Run dartfmt on generated file.

pkg/front_end/tool/_fasta/generate_messages.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.
 
 import 'dart:io';
 
 import 'dart:isolate';
 
 import 'package:yaml/yaml.dart' show loadYaml;
 
 import 'package:front_end/src/fasta/parser/error_kind.dart' show ErrorKind;
 
+import 'package:dart_style/dart_style.dart' show DartFormatter;

[Siggi Cherem (dart-lang), 2017/07/12 20:06:51]

note: this introduced a circular dependency on fasta_codes_generated.dart
(package:dart_style imports  package:analyzer which in turn imports
package:front_end including the generated file.)

As a result, if the file is missing or broken this script fails to run. I run
into this because of a merge conflict and wanted to regenerate the file without
bothering to revert it to a valid Dart file.

I suggest we run the formatter as a separate process instead.

[ahe, 2017/07/13 00:26:54]

We could do that, but then we have to use the slightly outdated version that's
stored somewhere in tools/. That's also a source of confusion.

What I've been doing is this:

git checkout current_branch_name --
pkg/front_end/lib/src/fasta/fasta_codes_generated.dart

Is that an acceptable workaround for you?

+
 main(List<String> arguments) async {
   var port = new ReceivePort();
   Uri messagesFile = Platform.script.resolve("../../messages.yaml");
   Map yaml = loadYaml(await new File.fromUri(messagesFile).readAsStringSync());
   Set<String> names =
       new Set<String>.from(yaml.keys.map((String s) => "ErrorKind.$s"));
   Set<String> kinds =
       new Set<String>.from(ErrorKind.values.map((kind) => "$kind"));
   Set<String> difference = kinds.difference(names);
   if (difference.isNotEmpty) {
@@ skipping 22 matching lines @@
 """);
 
   yaml.forEach((String name, description) {
     while (description is String) {
       description = yaml[description];
     }
     Map map = description;
     sb.writeln(compileTemplate(name, map['template'], map['tip']));
   });
 
+  String dartfmtedText = new DartFormatter().format("$sb");
+
   Uri problemsFile = await Isolate.resolvePackageUri(
       Uri.parse('package:front_end/src/fasta/problems.dart'));
-  await new File.fromUri(problemsFile).writeAsString("$sb", flush: true);
+  await new File.fromUri(problemsFile)
+      .writeAsString(dartfmtedText, flush: true);
   port.close();
 }
 
 final RegExp placeholderPattern = new RegExp("#[a-zA-Z0-9_]+");
 
 String compileTemplate(String name, String template, String tip) {
   var parameters = new Set<String>();
   var conversions = new Set<String>();
   var arguments = new Set<String>();
   for (Match match in placeholderPattern.allMatches("$template${tip ?? ''}")) {
@@ skipping 45 matching lines @@
   ${interpolate('message', template)}
   ${interpolate('tip', tip)}
     'code': ErrorKind.$name,
     'arguments': {
       ${arguments.join('\n      ')}
     },
   };
 }
 """;
 }