Issue 27475. Discourage users from naming constructors the same as the enclosing classes.

pkg/analysis_server/lib/src/services/refactoring/rename_constructor.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.rename_constructor;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol_server.dart' hide Element;
 import 'package:analysis_server/src/services/correction/source_range.dart';
@@ skipping 22 matching lines @@
   ConstructorElement get element => super.element as ConstructorElement;
 
   @override
   String get refactoringName {
     return "Rename Constructor";
   }
 
   @override
   Future<RefactoringStatus> checkFinalConditions() {
     RefactoringStatus result = new RefactoringStatus();
-    _analyzePossibleConflicts(result);
     return new Future.value(result);
   }
 
   @override
   RefactoringStatus checkNewName() {
     RefactoringStatus result = super.checkNewName();
     result.addStatus(validateConstructorName(newName));
+    if (newName != null) {
+      _analyzePossibleConflicts(result);
+    }
     return result;
   }
 
   @override
   Future fillChange() async {
     // prepare references
     List<SearchMatch> matches = await searchEngine.searchReferences(element);
     List<SourceReference> references = getSourceReferences(matches);
     // append declaration
     if (element.isSynthetic) {
       _replaceSynthetic();
     } else {
       references.add(_createDeclarationReference());
     }
     // update references
     String replacement = newName.isEmpty ? '' : '.$newName';
     for (SourceReference reference in references) {
       reference.addEdit(change, replacement);
     }
   }
 
   void _analyzePossibleConflicts(RefactoringStatus result) {
+    ClassElement parentClass = element.enclosingElement;
+    // Check if the "newName" is the name of the enclosing class.
+    if (parentClass.name == newName) {
+      result.addError('The constructor should not have the same name '
+          'as the name of the enclosing class.');
+    }
     // check if there are members with "newName" in the same ClassElement
-    ClassElement parentClass = element.enclosingElement;
     for (Element newNameMember in getChildren(parentClass, newName)) {
       String message = format(
           "Class '{0}' already declares {1} with name '{2}'.",
           parentClass.displayName,
           getElementKindName(newNameMember),
           newName);
       result.addError(message, newLocation_fromElement(newNameMember));
     }
   }
 
@@ skipping 24 matching lines @@
         change,
         classElement,
         new SourceEdit(
             location.offset,
             0,
             location.prefix +
                 '${classElement.name}.$newName();' +
                 location.suffix));
   }
 }