Use declared return type for inference of return and yield statements.

pkg/front_end/tool/fasta_perf.dart

 // Copyright (c) 2017, 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.
 
 /// An entrypoint used to run portions of fasta and measure its performance.
 library front_end.tool.fasta_perf;
 
 import 'dart:async';
 import 'dart:io';
 
 import 'package:analyzer/src/fasta/ast_builder.dart';
 import 'package:front_end/physical_file_system.dart';
 import 'package:front_end/src/fasta/dill/dill_target.dart' show DillTarget;
 import 'package:front_end/src/fasta/kernel/kernel_target.dart'
     show KernelTarget;
 import 'package:front_end/src/fasta/parser.dart';
 import 'package:front_end/src/fasta/scanner.dart';
 import 'package:front_end/src/fasta/scanner/io.dart' show readBytesFromFileSync;
 import 'package:front_end/src/fasta/source/directive_listener.dart';
 import 'package:front_end/src/fasta/ticker.dart' show Ticker;
 import 'package:front_end/src/fasta/translate_uri.dart' show TranslateUri;
 import 'package:front_end/src/fasta/translate_uri.dart';
 import 'package:front_end/src/fasta/parser/dart_vm_native.dart'
     show skipNativeClause;
+import 'package:kernel/ast.dart' show FunctionNode;
 
 /// Cumulative total number of chars scanned.
 int inputSize = 0;
 
 /// Cumulative time spent scanning.
 Stopwatch scanTimer = new Stopwatch();
 
 main(List<String> args) async {
   // TODO(sigmund): provide sdk folder as well.
   if (args.length < 2) {
@@ skipping 159 matching lines @@
   parser.parseUnit(tokens);
 }
 
 // Note: AstBuilder doesn't build compilation-units or classes, only method
 // bodies. So this listener is not feature complete.
 class _PartialAstBuilder extends AstBuilder {
   _PartialAstBuilder(Uri uri) : super(null, null, null, null, null, uri);
 
   // Note: this method converts the body to kernel, so we skip that here.
   @override
-  finishFunction(formals, asyncModifier, body) {}
+  finishFunction(FunctionNode function, formals, asyncModifier, body) {}
 }
 
 // Invoke the fasta kernel generator for the program starting in [entryUri]
 // TODO(sigmund): update to use the frontend api once fasta is being hit.
 generateKernel(Uri entryUri,
     {bool compileSdk: true, bool strongMode: false}) async {
   // TODO(sigmund): this is here only to compute the input size,
   // we should extract the input size from the frontend instead.
   scanReachableFiles(entryUri);
 
@@ skipping 38 matching lines @@
 /// Report that metric [name] took [time] micro-seconds to process
 /// [inputSize] characters.
 void report(String name, int time) {
   var sb = new StringBuffer();
   var padding = ' ' * (20 - name.length);
   sb.write('$name:$padding $time us, ${time ~/ 1000} ms');
   var invSpeed = (time * 1000 / inputSize).toStringAsFixed(2);
   sb.write(', $invSpeed ns/char');
   print('$sb');
 }