[vm/shared] Enforce pragma('vm:shared') annotations for captured local vars.

Fixes https://github.com/dart-lang/sdk/issues/61287
TEST=ffi/isolate_group_bound_captured_local_test

Change-Id: I9dc1e8aaf9e99d8ec9ad730cf1cd89ae3b4ed148
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/444923
Commit-Queue: Alexander Aprelev <aam@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>

runtime/vm/ffi_callback_metadata.cc

@@ -398,6 +398,16 @@ void FfiCallbackMetadata::EnsureOnlyTriviallyImmutableValuesInClosure(
     for (intptr_t i = 0; i < context.num_variables(); i++) {
       ValidateTriviallyImmutabilityOfAnObject(zone, &obj, context.At(i));
     }
+
+    if (!function.does_close_over_only_final_and_shared_vars()) {
+      const String& error = String::Handle(
+          zone,
+          String::New(
+              "Only final and 'vm:shared' variables can be captured by isolate "
+              "group callbacks."));
+      Exceptions::ThrowArgumentError(error);
+      UNREACHABLE();
+    }
   }
 }
 

runtime/vm/object.cc

@@ -8586,6 +8586,27 @@ void Function::set_awaiter_link(Function::AwaiterLink link) const {
   UNREACHABLE();
 }
 
+bool Function::does_close_over_only_final_and_shared_vars() const {
+  if (IsClosureFunction()) {
+    const Object& obj = Object::Handle(untag()->data());
+    ASSERT(!obj.IsNull());
+    return ClosureData::Cast(obj).does_close_over_only_final_and_shared_vars();
+  }
+  UNREACHABLE();
+}
+
+void Function::set_does_close_over_only_final_and_shared_vars(
+    bool value) const {
+  if (IsClosureFunction()) {
+    const Object& obj = Object::Handle(untag()->data());
+    ASSERT(!obj.IsNull());
+    ClosureData::Cast(obj).set_does_close_over_only_final_and_shared_vars(
+        value);
+    return;
+  }
+  UNREACHABLE();
+}
+
 ClosurePtr Function::implicit_static_closure() const {
   if (IsImplicitStaticClosureFunction()) {
     const Object& obj = Object::Handle(untag()->data());
@@ -12128,6 +12149,19 @@ void ClosureData::set_awaiter_link(Function::AwaiterLink link) const {
       link.index);
 }
 
+bool ClosureData::does_close_over_only_final_and_shared_vars() const {
+  return untag()
+      ->packed_fields_
+      .Read<UntaggedClosureData::DoesCloseOverOnlySharedFields>();
+}
+
+void ClosureData::set_does_close_over_only_final_and_shared_vars(
+    bool value) const {
+  untag()
+      ->packed_fields_
+      .Update<UntaggedClosureData::DoesCloseOverOnlySharedFields>(value);
+}
+
 ClosureDataPtr ClosureData::New() {
   ASSERT(Object::closure_data_class() != Class::null());
   return Object::Allocate<ClosureData>(Heap::kOld);

runtime/vm/object.h

@@ -3302,6 +3302,9 @@ class Function : public Object {
            (awaiter_link().depth != UntaggedClosureData::kNoAwaiterLinkDepth);
   }
 
+  void set_does_close_over_only_final_and_shared_vars(bool value) const;
+  bool does_close_over_only_final_and_shared_vars() const;
+
   // Enclosing function of this local function.
   FunctionPtr parent_function() const;
 
@@ -4393,6 +4396,9 @@ class ClosureData : public Object {
   Function::AwaiterLink awaiter_link() const;
   void set_awaiter_link(Function::AwaiterLink link) const;
 
+  bool does_close_over_only_final_and_shared_vars() const;
+  void set_does_close_over_only_final_and_shared_vars(bool value) const;
+
   // Enclosing function of this local function.
   PRECOMPILER_WSR_FIELD_DECLARATION(Function, parent_function)
 

runtime/vm/raw_object.h

@@ -1521,7 +1521,10 @@ class UntaggedClosureData : public UntaggedObject {
   using PackedAwaiterLinkIndex = BitField<decltype(packed_fields_),
                                           uint8_t,
                                           PackedAwaiterLinkDepth::kNextBit>;
-
+  using DoesCloseOverOnlySharedFields =
+      BitField<decltype(packed_fields_),
+               bool,
+               PackedAwaiterLinkIndex::kNextBit>;
   friend class Function;
   friend class UnitDeserializationRoots;
 };
@@ -2470,7 +2473,8 @@ class UntaggedContext : public UntaggedObject {
   V(Late)                                                                      \
   V(Nullable)                                                                  \
   V(Invisible)                                                                 \
-  V(AwaiterLink)
+  V(AwaiterLink)                                                               \
+  V(Shared)
 
 class UntaggedContextScope : public UntaggedObject {
   RAW_HEAP_OBJECT_IMPLEMENTATION(ContextScope);

runtime/vm/scopes.cc

@@ -462,6 +462,8 @@ ContextScopePtr LocalScope::PreserveOuterScope(
 
   LocalVariable* awaiter_link = nullptr;
 
