fixes #52, fields shadowing getters/setters or other fields

lib/runtime/dart/core.js

Index: lib/runtime/dart/core.js
diff --git a/lib/runtime/dart/core.js b/lib/runtime/dart/core.js
index 9c781a03433c26852c7ec9e28c779e90be7df37f..c1f6f8eea3c8aff470908cc91c3afd9bd1ae944b 100644
--- a/lib/runtime/dart/core.js
+++ b/lib/runtime/dart/core.js
@@ -1,6 +1,7 @@
 var core;
 (function(exports) {
   'use strict';
+  let name$ = dart.JsSymbol('name');
   class Object {
     constructor() {
       let name = this.constructor.name;
@@ -27,24 +28,35 @@ var core;
     }
   }
   class JsName extends Object {
+    get name() {
+      return this[name$];
+    }
     JsName(opts) {
       let name = opts && 'name' in opts ? opts.name : null;
-      this.name = name;
+      this[name$] = name;
     }
   }
+  let name$0 = dart.JsSymbol('name');

[Jacob, 2015/04/17 20:28:53]

high level question. why are both name$ and name$0 required? maybe I'm missing
something obvious.

[Jennifer Messerly, 2015/04/20 17:44:34]

They are semantically different members. Consider:

    class JsName { int name = init(42); // prints and returns 42 }
    class JsPeerInterface { int name = init(100); // prints and returns 100 }

    library my_separately_compiled_lib;
    class Boom extends JsName with JsPeerInterface {}
    // Does `new Boom().name` return the right thing?


Now granted, this can't happen between JsName and JsPeerInterface, as they both
have constructors with arguments and mixins don't currently don't allow those.
But in general, if "name" is unsealed we have to create per-class storage
symbols.

As that example shows, there are some cases where we could reuse storage slots:
if we know the two types can never be mixed together in the same inheritance
graph. For public types, this would depend on our current mixin restrictions, so
it's not really a long term optimization. For private types, we could simply
observe that they are not mixed together. Anyway, I'll add a TODO, but not sure
it's really worth improving right now. We'd get a lot more mileage out of
@sealed fields (either opt-in or opt-out).

We could also extend our JSTemporary to have two candidate names. I think using
the field "name" is most readable, but maybe if that is taken "JsName_name"
(i.e. qualified by the class) would be next most readable.

