Add plumbing for command line arguments on Windows (flutter#22094)

shell/platform/windows/client_wrapper/flutter_engine.cc

@@ -17,6 +17,19 @@ FlutterEngine::FlutterEngine(const DartProject& project) {
   c_engine_properties.icu_data_path = project.icu_data_path().c_str();
   c_engine_properties.aot_library_path = project.aot_library_path().c_str();
 
+  const std::vector<std::string>& entrypoint_args =
+      project.dart_entrypoint_arguments();
+  std::vector<const char*> entrypoint_argv;
+  std::transform(
+      entrypoint_args.begin(), entrypoint_args.end(),
+      std::back_inserter(entrypoint_argv),
+      [](const std::string& arg) -> const char* { return arg.c_str(); });
+
+  c_engine_properties.dart_entrypoint_argc =
+      static_cast<int>(entrypoint_argv.size());
+  c_engine_properties.dart_entrypoint_argv =
+      entrypoint_argv.size() > 0 ? entrypoint_argv.data() : nullptr;
+
   engine_ = FlutterDesktopEngineCreate(c_engine_properties);
 
   auto core_messenger = FlutterDesktopEngineGetMessenger(engine_);

shell/platform/windows/client_wrapper/flutter_engine_unittests.cc

@@ -20,6 +20,14 @@ class TestFlutterWindowsApi : public testing::StubFlutterWindowsApi {
   FlutterDesktopEngineRef EngineCreate(
       const FlutterDesktopEngineProperties& engine_properties) {
     create_called_ = true;
+
+    // dart_entrypoint_argv is only guaranteed to exist until this method
+    // returns, so copy it here for unit test validation
+    dart_entrypoint_arguments_.clear();
+    for (int i = 0; i < engine_properties.dart_entrypoint_argc; i++) {
+      dart_entrypoint_arguments_.push_back(
+          std::string(engine_properties.dart_entrypoint_argv[i]));
+    }
     return reinterpret_cast<FlutterDesktopEngineRef>(1);
   }
 
@@ -49,11 +57,16 @@ class TestFlutterWindowsApi : public testing::StubFlutterWindowsApi {
 
   bool reload_fonts_called() { return reload_fonts_called_; }
 
+  const std::vector<std::string>& dart_entrypoint_arguments() {
+    return dart_entrypoint_arguments_;
+  }
+
  private:
   bool create_called_ = false;
   bool run_called_ = false;
   bool destroy_called_ = false;
   bool reload_fonts_called_ = false;
+  std::vector<std::string> dart_entrypoint_arguments_;
 };
 
 }  // namespace
@@ -121,4 +134,21 @@ TEST(FlutterEngineTest, GetMessenger) {
   EXPECT_NE(engine.messenger(), nullptr);
 }
 
+TEST(FlutterEngineTest, DartEntrypointArgs) {
+  testing::ScopedStubFlutterWindowsApi scoped_api_stub(
+      std::make_unique<TestFlutterWindowsApi>());
+  auto test_api = static_cast<TestFlutterWindowsApi*>(scoped_api_stub.stub());
+
+  DartProject project(L"data");
+  std::vector<std::string> arguments = {"one", "two"};
+  project.set_dart_entrypoint_arguments(arguments);
+
+  FlutterEngine engine(project);
+  const std::vector<std::string>& arguments_ref =
+      test_api->dart_entrypoint_arguments();
+  ASSERT_EQ(2, arguments_ref.size());
+  EXPECT_TRUE(arguments[0] == arguments_ref[0]);
+  EXPECT_TRUE(arguments[1] == arguments_ref[1]);
+}
+
 }  // namespace flutter

shell/platform/windows/client_wrapper/include/flutter/dart_project.h

@@ -29,6 +29,18 @@ class DartProject {
 
   ~DartProject() = default;
 
