Require two type arguments for map literals (issue 4522).

utils/pub/version_solver.dart

 // Copyright (c) 2012, 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.
 
 /**
  * Attempts to resolve a set of version constraints for a package dependency
  * graph and select an appropriate set of best specific versions for all
  * dependent packages. It works iteratively and tries to reach a stable
  * solution where the constraints of all dependencies are met. If it fails to
  * reach a solution after a certain number of iterations, it assumes the
@@ skipping 55 matching lines @@
   final Package _root;
   final LockFile lockFile;
   final PubspecCache _pubspecs;
   final Map<String, Dependency> _packages;
   final Queue<WorkItem> _work;
   int _numIterations = 0;
 
   VersionSolver(SourceRegistry sources, this._root, this.lockFile)
       : _sources = sources,
         _pubspecs = new PubspecCache(sources),
-        _packages = <Dependency>{},
+        _packages = <String, Dependency>{},
         _work = new Queue<WorkItem>();
 
   Future<List<PackageId>> solve() {
     // Kick off the work by adding the root package at its concrete version to
     // the dependency graph.
     var ref = new PackageRef(new RootSource(_root), _root.version, _root.name);
     enqueue(new AddConstraint('(entrypoint)', ref));
     _pubspecs.cache(ref.atVersion(_root.version), _root.pubspec);
 
     Future processNextWorkItem(_) {
@@ skipping 142 matching lines @@
     });
   }
 
   /**
    * Get the dependencies at [version] of the package being changed.
    */
   Future<Map<String, PackageRef>> getDependencyRefs(VersionSolver solver,
       Version version) {
     // If there is no version, it means no package, so no dependencies.
     if (version == null) {
-      return new Future<Map<String, PackageRef>>.immediate(<PackageRef>{});
+      return
+          new Future<Map<String, PackageRef>>.immediate(<String, PackageRef>{});
     }
 
     var id = new PackageId(source, version, description);
     return solver._pubspecs.load(id).transform((pubspec) {
-      var dependencies = <PackageRef>{};
+      var dependencies = <String, PackageRef>{};
       for (var dependency in pubspec.dependencies) {
         dependencies[dependency.name] = dependency;
       }
       return dependencies;
     });
   }
 }
 
 /**
  * A constraint that a depending package places on a dependent package has
@@ skipping 208 matching lines @@
    * If no packages have a constraint on this one (which can happen when this
    * package is in the process of being added to the graph), returns `null`.
    */
   VersionConstraint get constraint() {
     if (_refs.isEmpty()) return null;
     return new VersionConstraint.intersect(
         _refs.getValues().map((ref) => ref.constraint));
   }
 
   Dependency(this.name)
-      : _refs = <PackageRef>{};
+      : _refs = <String, PackageRef>{};
 
   /**
    * Places [ref] as a constraint from [package] onto this.
    */
   void placeConstraint(String package, PackageRef ref) {
     // If this isn't the first constraint placed on this package, make sure it
     // matches the source and description of past constraints.
     if (_refs.isEmpty()) {
       source = ref.source;
       description = ref.description;
@@ skipping 88 matching lines @@
   final description1;
   final description2;
 
   DescriptionMismatchException(this.package, this.description1,
       this.description2);
 
   // TODO(nweiz): Dump to YAML when that's supported
   String toString() => "Package '$package' has conflicting descriptions "
     "'${JSON.stringify(description1)}' and '${JSON.stringify(description2)}'";
 }