Fix for 'Extract Local' in an expression function body.

pkg/analysis_server/lib/src/services/refactoring/extract_local.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_local;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:analysis_server/src/protocol_server.dart' hide Element;
@@ skipping 121 matching lines @@
           new SourceEdit(singleExpression.offset, 0, declarationSource);
       doSourceChange_addElementEdit(change, unitElement, edit);
       return new Future.value(change);
     }
     // prepare positions
     List<Position> positions = <Position>[];
     int occurrencesShift = 0;
     void addPosition(int offset) {
       positions.add(new Position(file, offset));
     }
+
     // add variable declaration
     {
       String declarationCode;
       int nameOffsetInDeclarationCode;
       if (stringLiteralPart != null) {
         declarationCode = 'var ';
         nameOffsetInDeclarationCode = declarationCode.length;
         declarationCode += "$name = '$stringLiteralPart';";
       } else {
         String keyword = _declarationKeyword;
@@ skipping 21 matching lines @@
           String code = '{' + eol + prefix + indent;
           addPosition(
               target.offset + code.length + nameOffsetInDeclarationCode);
           code += declarationCode + eol;
           code += prefix + indent + 'return ';
           SourceEdit edit =
               new SourceEdit(target.offset, expr.offset - target.offset, code);
           occurrencesShift = target.offset + code.length - expr.offset;
           doSourceChange_addElementEdit(change, unitElement, edit);
         }
-        doSourceChange_addElementEdit(change, unitElement,
-            new SourceEdit(expr.end, 0, ';' + eol + prefix + '}'));
+        doSourceChange_addElementEdit(
+            change,
+            unitElement,
+            new SourceEdit(
+                expr.end, target.end - expr.end, ';' + eol + prefix + '}'));
       }
     }
     // prepare replacement
     String occurrenceReplacement = name;
     if (stringLiteralPart != null) {
       occurrenceReplacement = "\${$name}";
       occurrencesShift += 2;
     }
     // replace occurrences with variable reference
     for (SourceRange range in occurrences) {
@@ skipping 96 matching lines @@
         }
       }
       // set selected expression
       if (coveringExpressionOffsets.isEmpty) {
         rootExpression = node;
       }
       // add the expression range
       coveringExpressionOffsets.add(node.offset);
       coveringExpressionLengths.add(node.length);
     }
-    // we need enclosing block to add variable declaration statement
+    // We need an enclosing function.
+    // If it has a block body, we can add a new variable declaration statement
+    // into this block.  If it has an expression body, we can convert it into
+    // the block body first.
     if (coveringNode == null ||
-        coveringNode.getAncestor((node) => node is Block) == null) {
+        coveringNode.getAncestor((node) => node is FunctionBody) == null) {
       return new RefactoringStatus.fatal(
-          'Expression inside of function must be selected '
+          'Expression inside a function must be selected '

[Brian Wilkerson, 2016/08/22 18:54:38]

"Expression" --> "An expression"?

[scheglov, 2016/08/22 18:57:44]

Done.

           'to activate this refactoring.');
     }
     // part of string literal
     if (coveringNode is StringLiteral) {
       if (selectionRange.length != 0 &&
           selectionRange.offset > coveringNode.offset &&
           selectionRange.end < coveringNode.end) {
         stringLiteralPart = selectionStr;
         return new RefactoringStatus();
       }
@@ skipping 371 matching lines @@
 
   _TokenLocalElementVisitor(this.map);
 
   visitSimpleIdentifier(SimpleIdentifier node) {
     Element element = node.staticElement;
     if (element is LocalVariableElement) {
       map[node.token] = element;
     }
   }
 }