   class JsPeerInterface extends Object {
+    get name() {
+      return this[name$0];
+    }
     JsPeerInterface(opts) {
       let name = opts && 'name' in opts ? opts.name : null;
-      this.name = name;
+      this[name$0] = name;
     }
   }
   class SupportJsExtensionMethod extends Object {
     SupportJsExtensionMethod() {
     }
   }
+  let expires$ = dart.JsSymbol('expires');
   class Deprecated extends Object {
+    get expires() {
+      return this[expires$];
+    }
     Deprecated(expires) {
-      this.expires = expires;
+      this[expires$] = expires;
     }
     toString() {
       return `Deprecated feature. Will be removed ${this.expires}`;
@@ -100,6 +112,8 @@ var core;
     return Comparable;
   });
   let Comparable = Comparable$();
+  let millisecondsSinceEpoch$ = dart.JsSymbol('millisecondsSinceEpoch');
+  let isUtc$ = dart.JsSymbol('isUtc');
   let _internal = dart.JsSymbol('_internal');
   let _now = dart.JsSymbol('_now');
   let _brokenDownDateToMillisecondsSinceEpoch = dart.JsSymbol('_brokenDownDateToMillisecondsSinceEpoch');
@@ -109,6 +123,12 @@ var core;
   let _threeDigits = dart.JsSymbol('_threeDigits');
   let _twoDigits = dart.JsSymbol('_twoDigits');
   class DateTime extends Object {
+    get millisecondsSinceEpoch() {
+      return this[millisecondsSinceEpoch$];
+    }
+    get isUtc() {
+      return this[isUtc$];
+    }
     DateTime(year, month, day, hour, minute, second, millisecond) {
       if (month === void 0)
         month = 1;
@@ -195,8 +215,8 @@ var core;
     }
     fromMillisecondsSinceEpoch(millisecondsSinceEpoch, opts) {
       let isUtc = opts && 'isUtc' in opts ? opts.isUtc : false;
-      this.millisecondsSinceEpoch = millisecondsSinceEpoch;
-      this.isUtc = isUtc;
+      this[millisecondsSinceEpoch$] = millisecondsSinceEpoch;
+      this[isUtc$] = isUtc;
       if (dart.notNull(millisecondsSinceEpoch.abs()) > dart.notNull(DateTime[_MAX_MILLISECONDS_SINCE_EPOCH])) {
         throw new ArgumentError(millisecondsSinceEpoch);
       }
@@ -307,12 +327,12 @@ var core;
       return new Duration({milliseconds: dart.notNull(ms) - dart.notNull(otherMs)});
     }
     [_internal](year, month, day, hour, minute, second, millisecond, isUtc) {
-      this.isUtc = typeof isUtc == 'boolean' ? isUtc : dart.throw_(new ArgumentError(isUtc));
-      this.millisecondsSinceEpoch = dart.as(_js_helper.checkInt(_js_helper.Primitives.valueFromDecomposedDate(year, month, day, hour, minute, second, millisecond, isUtc)), int);
+      this[isUtc$] = typeof isUtc == 'boolean' ? isUtc : dart.throw_(new ArgumentError(isUtc));
+      this[millisecondsSinceEpoch$] = dart.as(_js_helper.checkInt(_js_helper.Primitives.valueFromDecomposedDate(year, month, day, hour, minute, second, millisecond, isUtc)), int);
     }
     [_now]() {
-      this.isUtc = false;
-      this.millisecondsSinceEpoch = _js_helper.Primitives.dateNow();
+      this[isUtc$] = false;
+      this[millisecondsSinceEpoch$] = _js_helper.Primitives.dateNow();
     }
     static [_brokenDownDateToMillisecondsSinceEpoch](year, month, day, hour, minute, second, millisecond, isUtc) {
       return dart.as(_js_helper.Primitives.valueFromDecomposedDate(year, month, day, hour, minute, second, millisecond, isUtc), int);
@@ -582,15 +602,27 @@ var core;
       return "Throw of null.";
     }
   }
+  let invalidValue = dart.JsSymbol('invalidValue');
+  let name$1 = dart.JsSymbol('name');
+  let message$ = dart.JsSymbol('message');
   let _hasValue = dart.JsSymbol('_hasValue');
   class ArgumentError extends Error {
+    get invalidValue() {
+      return this[invalidValue];
+    }
+    get name() {
+      return this[name$1];
+    }
+    get message() {
+      return this[message$];
+    }
     ArgumentError(message) {
       if (message === void 0)
         message = null;
-      this.message = message;
-      this.invalidValue = null;
+      this[message$] = message;
+      this[invalidValue] = null;
       this[_hasValue] = false;
-      this.name = null;
+      this[name$1] = null;
       super.Error();
     }
     value(value, name, message) {
@@ -598,9 +630,9 @@ var core;
         name = null;
       if (message === void 0)
         message = "Invalid argument";
-      this.name = name;
-      this.message = message;
-      this.invalidValue = value;
+      this[name$1] = name;

[Jacob, 2015/04/17 20:28:53]

same here. why are multiple names required? private symbols in the same library
all have the same identifier, right?

[Jennifer Messerly, 2015/04/20 17:44:34]

Private method names in the same library are the same thing: they should
override eachother.

Field storage slots are different. Even private fields might need storage, if
they are overridden. This test illustrates:
https://codereview.chromium.org/1090313002/diff/1/test/codegen/expect/fields.js

For example given Dart:

class Foo {
  get _x => 0
}
class Bar extends Foo {
  int _x = 123;
}
class Baz extends Bar {
  int _x = 456;
}

we need one symbol for `_x` the private name, another symbol for Bar._x field
storage, and another symbol for Baz._x field storage. Note Foo, Bar, and Baz all
use the same private name for the `_x` getter.
 

