Start making server strong mode clean

pkg/analysis_server/lib/src/context_manager.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 context.directory.manager;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:convert';
 import 'dart:core' hide Resource;
@@ skipping 606 matching lines @@
     });
 
     configureContextOptions(info.context, options);
 
     // Nothing more to do.
     if (options == null) {
       return;
     }
 
     var analyzer = options[AnalyzerOptions.analyzer];
-    if (analyzer is! Map) {
-      // Done.
-      return;
-    }
-
-    // Set ignore patterns.
-    YamlList exclude = analyzer[AnalyzerOptions.exclude];
-    if (exclude != null) {
-      setIgnorePatternsForContext(info, exclude);
+    if (analyzer is Map) {
+      // Set ignore patterns.
+      YamlList exclude = analyzer[AnalyzerOptions.exclude];
+      if (exclude is List<String>) {
+        setIgnorePatternsForContext(info, exclude as List<String>);

[scheglov, 2016/03/31 00:53:18]

We can propagate the type of "exclude", but it is not enough for strong mode?
That's sad.

[Brian Wilkerson, 2016/03/31 15:27:12]

You're right, that does seem like it ought not to be necessary. I'll back it out
until we get further resolution.

[Leaf, 2016/03/31 17:59:14]

Intellij go to declaration can't seem to find the def of YamlList for me, so I'm
not sure I have the right class, but this YamlList:

https://www.dartdocs.org/documentation/yaml/2.1.8/yaml/YamlList-class.html

is a subtype of List<dynamic>.  That means that YamlList and List<String> are
not subtype related in strong mode (neither is a subtype of the other).  If I
recall correctly how the analyzer's promotion code works, this means no
promotion will happen.  Does that seem right?  Also, I believe that means the
cast will fail in strong mode.

[Brian Wilkerson, 2016/03/31 18:17:06]

Then the right solution is probably to change setIgnorePatternsForContext to
take a List<dynamic> and test the element types in that method.

+      }
     }
   }
 
   /**
    * Return the options from the analysis options file in the given [folder]
    * if exists, or in one of the parent folders, or `null` if no analysis
    * options file is found or if the contents of the file are not valid YAML.
    */
   Map<String, Object> readOptions(Folder folder) {
     try {
@@ skipping 1113 matching lines @@
       ResourceProvider resourceProvider) {
     if (packages != null) {
       // Construct package map for the SdkExtUriResolver.
       Map<String, List<Folder>> packageMap = buildPackageMap(resourceProvider);
       return <UriResolver>[new SdkExtUriResolver(packageMap)];
     } else {
       return const <UriResolver>[];
     }
   }
 }