add a warning if a build.yml file is found in the doctor command (#3616)

Author: jakemac53

build_runner/CHANGELOG.md

@@ -1,7 +1,9 @@
-## 2.4.7-wip
+## 2.4.7
 
 - Fix broken link in README.md.
 - Bump the min sdk to 3.0.0.
+- Add a warning to the `doctor` command if a `build.yml` file is found (instead
+  of a `build.yaml` file).
 
 ## 2.4.6
 

build_runner/lib/src/entrypoint/doctor.dart

@@ -3,6 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:async';
+import 'dart:io';
 
 import 'package:build/build.dart';
 import 'package:build_config/build_config.dart';
@@ -11,6 +12,7 @@ import 'package:build_runner_core/build_runner_core.dart';
 import 'package:build_runner_core/src/generate/phase.dart';
 import 'package:io/io.dart';
 import 'package:logging/logging.dart';
+import 'package:path/path.dart' as p;
 
 import '../logging/std_io_logging.dart';
 import '../package_graph/build_config_overrides.dart';
@@ -40,6 +42,14 @@ class DoctorCommand extends BuildRunnerCommand {
       isOk = isOk && builderOk;
     }
 
+    if (File(p.join(p.current, 'build.yml')).existsSync() &&
+        !File(p.join(p.current, 'build.yaml')).existsSync()) {
+      logger.warning(
+          'Found a `build.yml` file but no `build.yaml` file, rename it with '
+          'the `.yaml` extension for it to take effect.');
+      isOk = false;
+    }
+
     if (isOk) {
       logger.info('No problems found!\n');
     }

build_runner/pubspec.yaml

@@ -1,5 +1,5 @@
 name: build_runner
-version: 2.4.7-wip
+version: 2.4.7
 description: A build system for Dart code generation and modular compilation.
 repository: https://github.com/dart-lang/build/tree/master/build_runner