[analysis_server] Wire up analysis_options formatter/trailing_commas to formatter

+ validation + code completion

Fixes #60599

Change-Id: I383c888756e29e091c7abf8d4b8df66387714e31
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/424440
Reviewed-by: Konstantin Shcheglov <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Brian Wilkerson <[email protected]>

Author: DanTup

pkg/analysis_server/lib/src/handler/legacy/edit_format.dart

@@ -7,11 +7,10 @@ import 'dart:async';
 import 'package:analysis_server/protocol/protocol.dart';
 import 'package:analysis_server/protocol/protocol_generated.dart';
 import 'package:analysis_server/src/handler/legacy/legacy_handler.dart';
+import 'package:analysis_server/src/utilities/extensions/formatter_options.dart';
 import 'package:analyzer/dart/analysis/results.dart';
 import 'package:analyzer_plugin/protocol/protocol_common.dart';
-import 'package:dart_style/src/dart_formatter.dart';
-import 'package:dart_style/src/exceptions.dart';
-import 'package:dart_style/src/source_code.dart';
+import 'package:dart_style/dart_style.dart' hide TrailingCommas;
 
 /// The handler for the `edit.format` request.
 class EditFormatHandler extends LegacyHandler {
@@ -55,11 +54,13 @@ class EditFormatHandler extends LegacyHandler {
       selectionLength: length,
     );
 
-    var effectivePageWidth =
-        unit.analysisOptions.formatterOptions.pageWidth ?? params.lineLength;
+    var formatterOptions = unit.analysisOptions.formatterOptions;
+    var effectivePageWidth = formatterOptions.pageWidth ?? params.lineLength;
+    var effectiveTrailingCommas = formatterOptions.dartStyleTrailingCommas;
     var effectiveLanguageVersion = unit.unit.languageVersion.effective;
     var formatter = DartFormatter(
       pageWidth: effectivePageWidth,
+      trailingCommas: effectiveTrailingCommas,
       languageVersion: effectiveLanguageVersion,
     );
     SourceCode formattedResult;

pkg/analysis_server/lib/src/lsp/source_edits.dart

@@ -8,6 +8,7 @@ import 'package:analysis_server/src/lsp/mapping.dart';
 import 'package:analysis_server/src/protocol_server.dart'
     as server
     show SourceEdit;
+import 'package:analysis_server/src/utilities/extensions/formatter_options.dart';
 import 'package:analyzer/dart/analysis/features.dart';
 import 'package:analyzer/dart/analysis/results.dart';
 import 'package:analyzer/dart/ast/token.dart';
@@ -17,7 +18,7 @@ import 'package:analyzer/source/source.dart';
 import 'package:analyzer/src/dart/scanner/reader.dart';
 import 'package:analyzer/src/dart/scanner/scanner.dart';
 import 'package:analyzer_plugin/protocol/protocol_common.dart' as plugin;
-import 'package:dart_style/dart_style.dart';
+import 'package:dart_style/dart_style.dart' hide TrailingCommas;
 
 /// Checks whether a string contains only characters that are allowed to differ
 /// between unformattedformatted code (such as whitespace, commas, semicolons).
@@ -107,10 +108,11 @@ ErrorOr<List<TextEdit>?> generateEditsForFormatting(
 }) {
   var unformattedSource = result.content;
 
+  var formatterOptions = result.analysisOptions.formatterOptions;
   // The analysis options page width always takes priority over the default from
   // the LSP configuration.
-  var effectivePageWidth =
-      result.analysisOptions.formatterOptions.pageWidth ?? defaultPageWidth;
+  var effectivePageWidth = formatterOptions.pageWidth ?? defaultPageWidth;
+  var effectiveTrailingCommas = formatterOptions.dartStyleTrailingCommas;
   var effectiveLanguageVersion = result.unit.languageVersion.effective;
 
   var code = SourceCode(unformattedSource);
@@ -121,6 +123,7 @@ ErrorOr<List<TextEdit>?> generateEditsForFormatting(
     // https://github.com/dart-lang/dart_style/issues/1337
     var formatter = DartFormatter(
       pageWidth: effectivePageWidth,
+      trailingCommas: effectiveTrailingCommas,
       languageVersion: effectiveLanguageVersion,
     );
     formattedResult = formatter.formatSource(code);

pkg/analysis_server/lib/src/services/completion/yaml/analysis_options_generator.dart