+      this[message$] = message;
+      this[invalidValue] = value;
       this[_hasValue] = true;
       super.Error();
     }
@@ -626,10 +658,18 @@ var core;
   }
   dart.defineNamedConstructor(ArgumentError, 'value');
   dart.defineNamedConstructor(ArgumentError, 'notNull');
+  let start = dart.JsSymbol('start');
+  let end = dart.JsSymbol('end');
   class RangeError extends ArgumentError {
+    get start() {
+      return this[start];
+    }
+    get end() {
+      return this[end];
+    }
     RangeError(message) {
-      this.start = null;
-      this.end = null;
+      this[start] = null;
+      this[end] = null;
       super.ArgumentError(message);
     }
     value(value, name, message) {
@@ -637,8 +677,8 @@ var core;
         name = null;
       if (message === void 0)
         message = null;
-      this.start = null;
-      this.end = null;
+      this[start] = null;
+      this[end] = null;
       super.value(value, name, message != null ? message : "Value not in range");
     }
     range(invalidValue, minValue, maxValue, name, message) {
@@ -646,8 +686,8 @@ var core;
         name = null;
       if (message === void 0)
         message = null;
-      this.start = minValue;
-      this.end = maxValue;
+      this[start] = minValue;
+      this[end] = maxValue;
       super.value(invalidValue, name, message != null ? message : "Invalid value");
     }
     index(index, indexable, name, message, length) {
@@ -727,7 +767,15 @@ var core;
   dart.defineNamedConstructor(RangeError, 'value');
   dart.defineNamedConstructor(RangeError, 'range');
   dart.defineNamedConstructor(RangeError, 'index');
+  let indexable$ = dart.JsSymbol('indexable');
+  let length$ = dart.JsSymbol('length');
   class IndexError extends ArgumentError {
+    get indexable() {
+      return this[indexable$];
+    }
+    get length() {
+      return this[length$];
+    }
     IndexError(invalidValue, indexable, name, message, length) {
       if (name === void 0)
         name = null;
@@ -735,8 +783,8 @@ var core;
         message = null;
       if (length === void 0)
         length = null;
-      this.indexable = indexable;
-      this.length = dart.as(length != null ? length : dart.dload(indexable, 'length'), int);
+      this[indexable$] = indexable;
+      this[length$] = dart.as(length != null ? length : dart.dload(indexable, 'length'), int);
       super.value(invalidValue, name, message != null ? message : "Index out of range");
     }
     get start() {
@@ -827,20 +875,28 @@ var core;
       }
     }
   }
+  let message$0 = dart.JsSymbol('message');
   class UnsupportedError extends Error {
+    get message() {
+      return this[message$0];
+    }
     UnsupportedError(message) {
-      this.message = message;
+      this[message$0] = message;
       super.Error();
     }
     toString() {
       return `Unsupported operation: ${this.message}`;
     }
   }
+  let message$1 = dart.JsSymbol('message');
   class UnimplementedError extends Error {
+    get message() {
+      return this[message$1];
+    }
     UnimplementedError(message) {
       if (message === void 0)
         message = null;
-      this.message = message;
+      this[message$1] = message;
       super.Error();
     }
     toString() {
@@ -848,20 +904,28 @@ var core;
     }
   }
   UnimplementedError[dart.implements] = () => [UnsupportedError];
+  let message$2 = dart.JsSymbol('message');
   class StateError extends Error {
+    get message() {
+      return this[message$2];
+    }
     StateError(message) {
-      this.message = message;
+      this[message$2] = message;
       super.Error();
     }
     toString() {
       return `Bad state: ${this.message}`;
     }
   }
