Don't allow to extract a closure as a getter.

pkg/analysis_server/lib/src/services/refactoring/extract_method.dart

 // Copyright (c) 2014, 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.
 
 library services.src.refactoring.extract_method;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol_server.dart' hide Element;
 import 'package:analysis_server/src/services/correction/name_suggestion.dart';
@@ skipping 53 matching lines @@
   final int selectionLength;
   CompilationUnitElement unitElement;
   LibraryElement libraryElement;
   SourceRange selectionRange;
   CorrectionUtils utils;
   Set<LibraryElement> librariesToImport = new Set<LibraryElement>();
 
   String returnType;
   String name;
   bool extractAll = true;
+  bool canCreateGetter = false;
   bool createGetter = false;
   final List<String> names = <String>[];
   final List<int> offsets = <int>[];
   final List<int> lengths = <int>[];
 
   Set<String> _usedNames = new Set<String>();
   Set<String> _excludedNames = new Set<String>();
   List<RefactoringMethodParameter> _parameters = <RefactoringMethodParameter>[];
   Map<String, RefactoringMethodParameter> _parametersMap =
       <String, RefactoringMethodParameter>{};
   Map<String, List<SourceRange>> _parameterReferencesMap =
       <String, List<SourceRange>>{};
   DartType _returnType;
   String _returnVariableName;
   AstNode _parentMember;
   Expression _selectionExpression;
   FunctionExpression _selectionFunctionExpression;
   List<Statement> _selectionStatements;
   List<_Occurrence> _occurrences = [];
   bool _staticContext = false;
 
   ExtractMethodRefactoringImpl(this.searchEngine, this.unit,
       this.selectionOffset, this.selectionLength) {
     unitElement = unit.element;
     libraryElement = unitElement.library;
     selectionRange = new SourceRange(selectionOffset, selectionLength);
     utils = new CorrectionUtils(unit);
   }
 
-  bool get canCreateGetter {
+  /**
+   * Initializes [canCreateGetter] flag.
+   */
+  bool _computeCanCreateGetter() {
+    // is a function expression
+    if (_selectionFunctionExpression != null) {
+      return false;
+    }
+    // has parameters
     if (!parameters.isEmpty) {
       return false;
     }
+    // is assignment
     if (_selectionExpression != null) {
       if (_selectionExpression is AssignmentExpression) {
         return false;
       }
     }
+    // doesn't return a value
     if (_selectionStatements != null) {
       return returnType != 'void';
     }
+    // OK
     return true;
   }
 
   @override
   List<RefactoringMethodParameter> get parameters => _parameters;
 
   @override
   void set parameters(List<RefactoringMethodParameter> parameters) {
     _parameters = parameters.toList();
   }
@@ skipping 56 matching lines @@
   Future<RefactoringStatus> checkInitialConditions() {
     RefactoringStatus result = new RefactoringStatus();
     // selection
     result.addStatus(_checkSelection());
     if (result.hasFatalError) {
       return new Future.value(result);
     }
     // prepare parts
     result.addStatus(_initializeParameters());
     _initializeReturnType();
-    _initializeGetter();
     // occurrences
     _initializeOccurrences();
     _prepareOffsetsLengths();
+    // getter
+    canCreateGetter = _computeCanCreateGetter();
+    _initializeCreateGetter();
     // names
     _prepareExcludedNames();
     _prepareNames();
     // closure cannot have parameters
     if (_selectionFunctionExpression != null && !_parameters.isEmpty) {
       String message = format(
           'Cannot extract closure as method, it references {0} external variable(s).',
           _parameters.length);
       RefactoringStatus result = new RefactoringStatus.fatal(message);
       return new Future.value(result);
@@ skipping 299 matching lines @@
     return pattern;
   }
 
   String _getTypeCode(DartType type) {
     return utils.getTypeSource(type, librariesToImport);
   }
 
   /**
    * Initializes [createGetter] flag.
    */
-  void _initializeGetter() {
+  void _initializeCreateGetter() {
     createGetter = false;
     // maybe we cannot at all
     if (!canCreateGetter) {
       return;
     }
     // OK, just expression
     if (_selectionExpression != null) {
       createGetter = !_hasMethodInvocation(_selectionExpression);
       return;
     }
@@ skipping 617 matching lines @@
       return false;
     }
     for (int i = 0; i < parameterTypes.length; i++) {
       if (other.parameterTypes[i] != parameterTypes[i]) {
         return false;
       }
     }
     return true;
   }
 }