Add some stricter analysis (flutter#64)

- Enable errors that would fail internally
- Add `comment_references` lint - this makes DartDocs output more usable
  and there isn't any reason to have unclickable references.
- Add `prefer_typing_uninitialized_variables` lint - this prevents some
  unintentionally dynamic behavior.
- Disable implicit casts.
- Use function type syntax for the ManuallyClosedWatcher factory.
- Remove some unused utilities.

analysis_options.yaml

@@ -0,0 +1,14 @@
+analyzer:
+  strong-mode:
+    implicit-casts: false
+  errors:
+    todo: ignore
+    unused_import: error
+    unused_element: error
+    unused_local_variable: error
+    dead_code: error
+
+linter:
+  rules:
+    - comment_references
+    - prefer_typing_uninitialized_variables

benchmark/path_set.dart

@@ -31,7 +31,7 @@ abstract class PathSetBenchmark extends BenchmarkBase {
   /// Each virtual directory contains ten entries: either subdirectories or
   /// files.
   void walkTree(int depth, callback(String path)) {
-    recurse(path, remainingDepth) {
+    recurse(String path, remainingDepth) {
       for (var i = 0; i < 10; i++) {
         var padded = i.toString().padLeft(2, '0');
         if (remainingDepth == 0) {

lib/src/directory_watcher/linux.dart

@@ -79,13 +79,14 @@ class _LinuxDirectoryWatcher
         .transform(new BatchedStreamTransformer<FileSystemEvent>());
     _listen(innerStream, _onBatch, onError: _eventsController.addError);
 
-    _listen(new Directory(path).list(recursive: true), (entity) {
+    _listen(new Directory(path).list(recursive: true),
+        (FileSystemEntity entity) {
       if (entity is Directory) {
         _watchSubdir(entity.path);
       } else {
         _files.add(entity.path);
       }
-    }, onError: (error, stackTrace) {
+    }, onError: (error, StackTrace stackTrace) {
       _eventsController.addError(error, stackTrace);
       close();
     }, onDone: () {
@@ -207,14 +208,15 @@ class _LinuxDirectoryWatcher
 
   /// Emits [ChangeType.ADD] events for the recursive contents of [path].
   void _addSubdir(String path) {
-    _listen(new Directory(path).list(recursive: true), (entity) {
+    _listen(new Directory(path).list(recursive: true),
+        (FileSystemEntity entity) {
       if (entity is Directory) {
         _watchSubdir(entity.path);
       } else {
         _files.add(entity.path);
         _emit(ChangeType.ADD, entity.path);
       }
-    }, onError: (error, stackTrace) {
+    }, onError: (error, StackTrace stackTrace) {
       // Ignore an exception caused by the dir not existing. It's fine if it
       // was added and then quickly removed.
       if (error is FileSystemException) return;
@@ -252,7 +254,7 @@ class _LinuxDirectoryWatcher
   /// [_subscriptions] so that it can be canceled when [close] is called.
   void _listen<T>(Stream<T> stream, void onData(T event),
       {Function onError, void onDone(), bool cancelOnError}) {
-    var subscription;
+    StreamSubscription subscription;
     subscription = stream.listen(onData, onError: onError, onDone: () {
       _subscriptions.remove(subscription);
       if (onDone != null) onDone();

lib/src/directory_watcher/mac_os.dart

@@ -54,8 +54,8 @@ class _MacOSDirectoryWatcher
 
   /// The subscription to the stream returned by [Directory.watch].
   ///
-  /// This is separate from [_subscriptions] because this stream occasionally
-  /// needs to be resubscribed in order to work around issue 14849.
+  /// This is separate from [_listSubscriptions] because this stream
+  /// occasionally needs to be resubscribed in order to work around issue 14849.
   StreamSubscription<List<FileSystemEvent>> _watchSubscription;
 
   /// The subscription to the [Directory.list] call for the initial listing of
@@ -143,7 +143,7 @@ class _MacOSDirectoryWatcher
 
             _emitEvent(ChangeType.ADD, entity.path);
             _files.add(entity.path);
-          }, onError: (e, stackTrace) {
+          }, onError: (e, StackTrace stackTrace) {
             _emitError(e, stackTrace);
           }, onDone: () {
             _listSubscriptions.remove(subscription);
@@ -212,7 +212,7 @@ class _MacOSDirectoryWatcher
   /// one exists.
   ///
   /// If [batch] doesn't contain any contradictory events (e.g. DELETE and
-  /// CREATE, or events with different values for [isDirectory]), this returns a
+  /// CREATE, or events with different values for `isDirectory`), this returns a
   /// single event that describes what happened to the path in question.
   ///
   /// If [batch] does contain contradictory events, this returns `null` to

lib/src/directory_watcher/polling.dart

@@ -19,7 +19,7 @@ class PollingDirectoryWatcher extends ResubscribableWatcher
 
   /// Creates a new polling watcher monitoring [directory].
   ///
-  /// If [_pollingDelay] is passed, it specifies the amount of time the watcher
+  /// If [pollingDelay] is passed, it specifies the amount of time the watcher
   /// will pause between successive polls of the directory contents. Making this
   /// shorter will give more immediate feedback at the expense of doing more IO
   /// and higher CPU usage. Defaults to one second.
@@ -68,13 +68,13 @@ class _PollingDirectoryWatcher
 
