¬ make CXX=g++ CXXFLAGS="-std=c++1z -Wall"
CXX src/umv.cpp build/umv.o
In file included from src/wm/../utils/xcb_wrap.hpp:29:0,
                 from src/wm/tools.hpp:34,
                 from src/uwm.hpp:25,
                 from src/umv.cpp:25:
src/wm/../utils/../wm/connection.hpp:67:33: error: enclosing class of constexpr non-static member function ‘xcb_connection_t* uwm::connection::get() const’ is not a literal type
     constexpr xcb_connection_t* get() const
                                 ^~~
src/wm/../utils/../wm/connection.hpp:41:8: note: ‘uwm::connection’ is not literal because:
 struct connection
        ^~~~~~~~~~
src/wm/../utils/../wm/connection.hpp:41:8: note:   ‘uwm::connection’ has a non-trivial destructor
src/wm/../utils/../wm/connection.hpp:73:33: error: enclosing class of constexpr non-static member function ‘xcb_connection_t* uwm::connection::operator&() const’ is not a literal type
     constexpr xcb_connection_t* operator&() const noexcept
                                 ^~~~~~~~
src/wm/../utils/../wm/connection.hpp:76:15: error: enclosing class of constexpr non-static member function ‘uwm::connection::operator bool() const’ is not a literal type
     constexpr operator bool() const noexcept
               ^~~~~~~~
make: *** [Makefile:39: build/umv.o] Error 1