Implement metadata as an internal native. Be honest about which mirrors don't yet support metadata …

runtime/lib/mirrors_impl.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.
 
 // VM-specific implementation of the dart:mirrors library.
 
 // These values are allowed to be passed directly over the wire.
 bool _isSimpleValue(var value) {
   return (value == null || value is num || value is String || value is bool);
 }
@@ skipping 52 matching lines @@
 }
 
 Map<Uri, LibraryMirror> _createLibrariesMap(Map<String, LibraryMirror> map) {
     var result = new Map<Uri, LibraryMirror>();
     map.forEach((String url, LibraryMirror mirror) {
       result[Uri.parse(url)] = mirror;
     });
     return result;
 }
 
-List<InstanceMirror> _metadata(mirror) 

[rmacnak, 2013/07/16 21:11:15]

This annotation is incorrect. The native answered an array of plain instances,
which were later wrapped as instance mirrors.

-  native 'Mirrors_metadata';
+List _metadata(reflectee)
+  native 'DeclarationMirror_metadata';
 
 // This will verify the argument types, unwrap them, and ensure we have a fixed
 // array.
 List _unwarpAsyncPositionals(wrappedArgs){
   List unwrappedArgs = new List(wrappedArgs.length);
   for(int i = 0; i < wrappedArgs.length; i++){
     var wrappedArg = wrappedArgs[i];
     if(_isSimpleValue(wrappedArg)) {
       unwrappedArgs[i] = wrappedArg;
     } else if(wrappedArg is InstanceMirror) {
@@ skipping 79 matching lines @@
   String toString() => "IsolateMirror on '$debugName'";
 }
 
 // A VMReference is used to hold a reference to a VM-internal object,
 // which can include things like libraries, classes, etc.
 class VMReference extends NativeFieldWrapperClass1 {
 }
 
 abstract class _LocalVMObjectMirrorImpl extends _LocalMirrorImpl {
   _LocalVMObjectMirrorImpl(this._reference) {}
-
+  
   // For now, all VMObjects hold a VMReference.  We could consider
   // storing the Object reference itself here if the object is a Dart
   // language objects (except for objects of type VMReference, of
   // course).
   VMReference _reference;
 }
 
 abstract class _LocalObjectMirrorImpl extends _LocalVMObjectMirrorImpl
     implements ObjectMirror {
   _LocalObjectMirrorImpl(this._reflectee, ref) : super(ref) {}
@@ skipping 392 matching lines @@
                                       _n(constructorName),
                                       _unwarpAsyncPositionals(positionalArguments));
       return new Future.value(reflect(result)); 
     } on MirroredError catch(e) {
       return new Future.error(e);
     }
   }
 
   // get the metadata objects, convert them into InstanceMirrors using
   // reflect() and then make them into a Dart list
-  List<InstanceMirror> get metadata => _metadata(this).map(reflect).toList();
+  List<InstanceMirror> get metadata => _metadata(_reflectee).map(reflect).toList();
 
 
   static _name(reflectee)
       native "ClassMirror_name";
 
   _invoke(reflectee, memberName, positionalArguments)
       native 'ClassMirror_invoke';
 
   _invokeGetter(reflectee, getterName)
       native 'ClassMirror_invokeGetter';
@@ skipping 97 matching lines @@
   }
 
   var _upperBound;
   TypeMirror get upperBound {
     if (_upperBound is! Mirror) {
       _upperBound = _upperBound.resolve(mirrors);
     }
     return _upperBound;
   }
 
-  // get the metadata objects, convert them into InstanceMirrors using
-  // reflect() and then make them into a Dart list
-  List<InstanceMirror> get metadata => _metadata(this).map(reflect).toList();
+  List<InstanceMirror> get metadata {

[rmacnak, 2013/07/16 21:11:15]

Previously this would always answer an empty list, even if there was metadata.

