[model] Add stack trace helpers

Change-Id: I85088990e17862a6837d0a5ad03386bbf898c7f6
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/412282
Reviewed-by: Paul Berry <[email protected]>
Commit-Queue: Johnni Winther <[email protected]>
Reviewed-by: Jens Johansen <[email protected]>

Author: johnniwinther

pkg/_fe_analyzer_shared/lib/src/debug_helpers/stack_trace.dart

@@ -0,0 +1,121 @@
+// 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 'dart:collection';
+
+/// Debug helper that tracks updates to a property.
+///
+/// Use this in debugging to record stack traces for when a property is updated.
+/// For instance to track the field `bar` change
+///
+///     class Foo {
+///       Bar bar;
+///       Foo(this.bar);
+///     }
+///
+/// to
+///
+///     class Foo {
+///       StackTraceValue<Bar> _bar;
+///       Foo(Bar bar) : _bar = StackTraceValue(bar);
+///       Bar get bar => _bar.value;
+///       void set bar(Bar value) {
+///         _bar.value = value;
+///       }
+///     }
+///
+class StackTraceValue<T> {
+  T _value;
+  List<(T, StackTrace)> _stackTraces = [];
+
+  StackTraceValue(this._value) {
+    _stackTraces.add((_value, StackTrace.current));
+  }
+
+  T get value => _value;
+
+  void set value(T v) {
+    _stackTraces.add((_value, StackTrace.current));
+    _value = v;
+  }
+}
+
+/// Debug helper that tracks updates to a list.
+///
+/// Use this in debugging to record stack traces for when a list is updated.
+/// For instance to track the list `bars` change
+///
+///     class Foo {
+///       List<Bar> bars;
+///       Foo(this.bars);
+///     }
+///
+/// to
+///
+///     class Foo {
+///       StackTraceList<Bar> _bars;
+///       Foo(List<Bar> bars) : _bars = StackTraceList(bars);
+///       List<Bar> get bars => _bars;
+///       void set bars(List<Bar> value) {
+///         _bars.value = value;
+///       }
+///     }
+///
+class StackTraceList<T> with ListMixin<T> implements List<T> {
+  List<T> _list;
+  List<(String, Object?, StackTrace)> _stackTraces = [];
+
+  StackTraceList(this._list) {
+    _stackTraces.add(('init', _list, StackTrace.current));
+  }
+
+  List<T> get value => _list;
+
+  void set value(List<T> v) {
+    _stackTraces.add(('value', v, StackTrace.current));
+    _list = v;
+  }
+
+  @override
+  void add(T element) {
+    _stackTraces.add(('add', element, StackTrace.current));
+    _list.add(element);
+  }
+
+  @override
+  void addAll(Iterable<T> iterable) {
+    _stackTraces.add(('add', iterable.toList(), StackTrace.current));
+    _list.addAll(iterable);
+  }
+
+  @override
+  void clear() {
+    _stackTraces.add(('clear', null, StackTrace.current));
+    _list.clear();
+  }
+
+  @override
+  int get length => _list.length;
+
+  @override
+  void set length(int newLength) {
+    _stackTraces.add(('length=', newLength, StackTrace.current));
+    _list.length = newLength;
+  }
+
+  @override
+  T operator [](int index) => _list[index];
+
+  @override
+  void operator []=(int index, T value) {
+    _stackTraces.add(('[$index]=', value, StackTrace.current));
+    _list[index] = value;
+  }
+
+  @override
+  bool remove(Object? element) {
+    _stackTraces.add(('remove', element, StackTrace.current));
+    return _list.remove(element);
+  }
+}

pkg/front_end/test/spell_checking_list_code.txt

@@ -133,6 +133,7 @@ bail
 balance
 bang
 bar
+bars
 basename
 basically
 basis