Validate that a package doesn't depend on itself.

utils/pub/validator/dependency.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.
 
 library dependency_validator;
 
 import '../entrypoint.dart';
 import '../hosted_source.dart';
 import '../http.dart';
 import '../package.dart';
 import '../utils.dart';
 import '../validator.dart';
 import '../version.dart';
 
 /// A validator that validates a package's dependencies.
 class DependencyValidator extends Validator {
   DependencyValidator(Entrypoint entrypoint)
     : super(entrypoint);
 
   Future validate() {
     return Futures.forEach(entrypoint.root.pubspec.dependencies, (dependency) {
       if (dependency.source is! HostedSource) {
         return _warnAboutSource(dependency);
       }
 
+      if (dependency.name == entrypoint.root.name) {
+        warnings.add('You don\'t need to explicitly depend on your own '
+                'package.\n'
+            'Pub enables "package:${entrypoint.root.name}" imports '
+                'implicitly.');
+        return new Future.immediate(null);
+      }
+
       if (dependency.constraint.isAny &&
           // TODO(nweiz): once we have development dependencies (issue 5358), we
           // should warn about unittest. Until then, it's reasonable not to put
           // a constraint on it.
           dependency.name != 'unittest') {
         return _warnAboutConstraint(dependency);
       }
 
       return new Future.immediate(null);
     });
@@ skipping 46 matching lines @@
   }
 
   /// Returns the suggested version constraint for a dependency that was tested
   /// against [version].
   String _constraintForVersion(Version version) {
     if (version.major != 0) return '">=$version <${version.major + 1}.0.0"';
     return '">=$version <${version.major}.${version.minor}.'
         '${version.patch + 1}"';
   }
 }