report errors in included options files

pkg/analyzer/lib/source/analysis_options_provider.dart

 // Copyright (c) 2015, 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 analyzer.source.analysis_options_provider;
 
 import 'dart:core';
 
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/source/source_resource.dart';
+import 'package:analyzer/src/task/options.dart';
 import 'package:analyzer/src/util/yaml.dart';
 import 'package:source_span/source_span.dart';
 import 'package:yaml/yaml.dart';
 
 /// Provide the options found in the analysis options file.
 class AnalysisOptionsProvider {
   /// The source factory used to resolve include declarations
   /// in analysis options files or `null` if include is not supported.
   SourceFactory sourceFactory;
 
   AnalysisOptionsProvider([this.sourceFactory]);
 
   /// Provide the options found in either
   /// [root]/[AnalysisEngine.ANALYSIS_OPTIONS_FILE] or
   /// [root]/[AnalysisEngine.ANALYSIS_OPTIONS_YAML_FILE].
+  /// Recursively merge options referenced by an include directive
+  /// and remove the include directive from the resulting options map.
   /// Return an empty options map if the file does not exist.
   Map<String, YamlNode> getOptions(Folder root, {bool crawlUp: false}) {
     Resource resource;
     for (Folder folder = root; folder != null; folder = folder.parent) {
       resource = folder.getChild(AnalysisEngine.ANALYSIS_OPTIONS_FILE);
       if (resource.exists) {
         break;
       }
       resource = folder.getChild(AnalysisEngine.ANALYSIS_OPTIONS_YAML_FILE);
       if (resource.exists || !crawlUp) {
         break;
       }
     }
     return getOptionsFromFile(resource);
   }
 
   /// Provide the options found in [file].
+  /// Recursively merge options referenced by an include directive
+  /// and remove the include directive from the resulting options map.
   /// Return an empty options map if the file does not exist.
   Map<String, YamlNode> getOptionsFromFile(File file) {
     return getOptionsFromSource(new FileSource(file));
   }
 
   /// Provide the options found in [source].
+  /// Recursively merge options referenced by an include directive
+  /// and remove the include directive from the resulting options map.
   /// Return an empty options map if the file does not exist.
   Map<String, YamlNode> getOptionsFromSource(Source source) {
     Map<String, YamlNode> options =
         getOptionsFromString(_readAnalysisOptions(source));
-    YamlNode node = options.remove('include');
+    YamlNode node = options.remove(AnalyzerOptions.include);
     if (sourceFactory != null && node is YamlScalar) {
       var path = node.value;
       if (path is String) {
         Source parent = sourceFactory.resolveUri(source, path);
         options = merge(getOptionsFromSource(parent), options);
       }
     }
     return options;
   }
 
   /// Provide the options found in [optionsSource].
+  /// An include directive, if present, will be left as-is,
+  /// and the referenced options will NOT be merged into the result.
   /// Return an empty options map if the source is null.
   Map<String, YamlNode> getOptionsFromString(String optionsSource) {
     Map<String, YamlNode> options = <String, YamlNode>{};
     if (optionsSource == null) {
       return options;
     }
 
     YamlNode safelyLoadYamlNode() {
       try {
         return loadYamlNode(optionsSource);
@@ skipping 70 matching lines @@
 /// Thrown on options format exceptions.
 class OptionsFormatException implements Exception {
   final String message;
   final SourceSpan span;
   OptionsFormatException(this.message, [this.span]);
 
   @override
   String toString() =>
       'OptionsFormatException: ${message?.toString()}, ${span?.toString()}';
 }