Tighten up types (#1776)

Author: kevmoo

lib/src/barback/load_all_transformers.dart

@@ -133,7 +133,7 @@ List<Set<TransformerId>> _stageTransformers(
   var stageNumbers = <TransformerId, int>{};
   var stages = <Set<TransformerId>>[];
 
-  stageNumberFor(TransformerId id) {
+  int stageNumberFor(TransformerId id) {
     // Built-in transformers don't have to be loaded in stages, since they're
     // run from pub's source. Return -1 so that the "next stage" is 0.
     if (id.isBuiltInTransformer) return -1;

lib/src/io.dart

@@ -354,7 +354,7 @@ void _attempt(String description, void operation()) {
     return;
   }
 
-  getErrorReason(error) {
+  String getErrorReason(FileSystemException error) {
     if (error.osError.errorCode == 5) {
       return "access was denied";
     }

lib/src/utils.dart

@@ -322,15 +322,16 @@ Set<String> createDirectoryFilter(Iterable<String> dirs) {
 /// Returns the maximum value in [iter] by [compare].
 ///
 /// [compare] defaults to [Comparable.compare].
-T maxAll<T>(Iterable<T> iter, [int compare(T value, T value2)]) {
-  compare ??= (value1, value2) => (value1 as Comparable).compareTo(value2);
+T maxAll<T extends Comparable>(Iterable<T> iter,
+    [int compare(T element1, T element2)]) {
+  if (compare == null) compare = Comparable.compare;
   return iter
       .reduce((max, element) => compare(element, max) > 0 ? element : max);
 }
 
 /// Replace each instance of [matcher] in [source] with the return value of
 /// [fn].
-String replace(String source, Pattern matcher, String fn(Match)) {
+String replace(String source, Pattern matcher, String fn(Match match)) {
   var buffer = new StringBuffer();
   var start = 0;
   for (var match in matcher.allMatches(source)) {
@@ -399,7 +400,7 @@ Future<Stream<T>> validateStream<T>(Stream<T> stream) {
     // We got a value, so the stream is valid.
     if (!completer.isCompleted) completer.complete(controller.stream);
     controller.add(value);
-  }, onError: (error, [stackTrace]) {
+  }, onError: (error, [StackTrace stackTrace]) {
     // If the error came after values, it's OK.
     if (completer.isCompleted) {
       controller.addError(error, stackTrace);
@@ -425,13 +426,13 @@ Future<Stream<T>> validateStream<T>(Stream<T> stream) {
 /// Returns a [Future] that will complete to the first element of [stream].
 ///
 /// Unlike [Stream.first], this is safe to use with single-subscription streams.
-Future streamFirst(Stream stream) {
+Future<T> streamFirst<T>(Stream<T> stream) {
   var completer = new Completer();
   var subscription;
   subscription = stream.listen((value) {
     subscription.cancel();
     completer.complete(value);
-  }, onError: (e, [stackTrace]) {
+  }, onError: (e, [StackTrace stackTrace]) {
     completer.completeError(e, stackTrace);
   }, onDone: () {
     completer.completeError(new StateError("No elements"), new Chain.current());