/home/user/Projects/expression-parsing/main.cpp: In member function ‘std::unique_ptr<node> parser::parse_additive(std::deque<token>&)’:
/home/user/Projects/expression-parsing/main.cpp:485:93: error: no matching function for call to ‘make_unique<node>(sum_node)’
  485 |                 node = std::make_unique<node>(sum_node(*node, *parse_multiplicative(tokens)));
      |                                                                                             ^
In file included from /usr/include/c++/9.1.0/memory:80,
                 from /home/user/Projects/expression-parsing/main.cpp:11:
/usr/include/c++/9.1.0/bits/unique_ptr.h:852:5: note: candidate: ‘template<class _Tp, class ... _Args> typename std::_MakeUniq<_Tp>::__single_object std::make_unique(_Args&& ...)’
  852 |     make_unique(_Args&&... __args)
      |     ^~~~~~~~~~~
/usr/include/c++/9.1.0/bits/unique_ptr.h:852:5: note:   template argument deduction/substitution failed:
/usr/include/c++/9.1.0/bits/unique_ptr.h:858:5: note: candidate: ‘template<class _Tp> typename std::_MakeUniq<_Tp>::__array std::make_unique(std::size_t)’
  858 |     make_unique(size_t __num)
      |     ^~~~~~~~~~~
/usr/include/c++/9.1.0/bits/unique_ptr.h:858:5: note:   template argument deduction/substitution failed:
/usr/include/c++/9.1.0/bits/unique_ptr.h:864:5: note: candidate: ‘template<class _Tp, class ... _Args> typename std::_MakeUniq<_Tp>::__invalid_type std::make_unique(_Args&& ...)’ <deleted>
  864 |     make_unique(_Args&&...) = delete;
      |     ^~~~~~~~~~~
/usr/include/c++/9.1.0/bits/unique_ptr.h:864:5: note:   template argument deduction/substitution failed:
/home/user/Projects/expression-parsing/main.cpp:488:5: warning: no return statement in function returning non-void [-Wreturn-type]
  488 |     }
      |     ^
In file included from /usr/include/c++/9.1.0/memory:80,
                 from /home/user/Projects/expression-parsing/main.cpp:11:
/usr/include/c++/9.1.0/bits/unique_ptr.h: In instantiation of ‘typename std::_MakeUniq<_Tp>::__single_object std::make_unique(_Args&& ...) [with _Tp = node; _Args = {const node&}; typename std::_MakeUniq<_Tp>::__single_object = std::unique_ptr<node>]’:
/home/user/Projects/expression-parsing/main.cpp:422:141:   required from here
/usr/include/c++/9.1.0/bits/unique_ptr.h:853:30: error: invalid new-expression of abstract class type ‘node’
  853 |     { return unique_ptr<_Tp>(new _Tp(std::forward<_Args>(__args)...)); }
      |                              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/user/Projects/expression-parsing/main.cpp:403:8: note:   because the following virtual functions are pure within ‘node’:
  403 | struct node {
      |        ^~~~
/home/user/Projects/expression-parsing/main.cpp:405:20: note: 	‘virtual number node::compute()’
  405 |     virtual number compute() = 0;
      |                    ^~~~~~~
In file included from /usr/include/c++/9.1.0/memory:80,
                 from /home/user/Projects/expression-parsing/main.cpp:11:
/usr/include/c++/9.1.0/bits/unique_ptr.h: In instantiation of ‘typename std::_MakeUniq<_Tp>::__single_object std::make_unique(_Args&& ...) [with _Tp = node; _Args = {number_node}; typename std::_MakeUniq<_Tp>::__single_object = std::unique_ptr<node>]’:
/home/user/Projects/expression-parsing/main.cpp:455:63:   required from here
/usr/include/c++/9.1.0/bits/unique_ptr.h:853:30: error: invalid new-expression of abstract class type ‘node’
  853 |     { return unique_ptr<_Tp>(new _Tp(std::forward<_Args>(__args)...)); }
      |                              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/9.1.0/bits/unique_ptr.h: In instantiation of ‘typename std::_MakeUniq<_Tp>::__single_object std::make_unique(_Args&& ...) [with _Tp = node; _Args = {call_node}; typename std::_MakeUniq<_Tp>::__single_object = std::unique_ptr<node>]’:
/home/user/Projects/expression-parsing/main.cpp:463:109:   required from here
/usr/include/c++/9.1.0/bits/unique_ptr.h:853:30: error: invalid new-expression of abstract class type ‘node’
make[3]: *** [CMakeFiles/expression_parsing.dir/build.make:63: CMakeFiles/expression_parsing.dir/main.cpp.o] Error 1
make[2]: *** [CMakeFiles/Makefile2:76: CMakeFiles/expression_parsing.dir/all] Error 2
make[1]: *** [CMakeFiles/Makefile2:83: CMakeFiles/expression_parsing.dir/rule] Error 2
make: *** [Makefile:118: expression_parsing] Error 2