[messages] Make a script to move shared diagnostics.

Adds a new file, `move_shared_diagnostics.dart`, which moves entries
from `pkg/front_end/messages.yaml` to a new
`pkg/_fe_analyzer_shared/messages.yaml` files.

Only messages that are actually shared (those with an `index` parameter) are
moved.

This script is in its own CL for easier code review. In a follow-up CL
I will run the script, which will produce several thousand lines of
diffs.

Change-Id: I6a6a6964793135f54e7e2921643e7b8e4451e801
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/448606
Commit-Queue: Paul Berry <[email protected]>
Reviewed-by: Johnni Winther <[email protected]>

Author: stereotype441

pkg/analyzer_utilities/pubspec.yaml

@@ -20,5 +20,7 @@ dependencies:
 
 # Use 'any' constraints here; we get our versions from the DEPS file.
 dev_dependencies:
+  analyzer_plugin: any
   lints: any
+  source_span: any
   test_reflective_loader: any

pkg/analyzer_utilities/tool/messages/move_shared_diagnostics.dart

@@ -0,0 +1,89 @@
+// 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.
+
+/// This is a temporary utility script that moves entries from
+/// `pkg/front_end/messages.yaml` to a new
+/// `pkg/_fe_analyzer_shared/messages.yaml` file.
+///
+/// Only messages that are actually shared (those with an `index` parameter) are
+/// moved.
+library;
+
+import 'dart:io';
+
+import 'package:analyzer_plugin/protocol/protocol_common.dart';
+import 'package:analyzer_testing/package_root.dart' as pkg_root;
+import 'package:analyzer_utilities/messages.dart';
+import 'package:collection/collection.dart';
+import 'package:path/path.dart';
+import 'package:source_span/src/location.dart';
+import 'package:yaml/yaml.dart';
+
+void main() {
+  Map<Uri, _EditAccumulator> editAccumulators = {};
+  var sharedYamlContents = StringBuffer('''
+# Copyright (c) 2017, 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.
+
+# This file contains error messages that are shared between the analyzer and the
+# front end.
+
+# See pkg/front_end/messages.yaml for documentation about this file.
+
+# Currently, the code generation logic uses the presence of an `index` entry to
+# determine whether a given error message should be generated into both the
+# analyzer and the front end, so all error messages in this file should have a
+# non-null `index`.
+# TODO(paulberry): remove the need for the `index` field.
+
+''');
+
+  for (var MapEntry(key: name, value: message) in frontEndMessages.entries) {
+    if (message.index != null) {
+      var node = message.yamlNode!;
+      sharedYamlContents.write('$name:\n  ${node.span.text}');
+      var uri = node.span.sourceUrl!;
+      (editAccumulators[uri] ??= _EditAccumulator(uri)).deleteMessage(node);
+    }
+  }
+  for (var editAccumulator in editAccumulators.values) {
+    editAccumulator.apply();
+  }
+  File(
+    join(pkg_root.packageRoot, '_fe_analyzer_shared', 'messages.yaml'),
+  ).writeAsStringSync(sharedYamlContents.toString());
+}
+
+class _EditAccumulator {
+  final File _file;
+  final Set<int> _nodeOffsetsToDelete = {};
+  late final content = _file.readAsStringSync();
+
+  _EditAccumulator(Uri uri) : _file = File(uri.toFilePath());
+
+  void apply() {
+    if (_nodeOffsetsToDelete.isEmpty) return;
+    var document = loadYamlDocument(content);
+    var edits = <SourceEdit>[];
+    for (var entry in (document.contents as YamlMap).nodes.entries) {
+      if (_nodeOffsetsToDelete.contains(entry.value.span.start.offset)) {
+        var deletionStart = _startOfLine((entry.key as YamlScalar).span.start);
+        var deletionEnd = entry.value.span.end.offset;
+        edits.add(SourceEdit(deletionStart, deletionEnd - deletionStart, ''));
+      }
+    }
+    edits.sortBy((e) => -e.offset);
+    var newContent = SourceEdit.applySequence(content, edits);
+    _file.writeAsStringSync(newContent);
+    _nodeOffsetsToDelete.clear();
+  }
+
+  void deleteMessage(YamlNode node) {
+    _nodeOffsetsToDelete.add(node.span.start.offset);
+  }
+
+  int _startOfLine(SourceLocation start) =>
+      content.lastIndexOf('\n', start.offset) + 1;
+}