[3.0 alpha] Remove deprecated BidirectionalIterator.

Requires releasing `package:quiver` 3.2.0 so Flutter can upgrade to that.


Change-Id: Ibd9acc5fa11a67ca50d06172dfe0f9175b240522
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/276741
Commit-Queue: Lasse Nielsen <lrn@google.com>
Reviewed-by: Aske Simon Christensen <askesc@google.com>

CHANGELOG.md

@@ -30,6 +30,9 @@
     ways instead, possibly with a StackOverflowError.
   - Removed the deprecated [`NoSuchMethodError`][] default constructor.
     Use the [`NoSuchMethodError.withInvocation`][] named constructor instead.
+  - Removed the deprecated [`BidirectionalIterator`][] class.
+    Existing bidirectional iterators can still work, they just don't have
+    a shared supertype locking them to a specific name for moving backwards.
 
 [#49529]: https://github.com/dart-lang/sdk/issues/49529
 [`List.filled`]: https://api.dart.dev/stable/2.18.6/dart-core/List/List.filled.html
@@ -54,6 +57,7 @@
 [`NullThrownError`]: https://api.dart.dev/dev/2.19.0-430.0.dev/dart-core/NullThrownError-class.html
 [`AbstractClassInstantiationError`]: https://api.dart.dev/stable/2.18.3/dart-core/AbstractClassInstantiationError-class.html
 [`CyclicInitializationError`]: https://api.dart.dev/dev/2.19.0-430.0.dev/dart-core/CyclicInitializationError-class.html
+[`BidirectionalIterator`]: https://api.dart.dev/dev/2.19.0-430.0.dev/dart-core/BidirectionalIterator-class.html
 
 #### `dart:async`
 
@@ -68,7 +72,7 @@
 #### `dart:developer`
 
 - **Breaking change** [#49529][]:
-  - Removed the deprecated [`MAX_USER_TAGS`][] constant. 
+  - Removed the deprecated [`MAX_USER_TAGS`][] constant.
     Use [`maxUserTags`][] instead.
 - Callbacks passed to `registerExtension` will be run in the zone from which
   they are registered.

pkg/front_end/testcases/general/error_export_from_dill/main.dart.strong.expect

@@ -121,7 +121,6 @@ additionalExports = (core::Deprecated,
   core::int,
   core::Invocation,
   core::Iterable,
-  core::BidirectionalIterator,
   core::Iterator,
   core::List,
   core::Map,

pkg/front_end/testcases/general/error_export_from_dill/main.dart.strong.transformed.expect

@@ -117,7 +117,6 @@ additionalExports = (core::Deprecated,
   core::int,
   core::Invocation,
   core::Iterable,
-  core::BidirectionalIterator,
   core::Iterator,
   core::List,
   core::Map,

pkg/front_end/testcases/general/error_export_from_dill/main.dart.weak.expect

@@ -121,7 +121,6 @@ additionalExports = (core::Deprecated,
   core::int,
   core::Invocation,
   core::Iterable,
-  core::BidirectionalIterator,
   core::Iterator,
   core::List,
   core::Map,

pkg/front_end/testcases/general/error_export_from_dill/main.dart.weak.outline.expect

@@ -56,7 +56,6 @@ additionalExports = (core::Deprecated,
   core::int,
   core::Invocation,
   core::Iterable,
-  core::BidirectionalIterator,
   core::Iterator,
   core::List,
   core::Map,

pkg/front_end/testcases/general/error_export_from_dill/main.dart.weak.transformed.expect

@@ -117,7 +117,6 @@ additionalExports = (core::Deprecated,
   core::int,
   core::Invocation,
   core::Iterable,
-  core::BidirectionalIterator,
   core::Iterator,
   core::List,
   core::Map,

pkg/front_end/testcases/incremental/export_core.yaml.world.2.expect

@@ -11,7 +11,6 @@ additionalExports = (asy::Future,
   core::Comparator,
   core::ArgumentError,
   core::AssertionError,
-  core::BidirectionalIterator,
   core::BigInt,
   core::Comparable,
   core::ConcurrentModificationError,

pkg/front_end/testcases/incremental/export_core.yaml.world.3.expect

@@ -11,7 +11,6 @@ additionalExports = (asy::Future,
   core::Comparator,
   core::ArgumentError,
   core::AssertionError,
-  core::BidirectionalIterator,
   core::BigInt,
   core::Comparable,
   core::ConcurrentModificationError,

runtime/tools/dartfuzz/gen_type_table.dart

@@ -1394,7 +1394,6 @@ void visitCompilationUnit(
           (classElement.name == 'StackTrace') ||
           (classElement.name == 'NoSuchMethodError') ||
           (classElement.name == 'Comparable') ||
-          (classElement.name == 'BidirectionalIterator') ||
           (classElement.name == 'Iterator') ||
           (classElement.name == 'Stopwatch') ||
           (classElement.name == 'Finalizer') ||

sdk/lib/core/iterable.dart

@@ -822,22 +822,3 @@ class _GeneratorIterable<E> extends ListIterable<E> {
   /// Helper function used as default _generator function.
   static int _id(int n) => n;
 }
-
-/// An [Iterator] that allows moving backwards as well as forwards.
-///
-/// Deprecation note: This interface has turned out to not be
-/// valuable as a general reusable interface. There is still only
-/// one class implementing it, [RuneIterator], and at least one other
-/// bidirectional iterator preferred a different name than `movePrevious`
-/// for the other direction.
-/// As such, this interface does not carry its own weight, and will be
-/// removed in a later release.
-@Deprecated("Use the implementing class directly")
-abstract class BidirectionalIterator<E> implements Iterator<E> {
-  /// Move back to the previous element.
-  ///
-  /// Returns true and updates [current] if successful. Returns false
-  /// and updates [current] to an implementation defined state if there is no
-  /// previous element
-  bool movePrevious();
-}

sdk/lib/core/string.dart

@@ -799,7 +799,7 @@ int _combineSurrogatePair(int start, int end) {
 }
 
 /// [Iterator] for reading runes (integer Unicode code points) of a Dart string.
-class RuneIterator implements BidirectionalIterator<int> {
+class RuneIterator implements Iterator<int> {
   /// String being iterated.
   final String string;
 
@@ -906,6 +906,10 @@ class RuneIterator implements BidirectionalIterator<int> {
     return string.substring(_position, _nextPosition);
   }
 
+  /// Move to the next code point.
+  ///
+  /// Returns `true` and updates [current] if there is a next code point.
+  /// Returns `false` otherwise, and then there is no current code point.
   bool moveNext() {
     _position = _nextPosition;
     if (_position == string.length) {
@@ -927,6 +931,10 @@ class RuneIterator implements BidirectionalIterator<int> {
     return true;
   }
 
+  /// Move back to the previous code point.
+  ///
+  /// Returns `true` and updates [current] if there is a previous code point.
+  /// Returns `false` otherwise, and then there is no current code point.
   bool movePrevious() {
     _nextPosition = _position;
     if (_position == 0) {