+  let modifiedObject$ = dart.JsSymbol('modifiedObject');
   class ConcurrentModificationError extends Error {
+    get modifiedObject() {
+      return this[modifiedObject$];
+    }
     ConcurrentModificationError(modifiedObject) {
       if (modifiedObject === void 0)
         modifiedObject = null;
-      this.modifiedObject = modifiedObject;
+      this[modifiedObject$] = modifiedObject;
       super.Error();
     }
     toString() {
@@ -893,11 +957,15 @@ var core;
     }
   }
   StackOverflowError[dart.implements] = () => [Error];
+  let variableName$ = dart.JsSymbol('variableName');
   class CyclicInitializationError extends Error {
+    get variableName() {
+      return this[variableName$];
+    }
     CyclicInitializationError(variableName) {
       if (variableName === void 0)
         variableName = null;
-      this.variableName = variableName;
+      this[variableName$] = variableName;
       super.Error();
     }
     toString() {
@@ -924,7 +992,19 @@ var core;
     }
   }
   _ExceptionImplementation[dart.implements] = () => [Exception];
+  let message$3 = dart.JsSymbol('message');
+  let source$ = dart.JsSymbol('source');
+  let offset$ = dart.JsSymbol('offset');
   class FormatException extends Object {
+    get message() {
+      return this[message$3];
+    }
+    get source() {
+      return this[source$];
+    }
+    get offset() {
+      return this[offset$];
+    }
     FormatException(message, source, offset) {
       if (message === void 0)
         message = "";
@@ -932,9 +1012,9 @@ var core;
         source = null;
       if (offset === void 0)
         offset = -1;
-      this.message = message;
-      this.source = source;
-      this.offset = offset;
+      this[message$3] = message;
+      this[source$] = source;
+      this[offset$] = offset;
     }
     toString() {
       let report = "FormatException";
@@ -1021,16 +1101,20 @@ var core;
     }
   }
   IntegerDivisionByZeroException[dart.implements] = () => [Exception];
+  let name$2 = dart.JsSymbol('name');
   let _EXPANDO_PROPERTY_NAME = dart.JsSymbol('_EXPANDO_PROPERTY_NAME');
   let _getKey = dart.JsSymbol('_getKey');
   let _KEY_PROPERTY_NAME = dart.JsSymbol('_KEY_PROPERTY_NAME');
   let _keyCount = dart.JsSymbol('_keyCount');
   let Expando$ = dart.generic(function(T) {
     class Expando extends Object {
+      get name() {
+        return this[name$2];
+      }
       Expando(name) {
         if (name === void 0)
           name = null;
-        this.name = name;
+        this[name$2] = name;
       }
       toString() {
         return `Expando:${this.name}`;
@@ -1129,10 +1213,10 @@ var core;
     return _Generator;
   });
   let _Generator = _Generator$();
+  let _id = dart.JsSymbol('_id');
   let _end = dart.JsSymbol('_end');
   let _start = dart.JsSymbol('_start');
   let _generator = dart.JsSymbol('_generator');
-  let _id = dart.JsSymbol('_id');
   let $iterator = dart.JsSymbol('$iterator');
   let $skip = dart.JsSymbol('$skip');
   let $take = dart.JsSymbol('$take');
@@ -1473,12 +1557,16 @@ var core;
   dart.defineNamedConstructor(String, 'fromCharCodes');
   dart.defineNamedConstructor(String, 'fromCharCode');
   dart.defineNamedConstructor(String, 'fromEnvironment');
+  let string$ = dart.JsSymbol('string');
   let $last = dart.JsSymbol('$last');
   dart.defineLazyClass(exports, {
     get Runes() {
       class Runes extends collection.IterableBase$(int) {
+        get string() {
+          return this[string$];
+        }
         Runes(string) {
-          this.string = string;
+          this[string$] = string;
           super.IterableBase();
         }
         get [exports.$iterator]() {
@@ -1514,19 +1602,23 @@ var core;
   function _combineSurrogatePair(start, end) {
