Issue 22845. Rename should prevent the use of invalid identifiers.

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

Index: pkg/analysis_server/lib/src/services/refactoring/naming_conventions.dart
diff --git a/pkg/analysis_server/lib/src/services/refactoring/naming_conventions.dart b/pkg/analysis_server/lib/src/services/refactoring/naming_conventions.dart
index 35033117be0bc2d99512d7bb82c49ba4deabb26c..aac52754c741badc30a5c0c30db99e3bc55b8b62 100644
--- a/pkg/analysis_server/lib/src/services/refactoring/naming_conventions.dart
+++ b/pkg/analysis_server/lib/src/services/refactoring/naming_conventions.dart
@@ -6,6 +6,7 @@ library services.src.refactoring.naming_conventions;
 
 import 'package:analysis_server/src/services/correction/status.dart';
 import 'package:analysis_server/src/services/correction/strings.dart';
+import 'package:analyzer/src/generated/scanner.dart';
 
 /**
  * Returns the [RefactoringStatus] with severity:
@@ -164,6 +165,15 @@ RefactoringStatus _validateIdentifier(
     String message = "$desc must not be empty.";
     return new RefactoringStatus.fatal(message);
   }
+  // keyword
+  {
+    Keyword keyword = Keyword.keywords[identifier];
+    if (keyword != null && !keyword.isPseudoKeyword) {
+      String message = "$desc must not be a keyword.";
+      return new RefactoringStatus.fatal(message);
+    }
+  }
+  // first character
   int currentChar = identifier.codeUnitAt(0);
   if (!isLetter(currentChar) &&
       currentChar != CHAR_UNDERSCORE &&
@@ -171,6 +181,7 @@ RefactoringStatus _validateIdentifier(
     String message = "$desc must begin with $beginDesc.";
     return new RefactoringStatus.fatal(message);
   }
+  // other characters
   for (int i = 1; i < length; i++) {
     currentChar = identifier.codeUnitAt(i);
     if (!isLetterOrDigit(currentChar) &&
@@ -181,6 +192,7 @@ RefactoringStatus _validateIdentifier(
       return new RefactoringStatus.fatal(message);
     }
   }
+  // OK
   return new RefactoringStatus();
 }