[macOS] Set correct Platform.executable (argv[0]) (flutter#33128)

shell/platform/darwin/macos/framework/Source/FlutterEngine.mm

@@ -264,11 +264,9 @@ - (BOOL)runWithEntrypoint:(NSString*)entrypoint {
 
   // TODO(stuartmorgan): Move internal channel registration from FlutterViewController to here.
 
-  // FlutterProjectArgs is expecting a full argv, so when processing it for
-  // flags the first item is treated as the executable and ignored. Add a dummy
-  // value so that all provided arguments are used.
+  // The first argument of argv is required to be the executable name.
+  std::vector<const char*> argv = {[self.executableName UTF8String]};
   std::vector<std::string> switches = _project.switches;
-  std::vector<const char*> argv = {"placeholder"};
   std::transform(switches.begin(), switches.end(), std::back_inserter(argv),
                  [](const std::string& arg) -> const char* { return arg.c_str(); });
 
@@ -517,6 +515,10 @@ - (void)updateDisplayConfig {
   return _bridge;
 }
 
+- (nonnull NSString*)executableName {
+  return [[[NSProcessInfo processInfo] arguments] firstObject] ?: @"Flutter";
+}
+
 - (void)updateWindowMetrics {
   if (!_engine || !_viewController.viewLoaded) {
     return;

shell/platform/darwin/macos/framework/Source/FlutterEngineTest.mm

@@ -39,6 +39,23 @@ @interface FlutterEngine (Test)
   EXPECT_TRUE(engine.running);
 }
 
+TEST_F(FlutterEngineTest, HasNonNullExecutableName) {
+  // Launch the test entrypoint.
+  FlutterEngine* engine = GetFlutterEngine();
+  std::string executable_name = [[engine executableName] UTF8String];
+  EXPECT_TRUE([engine runWithEntrypoint:@"executableNameNotNull"]);
+
+  // Block until notified by the Dart test of the value of Platform.executable.
+  fml::AutoResetWaitableEvent latch;
+  AddNativeCallback("NotifyStringValue", CREATE_NATIVE_ENTRY([&](Dart_NativeArguments args) {
+                      const auto dart_string = tonic::DartConverter<std::string>::FromDart(
+                          Dart_GetNativeArgument(args, 0));
+                      EXPECT_EQ(executable_name, dart_string);
+                      latch.Signal();
+                    }));
+  latch.Wait();
+}
+
 TEST_F(FlutterEngineTest, MessengerSend) {
   FlutterEngine* engine = GetFlutterEngine();
   EXPECT_TRUE([engine runWithEntrypoint:@"main"]);

shell/platform/darwin/macos/framework/Source/FlutterEngine_Internal.h

@@ -39,6 +39,11 @@
  */
 @property(nonatomic) BOOL semanticsEnabled;
 
+/**
+ * The executable name for the current process.
+ */
+@property(nonatomic, readonly, nonnull) NSString* executableName;
+
 /**
  * Informs the engine that the associated view controller's view size has changed.
  */

shell/platform/darwin/macos/framework/Source/fixtures/flutter_desktop_test.dart

@@ -2,13 +2,25 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:io';
 import 'dart:ui';
 
 void signalNativeTest() native 'SignalNativeTest';
 
 void main() {
 }
 
+/// Notifies the test of a string value.
+///
+/// This is used to notify the native side of the test of a string value from
+/// the Dart fixture under test.
+void notifyStringValue(String s) native 'NotifyStringValue';
+
+@pragma('vm:entry-point')
+void executableNameNotNull() {
+  notifyStringValue(Platform.executable);
+}
+
 @pragma('vm:entry-point')
 void canLogToStdout() {
   // Emit hello world message to output then signal the test.