Make some name validation errors warnings.

utils/pub/validator/name.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 name_validator;
 
 import 'dart:async';
 import 'dart:io';
 
 import '../../../pkg/path/lib/path.dart' as path;
@@ skipping 10 matching lines @@
   "new", "null", "return", "super", "switch", "this", "throw", "true", "try",
   "var", "void", "while", "with"
 ];
 
 /// A validator that validates the name of the package and its libraries.
 class NameValidator extends Validator {
   NameValidator(Entrypoint entrypoint)
     : super(entrypoint);
 
   Future validate() {
-    _checkName(entrypoint.root.name, 'Package name "${entrypoint.root.name}"');
+    _checkName(entrypoint.root.name, 'Package name "${entrypoint.root.name}"',
+        isPackage: true);
 
     return _libraries.then((libraries) {
       for (var library in libraries) {
         var libName = path.basenameWithoutExtension(library);
-        _checkName(libName, 'The name of "$library", "$libName",');
+        _checkName(libName, 'The name of "$library", "$libName",',
+            isPackage: false);
       }
 
       if (libraries.length == 1) {
         var libName = path.basenameWithoutExtension(libraries[0]);
         if (libName == entrypoint.root.name) return;
         warnings.add('The name of "${libraries[0]}", "$libName", should match '
             'the name of the package, "${entrypoint.root.name}".\n'
             'This helps users know what library to import.');
       }
     });
   }
 
   /// Returns a list of all libraries in the current package as paths relative
   /// to the package's root directory.
   Future<List<String>> get _libraries {
     var libDir = path.join(entrypoint.root.dir, "lib");
     return defer(() {
       if (!dirExists(libDir)) return [];
       return listDir(libDir, recursive: true);
     }).then((files) {
       return files
           .map((file) => path.relative(file, from: path.dirname(libDir)))
           .where((file) => !path.split(file).contains("src") &&
                            path.extension(file) == '.dart')
           .toList();
     });
   }
 
-  void _checkName(String name, String description) {
+  void _checkName(String name, String description, {bool isPackage}) {
     if (name == "") {
       errors.add("$description may not be empty.");
     } else if (!new RegExp(r"^[a-zA-Z0-9_]*$").hasMatch(name)) {
-      errors.add("$description may only contain letters, numbers, and "
+      warnings.add("$description may only contain letters, numbers, and "
           "underscores.\n"
           "Using a valid Dart identifier makes the name usable in Dart code.");
     } else if (!new RegExp(r"^[a-zA-Z]").hasMatch(name)) {
-      errors.add("$description must begin with letter.\n"
+      warnings.add("$description must begin with letter.\n"
           "Using a valid Dart identifier makes the name usable in Dart code.");
     } else if (_RESERVED_WORDS.contains(name.toLowerCase())) {
-      errors.add("$description may not be a reserved word in Dart.\n"
+      var messages = isPackage ? errors : warnings;
+      messages.add("$description may not be a reserved word in Dart.\n"
           "Using a valid Dart identifier makes the name usable in Dart code.");
     } else if (new RegExp(r"[A-Z]").hasMatch(name)) {
       warnings.add('$description should be lower-case. Maybe use '
           '"${_unCamelCase(name)}"?');
     }
   }
 
   String _unCamelCase(String source) {
     var builder = new StringBuffer();
     var lastMatchEnd = 0;
     for (var match in new RegExp(r"[a-z]([A-Z])").allMatches(source)) {
       builder
         ..add(source.substring(lastMatchEnd, match.start + 1))
         ..add("_")
         ..add(match.group(1).toLowerCase());
       lastMatchEnd = match.end;
     }
     builder.add(source.substring(lastMatchEnd));
     return builder.toString().toLowerCase();
   }
 }