+  bool does_capture_only_final_and_shared_vars = true;
+
   // Create a descriptor for each referenced captured variable of enclosing
   // functions to preserve its name and its context allocation information.
   int captured_idx = 0;
@@ -500,6 +502,13 @@ ContextScopePtr LocalScope::PreserveOuterScope(
       if (is_awaiter_link) {
         awaiter_link = variable;
       }
+
+      bool is_shared = variable->ComputeIfShared(library);
+      context_scope.SetIsSharedAt(captured_idx, is_shared);
+      if (!is_shared && !variable->is_final()) {
+        does_capture_only_final_and_shared_vars = false;
+      }
+
       captured_idx++;
     }
   }
@@ -523,6 +532,11 @@ ContextScopePtr LocalScope::PreserveOuterScope(
     }
   }
 
+  if (!function.IsNull()) {
+    function.set_does_close_over_only_final_and_shared_vars(
+        does_capture_only_final_and_shared_vars);
+  }
+
   return context_scope.ptr();
 }
 
@@ -542,6 +556,7 @@ LocalScope* LocalScope::RestoreOuterScope(const ContextScope& context_scope) {
         String::ZoneHandle(context_scope.NameAt(i)), static_type,
         context_scope.KernelOffsetAt(i), inferred_type);
     variable->set_is_awaiter_link(context_scope.IsAwaiterLinkAt(i));
+    variable->set_is_shared(context_scope.IsSharedAt(i));
     variable->set_is_captured();
     variable->set_index(VariableIndex(context_scope.ContextIndexAt(i)));
     if (context_scope.IsFinalAt(i)) {
@@ -693,6 +708,19 @@ bool LocalVariable::ComputeIfIsAwaiterLink(const Library& library) {
   return is_awaiter_link_ == IsAwaiterLink::kLink;
 }
 
+bool LocalVariable::ComputeIfShared(const Library& library) {
+  if (is_shared_ == IsShared::kUnknown) {
+    RELEASE_ASSERT(annotations_offset_ != kNoKernelOffset);
+    Thread* T = Thread::Current();
+    Zone* Z = T->zone();
+    const auto& metadata = Object::Handle(
+        Z, kernel::EvaluateMetadata(library, annotations_offset_,
+                                    /* is_annotations_offset = */ true));
+    set_is_shared(FindPragmaInMetadata(T, metadata, Symbols::vm_shared()));
+  }
+  return is_shared_ == IsShared::kShared;
+}
+
 bool LocalVariable::Equals(const LocalVariable& other) const {
   if (HasIndex() && other.HasIndex() && (index() == other.index())) {
     if (is_captured() == other.is_captured()) {

runtime/vm/scopes.h

@@ -104,7 +104,8 @@ class LocalVariable : public ZoneAllocated {
         late_init_offset_(0),
         type_check_mode_(kDoTypeCheck),
         index_(),
-        is_awaiter_link_(IsAwaiterLink::kNotLink) {
+        is_awaiter_link_(IsAwaiterLink::kNotLink),
+        is_shared_(IsShared::kNotShared) {
     DEBUG_ASSERT(static_type.IsNotTemporaryScopedHandle());
     ASSERT(static_type.IsFinalized());
     ASSERT(inferred_type != nullptr);
@@ -129,6 +130,8 @@ class LocalVariable : public ZoneAllocated {
     annotations_offset_ = offset;
     is_awaiter_link_ = (offset == kNoKernelOffset) ? IsAwaiterLink::kNotLink
                                                    : IsAwaiterLink::kUnknown;
+    is_shared_ =
+        (offset == kNoKernelOffset) ? IsShared::kNotShared : IsShared::kUnknown;
   }
 
   const AbstractType& static_type() const { return static_type_; }
@@ -151,6 +154,11 @@ class LocalVariable : public ZoneAllocated {
   bool is_late() const { return IsLateBit::decode(bitfield_); }
   void set_is_late() { bitfield_ = IsLateBit::update(true, bitfield_); }
 
