Fix running from a subdirectory.

build_runner/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 2.10.3-wip
+
+- Bug fix: fix crash when you run `dart run build_runner build` in a
+  subdirectory of a package.
+
 ## 2.10.2
 
 - Bug fix: fix issue with webdev failing due to a modification during a build.

build_runner/lib/src/build_plan/package_graph.dart

@@ -12,6 +12,7 @@ import 'package:yaml/yaml.dart';
 
 import '../constants.dart';
 import '../io/asset_path_provider.dart';
+import '../logging/build_log.dart';
 
 /// The SDK package, we filter this to the core libs and dev compiler
 /// resources.
@@ -67,6 +68,8 @@ class PackageGraph implements AssetPathProvider {
   /// Creates a [PackageGraph] for the package whose top level directory lives
   /// at [packagePath] (no trailing slash).
   static Future<PackageGraph> forPath(String packagePath) async {
+    buildLog.debug('forPath $packagePath');
+
     /// Read in the pubspec file and parse it as yaml.
     final pubspec = File(p.join(packagePath, 'pubspec.yaml'));
     if (!pubspec.existsSync()) {

build_runner/lib/src/build_runner.dart

@@ -67,7 +67,17 @@ class BuildRunner {
 
     // Option parsing depends on the package name in `pubspec.yaml`.
     // Fortunately, `dart run build_runner` checks that `pubspec.yaml` is
-    // present and valid, so there must be a `name`.
+    // present in the current or a parent directory, and that it's valid, so
+    // there must be a `name`.
+    //
+    // Start by changing the current directory to the package root.
+    while (!File(p.join(Directory.current.path, 'pubspec.yaml')).existsSync()) {
+      final parent = Directory.current.parent;
+      if (parent.path == Directory.current.path) {
+        throw StateError('Missing pubspec.yaml.');
+      }
+      Directory.current = parent;
+    }
     final rootPackage =
         (loadYaml(File(p.join(p.current, 'pubspec.yaml')).readAsStringSync())
                 as YamlMap)['name']!

build_runner/pubspec.yaml

@@ -1,5 +1,5 @@
 name: build_runner
-version: 2.10.2
+version: 2.10.3-wip
 description: A build system for Dart code generation and modular compilation.
 repository: https://github.com/dart-lang/build/tree/master/build_runner
 resolution: workspace

build_runner/test/integration_tests/build_command_packages_and_paths_test.dart

@@ -0,0 +1,33 @@
+// Copyright (c) 2025, 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.
+
+@Tags(['integration4'])
+library;
+
+import 'package:test/test.dart';
+
+import '../common/common.dart';
+
+void main() async {
+  test('build command packages and paths', () async {
+    final pubspecs = await Pubspecs.load();
+    final tester = BuildRunnerTester(pubspecs);
+
+    tester.writeFixturePackage(
+      FixturePackages.copyBuilder(buildToCache: true, applyToAllPackages: true),
+    );
+    tester.writePackage(
+      name: 'root_pkg',
+      dependencies: ['build_runner'],
+      pathDependencies: ['builder_pkg'],
+      files: {'lib/a.txt': 'a'},
+    );
+
+    // Runs in a subdirectory of the package.
+    await tester.run('root_pkg/lib', 'dart run build_runner build');
+    expect(tester.readFileTree('root_pkg/.dart_tool/build/generated'), {
+      'root_pkg/lib/a.txt.copy': 'a',
+    });
+  });
+}

build_test/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 3.5.3-wip
+
+- Use `build_runner` 2.10.3.
+
 ## 3.5.2
 
 - Use `build_runner` 2.10.2.

build_test/pubspec.yaml

@@ -1,6 +1,6 @@
 name: build_test
 description: Utilities for writing unit tests of Builders.
-version: 3.5.2
+version: 3.5.3-wip
 repository: https://github.com/dart-lang/build/tree/master/build_test
 resolution: workspace
 
@@ -10,7 +10,7 @@ environment:
 dependencies:
   build: ^4.0.0
   build_config: ^1.0.0
-  build_runner: '2.10.2'
+  build_runner: '2.10.3-wip'
   built_collection: ^5.1.1
   crypto: ^3.0.0
   glob: ^2.0.0