compilation errors on Ubuntu 22.04

[christianrauch]

I am getting a couple of compiler (GNU 11.2.0) errors:

In file included from /tmp/SonyHeadphonesClient/Client/CrossPlatformGUI.h:10,
                 from /tmp/SonyHeadphonesClient/Client/CrossPlatformGUI.cpp:1:
/tmp/SonyHeadphonesClient/Client/SingleInstanceFuture.h:15:33: error: expected unqualified-id before ‘)’ token
   15 |         SingleInstanceFuture<T>() = default;
      |                                 ^
/tmp/SonyHeadphonesClient/Client/SingleInstanceFuture.h:21:48: error: invalid declarator before ‘other’
   21 |         SingleInstanceFuture<T>(std::future<T> other);
      |                                                ^~~~~
/tmp/SonyHeadphonesClient/Client/SingleInstanceFuture.h:21:47: error: expected ‘)’ before ‘other’
   21 |         SingleInstanceFuture<T>(std::future<T> other);
      |                                ~              ^~~~~~
      |                                               )
/tmp/SonyHeadphonesClient/Client/SingleInstanceFuture.h:48:8: error: no declaration matches ‘SingleInstanceFuture<T>::SingleInstanceFuture(std::future<_Res>)’
   48 | inline SingleInstanceFuture<T>::SingleInstanceFuture(std::future<T> other) : std::future<T>(std::move(other)) {}
      |        ^~~~~~~~~~~~~~~~~~~~~~~
/tmp/SonyHeadphonesClient/Client/SingleInstanceFuture.h:48:8: note: no functions named ‘SingleInstanceFuture<T>::SingleInstanceFuture(std::future<_Res>)’
/tmp/SonyHeadphonesClient/Client/SingleInstanceFuture.h:12:7: note: ‘class SingleInstanceFuture<T>’ defined here
   12 | class SingleInstanceFuture : public std::future<T>
      |       ^~~~~~~~~~~~~~~~~~~~
/tmp/SonyHeadphonesClient/Client/SingleInstanceFuture.h: In instantiation of ‘void SingleInstanceFuture<T>::setFromAsync(Func, Args&& ...) [with Func = CrossPlatformGUI::_drawDeviceDiscovery()::<lambda()>; Args = {}; T = void]’:
/tmp/SonyHeadphonesClient/Client/CrossPlatformGUI.cpp:112:40:   required from here
/tmp/SonyHeadphonesClient/Client/SingleInstanceFuture.h:33:15: error: cannot bind non-const lvalue reference of type ‘std::future<void>&’ to an rvalue of type ‘std::future<void>’
   33 |         *this = std::async(std::launch::async, func, std::forward<Args>(args)...);
      |         ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/tmp/SonyHeadphonesClient/Client/SingleInstanceFuture.h:51:83: note:   initializing argument 1 of ‘SingleInstanceFuture<T> SingleInstanceFuture<T>::operator=(std::future<_Res>&) [with T = void]’
   51 | anceFuture<T> SingleInstanceFuture<T>::operator=(std::future<T>& other)
      |                                                  ~~~~~~~~~~~~~~~~^~~~~

/tmp/SonyHeadphonesClient/Client/SingleInstanceFuture.h: In instantiation of ‘void SingleInstanceFuture<T>::setFromAsync(Func, Args&& ...) [with Func = CrossPlatformGUI::_drawDeviceDiscovery()::<lambda()>; Args = {}; T = std::vector<BluetoothDevice>]’:
/tmp/SonyHeadphonesClient/Client/CrossPlatformGUI.cpp:146:48:   required from here
/tmp/SonyHeadphonesClient/Client/SingleInstanceFuture.h:33:15: error: cannot bind non-const lvalue reference of type ‘std::future<std::vector<BluetoothDevice> >&’ to an rvalue of type ‘std::future<std::vector<BluetoothDevice> >’
   33 |         *this = std::async(std::launch::async, func, std::forward<Args>(args)...);
      |         ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/tmp/SonyHeadphonesClient/Client/SingleInstanceFuture.h:51:83: note:   initializing argument 1 of ‘SingleInstanceFuture<T> SingleInstanceFuture<T>::operator=(std::future<_Res>&) [with T = std::vector<BluetoothDevice>]’
   51 | anceFuture<T> SingleInstanceFuture<T>::operator=(std::future<T>& other)
      |                                                  ~~~~~~~~~~~~~~~~^~~~~

/tmp/SonyHeadphonesClient/Client/SingleInstanceFuture.h: In instantiation of ‘void SingleInstanceFuture<T>::setFromAsync(Func, Args&& ...) [with Func = CrossPlatformGUI::_drawASMControls()::<lambda()>; Args = {}; T = int]’:
/tmp/SonyHeadphonesClient/Client/CrossPlatformGUI.cpp:223:41:   required from here
/tmp/SonyHeadphonesClient/Client/SingleInstanceFuture.h:33:15: error: cannot bind non-const lvalue reference of type ‘std::future<int>&’ to an rvalue of type ‘std::future<int>’
   33 |         *this = std::async(std::launch::async, func, std::forward<Args>(args)...);
      |         ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/tmp/SonyHeadphonesClient/Client/SingleInstanceFuture.h:51:83: note:   initializing argument 1 of ‘SingleInstanceFuture<T> SingleInstanceFuture<T>::operator=(std::future<_Res>&) [with T = int]’
   51 | anceFuture<T> SingleInstanceFuture<T>::operator=(std::future<T>& other)
      |                                                  ~~~~~~~~~~~~~~~~^~~~~

/tmp/SonyHeadphonesClient/Client/SingleInstanceFuture.h: In instantiation of ‘void SingleInstanceFuture<T>::setFromAsync(Func, Args&& ...) [with Func = CrossPlatformGUI::CrossPlatformGUI(BluetoothWrapper)::<lambda()>; Args = {}; T = std::vector<BluetoothDevice>]’:
/tmp/SonyHeadphonesClient/Client/CrossPlatformGUI.cpp:245:44:   required from here
/tmp/SonyHeadphonesClient/Client/SingleInstanceFuture.h:33:15: error: cannot bind non-const lvalue reference of type ‘std::future<std::vector<BluetoothDevice> >&’ to an rvalue of type ‘std::future<std::vector<BluetoothDevice> >’
   33 |         *this = std::async(std::launch::async, func, std::forward<Args>(args)...);
      |         ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/tmp/SonyHeadphonesClient/Client/SingleInstanceFuture.h:51:83: note:   initializing argument 1 of ‘SingleInstanceFuture<T> SingleInstanceFuture<T>::operator=(std::future<_Res>&) [with T = std::vector<BluetoothDevice>]’
   51 | anceFuture<T> SingleInstanceFuture<T>::operator=(std::future<T>& other)
      |                                                  ~~~~~~~~~~~~~~~~^~~~~

[christianrauch]

Whoops, duplicate of #51.