+    throw new UnimplementedError(
+        'TypeVariableMirror.metadata is not implemented');
+  }
 
   String toString() => "TypeVariableMirror on '${_n(simpleName)}'";
 }
 
 
 class _LocalTypedefMirrorImpl extends _LocalMirrorImpl
     implements TypedefMirror {
   _LocalTypedefMirrorImpl(String simpleName,
                           this._owner,
                           this._referent)
@@ skipping 123 matching lines @@
   Map<Symbol, VariableMirror> get variables {
     if (_variables == null) {
       _variables = _filterMap(members,
                               (key, value) => (value is VariableMirror));
     }
     return _variables;
   }
 
   // get the metadata objects, convert them into InstanceMirrors using
   // reflect() and then make them into a Dart list
-  List<InstanceMirror> get metadata => _metadata(this).map(reflect).toList();
+  List<InstanceMirror> get metadata => _metadata(_reflectee).map(reflect).toList();
 
   String toString() => "LibraryMirror on '${_n(simpleName)}'";
 
   _invoke(reflectee, memberName, positionalArguments)
       native 'LibraryMirror_invoke';
 
   _invokeGetter(reflectee, getterName)
       native 'LibraryMirror_invokeGetter';
 
   _invokeSetter(reflectee, setterName, value)
@@ skipping 101 matching lines @@
 
   final bool isConstConstructor;
   final bool isGenerativeConstructor;
   final bool isRedirectingConstructor;
   final bool isFactoryConstructor;
 
   List<InstanceMirror> get metadata {
     owner; // ensure owner is computed
     // get the metadata objects, convert them into InstanceMirrors using
     // reflect() and then make them into a Dart list
-    return _metadata(this).map(reflect).toList();
+    return _metadata(_reflectee).map(reflect).toList();
   }
 
   String toString() => "MethodMirror on '${_n(simpleName)}'";
 
   static String _MethodMirror_name(reflectee)
       native "MethodMirror_name";
 }
 
 class _LocalVariableMirrorImpl extends _LocalMirrorImpl
     implements VariableMirror {
-  _LocalVariableMirrorImpl(String simpleName,
+  _LocalVariableMirrorImpl(this._reflectee,
+                           String simpleName,
                            this._owner,
                            this._type,
                            this.isStatic,
                            this.isFinal)
       : this.simpleName = _s(simpleName);
 
+  final _MirrorReference _reflectee;
   final Symbol simpleName;
 
   Symbol _qualifiedName = null;
   Symbol get qualifiedName {
     if (_qualifiedName == null) {
       _qualifiedName = _computeQualifiedName(owner, simpleName);
     }
     return _qualifiedName;
   }
 
@@ skipping 23 matching lines @@
     if (_type is! Mirror) {
       _type = _type.resolve(mirrors);
     }
     return _type;
   }
 
   final bool isStatic;
   final bool isFinal;
 
   List<InstanceMirror> get metadata {
-    owner; // ensure owner is computed
     // get the metadata objects, convert them into InstanceMirrors using
     // reflect() and then make them into a Dart list
-    return _metadata(this).map(reflect).toList();
+    return _metadata(_reflectee).map(reflect).toList();
   }
 
   String toString() => "VariableMirror on '${_n(simpleName)}'";
 }
 
 class _LocalParameterMirrorImpl extends _LocalVariableMirrorImpl
     implements ParameterMirror {
   _LocalParameterMirrorImpl(type, this.isOptional)
-      : super('<TODO:unnamed>', null, type, false, false) {}
+      : super(null, '<TODO:unnamed>', null, type, false, false) {}
 
   final bool isOptional;
 
   String get defaultValue {
     throw new UnimplementedError(
         'ParameterMirror.defaultValue is not implemented');
   }
 
   bool get hasDefaultValue {
     throw new UnimplementedError(
         'ParameterMirror.hasDefaultValue is not implemented');
   }
+
+  // TODO(11418): Implement.
+  List<InstanceMirror> get metadata {

[rmacnak, 2013/07/16 21:11:15]

Previously this raised a fatal, non-meaningful error.

+    throw new UnimplementedError(
+        'ParameterMirror.metadata is not implemented');
+  }
 }
 
 class _SpecialTypeMirrorImpl extends _LocalMirrorImpl
     implements TypeMirror, DeclarationMirror {
   _SpecialTypeMirrorImpl(this.simpleName);
 
   final bool isPrivate = false;
   final bool isTopLevel = true;
 
   // Fixed length 0, therefore immutable.
@@ skipping 57 matching lines @@
   }
 
   // Creates a new local ClassMirror.
   static ClassMirror makeLocalClassMirror(Type key)
       native "Mirrors_makeLocalClassMirror";
 
   static ClassMirror reflectClass(Type key) {
     return makeLocalClassMirror(key);
   }
 }