Add a new annotation

pkg/meta/lib/meta.dart

Index: pkg/meta/lib/meta.dart
diff --git a/pkg/meta/lib/meta.dart b/pkg/meta/lib/meta.dart
index 984287546f6558dfa0ef1395c7950449d28d840d..9ab5e835db68021b553a6c289bfbac34ebb6d98e 100644
--- a/pkg/meta/lib/meta.dart
+++ b/pkg/meta/lib/meta.dart
@@ -18,6 +18,14 @@
 /// in the language tour.
 library meta;
 
+/// Used to annotate a parameter of an instance method that overrides another
+/// method.
+///
+/// Indicates that this parameter may have a tighter type than the parameter on
+/// its superclass. The actual argument will be checked at runtime to ensure it
+/// is a subtype of the overridden parameter type.
+const _Checked checked = const _Checked();
+
 /// Used to annotate an instance or static method `m`. Indicates that `m` must
 /// either be abstract or must return a newly allocated object or `null`. In
 /// addition, every method that either implements or overrides `m` is implicitly
@@ -97,6 +105,21 @@ const _Protected protected = const _Protected();
 ///   corresponding to a named parameter that has this annotation.
 const Required required = const Required();
 
+/// Used to annotate a field that is allowed to be overridden in Strong Mode.
+const _Virtual virtual = const _Virtual();

[Alexei Diaz, 2016/10/13 16:36:58]

Could this somehow be extended to methods? Like the virtual access modifier in
C#.https://msdn.microsoft.com/en-us/library/9fkccyh4.aspx

[Brian Wilkerson, 2016/10/13 18:17:00]

This annotation (which wasn't added by this CL, merely moved when the file was
sorted) is used by DDC to allow more efficient code for fields that are not
annotated. There's currently no other benefit, and DDC currently doesn't provide
any benefit from using it for methods, so I'd hesitate to expand it's use.

+
+/// Used to annotate an instance member that was made public so that it could be
+/// overridden but that is not intended to be referenced from outside the
+/// defining library.
+///
+/// Tools, such as the analyzer, can provide feedback if
+///
+/// * the annotation is associated with a declaration other than a public
+///   instance member in a class, or
+/// * the member is referenced outside of the defining library.
+const _VisibleForOverriding visibleForOverriding =
+    const _VisibleForOverriding();
+
 /// Used to annotate a declaration was made public, so that it is more visible
 /// than otherwise necessary, to make code testable.
 ///
@@ -128,17 +151,6 @@ class Required {
   const Required([this.reason]);
 }
 
-/// Used to annotate a parameter of an instance method that overrides another
-/// method.
-///
-/// Indicates that this parameter may have a tighter type than the parameter on
-/// its superclass. The actual argument will be checked at runtime to ensure it
-/// is a subtype of the overridden parameter type.
-const _Checked checked = const _Checked();
-
-/// Used to annotate a field is allowed to be overridden in Strong Mode.
-const _Virtual virtual = const _Virtual();
-
 class _Checked {
   const _Checked();
 }
@@ -167,6 +179,10 @@ class _Virtual {
   const _Virtual();
 }
 
+class _VisibleForOverriding {
+  const _VisibleForOverriding();
+}
+
 class _VisibleForTesting {
   const _VisibleForTesting();
 }