/in/map.cpp:127:67: error: implicit conversion changes signedness: 'char' to 'std::vector::size_type' (aka 'unsigned long') [-Werror,-Wsign-conversion]
           discovered[color][y][x] || (is_button(c) && discovered[button_to_id(c)][y][x]);
                                                       ~~~~~~~~~~ ^~~~~~~~~~~~~~~
/in/map.cpp:158:16: error: implicit conversion changes signedness: 'char' to 'std::vector::size_type' (aka 'unsigned long') [-Werror,-Wsign-conversion]
    discovered[c][y][x] = 1;
    ~~~~~~~~~~ ^
/in/map.cpp:262:43: error: implicit conversion changes signedness: 'char' to 'std::vector::size_type' (aka 'unsigned long') [-Werror,-Wsign-conversion]
        char action = backtracker[current.color][current.y][current.x];
                      ~~~~~~~~~~~ ~~~~~~~~^~~~~
3 errors generated.