@@ -5,6 +5,7 @@
 import 'package:analysis_server/src/protocol_server.dart';
 import 'package:analysis_server/src/services/completion/yaml/producer.dart';
 import 'package:analysis_server/src/services/completion/yaml/yaml_completion_generator.dart';
+import 'package:analyzer/dart/analysis/formatter_options.dart';
 import 'package:analyzer/error/error.dart';
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/src/dart/analysis/experiments.dart';
@@ -41,6 +42,9 @@ class AnalysisOptionsGenerator extends YamlCompletionGenerator {
     }),
     AnalysisOptionsFile.formatter: MapProducer({
       AnalysisOptionsFile.pageWidth: EmptyProducer(),
+      AnalysisOptionsFile.trailingCommas: EnumProducer(
+        TrailingCommas.values.map((item) => item.name).toList(),
+      ),
     }),
     // TODO(brianwilkerson): Create a producer to produce `package:` URIs.
     AnalysisOptionsFile.include: EmptyProducer(),

pkg/analysis_server/lib/src/utilities/extensions/formatter_options.dart

@@ -0,0 +1,21 @@
+// 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.
+
+import 'package:analyzer/dart/analysis/formatter_options.dart'
+    hide TrailingCommas;
+import 'package:collection/collection.dart';
+import 'package:dart_style/dart_style.dart';
+
+extension FormatterOptionsExtension on FormatterOptions {
+  /// The trailing commas preference converted from the analyzer enum to the
+  /// dart_style enum.
+  TrailingCommas? get dartStyleTrailingCommas {
+    return switch (trailingCommas) {
+      var trailingCommas? => TrailingCommas.values.firstWhereOrNull(
+        (item) => item.name == trailingCommas.name,
+      ),
+      null => null,
+    };
+  }
+}

pkg/analysis_server/test/domain_completion_test.dart

@@ -2038,6 +2038,32 @@ suggestions
 ''');
   }
 
+  Future<void> test_yaml_analysisOptions_formatter() async {
+    await _configureWithWorkspaceRoot();
+
+    var path = convertPath('$testPackageRootPath/analysis_options.yaml');
+    var response = await _getCodeSuggestions(
+      path: path,
+      content: '''
+formatter:
+  ^
+''',
+    );
+
+    printerConfiguration
+      ..filter = ((_) => true)
+      ..withIsNotImported = false
+      ..withLibraryUri = false;
+
+    assertResponseText(response, r'''
+suggestions
+  |page_width: |
+    kind: identifier
+  |trailing_commas: |
+    kind: identifier
+''');
+  }
+
   Future<void> test_yaml_analysisOptions_root() async {
     await _configureWithWorkspaceRoot();
 

pkg/analysis_server/test/edit/format_test.dart

@@ -174,6 +174,71 @@ void f() {
     expect(formatResult.selectionLength, equals(3));
   }
 
+  Future<void> test_format_trailingCommas_automate() async {
+    writeTestPackageAnalysisOptionsFile(r'''
+formatter:
+  trailing_commas: automate
+''');
+    var content = '''
+enum A {
+  a,
+  b,
+}
+''';
+    addTestFile(content);
+    await waitForTasksFinished();
+    var formatResult = await _formatAt(0, 3);
+
+    expect(
+      formatResult.edits.single.replacement,
+      equals('''
+enum A { a, b }
+'''),
+    );
+  }
+
+  Future<void> test_format_trailingCommas_preserve() async {
+    writeTestPackageAnalysisOptionsFile(r'''
+formatter:
+  trailing_commas: preserve
+''');
+    var content = '''
+enum A { a, b, }
+''';
+    addTestFile(content);
+    await waitForTasksFinished();
+    var formatResult = await _formatAt(0, 3);
+
+    expect(
+      formatResult.edits.single.replacement,
+      equals('''
+enum A {
+  a,
+  b,
+}
+'''),
+    );
+  }
+
+  Future<void> test_format_trailingCommas_unspecified() async {
+    var content = '''
+enum A {
+  a,
+  b,
+}
+''';
+    addTestFile(content);
+    await waitForTasksFinished();
+    var formatResult = await _formatAt(0, 3);
+
+    expect(
+      formatResult.edits.single.replacement,
+      equals('''
+enum A { a, b }
+'''),
+    );
+  }
+
   /// Verify version 2.19 is passed to the formatter so it will not produce any
   /// edits for code containing records (since it fails to parse).
   Future<void> test_format_version_2_19() async {

pkg/analysis_server/test/lsp/format_test.dart

@@ -859,6 +859,73 @@ void f() {
     await expectFormattedContents(mainFileUri, contents, expected);
   }
 