     return 65536 + ((dart.notNull(start) & 1023) << 10) + (dart.notNull(end) & 1023);
   }
+  let string$0 = dart.JsSymbol('string');
   let _position = dart.JsSymbol('_position');
   let _nextPosition = dart.JsSymbol('_nextPosition');
   let _currentCodePoint = dart.JsSymbol('_currentCodePoint');
   let _checkSplitSurrogate = dart.JsSymbol('_checkSplitSurrogate');
   class RuneIterator extends Object {
+    get string() {
+      return this[string$0];
+    }
     RuneIterator(string) {
-      this.string = string;
+      this[string$0] = string;
       this[_position] = 0;
       this[_nextPosition] = 0;
       this[_currentCodePoint] = null;
     }
     at(string, index) {
-      this.string = string;
+      this[string$0] = string;
       this[_position] = index;
       this[_nextPosition] = index;
       this[_currentCodePoint] = null;
@@ -1675,6 +1767,7 @@ var core;
     }
   }
   class Type extends Object {}
+  let scheme$ = dart.JsSymbol('scheme');
   let _writeAuthority = dart.JsSymbol('_writeAuthority');
   let _userInfo = dart.JsSymbol('_userInfo');
   let _host = dart.JsSymbol('_host');
@@ -1709,6 +1802,7 @@ var core;
   let _makeWindowsFileUrl = dart.JsSymbol('_makeWindowsFileUrl');
   let _makeFileUri = dart.JsSymbol('_makeFileUri');
   let _checkNonWindowsPathReservedCharacters = dart.JsSymbol('_checkNonWindowsPathReservedCharacters');
+  let $forEach = dart.JsSymbol('$forEach');
   let _checkWindowsPathReservedCharacters = dart.JsSymbol('_checkWindowsPathReservedCharacters');
   let _checkWindowsDriveLetter = dart.JsSymbol('_checkWindowsDriveLetter');
   let _UPPER_CASE_A = dart.JsSymbol('_UPPER_CASE_A');
@@ -1716,6 +1810,8 @@ var core;
   let _LOWER_CASE_A = dart.JsSymbol('_LOWER_CASE_A');
   let _LOWER_CASE_Z = dart.JsSymbol('_LOWER_CASE_Z');
   let _BACKSLASH = dart.JsSymbol('_BACKSLASH');
+  let $map = dart.JsSymbol('$map');
+  let $toList = dart.JsSymbol('$toList');
   let _normalizeRegName = dart.JsSymbol('_normalizeRegName');
   let _isRegNameChar = dart.JsSymbol('_isRegNameChar');
   let _PERCENT = dart.JsSymbol('_PERCENT');
@@ -1741,6 +1837,8 @@ var core;
   let _DOT = dart.JsSymbol('_DOT');
   let _hasDotSegments = dart.JsSymbol('_hasDotSegments');
   let _removeDotSegments = dart.JsSymbol('_removeDotSegments');
+  let $isEmpty = dart.JsSymbol('$isEmpty');
+  let $removeLast = dart.JsSymbol('$removeLast');
   let _toWindowsFilePath = dart.JsSymbol('_toWindowsFilePath');
   let _toFilePath = dart.JsSymbol('_toFilePath');
   let _isPathAbsolute = dart.JsSymbol('_isPathAbsolute');
@@ -1748,16 +1846,14 @@ var core;
   let _unreserved2396Table = dart.JsSymbol('_unreserved2396Table');
   let _uriDecode = dart.JsSymbol('_uriDecode');
   let _encodeFullTable = dart.JsSymbol('_encodeFullTable');
+  let $fold = dart.JsSymbol('$fold');
   let _SPACE = dart.JsSymbol('_SPACE');
   let _PLUS = dart.JsSymbol('_PLUS');
   let _hexCharPairToByte = dart.JsSymbol('_hexCharPairToByte');
-  let $forEach = dart.JsSymbol('$forEach');
-  let $map = dart.JsSymbol('$map');
-  let $toList = dart.JsSymbol('$toList');
-  let $isEmpty = dart.JsSymbol('$isEmpty');
-  let $removeLast = dart.JsSymbol('$removeLast');
-  let $fold = dart.JsSymbol('$fold');
   class Uri extends Object {
+    get scheme() {
+      return this[scheme$];
+    }
     get authority() {
       if (!dart.notNull(this.hasAuthority))
         return "";
@@ -1965,7 +2061,7 @@ var core;
       throw new FormatException(message, uri, index);
     }
     [_internal](scheme, userInfo, host, port, path, query, fragment) {
-      this.scheme = scheme;
+      this[scheme$] = scheme;
       this[_userInfo] = userInfo;
       this[_host] = host;
       this[_port] = port;