Add unawaited to package:meta

Change-Id: I09df4989591327bd4d148e73a5887b900902576c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/152680
Commit-Queue: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Jake Macdonald <jakemac@google.com>

DEPS

@@ -123,7 +123,7 @@ vars = {
   "oauth2_tag": "1.6.0",
   "package_config_rev": "9c586d04bd26fef01215fd10e7ab96a3050cfa64",
   "path_rev": "4f3bb71843fe5493ba490828a1721821d7b33746",
-  "pedantic_tag": "v1.9.0",
+  "pedantic_tag": "v1.9.1",
   "ply_rev": "604b32590ffad5cbb82e4afef1d305512d06ae93",
   "pool_rev": "86fbb2cde9bbc66c8d159909d2f65a5981ea5b50",
   "protobuf_rev": "3746c8fd3f2b0147623a8e3db89c3ff4330de760",

pkg/meta/CHANGELOG.md

@@ -1,9 +1,20 @@
-## 1.2.0-nnbd
+## 1.3.0-nnbd
 
 * Opt into null safety.
+
+## 1.2.1
+
+* Fixed a bug by adding an import of dart:async so that the code really is
+  compatible with the lower bound of the SDK constraints.
+
+## 1.2.0
+
 * Introduce `@doNotStore` to annotate methods, getters and functions to
   indicate that values obtained by invoking them should not be stored in a
   field or top-level variable.
+* Introduce `unawaited` to mark invocations that return a `Future` where it's
+  intentional that the future is not being awaited. (Moved from
+  `package:pedantic`.)
 
 ## 1.1.8
 

pkg/meta/lib/meta.dart

@@ -1,8 +1,9 @@
-// Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
+// 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.
+/// Constants and functions that developers can use to express the intentions
+/// that otherwise can't be deduced by statically analyzing the source code.
 ///
 /// See also `@deprecated` and `@override` in the `dart:core` library.
 ///
@@ -12,7 +13,7 @@
 /// function's name differently.
 ///
 /// For information on installing and importing this library, see the [meta
-/// package on pub.dev](https://pub.dev/packages/meta).  For examples of using
+/// package on pub.dev](https://pub.dev/packages/meta). For examples of using
 /// annotations, see
 /// [Metadata](https://dart.dev/guides/language/language-tour#metadata) in the
 /// language tour.
@@ -266,6 +267,26 @@ const _VisibleForOverriding visibleForOverriding = _VisibleForOverriding();
 ///   library which is in the `test` folder of the defining package.
 const _VisibleForTesting visibleForTesting = _VisibleForTesting();
 
+/// Indicates to tools that [future] is intentionally not `await`-ed.
+///
+/// In an `async` context, it is normally expected that all [Future]s are
+/// awaited, and that is the basis of the lint `unawaited_futures`. However,
+/// there are times where one or more futures are intentionally not awaited.
+/// This function may be used to ignore a particular future. It silences the
+/// `unawaited_futures` lint.
+///
+/// ```
+/// Future<void> saveUserPreferences() async {
+///   await _writePreferences();
+///
+///   // While 'log' returns a Future, the consumer of 'saveUserPreferences'
+///   // is unlikely to want to wait for that future to complete; they only
+///   // care about the preferences being written).
+///   unawaited(log('Preferences saved!'));
+/// }
+/// ```
+void unawaited(Future<void>? future) {}
+
 /// Used to annotate a class.
 ///
 /// See [immutable] for more details.

pkg/meta/pubspec.yaml

@@ -1,11 +1,11 @@
 name: meta
-version: 1.2.0-nnbd
-author: Dart Team <misc@dartlang.org>
+version: 1.3.0-nnbd
 homepage: https://github.com/dart-lang/sdk/tree/master/pkg/meta
 description: >
- This library contains the definitions of annotations that provide additional
- semantic information about the program being annotated. These annotations are
- intended to be used by tools to provide a better user experience.
+ This library contains the declarations of constants and functions that
+ developers can use to express the intentions that otherwise can't be deduced by
+ statically analyzing the source code. These declarations are intended to be
+ used by tools to provide a better user experience.
 environment:
   # This must remain a tight constraint (only allow dev versions) until nnbd is
   # stable.