   /// The set of files that have been seen in the current directory listing.
   ///
-  /// Used to tell which files have been removed: files that are in [_statuses]
-  /// but not in here when a poll completes have been removed.
+  /// Used to tell which files have been removed: files that are in
+  /// [_lastModifieds] but not in here when a poll completes have been removed.
   final _polledFiles = new Set<String>();
 
   _PollingDirectoryWatcher(this.path, this._pollingDelay) {
-    _filesToProcess =
-        new AsyncQueue<String>(_processFile, onError: (e, stackTrace) {
+    _filesToProcess = new AsyncQueue<String>(_processFile,
+        onError: (e, StackTrace stackTrace) {
       if (!_events.isClosed) _events.addError(e, stackTrace);
     });
 
@@ -113,7 +113,7 @@ class _PollingDirectoryWatcher
 
       if (entity is! File) return;
       _filesToProcess.add(entity.path);
-    }, onError: (error, stackTrace) {
+    }, onError: (error, StackTrace stackTrace) {
       if (!isDirectoryNotFoundException(error)) {
         // It's some unknown error. Pipe it over to the event stream so the
         // user can see it.

lib/src/directory_watcher/windows.dart

@@ -188,7 +188,7 @@ class _WindowsDirectoryWatcher
             _files.add(entity.path);
           }, onDone: () {
             _listSubscriptions.remove(subscription);
-          }, onError: (e, stackTrace) {
+          }, onError: (e, StackTrace stackTrace) {
             _listSubscriptions.remove(subscription);
             _emitError(e, stackTrace);
           }, cancelOnError: true);
@@ -253,7 +253,7 @@ class _WindowsDirectoryWatcher
   /// one exists.
   ///
   /// If [batch] doesn't contain any contradictory events (e.g. DELETE and
-  /// CREATE, or events with different values for [isDirectory]), this returns a
+  /// CREATE, or events with different values for `isDirectory`), this returns a
   /// single event that describes what happened to the path in question.
   ///
   /// If [batch] does contain contradictory events, this returns `null` to
@@ -382,7 +382,7 @@ class _WindowsDirectoryWatcher
     _files.clear();
     var completer = new Completer();
     var stream = new Directory(path).list(recursive: true);
-    void handleEntity(entity) {
+    void handleEntity(FileSystemEntity entity) {
       if (entity is! Directory) _files.add(entity.path);
     }
 

lib/src/file_watcher.dart

@@ -15,7 +15,7 @@ import 'file_watcher/polling.dart';
 /// it will emit a single [ChangeType.REMOVE] event and then close the stream.
 ///
 /// If the file is deleted and quickly replaced (when a new file is moved in its
-/// place, for example) this will emit a [ChangeTime.MODIFY] event.
+/// place, for example) this will emit a [ChangeType.MODIFY] event.
 abstract class FileWatcher implements Watcher {
   /// Creates a new [FileWatcher] monitoring [file].
   ///

lib/src/file_watcher/polling.dart

@@ -58,7 +58,7 @@ class _PollingFileWatcher implements FileWatcher, ManuallyClosedWatcher {
       return;
     }
 
-    var modified;
+    DateTime modified;
     try {
       try {
         modified = await getModificationTime(path);

lib/src/path_set.dart

@@ -49,13 +49,13 @@ class PathSet {
   /// empty set.
   Set<String> remove(String path) {
     path = _normalize(path);
-    var parts = new Queue.from(p.split(path));
+    var parts = new Queue.of(p.split(path));
 
     // Remove the children of [dir], as well as [dir] itself if necessary.
     //
     // [partialPath] is the path to [dir], and a prefix of [path]; the remaining
     // components of [path] are in [parts].
-    Set<String> recurse(dir, partialPath) {
+    Set<String> recurse(_Entry dir, String partialPath) {
       if (parts.length > 1) {
         // If there's more than one component left in [path], recurse down to
         // the next level.
@@ -97,7 +97,7 @@ class PathSet {
   /// [dirPath] should be the path to [dir].
   Set<String> _explicitPathsWithin(_Entry dir, String dirPath) {
     var paths = new Set<String>();
-    recurse(dir, path) {
+    recurse(_Entry dir, String path) {
       dir.contents.forEach((name, entry) {
         var entryPath = p.join(path, name);
         if (entry.isExplicit) paths.add(p.join(root, entryPath));
@@ -110,9 +110,9 @@ class PathSet {
     return paths;
   }
 
