Fix various clang-tidy errors

Having fixed the clang-tidy Travis build, it's now necessary to fix all
the errors it highlights.

src/character.cpp

@@ -550,10 +550,7 @@ void Character::set_stashed_activity( player_activity act, player_activity act_b
 
 bool Character::has_stashed_activity() const
 {
-    if( stashed_outbounds_activity ) {
-        return true;
-    }
-    return false;
+    return static_cast<bool>( stashed_outbounds_activity );
 }
 
 void Character::assign_stashed_activity()

src/handle_action.cpp

@@ -976,9 +976,9 @@ static void sleep()
 
         as_m.reset();
         as_m.text = can_hibernate ?
-                    _( "You're engorged to hibernate. The alarm would only attract attention. Set an alarm anyway?" +
+                    _( "You're engorged to hibernate.  The alarm would only attract attention.  Set an alarm anyway?" +
                        deaf_text ) :
-                    _( "You have an alarm clock. Set an alarm?" + deaf_text );
+                    _( "You have an alarm clock.  Set an alarm?" + deaf_text );
 
         as_m.entries.emplace_back( 0, true,
                                    get_option<bool>( "FORCE_CAPITAL_YN" ) ? 'N' : 'n',

src/json.cpp

@@ -1042,7 +1042,7 @@ number_sci_notation JsonIn::get_any_int()
         error( "Integers cannot have a decimal point or negative order of magnitude." );
     }
     // Manually apply scientific notation, since std::pow converts to double under the hood.
-    for( int i = 0; i < n.exp; i++ ) {
+    for( int64_t i = 0; i < n.exp; i++ ) {
         if( n.number > std::numeric_limits<uint64_t>::max() / 10ULL ) {
             error( "Specified order of magnitude too large -- encountered overflow applying it." );
         }

src/mapgen_functions.cpp

@@ -2293,17 +2293,17 @@ void mapgen_generic_house( mapgendata &dat, int variant )
 
     // West external wall
     lw = rng( 0, 4 );
-    // NOLINTNEXTLINE(clang-analyzer-deadcode.DeadStores)
     // Middle wall between bedroom & kitchen/bath
+    // NOLINTNEXTLINE(clang-analyzer-deadcode.DeadStores)
     mw = lw + rng( 7, 10 );
     // East external wall
     rw = SEEX * 2 - rng( 1, 5 );
     // North external wall
     tw = rng( 1, 6 );
     // South external wall
     bw = SEEX * 2 - rng( 2, 5 );
-    // NOLINTNEXTLINE(clang-analyzer-deadcode.DeadStores)
     // Middle wall between living room & kitchen/bed
+    // NOLINTNEXTLINE(clang-analyzer-deadcode.DeadStores)
     cw = tw + rng( 4, 7 );
     //reserving some space for backyard. Actual south external wall.
     actual_house_height = bw - rng( 4, 6 );

src/mondefense.cpp

@@ -30,8 +30,6 @@
 static const skill_id skill_gun( "gun" );
 static const skill_id skill_rifle( "rifle" );
 
-std::vector<tripoint> closest_tripoints_first( int radius, const tripoint &p );
-
 void mdefense::none( monster &, Creature *, const dealt_projectile_attack * )
 {
 }

src/npcmove.cpp

@@ -804,12 +804,10 @@ void npc::move()
         if( has_stashed_activity() ) {
             if( !check_outbounds_activity( get_stashed_activity(), true ) ) {
                 assign_stashed_activity();
-                action = npc_player_activity;
             } else {
                 // wait a turn, because next turn, the object of our activity
                 // may have been loaded in.
                 set_moves( 0 );
-                action = npc_pause;
             }
             return;
         }

src/player_display.cpp

@@ -345,7 +345,7 @@ static void draw_stats_tab( const catacurses::window &w_stats, const catacurses:
         const int lines = fold_and_print( w_info, point( 1, 0 ), FULL_SCREEN_WIDTH - 2, c_magenta,
                                           _( "Your weight is a general indicator of how much fat your body has stored up,"
                                              " which in turn shows how prepared you are to survive for a time without food."
-                                             " Having too much, or too little, can be unhealthy." ) );
+                                             "  Having too much, or too little, can be unhealthy." ) );
         fold_and_print( w_info, point( 1, 1 + lines ), FULL_SCREEN_WIDTH - 2, c_magenta,
                         you.get_weight_description() );
     }

src/veh_interact.cpp

@@ -85,14 +85,11 @@ static auto can_refill = []( const vehicle_part &pt )
     return pt.can_reload();
 };
 
-namespace
-{
 static const quality_id LIFT( "LIFT" );
 static const quality_id JACK( "JACK" );
 static const quality_id SELF_JACK( "SELF_JACK" );
 static const skill_id skill_mechanics( "mechanics" );
 static const itype_id fuel_type_battery( "battery" );
-} // namespace
 
 void act_vehicle_siphon( vehicle *veh );
 void act_vehicle_unload_fuel( vehicle *veh );

tests/active_item_cache.cpp

@@ -37,7 +37,7 @@ TEST_CASE( "place_active_item_at_various_coordinates", "[item]" )
             CHECK( !g->m.get_submaps_with_active_items().empty() );
             CHECK( g->m.get_submaps_with_active_items().find( abs_loc ) !=
                    g->m.get_submaps_with_active_items().end() );
-            CHECK( g->m.i_at( { x, y, z } ).size() != 0 );
+            CHECK( !g->m.i_at( { x, y, z } ).empty() );
             g->m.i_clear( { x, y, z } );
         }
     }