+  Future<void> test_trailingCommas_automate() async {
+    const optionsContent = '''
+formatter:
+  trailing_commas: automate
+''';
+    const initialContent = '''
+enum A {
+  a,
+  b,
+}
+''';
+    const expectedContent = '''
+enum A { a, b }
+''';
+
+    newFile(analysisOptionsPath, optionsContent);
+    newFile(mainFilePath, initialContent);
+    await initialize();
+
+    // Ignore trailing newlines when checking for wrapping.
+    var formatted = await formatContents(mainFileUri, initialContent);
+    expect(formatted.trim(), expectedContent.trim());
+  }
+
+  Future<void> test_trailingCommas_preserve() async {
+    const optionsContent = '''
+formatter:
+  trailing_commas: preserve
+''';
+    const initialContent = '''
+enum A { a, b, }
+''';
+    const expectedContent = '''
+enum A {
+  a,
+  b,
+}
+''';
+
+    newFile(analysisOptionsPath, optionsContent);
+    newFile(mainFilePath, initialContent);
+    await initialize();
+
+    // Ignore trailing newlines when checking for wrapping.
+    var formatted = await formatContents(mainFileUri, initialContent);
+    expect(formatted.trim(), expectedContent.trim());
+  }
+
+  Future<void> test_trailingCommas_unspecified() async {
+    const initialContent = '''
+enum A {
+  a,
+  b,
+}
+''';
+    const expectedContent = '''
+enum A { a, b }
+''';
+
+    newFile(mainFilePath, initialContent);
+    await initialize();
+
+    // Ignore trailing newlines when checking for wrapping.
+    var formatted = await formatContents(mainFileUri, initialContent);
+    expect(formatted.trim(), expectedContent.trim());
+  }
+
   Future<void> test_unopenFile() async {
     const contents = '''
     void f  ()

pkg/analysis_server/test/src/services/completion/yaml/analysis_options_generator_test.dart

@@ -161,6 +161,16 @@ formatter:
   ^
 ''');
     assertSuggestion('${AnalysisOptionsFile.pageWidth}: ');
+    assertSuggestion('${AnalysisOptionsFile.trailingCommas}: ');
+  }
+
+  void test_formatter_trailingCommas() {
+    getCompletions('''
+formatter:
+  trailing_commas: ^
+''');
+    assertSuggestion('automate');
+    assertSuggestion('preserve');
   }
 
   void test_linter() {

pkg/analyzer/api.txt

@@ -141,8 +141,13 @@ package:analyzer/dart/analysis/features.dart:
     values (static getter: List<FeatureStatus>)
 package:analyzer/dart/analysis/formatter_options.dart:
   FormatterOptions (class extends Object):
-    new (constructor: FormatterOptions Function({int? pageWidth}))
+    new (constructor: FormatterOptions Function({int? pageWidth, TrailingCommas? trailingCommas}))
     pageWidth (getter: int?)
+    trailingCommas (getter: TrailingCommas?)
+  TrailingCommas (enum):
+    automate (static getter: TrailingCommas)
+    preserve (static getter: TrailingCommas)
+    values (static getter: List<TrailingCommas>)
 package:analyzer/dart/analysis/results.dart:
   AnalysisResult (class extends Object):
     new (constructor: AnalysisResult Function())

pkg/analyzer/lib/dart/analysis/formatter_options.dart

@@ -8,5 +8,11 @@ final class FormatterOptions {
   /// The width configured for where the formatter should wrap code.
   final int? pageWidth;
 
-  FormatterOptions({this.pageWidth});
+  /// How trailing commas in various constructs should affect formatting.
+  final TrailingCommas? trailingCommas;
+
+  FormatterOptions({this.pageWidth, this.trailingCommas});
 }
+
+/// How trailing commas in various constructs should affect formatting.
+enum TrailingCommas { automate, preserve }