add warning for deprecated .analysis_options file name

pkg/analyzer/lib/src/task/options.dart

Index: pkg/analyzer/lib/src/task/options.dart
diff --git a/pkg/analyzer/lib/src/task/options.dart b/pkg/analyzer/lib/src/task/options.dart
index 050d3bce27f8843cf8cde03cf5f6bde82a5fa1f5..c23b71e1aeab74fb0a8221e291a5f747bf2169ee 100644
--- a/pkg/analyzer/lib/src/task/options.dart
+++ b/pkg/analyzer/lib/src/task/options.dart
@@ -238,6 +238,18 @@ class GenerateOptionsErrorsTask extends SourceBasedAnalysisTask {
     Source initialSource = source;
     SourceSpan initialIncludeSpan;
 
+    // Suggest user rename deprecated .analysis_options file
+    String fullName = target?.source?.fullName;
+    if (fullName != null &&
+        fullName.endsWith(AnalysisEngine.ANALYSIS_OPTIONS_FILE)) {
+      errors.add(new AnalysisError(
+          source,
+          0, // offset
+          1, // length
+          AnalysisOptionsWarningCode.DEPRECATED_ANALYSIS_OPTIONS_FILE_NAME,
+          [fullName]));
+    }
+
     // Validate the specified options and any included option files
     void validate(Source source, Map<String, YamlNode> options) {
       List<AnalysisError> validationErrors =