Disable implicit downcasts

Make the code safer.

Context: dart-lang/sdk#30392

Author: filiph

.analysis_options

@@ -1,5 +1,6 @@
 analyzer:
-  strong-mode: true
+  strong-mode:
+    implicit-casts: false
   exclude:
     - drivedump/**
 linter:
@@ -40,4 +41,4 @@ linter:
     - unnecessary_brace_in_string_interp
     - unnecessary_getters_setters
     - unrelated_type_equality_checks
-    - valid_regexps
+    - valid_regexps

lib/fractal_stories/action.dart

@@ -36,7 +36,7 @@ Iterable<EnemyTargetAction> generateEnemyTargetActions(
 /// an [actor] and a [builder].
 Iterable<ExitAction> generateExitActions(
     Actor actor, WorldState world, ExitActionBuilder builder) sync* {
-  RoomRoamingSituation situation = world.currentSituation;
+  final situation = world.currentSituation as RoomRoamingSituation;
   var room = world.getRoomByName(situation.currentRoomName);
 
   for (var exit in room.exits) {
@@ -50,7 +50,7 @@ Iterable<ExitAction> generateExitActions(
 /// an [actor] and a [builder].
 Iterable<ItemAction> generateItemActions(
     Actor actor, WorldState world, ItemActionBuilder builder) sync* {
-  FightSituation situation = world.currentSituation;
+  final situation = world.currentSituation as FightSituation;
 
   for (var item in situation.droppedItems) {
     var action = builder(item);
@@ -248,11 +248,11 @@ abstract class Action {
       ..wasAggressive = isAggressive
       ..wasProactive = isProactive;
     if (this is EnemyTargetAction) {
-      EnemyTargetAction action = this;
+      final action = this as EnemyTargetAction;
       builder.sufferers.add(action.enemy.id);
     }
     if (this is ExitAction) {
-      ExitAction action = this;
+      final action = this as ExitAction;
       builder.dataString = action.exit.destinationRoomName;
     }
     return builder;

lib/fractal_stories/actor.dart

@@ -199,7 +199,7 @@ abstract class Actor extends Object
     for (var item in items) {
       if (item is! Weapon) continue;
       if (item.value > value) {
-        best = item;
+        best = item as Weapon;
         value = item.value;
       }
     }

lib/fractal_stories/looped_event/looped_event.dart

@@ -73,7 +73,7 @@ abstract class LoopedEvent /*TODO: implements Saveable ?*/ {
       return;
     }
 
-    while (!finished && _choices.isEmpty && _stringBuffer.isEmpty) {
+    while (!finished && _choices.isEmpty as bool && _stringBuffer.isEmpty) {
       await update();
     }
 

lib/fractal_stories/world.dart

@@ -184,7 +184,7 @@ class WorldState {
 
   Actor getActorById(int id) {
     assert(actors.where((actor) => actor.id == id).length > 0,
-    "No actor of id=$id in world: $this.");
+        "No actor of id=$id in world: $this.");
     assert(actors.where((actor) => actor.id == id).length < 2,
         "Too many actors of id=$id in world: $this.");
     return actors.singleWhere((actor) => actor.id == id);

lib/src/fight/actions/disarm_kick.dart

@@ -67,7 +67,7 @@ class DisarmKick extends EnemyTargetAction {
       s.add("<owner's> <subject> fl<ies> away",
           subject: enemy.currentWeapon, owner: enemy);
     });
-    FightSituation situation = w.currentSituation;
+    final situation = w.currentSituation as FightSituation;
     w.replaceSituationById(
         situation.id,
         situation.rebuild((FightSituationBuilder b) =>

lib/src/fight/actions/pass.dart

@@ -24,7 +24,6 @@ class Pass extends Action {
   @override
   final Resource rerollResource = null;
 
-
   @override
   String get command => "Stand off.";
 

lib/src/fight/actions/start_slash_out_of_balance.dart

@@ -63,16 +63,15 @@ EnemyTargetAction startSlashOutOfBalancePlayerBuilder(Actor enemy) =>
         (a, w, enemy) => new SlashSituation.initialized(a, enemy),
         (a, w, enemy) => new SlashDefenseSituation.initialized(a, enemy,
             predeterminedResult: Predetermination.failureGuaranteed),
-        enemy,
-        successChanceGetter: (a, w, enemy) {
-          // This is intentional. Since the action can only lead to either
-          // complete miss (attacker's failure) or guaranteed failure
-          // of enemy's defense (attacker's success), we do need to count
-          // defender's shield here. Let's say the attacking player tries
-          // not to hit the shield and therefore misses completely.
-          final shieldPenalty = enemy.currentShield != null ? 0.2 : 0.0;
-          return 0.5 - shieldPenalty;
-        },
+        enemy, successChanceGetter: (a, w, enemy) {
+      // This is intentional. Since the action can only lead to either
+      // complete miss (attacker's failure) or guaranteed failure
+      // of enemy's defense (attacker's success), we do need to count
+      // defender's shield here. Let's say the attacking player tries
+      // not to hit the shield and therefore misses completely.
+      final shieldPenalty = enemy.currentShield != null ? 0.2 : 0.0;
+      return 0.5 - shieldPenalty;
+    },
         applyStartOfFailure: startSlashOutOfBalanceApplyFailure,
         buildSituationsOnFailure: false);
 

lib/src/fight/actions/take_dropped_shield.dart

@@ -39,7 +39,7 @@ class TakeDroppedShield extends ItemAction {
 
   @override
   String applySuccess(Actor a, WorldState w, Storyline s) {
-    FightSituation situation = w.currentSituation;
+    final situation = w.currentSituation as FightSituation;
     w.replaceSituationById(
         situation.id,
         situation.rebuild(

lib/src/fight/actions/take_dropped_weapon.dart

@@ -42,7 +42,7 @@ class TakeDroppedWeapon extends ItemAction {
 
   @override
   String applySuccess(Actor a, WorldState w, Storyline s) {
-    FightSituation situation = w.currentSituation;
+    final situation = w.currentSituation as FightSituation;
     w.replaceSituationById(
         situation.id,
         situation.rebuild(
@@ -70,7 +70,7 @@ class TakeDroppedWeapon extends ItemAction {
     // TODO: remove the next condition
     if (item is Spear) return false;
     if (!a.canWield) return false;
-    Weapon weapon = item;
+    final weapon = item as Weapon;
     final isSwordForSpear = a.currentWeapon is Spear && weapon is Sword;
     if (weapon.value <= a.currentWeapon.value && !isSwordForSpear) return false;
     var disarmedRecency = w.timeSinceLastActionRecord(