[VM/Debugger] Ignore optimized out variables when building scope in ActivationFrame::BuildParameters

TEST=pkg/vm_service/test/evaluate_optimized_out_variable_test.dart

Issue: https://github.com/dart-lang/sdk/issues/53996
Change-Id: I5e6f0b2c02455af73c2108e6996039c95d3f1f31
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/347940
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Commit-Queue: Derek Xu <derekx@google.com>

pkg/vm_service/test/evaluate_optimized_out_variable_test.dart

@@ -0,0 +1,85 @@
+// Copyright (c) 2024, 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.
+
+// Regression test for https://dartbug.com/53996.
+
+import 'package:test/test.dart';
+import 'package:vm_service/vm_service.dart';
+
+import 'common/service_test_common.dart';
+import 'common/test_helper.dart';
+
+// AUTOGENERATED START
+//
+// Update these constants by running:
+//
+// dart pkg/vm_service/test/update_line_numbers.dart <test.dart>
+//
+const LINE_A = 27;
+// AUTOGENERATED END
+
+bool debug = false;
+
+bool bar(int i) {
+  if (i == 2) {
+    if (debug) {
+      print('woke up'); // LINE_A
+    }
+    return true;
+  }
+  return false;
+}
+
+void foo() {
+  final List<int> data = [1, 2, 3];
+  for (int i in data) {
+    if (bar(i)) {
+      break;
+    }
+  }
+}
+
+void testeeMain() {
+  // Trigger optimization of [foo].
+  for (int i = 0; i < 20; i++) {
+    foo();
+  }
+  debug = true;
+  foo();
+}
+
+final tests = <IsolateTest>[
+  hasPausedAtStart,
+  setBreakpointAtLine(LINE_A),
+  resumeIsolate,
+  hasStoppedAtBreakpoint,
+  stoppedAtLine(LINE_A),
+  (VmService service, IsolateRef isolateRef) async {
+    final isolateId = isolateRef.id!;
+    try {
+      await service.evaluateInFrame(
+        isolateId,
+        1,
+        'data.length',
+      );
+      fail('Expected evaluateInFrame to throw an RPCError');
+    } on RPCError catch (e) {
+      expect(e.code, RPCErrorKind.kExpressionCompilationError.code);
+      expect(e.message, 'Expression compilation error');
+    }
+  },
+];
+
+void main([args = const <String>[]]) => runIsolateTests(
+      args,
+      tests,
+      'evaluate_optimized_out_variable_test.dart',
+      testeeConcurrent: testeeMain,
+      pauseOnStart: true,
+      extraArgs: const [
+        '--deterministic',
+        '--prune-dead-locals',
+        '--optimization-counter-threshold=10',
+      ],
+    );

runtime/vm/debugger.cc

@@ -1111,7 +1111,8 @@ TypeArgumentsPtr ActivationFrame::BuildParameters(
       type_arguments_available = true;
       type_arguments ^= value.ptr();
     } else if (!name.Equals(Symbols::This()) &&
-               !IsSyntheticVariableName(name)) {
+               !IsSyntheticVariableName(name) &&
+               value.ptr() != Object::optimized_out().ptr()) {
       if (IsPrivateVariableName(name)) {
         name = Symbols::New(Thread::Current(), String::ScrubName(name));
       }

runtime/vm/object.cc

@@ -4853,6 +4853,11 @@ static ObjectPtr EvaluateCompiledExpressionHelper(
     const TypeArguments& type_arguments) {
   // type_arguments is null if all type arguments are dynamic.
   if (type_definitions.Length() == 0 || type_arguments.IsNull()) {
+#if defined(DEBUG)
+    for (intptr_t i = 0; i < arguments.Length(); ++i) {
+      ASSERT(arguments.At(i) != Object::optimized_out().ptr());
+    }
+#endif  // defined(DEBUG)
     return DartEntry::InvokeFunction(eval_function, arguments);
   }
 
@@ -4863,6 +4868,7 @@ static ObjectPtr EvaluateCompiledExpressionHelper(
   Object& arg = Object::Handle(zone);
   for (intptr_t i = 0; i < arguments.Length(); ++i) {
     arg = arguments.At(i);
+    ASSERT(arg.ptr() != Object::optimized_out().ptr());
     real_arguments.SetAt(i + 1, arg);
   }