Added for-loop variable tracking and regular closures/initializers captured variable tracking.

pkg/compiler/lib/src/closure.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'common/names.dart' show Identifiers;
 import 'common/resolution.dart' show ParsingContext, Resolution;
 import 'common/tasks.dart' show CompilerTask, Measurer;
 import 'common.dart';
 import 'compiler.dart' show Compiler;
 import 'constants/expressions.dart';
@@ skipping 82 matching lines @@
   /// the correct updated value. The variables in variablesUsedInTryOrSync may
   /// be included in this set.
   ///
   /// In the case of loops, this is the set of iteration variables (or any
   /// variables declared in the for loop expression (`for (...here...)`) that
   /// need to be boxed to snapshot their value.
   void forEachBoxedVariable(f(Local local, FieldEntity field)) {}
 
   /// True if [variable] has been mutated and is also used in another scope.
   bool isBoxed(Local variable) => false;
-
-  /// True if this scope declares any variables that need to be boxed.
-  bool get hasBoxedVariables => false;
 }
 
 /// Class representing the usage of a scope that has been captured in the
 /// context of a closure.
 class ClosureScope extends ScopeInfo {
   const ClosureScope();
 
   /// If true, this closure accesses a variable that was defined in an outside
   /// scope and this variable gets modified at some point (sometimes we say that
   /// variable has been "captured"). In this situation, access to this variable
@@ skipping 18 matching lines @@
 ///     var lst = [];
 ///     for (int i = 0; i < 5; i++) lst.add(()=>i);
 ///     var result = list.map((f) => f()).toList();
 ///
 /// `result` will be [0, 1, 2, 3, 4], whereas were this JS code
 /// the result would be [5, 5, 5, 5, 5]. Because of this difference we need to
 /// create a closure for these sorts of loops to capture the variable's value at
 /// each iteration, by boxing the iteration variable[s].
 class LoopClosureScope extends ClosureScope {
   const LoopClosureScope();
+
+  /// True if this loop scope declares in the first part of the loop
+  /// `for (<here>;...;...)` any variables that need to be boxed.
+  bool get hasBoxedLoopVariables => false;
+
+  /// The set of iteration variables (or variables declared in the for loop
+  /// expression (`for (<here>; ... ; ...)`) that need to be boxed to snapshot
+  /// their value. These variables are also included in the set of
+  /// `forEachBoxedVariable` method. The distinction between these two sets is
+  /// in this example:
+  ///
+  ///     run(f) => f();
+  ///     var a;
+  ///     for (int i = 0; i < 3; i++) {
+  ///       var b = 3;
+  ///       a = () => b = i;
+  ///     }
+  ///
+  /// `i` would be a part of the boxedLoopVariables AND boxedVariables, but b
+  /// would only be a part of boxedVariables.
+  List<Local> get boxedLoopVariables => const <Local>[];
 }
 
 /// Class that describes the actual mechanics of how the converted, rewritten
 /// closure is implemented. For example, for the following closure (named foo
 /// for convenience):
 ///
 ///   var foo = (x) => y + x;
 ///
 /// We would produce the following class to control access to these variables in
 /// the following way (modulo naming of variables, assuming that y is modified
@@ skipping 486 matching lines @@
   // Otherwise contains the empty List.
   List<Local> boxedLoopVariables = const <Local>[];
 
   ClosureScopeImpl(this.boxElement, this.capturedVariables);
 
   Local get context => boxElement;
 
   bool get requiresContextBox => capturedVariables.keys.isNotEmpty;
 
   void forEachBoxedVariable(f(Local local, FieldEntity field)) {
-    if (capturedVariables.isNotEmpty) {
-      capturedVariables.forEach(f);
-    } else {
-      for (Local l in boxedLoopVariables) {
-        // The boxes for loop variables are constructed on-demand per-iteration
-        // in the locals handler.
-        f(l, null);
-      }
-    }
+    capturedVariables.forEach(f);
   }
 
-  bool get hasBoxedVariables => !capturedVariables.isEmpty;
+  bool get hasBoxedLoopVariables => boxedLoopVariables.isNotEmpty;
 
   bool isBoxed(Local variable) {
     return capturedVariables.containsKey(variable);
   }
 
   void forEachCapturedVariable(
       f(LocalVariableElement variable, BoxFieldElement boxField)) {
     capturedVariables.forEach(f);
   }
 
@@ skipping 67 matching lines @@
   /// control flow can be non-linear.
   ///
   /// Also parameters to a `sync*` generator must be boxed, because of the way
   /// we rewrite sync* functions. See also comments in [useLocal].
   // TODO(johnniwinther): Add variables to this only if the variable is mutated.
   final Set<Local> variablesUsedInTryOrSync = new Set<Local>();
 
   ClosureClassMap(this.closureEntity, this.closureClassEntity, this.callMethod,
       this.thisLocal);
 
-  bool get hasBoxedVariables =>
-      throw new UnsupportedError("ClosureClassMap.hasBoxedVariables");
-
   List<Local> get createdFieldEntities {
     List<Local> fields = <Local>[];
     if (closureClassEntity == null) return const <Local>[];
     closureClassEntity.closureFields.forEach((field) {
       fields.add(field.local);
     });
     return fields;
   }
 
   void addFreeVariable(Local element) {
@@ skipping 763 matching lines @@
 ///
 /// Move the below classes to a JS model eventually.
 ///
 abstract class JSEntity implements MemberEntity {
   Local get declaredEntity;
 }
 
 abstract class PrivatelyNamedJSEntity implements JSEntity {
   Entity get rootOfScope;
 }