+  bool ComputeIfShared(const Library& library);
+  void set_is_shared(bool value) {
+    is_shared_ = value ? IsShared::kShared : IsShared::kNotShared;
+  }
+
   intptr_t late_init_offset() const { return late_init_offset_; }
   void set_late_init_offset(intptr_t late_init_offset) {
     late_init_offset_ = late_init_offset;
@@ -264,6 +272,13 @@ class LocalVariable : public ZoneAllocated {
   };
   IsAwaiterLink is_awaiter_link_;
 
+  enum class IsShared {
+    kUnknown,
+    kNotShared,
+    kShared,
+  };
+  IsShared is_shared_;
+
   friend class LocalScope;
   DISALLOW_COPY_AND_ASSIGN(LocalVariable);
 };

runtime/vm/symbols.h

@@ -577,6 +577,7 @@ class ObjectPointerVisitor;
   V(vm_notify_debugger_on_exception, "vm:notify-debugger-on-exception")        \
   V(vm_prefer_inline, "vm:prefer-inline")                                      \
   V(vm_recognized, "vm:recognized")                                            \
+  V(vm_shared, "vm:shared")                                                    \
   V(vm_testing_print_flow_graph, "vm:testing:print-flow-graph")                \
   V(vm_trace_entrypoints, "vm:testing.unsafe.trace-entrypoints-fn")            \
   V(vm_unsafe_no_interrupts, "vm:unsafe:no-interrupts")                        \

tests/ffi/isolate_group_bound_captured_local_test.dart

@@ -0,0 +1,63 @@
+// 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.
+
+// Test that exception is thrown when captured variables doesn't have
+// pragma('vm:shared') annotation.
+//
+// VMOptions=--experimental-shared-data
+
+import 'dart:async';
+import 'dart:ffi';
+import 'dart:isolate';
+
+import 'package:dart_internal/isolate_group.dart' show IsolateGroup;
+
+import "package:expect/async_helper.dart";
+import "package:expect/expect.dart";
+
+typedef CallbackNativeType = Void Function(Int64, Int32);
+
+Future<void> testCapturedLocalVarNoDecoration() async {
+  int foo_result = 42;
+  Expect.throws(() {
+    final callback = NativeCallable<CallbackNativeType>.isolateGroupBound((
+      int a,
+      int b,
+    ) {
+      foo_result += (a * b);
+    });
+  }, (e) => e.toString().contains("variables can be captured"));
+}
+
+Future<void> testCapturedLocalVarPragmaVmShared() async {
+  @pragma('vm:shared')
+  int foo_result = 42;
+  final callback = NativeCallable<CallbackNativeType>.isolateGroupBound((
+    int a,
+    int b,
+  ) {
+    foo_result += (a * b);
+  });
+  callback.close();
+}
+
+Future<void> testCapturedLocalVarFinal() async {
+  final int foo_result = 42;
+  final callback = NativeCallable<CallbackNativeType>.isolateGroupBound((
+    int a,
+    int b,
+  ) {
+    foo_result + (a * b);
+  });
+  callback.close();
+}
+
+main(args, message) async {
+  asyncStart();
+  await testCapturedLocalVarNoDecoration();
+  await testCapturedLocalVarPragmaVmShared();
+  await testCapturedLocalVarFinal();
+  asyncEnd();
+  print("All tests completed :)");
+}

tests/ffi/isolate_group_bound_init_test.dart

@@ -62,8 +62,10 @@ testInitStrings() async {
   for (int i = 0; i < nWorkers; i++) {
     Isolate.spawn(
       (sendPort) {
+        @pragma('vm:shared')
+        final sp = sendPort;
         IsolateGroup.runSync(() {
-          sendPort.send(shared_late_final_string);
+          sp.send(shared_late_final_string);
         });
       },
       rp.sendPort,
@@ -100,9 +102,11 @@ testInitThrows() async {
   for (int i = 0; i < nWorkers; i++) {
     Isolate.spawn(
       (sendPort) {
+        @pragma('vm:shared')
+        final sp = sendPort;
         IsolateGroup.runSync(() {
           try {
-            sendPort.send(shared_late_final_throw);
+            sp.send(shared_late_final_throw);
           } catch (e) {
             Expect.equals("165", e);
             rethrow;

tests/ffi/run_isolate_group_run_test.dart

@@ -54,6 +54,7 @@ String string_foo = "";
 SendPort? sp;
 
 StringMethodTearoffTest() {
+  @pragma('vm:shared')
   final stringTearoff = "abc".toString;
   IsolateGroup.runSync(() {
     stringTearoff;