Annotation for `@optionalTypeArgs` (linter#196).

pkg/meta/lib/meta.dart

 // Copyright (c) 2016, 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.
 
 /// Constants for use in metadata annotations.
 ///
 /// See also `@deprecated` and `@override` in the `dart:core` library.
 ///
 /// Annotations provide semantic information that tools can use to provide a
 /// better user experience. For example, an IDE might not autocomplete the name
@@ skipping 38 matching lines @@
 /// Note that private methods with this annotation cannot be validly overridden
 /// outside of the library that defines the annotated method.
 ///
 /// Tools, such as the analyzer, can provide feedback if
 /// * the annotation is associated with anything other than an instance method,
 ///   or
 /// * a method that overrides a method that has this annotation can return
 ///   without invoking the overridden method.
 const _MustCallSuper mustCallSuper = const _MustCallSuper();
 
+/// Used to annotate a class declaration `c`. Indicates that any type arguments

[Brian Wilkerson, 2016/04/11 23:51:24]

nit: class names are typically capitalized

[pquitslund, 2016/04/11 23:58:21]

Fixed!

+/// declared on `c` are to be treated as optional.  Tools such as the analyzer
+/// and linter can use this information to suppress warnings that would
+/// otherwise require type arguments to be provided for instances of `c`.
+const _OptionalTypeArgs optionalTypeArgs = const _OptionalTypeArgs();
+
 /// Used to annotate an instance member (method, getter, setter, operator, or
 /// field) `m` in a class `C`. If the annotation is on a field it applies to the
 /// getter, and setter if appropriate, that are induced by the field. Indicates
 /// that `m` should only be invoked from instance methods of `C` or classes that
 /// extend or mix in `C`, either directly or indirectly. Additionally indicates
 /// that `m` should only be invoked on `this`, whether explicitly or implicitly.
 ///
 /// Tools, such as the analyzer, can provide feedback if
 /// * the annotation is associated with anything other than an instance member,
 ///   or
@@ skipping 41 matching lines @@
 }
 
 class _Literal {
   const _Literal();
 }
 
 class _MustCallSuper {
   const _MustCallSuper();
 }
 
+class _OptionalTypeArgs {
+  const _OptionalTypeArgs();
+}
+
 class _Protected {
   const _Protected();
 }