+  // Sets the command line arguments that should be passed to the Dart
+  // entrypoint.
+  void set_dart_entrypoint_arguments(std::vector<std::string> arguments) {
+    dart_entrypoint_arguments_ = std::move(arguments);
+  }
+
+  // Returns any command line arguments that should be passed to the Dart
+  // entrypoint.
+  const std::vector<std::string>& dart_entrypoint_arguments() const {
+    return dart_entrypoint_arguments_;
+  }
+
  private:
   // Accessors for internals are private, so that they can be changed if more
   // flexible options for project structures are needed later without it
@@ -49,6 +61,8 @@ class DartProject {
   // The path to the AOT library. This will always return a path, but non-AOT
   // builds will not be expected to actually have a library at that path.
   std::wstring aot_library_path_;
+  // The list of arguments to pass through to the Dart entrypoint.
+  std::vector<std::string> dart_entrypoint_arguments_;
 };
 
 }  // namespace flutter

shell/platform/windows/flutter_project_bundle.cc

@@ -20,6 +20,11 @@ FlutterProjectBundle::FlutterProjectBundle(
     aot_library_path_ = std::filesystem::path(properties.aot_library_path);
   }
 
+  for (int i = 0; i < properties.dart_entrypoint_argc; i++) {
+    dart_entrypoint_arguments_.push_back(
+        std::string(properties.dart_entrypoint_argv[i]));
+  }
+
   // Resolve any relative paths.
   if (assets_path_.is_relative() || icu_path_.is_relative() ||
       (!aot_library_path_.empty() && aot_library_path_.is_relative())) {

shell/platform/windows/flutter_project_bundle.h

@@ -51,12 +51,21 @@ class FlutterProjectBundle {
   // Logs and returns nullptr on failure.
   UniqueAotDataPtr LoadAotData();
 
+  // Returns the command line arguments to be passed through to the Dart
+  // entrypoint.
+  const std::vector<std::string>& dart_entrypoint_arguments() const {
+    return dart_entrypoint_arguments_;
+  }
+
  private:
   std::filesystem::path assets_path_;
   std::filesystem::path icu_path_;
 
   // Path to the AOT library file, if any.
   std::filesystem::path aot_library_path_;
+
+  // Dart entrypoint arguments.
+  std::vector<std::string> dart_entrypoint_arguments_;
 };
 
 }  // namespace flutter

shell/platform/windows/flutter_windows_engine.cc

@@ -143,6 +143,14 @@ bool FlutterWindowsEngine::RunWithEntrypoint(const char* entrypoint) {
       switches.begin(), switches.end(), std::back_inserter(argv),
       [](const std::string& arg) -> const char* { return arg.c_str(); });
 
+  const std::vector<std::string>& entrypoint_args =
+      project_->dart_entrypoint_arguments();
+  std::vector<const char*> entrypoint_argv;
+  std::transform(
+      entrypoint_args.begin(), entrypoint_args.end(),
+      std::back_inserter(entrypoint_argv),
+      [](const std::string& arg) -> const char* { return arg.c_str(); });
+
   // Configure task runners.
   FlutterTaskRunnerDescription platform_task_runner = {};
   platform_task_runner.struct_size = sizeof(FlutterTaskRunnerDescription);
@@ -166,6 +174,9 @@ bool FlutterWindowsEngine::RunWithEntrypoint(const char* entrypoint) {
   args.icu_data_path = icu_path_string.c_str();
   args.command_line_argc = static_cast<int>(argv.size());
   args.command_line_argv = argv.size() > 0 ? argv.data() : nullptr;
+  args.dart_entrypoint_argc = static_cast<int>(entrypoint_argv.size());
+  args.dart_entrypoint_argv =
+      entrypoint_argv.size() > 0 ? entrypoint_argv.data() : nullptr;
   args.platform_message_callback =
       [](const FlutterPlatformMessage* engine_message,
          void* user_data) -> void {

shell/platform/windows/public/flutter_windows.h

@@ -46,6 +46,13 @@ typedef struct {
   // containing the executable. This can be nullptr for a non-AOT build, as
   // it will be ignored in that case.
   const wchar_t* aot_library_path;
+
+  // Number of elements in the array passed in as dart_entrypoint_argv.
+  int dart_entrypoint_argc;
+
+  // Array of Dart entrypoint arguments. This is deep copied during the call
+  // to FlutterDesktopEngineCreate.
+  const char** dart_entrypoint_argv;
 } FlutterDesktopEngineProperties;
 
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