Reduce warnings in polymer:

pkg/polymer/lib/src/build/linter.dart

 // Copyright (c) 2013, 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.
 
 /// Logic to validate that developers are correctly using Polymer constructs.
 /// This is mainly used to produce warnings for feedback in the editor.
 library polymer.src.build.linter;
 
 import 'dart:async';
 
@@ skipping 53 matching lines @@
           }
           return _addElements(document, transform.logger, elements);
         })
         .then((_) => elements);
   }
 
   Future _readAndCollectElements(AssetId id, Transform transform,
       Set<AssetId> seen, Map<String, _ElementSummary> elements) {
     if (id == null || seen.contains(id)) return new Future.value(null);
     seen.add(id);
-    return readAsHtml(id, transform).then(
+    return readAsHtml(id, transform, showWarnings: false).then(
         (doc) => _collectElements(doc, id, transform, seen, elements));
   }
 
   Future<List<AssetId>> _getImportedIds(
       Document document, AssetId sourceId, Transform transform) {
     var importIds = [];
     var logger = transform.logger;
     for (var tag in document.querySelectorAll('link')) {
       if (tag.attributes['rel'] != 'import') continue;
       var href = tag.attributes['href'];
       var span = tag.sourceSpan;
       var id = uriToAssetId(sourceId, href, logger, span);
       if (id == null) continue;
       importIds.add(assetExists(id, transform).then((exists) {
         if (exists) return id;
         if (sourceId == transform.primaryInput.id) {
-          logger.error('couldn\'t find imported asset "${id.path}" in package '
-              '"${id.package}".', span: span);
+          logger.warning('couldn\'t find imported asset "${id.path}" in package'

[Siggi Cherem (dart-lang), 2014/06/14 02:24:57]

no reason to make this an error (errors make the build fail)

+              ' "${id.package}".', span: span);
         }
       }));
     }
     return Future.wait(importIds);
   }
 
   void _addElements(Document document, TransformLogger logger,
       Map<String, _ElementSummary> elements) {
     for (var tag in document.querySelectorAll('polymer-element')) {
       var name = tag.attributes['name'];
@@ skipping 25 matching lines @@
 /// Note: these are only created for polymer-element, because pure custom
 /// elements don't have a declarative form.
 class _ElementSummary {
   final String tagName;
   final String extendsTag;
   final Span span;
 
   _ElementSummary extendsType;
   bool hasConflict = false;
 
-  String get baseExtendsTag => extendsType == null
-      ? extendsTag : extendsType.baseExtendsTag;
+  String get baseExtendsTag {
+    if (extendsType != null) return extendsType.baseExtendsTag;
+    if (extendsTag != null && !extendsTag.contains('-')) return extendsTag;

[Siggi Cherem (dart-lang), 2014/06/14 02:24:57]

this compensates for allowing the warning above

+    return null;
+  }
 
   _ElementSummary(this.tagName, this.extendsTag, this.span);
 
   String toString() => "($tagName <: $extendsTag)";
 }
 
 class _LinterVisitor extends TreeVisitor {
   TransformLogger _logger;
   AssetId _sourceId;
   bool _inPolymerElement = false;
@@ skipping 225 matching lines @@
       _logger.warning('PolymerElement no longer recognizes attribute names with '
           'dashes such as "$name". Use "$newName" or "${newName.toLowerCase()}" '
           'instead (both forms are equivalent in HTML).', span: span);
       return false;
     }
     return true;
   }
 
   /// Validate event handlers are used correctly.
   void _validateEventHandler(Element node, String name, String value) {
-    if (!name.startsWith('on-')) {
-      // TODO(sigmund): technically these are valid attribtues in HTML, so we
-      // might want to remove this warning, or only produce it if the value
-      // looks like a binding.
-      _logger.warning('Event handler "$name" will be interpreted as an inline'
-          ' JavaScript event handler. Use the form '
-          'on-event-name="{{handlerName}}" if you want a Dart handler '
-          'that will automatically update the UI based on model changes.',
-          span: node.attributeSpans[name]);
-      return;
-    }
+    if (!name.startsWith('on-')) return;
 
     if (!_inPolymerElement) {
       _logger.warning('Inline event handlers are only supported inside '
           'declarations of <polymer-element>.',
           span: node.attributeSpans[name]);
       return;
     }
 
 
     // Valid bindings have {{ }}, don't look like method calls foo(bar), and are
@@ skipping 38 matching lines @@
 const String USE_INIT_DART =
     'To run a polymer application, you need to call "initPolymer". You can '
     'either include a generic script tag that does this for you:'
     '\'<script type="application/dart">export "package:polymer/init.dart";'
     '</script>\' or add your own script tag and call that function. '
     'Make sure the script tag is placed after all HTML imports.';
 
 const String NO_DART_SCRIPT_AND_EXPERIMENTAL =
     'The experimental bootstrap feature doesn\'t support script tags on '
     'the main document (for now).';