-  /// Returns whether [this] contains [path].
+  /// Returns whether this set contains [path].
   ///
-  /// This only returns true for paths explicitly added to [this].
+  /// This only returns true for paths explicitly added to this set.
   /// Implicitly-added directories can be inspected using [containsDir].
   bool contains(String path) {
     path = _normalize(path);
@@ -126,7 +126,7 @@ class PathSet {
     return entry.isExplicit;
   }
 
-  /// Returns whether [this] contains paths beneath [path].
+  /// Returns whether this set contains paths beneath [path].
   bool containsDir(String path) {
     path = _normalize(path);
     var entry = _entries;
@@ -143,7 +143,7 @@ class PathSet {
   List<String> get paths {
     var result = <String>[];
 
-    recurse(dir, path) {
+    recurse(_Entry dir, String path) {
       for (var name in dir.contents.keys) {
         var entry = dir.contents[name];
         var entryPath = p.join(path, name);
@@ -156,7 +156,7 @@ class PathSet {
     return result;
   }
 
-  /// Removes all paths from [this].
+  /// Removes all paths from this set.
   void clear() {
     _entries.contents.clear();
   }

lib/src/resubscribable.dart

@@ -7,8 +7,6 @@ import 'dart:async';
 import '../watcher.dart';
 import 'watch_event.dart';
 
-typedef ManuallyClosedWatcher WatcherFactory();
-
 /// A wrapper for [ManuallyClosedWatcher] that encapsulates support for closing
 /// the watcher when it has no subscribers and re-opening it when it's
 /// re-subscribed.
@@ -24,7 +22,7 @@ typedef ManuallyClosedWatcher WatcherFactory();
 /// takes a factory function that produces instances of the inner class.
 abstract class ResubscribableWatcher implements Watcher {
   /// The factory function that produces instances of the inner class.
-  final WatcherFactory _factory;
+  final ManuallyClosedWatcher Function() _factory;
 
   final String path;
 
@@ -39,8 +37,8 @@ abstract class ResubscribableWatcher implements Watcher {
   /// Creates a new [ResubscribableWatcher] wrapping the watchers
   /// emitted by [_factory].
   ResubscribableWatcher(this.path, this._factory) {
-    var watcher;
-    var subscription;
+    ManuallyClosedWatcher watcher;
+    StreamSubscription subscription;
 
     _eventsController = new StreamController<WatchEvent>.broadcast(
         onListen: () {

lib/src/utils.dart

@@ -6,8 +6,6 @@ import 'dart:async';
 import 'dart:io';
 import 'dart:collection';
 
-import 'package:async/async.dart';
-
 /// Returns `true` if [error] is a [FileSystemException] for a missing
 /// directory.
 bool isDirectoryNotFoundException(error) {
@@ -22,55 +20,6 @@ bool isDirectoryNotFoundException(error) {
 Set<T> unionAll<T>(Iterable<Set<T>> sets) =>
     sets.fold(new Set<T>(), (union, set) => union.union(set));
 
-/// Returns a buffered stream that will emit the same values as the stream
-/// returned by [future] once [future] completes.
-///
-/// If [future] completes to an error, the return value will emit that error and
-/// then close.
-///
-/// If [broadcast] is true, a broadcast stream is returned. This assumes that
-/// the stream returned by [future] will be a broadcast stream as well.
-/// [broadcast] defaults to false.
-Stream<T> futureStream<T>(Future<Stream<T>> future, {bool broadcast: false}) {
-  var subscription;
-  StreamController<T> controller;
-
-  future = DelegatingFuture.typed(future.catchError((e, stackTrace) {
-    // Since [controller] is synchronous, it's likely that emitting an error
-    // will cause it to be cancelled before we call close.
-    if (controller != null) controller.addError(e, stackTrace);
-    if (controller != null) controller.close();
-    controller = null;
-  }));
-
-  onListen() {
-    future.then((stream) {
-      if (controller == null) return;
-      subscription = stream.listen(controller.add,
-          onError: controller.addError, onDone: controller.close);
-    });
-  }
-
-  onCancel() {
-    if (subscription != null) subscription.cancel();
-    subscription = null;
-    controller = null;
-  }
-
-  if (broadcast) {
-    controller = new StreamController.broadcast(
-        sync: true, onListen: onListen, onCancel: onCancel);
-  } else {
-    controller = new StreamController(
-        sync: true, onListen: onListen, onCancel: onCancel);
-  }
-  return controller.stream;
-}
-
-/// Like [new Future], but avoids around issue 11911 by using [new Future.value]
-/// under the covers.
-Future newFuture(callback()) => new Future.value().then((_) => callback());
-
 /// A stream transformer that batches all events that are sent at the same time.
 ///
 /// When multiple events are synchronously added to a stream controller, the