refactor: fix compiler warnings (#6015)

src/character.cpp

@@ -8764,7 +8764,6 @@ void Character::on_hit( Creature *source, bodypart_id bp_hit,
     bool in_skater_vehicle = in_vehicle && veh_part.part_with_feature( "SEAT_REQUIRES_BALANCE", false );
 
     if( ( worn_with_flag( flag_REQUIRES_BALANCE ) || in_skater_vehicle ) && !is_on_ground() ) {
-        int rolls = 4;
         if( worn_with_flag( flag_ROLLER_ONE ) && !in_skater_vehicle ) {
             if( worn_with_flag( flag_REQUIRES_BALANCE ) && !has_effect( effect_downed ) ) {
                 int rolls = 4;

src/game.cpp

@@ -8534,7 +8534,7 @@ void game::butcher()
                 disassembly_stacks_res.emplace_back( stack.first->typeId(), stack.second );
             }
 
-            for( int i = 0; i < disassembly_stacks_res.size(); i++ ) {
+            for( int i = 0; i < static_cast<int>( disassembly_stacks_res.size() ); i++ ) {
                 const auto dis = recipe_dictionary::get_uncraft( disassembly_stacks_res[i].first );
                 time_to_disassemble_rec += dis.time * disassembly_stacks_res[i].second;
                 //uses default craft materials to estimate recursive disassembly time

src/recipe.cpp

@@ -602,7 +602,7 @@ std::function<bool( const item & )> recipe::get_component_filter(
     };
 }
 
-static std::string dump_requirements(
+[[maybe_unused]] static std::string dump_requirements(
     const requirement_data &reqs,
     int move_cost,
     const std::map<skill_id, int> &skills )

src/vehicle_move.cpp

@@ -656,13 +656,6 @@ veh_collision vehicle::part_collision( int part, const tripoint &p,
     // 0.001 -> 1 meter. Left modifiable so that armor or other parts can affect it.
     float deformation_distance = density_factor / 100;
 
-    //Calculates mass factor. Depreciated, maintained for stats.
-    // factor = -25 if mass is much greater than mass2
-    // factor = +25 if mass2 is much greater than mass
-    const float weight_factor = mass >= mass2 ?
-                                -25 * ( std::log( mass ) - std::log( mass2 ) ) / std::log( mass ) :
-                                25 * ( std::log( mass2 ) - std::log( mass ) ) / std::log( mass2 );
-
     bool smashed = true;
     const std::string snd = _( "smash!" );
     float part_dmg = 0;