[messages] Move LocatedError to its own library.

This will make it possible to re-use in other parts of the codebase
without necessarily having to import logic related to messages.

Change-Id: I6a6a6964ad824e13f45ef8da6fc50f4a120ea74a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/462701
Commit-Queue: Paul Berry <paulberry@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>

pkg/analyzer/tool/messages/generate.dart

@@ -20,6 +20,7 @@ import 'dart:convert';
 
 import 'package:analyzer_testing/package_root.dart' as pkg_root;
 import 'package:analyzer_utilities/analyzer_messages.dart';
+import 'package:analyzer_utilities/located_error.dart';
 import 'package:analyzer_utilities/messages.dart';
 import 'package:analyzer_utilities/tools.dart';
 

pkg/analyzer_utilities/lib/analyzer_messages.dart

@@ -11,6 +11,7 @@ import 'dart:io';
 import 'package:analyzer_testing/package_root.dart' as pkg_root;
 import 'package:analyzer_utilities/analyzer_message_constant_style.dart';
 import 'package:analyzer_utilities/extensions/string.dart';
+import 'package:analyzer_utilities/located_error.dart';
 import 'package:analyzer_utilities/messages.dart';
 import 'package:analyzer_utilities/tools.dart';
 import 'package:path/path.dart';

pkg/analyzer_utilities/lib/located_error.dart

@@ -0,0 +1,44 @@
+// 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:source_span/source_span.dart';
+
+/// An error with an associated source span.
+class LocatedError {
+  final SourceSpan span;
+  final String message;
+
+  LocatedError(this.message, {required this.span});
+
+  @override
+  String toString() => '${span.location}: $message';
+
+  /// Executes [callback], converting any exceptions it generates to a
+  /// [LocatedError] that points to [node].
+  static T wrap<T>(T Function() callback, {required SourceSpan span}) {
+    try {
+      return callback();
+    } catch (error, stackTrace) {
+      if (error is! LocatedError) {
+        Error.throwWithStackTrace(
+          LocatedError(error.toString(), span: span),
+          stackTrace,
+        );
+      } else {
+        rethrow;
+      }
+    }
+  }
+}
+
+extension SourceSpanLocation on SourceSpan {
+  /// A string suitable for identifying this span in the source YAML file.
+  String get location {
+    var path = start.sourceUrl?.toFilePath() ?? '<unknown>';
+    // Convert line/column to 1-based because that's what most editors expect
+    var line = start.line + 1;
+    var column = start.column + 1;
+    return '$path:$line:$column';
+  }
+}

pkg/analyzer_utilities/lib/messages.dart

@@ -11,6 +11,7 @@ import 'dart:io';
 import 'package:analyzer_testing/package_root.dart' as pkg_root;
 import 'package:analyzer_utilities/analyzer_messages.dart';
 import 'package:analyzer_utilities/extensions/string.dart';
+import 'package:analyzer_utilities/located_error.dart';
 import 'package:collection/collection.dart';
 import 'package:path/path.dart';
 import 'package:source_span/source_span.dart';
@@ -554,34 +555,6 @@ class LabelerConversion implements Conversion {
   }) => 'labeler.$methodName($name)';
 }
 
-/// An error with an associated source span.
-class LocatedError {
-  final SourceSpan span;
-  final String message;
-
-  LocatedError(this.message, {required this.span});
-
-  @override
-  String toString() => '${span.location}: $message';
-
-  /// Executes [callback], converting any exceptions it generates to a
-  /// [LocatedError] that points to [node].
-  static T wrap<T>(T Function() callback, {required SourceSpan span}) {
-    try {
-      return callback();
-    } catch (error, stackTrace) {
-      if (error is! LocatedError) {
-        Error.throwWithStackTrace(
-          LocatedError(error.toString(), span: span),
-          stackTrace,
-        );
-      } else {
-        rethrow;
-      }
-    }
-  }
-}
-
 /// In-memory representation of diagnostic information obtained from either the
 /// analyzer or the front end's `messages.yaml` file.  This class contains the
 /// common functionality supported by both formats.
@@ -1109,14 +1082,3 @@ class _DuplicateChecker<Code> {
     }
   }
 }
-
-extension SourceSpanLocation on SourceSpan {
-  /// A string suitable for identifying this span in the source YAML file.
-  String get location {
-    var path = start.sourceUrl?.toFilePath() ?? '<unknown>';
-    // Convert line/column to 1-based because that's what most editors expect
-    var line = start.line + 1;
-    var column = start.column + 1;
-    return '$path:$line:$column';
-  }
-}

pkg/front_end/tool/generate_messages_lib.dart

@@ -6,6 +6,7 @@
 library;
 
 import 'package:analyzer_utilities/extensions/string.dart';
+import 'package:analyzer_utilities/located_error.dart';
 import 'package:analyzer_utilities/messages.dart';
 
 Uri computeSharedGeneratedFile(Uri repoDir) {