’
  480 |       operator=(function&& __x) noexcept
      |                 ~~~~~~~~~~~^~~
      
/usr/include/c++/9/bits/std_function.h:494:7: note: candidate: ‘std::function<_Res(_ArgTypes ...)>& std::function<_Res(_ArgTypes ...)>::operator=(std::nullptr_t) [with _Res = void; _ArgTypes = {std::shared_future<std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> > >}; std::nullptr_t = std::nullptr_t]’
  494 |       operator=(nullptr_t) noexcept
      |       ^~~~~~~~
      
/usr/include/c++/9/bits/std_function.h:494:17: note:   no known conversion for argument 1 from ‘std::_Bind_helper<false, void (MinimalActionClient::*)(std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> >), MinimalActionClient*, const std::_Placeholder<1>&>::type’ {aka ‘std::_Bind<void (MinimalActionClient::*(MinimalActionClient*, std::_Placeholder<1>))(std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> >)>’} to ‘std::nullptr_t’
  494 |       operator=(nullptr_t) noexcept
      |                 ^~~~~~~~~
      
/usr/include/c++/9/bits/std_function.h:523:2: note: candidate: ‘template<class _Functor> std::function<_Res(_ArgTypes ...)>::_Requires<std::function<_Res(_ArgTypes ...)>::_Callable<typename std::decay<_Functor>::type>, std::function<_Res(_ArgTypes ...)>&> std::function<_Res(_ArgTypes ...)>::operator=(_Functor&&) [with _Functor = _Functor; _Res = void; _ArgTypes = {std::shared_future<std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> > >}]’
  523 |  operator=(_Functor&& __f)
      |  ^~~~~~~~
      
/usr/include/c++/9/bits/std_function.h:523:2: note:   template argument deduction/substitution failed:
/usr/include/c++/9/bits/std_function.h: In substitution of ‘template<class _Res, class ... _ArgTypes> template<class _Cond, class _Tp> using _Requires = typename std::enable_if<_Cond::value, _Tp>::type [with _Cond = std::function<void(std::shared_future<std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> > >)>::_Callable<std::_Bind<void (MinimalActionClient::*(MinimalActionClient*, std::_Placeholder<1>))(std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> >)>, std::__invoke_result<std::_Bind<void (MinimalActionClient::*(MinimalActionClient*, std::_Placeholder<1>))(std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> >)>&, std::shared_future<std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> > > > >; _Tp = std::function<void(std::shared_future<std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> > >)>&; _Res = void; _ArgTypes = {std::shared_future<std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> > >}]’:
/usr/include/c++/9/bits/std_function.h:523:2:   required by substitution of ‘template<class _Functor> std::function<void(std::shared_future<std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> > >)>::_Requires<std::function<void(std::shared_future<std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> > >)>::_Callable<typename std::decay<_Tp>::type, std::__invoke_result<typename std::decay<_Tp>::type&, std::shared_future<std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> > > > >, std::function<void(std::shared_future<std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> > >)>&> std::function<void(std::shared_future<std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> > >)>::operator=<_Functor>(_Functor&&) [with _Functor = std::_Bind<void (MinimalActionClient::*(MinimalActionClient*, std::_Placeholder<1>))(std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> >)>]’
/home/brutus/ros2/examples_ws/src/examples/rclcpp/actions/minimal_action_client/member_functions.cpp:78:71:   required from here
/usr/include/c++/9/bits/std_function.h:385:8: error: no type named ‘type’ in ‘struct std::enable_if<false, std::function<void(std::shared_future<std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> > >)>&>’
  385 |  using _Requires = typename enable_if<_Cond::value, _Tp>::type;
      |        ^~~~~~~~~
      
/usr/include/c++/9/bits/std_function.h:532:2: note: candidate: ‘template<class _Functor> std::function<_Res(_ArgTypes ...)>& std::function<_Res(_ArgTypes ...)>::operator=(std::reference_wrapper<_Functor>) [with _Functor = _Functor; _Res = void; _ArgTypes = {std::shared_future<std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> > >}]’
  532 |  operator=(reference_wrapper<_Functor> __f) noexcept
      |  ^~~~~~~~
      
/usr/include/c++/9/bits/std_function.h:532:2: note:   template argument deduction/substitution failed:
/home/brutus/ros2/examples_ws/src/examples/rclcpp/actions/minimal_action_client/member_functions.cpp:78:71: note:   ‘std::_Bind<void (MinimalActionClient::*(MinimalActionClient*, std::_Placeholder<1>))(std::shared_ptr<rclcpp_action::ClientGoalHandle<example_interfaces::action::Fibonacci> >)>’ is not derived from ‘std::reference_wrapper<_Tp>’
   78 |       std::bind(&MinimalActionClient::goal_response_callback, this, _1);
      |                                                                       ^
      
make[2]: *** [CMakeFiles/action_client_member_functions.dir/build.make:63: CMakeFiles/action_client_member_functions.dir/member_functions.cpp.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:165: CMakeFiles/action_client_member_functions.dir/all] Error 2
make: *** [Makefile:141: all] Error 2
---
Failed   <<< examples_rclcpp_minimal_action_client [3.33s, exited with code 2]

Start with examples/rclcpp/actions/minimal_action_client/member_functions.cpp around line 78 and compare the compiler's expected GoalResponseCallback type with the callback used there. Rebuild examples_rclcpp_minimal_action_client on the stated Ubuntu-MATE 20.04 Foxy binary setup and confirm the package builds successfully.