[analysis_server] Use the correct language version for formatting in the LSP server

Fixes #56941

Change-Id: I675e732ceba98ab88904906c8076e805fcc9ca2d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/391663
Commit-Queue: Brian Wilkerson <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>
Reviewed-by: Phil Quitslund <[email protected]>

Author: DanTup

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

@@ -13,10 +13,12 @@ import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/error/listener.dart';
 import 'package:analyzer/source/line_info.dart';
 import 'package:analyzer/source/source.dart';
+import 'package:analyzer/src/dart/analysis/results.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:pub_semver/pub_semver.dart';
 
 /// Checks whether a string contains only characters that are allowed to differ
 /// between unformattedformatted code (such as whitespace, commas, semicolons).
@@ -97,17 +99,20 @@ ErrorOr<List<TextEdit>?> generateEditsForFormatting(
   var effectivePageWidth =
       result.analysisOptions.formatterOptions.pageWidth ?? defaultPageWidth;
 
+  var effectiveLanguageVersion = switch (result.unit.languageVersionToken) {
+    var token? => Version(token.major, token.minor, 0),
+    _ => (result as ParsedUnitResultImpl).fileState.packageLanguageVersion,
+  };
+
   var code = SourceCode(unformattedSource);
   SourceCode formattedResult;
   try {
     // Create a new formatter on every request because it may contain state that
     // affects repeated formats.
     // https://github.com/dart-lang/dart_style/issues/1337
-    var languageVersion =
-        result.unit.declaredElement?.library.languageVersion.effective ??
-            DartFormatter.latestLanguageVersion;
     var formatter = DartFormatter(
-        pageWidth: effectivePageWidth, languageVersion: languageVersion);
+        pageWidth: effectivePageWidth,
+        languageVersion: effectiveLanguageVersion);
     formattedResult = formatter.formatSource(code);
   } on FormatterException {
     // If the document fails to parse, just return no edits to avoid the

pkg/analysis_server/test/lsp/source_edits_test.dart

@@ -21,6 +21,52 @@ void main() {
 
 @reflectiveTest
 class SourceEditsTest extends AbstractSingleUnitTest with LspEditHelpersMixin {
+  Future<void> test_format_version_defaultsToLatest() async {
+    // Latest version should parse and format records.
+    const startContent = '''
+var    a = (1, 2);
+''';
+    const endContent = '''
+var a = (1, 2);
+''';
+    const expectedEdits = r'''
+Delete 1:5-1:8
+''';
+
+    await _assertFormatEdits(startContent, endContent, expectedEdits);
+  }
+
+  Future<void> test_format_version_languageVersionToken() async {
+    // 2.19 will not parse/format records.
+    const content = '''
+// @dart = 2.19
+var    a = (1, 2);
+''';
+
+    await _assertNoFormatEdits(content);
+  }
+
+  Future<void> test_format_version_packageConfig() async {
+    // 2.19 will not parse/format records.
+    writeTestPackageConfig(languageVersion: '2.19');
+    const content = '''
+var    a = (1, 2);
+''';
+
+    await _assertNoFormatEdits(content);
+  }
+
+  Future<void> test_format_version_versionToken_overridesPackageConfig() async {
+    // 2.19 will not parse/format records.
+    writeTestPackageConfig(languageVersion: '3.0');
+    const content = '''
+// @dart = 2.19
+var    a = (1, 2);
+''';
+
+    await _assertNoFormatEdits(content);
+  }
+
   Future<void> test_minimalEdits_comma_delete() async {
     const startContent = '''
 void f(int a,) {}
@@ -572,6 +618,26 @@ void g() {
     );
   }
 
+  /// Assert that generating edits to format [start] match those described
+  /// in [expected] and when applied, result in [end].
+  ///
+  /// Edits will be automatically applied and verified. [expected] is to ensure
+  /// the edits are minimal and we didn't accidentally produces a single edit
+  /// replacing the entire file.
+  Future<void> _assertFormatEdits(
+    String start,
+    String end,
+    String expected, {
+    String? expectedFormatResult,
+    Range? range,
+  }) async {
+    await parseTestCode(start);
+    var edits =
+        generateEditsForFormatting(testParsedResult, range: range).result!;
+    expect(edits.toText().trim(), expected.trim());
+    expect(applyTextEdits(start, edits), expectedFormatResult ?? end);
+  }
+
   /// Assert that computing minimal edits to convert [start] to [end] produces
   /// the set of edits described in [expected].
   ///
@@ -595,6 +661,13 @@ void g() {
     expect(edits.toText().trim(), expected);
     expect(applyTextEdits(start, edits.result), expectedFormatResult ?? end);
   }
+
+  /// Assert that formatting [content] produces no edits.
+  Future<void> _assertNoFormatEdits(String content) async {
+    await parseTestCode(content);
+    var edits = generateEditsForFormatting(testParsedResult).result;
+    expect(edits, isNull);
+  }
 }
 
 /// Helpers for building simple text representations of edits to verify that