Support conditional directives in the options file.

pkg/analyzer/lib/src/task/options.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.src.task.options;
 
 import 'dart:collection';
 
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/plugin/options.dart';
@@ skipping 29 matching lines @@
 void configureContextOptions(
         AnalysisContext context, Map<String, Object> options) =>
     _processor.configure(context, options);
 
 /// `analyzer` analysis options constants.
 class AnalyzerOptions {
   static const String analyzer = 'analyzer';
   static const String enableAsync = 'enableAsync';
   static const String enableGenericMethods = 'enableGenericMethods';
   static const String enableSuperMixins = 'enableSuperMixins';
+  static const String enableConditionalDirectives =
+      "enableConditionalDirectives";
   static const String errors = 'errors';
   static const String exclude = 'exclude';
   static const String language = 'language';
   static const String plugins = 'plugins';
   static const String strong_mode = 'strong-mode';
 
   /// Ways to say `ignore`.
   static const List<String> ignoreSynonyms = const ['ignore', 'false'];
 
   /// Valid error `severity`s.
@@ skipping 12 matching lines @@
     exclude,
     language,
     plugins,
     strong_mode
   ];
 
   /// Supported `analyzer` language configuration options.
   static const List<String> languageOptions = const [
     enableAsync,
     enableGenericMethods,
-    enableSuperMixins
+    enableSuperMixins,
+    enableConditionalDirectives,
   ];
 }
 
 /// Validates `analyzer` options.
 class AnalyzerOptionsValidator extends CompositeValidator {
   AnalyzerOptionsValidator()
       : super([
           new TopLevelAnalyzerOptionsValidator(),
           new StrongModeOptionValueValidator(),
           new ErrorFilterOptionValidator(),
@@ skipping 390 matching lines @@
       }
     }
     if (feature == AnalyzerOptions.enableGenericMethods) {
       if (isTrue(value)) {
         AnalysisOptionsImpl options =
             new AnalysisOptionsImpl.from(context.analysisOptions);
         options.enableGenericMethods = true;
         context.analysisOptions = options;
       }
     }
+    if (feature == AnalyzerOptions.enableConditionalDirectives) {
+      if (isTrue(value)) {
+        AnalysisOptionsImpl options =
+            new AnalysisOptionsImpl.from(context.analysisOptions);
+        options.enableConditionalDirectives = true;
+        context.analysisOptions = options;
+      }
+    }
   }
 
   void setLanguageOptions(AnalysisContext context, Object configs) {
     if (configs is YamlMap) {
       configs.nodes.forEach((k, v) {
         if (k is YamlScalar && v is YamlScalar) {
           String feature = k.value?.toString();
           setLanguageOption(context, feature, v.value);
         }
       });
@@ skipping 41 matching lines @@
           String feature = key.value?.toString();
           _applyLanguageOption(options, feature, value.value);
         }
       });
     } else if (configs is Map) {
       configs
           .forEach((key, value) => _applyLanguageOption(options, key, value));
     }
   }
 }