Raise an informative error when running on macOS under Rosetta 2.

Current users only get a cryptic "Illegal instruction" crash.

Context: https://github.com/deepmind/mujoco/issues/611
PiperOrigin-RevId: 491705647
Change-Id: I1285897a36e858300ee3d125957e90754be9a7f7

simulate/CMakeLists.txt

@@ -122,7 +122,7 @@ target_include_directories(libsimulate PUBLIC $<TARGET_PROPERTY:glfw,INTERFACE_I
 target_link_options(libsimulate PRIVATE ${MUJOCO_SIMULATE_LINK_OPTIONS})
 
 if(APPLE)
-  target_sources(libsimulate PRIVATE macos_save.mm)
+  target_sources(libsimulate PRIVATE macos_gui.mm)
   target_link_libraries(libsimulate PUBLIC "-framework Cocoa")
 endif()
 

simulate/Makefile.macos

@@ -11,8 +11,8 @@ CXXFLAGS=$(CFLAGS) -std=c++17 -stdlib=libc++
 ALLFLAGS=$(CXXFLAGS) -L$(GLFWROOT)/lib -Wl,-rpath,$(MUJOCOPATH)
 
 all:
-	clang++ $(CXXFLAGS)      -c macos_save.mm
+	clang++ $(CXXFLAGS)      -c macos_gui.mm
 	clang++ $(CXXFLAGS)      -c simulate.cc
 	clang $(CFLAGS) -std=c11 -c uitools.c
-	clang++ $(CXXFLAGS) main.cc macos_save.o simulate.o uitools.o  -framework mujoco -framework Cocoa -lglfw -o simulate
+	clang++ $(CXXFLAGS) main.cc macos_gui.o simulate.o uitools.o  -framework mujoco -framework Cocoa -lglfw -o simulate
 	rm *.o

simulate/macos_gui.mm

@@ -17,7 +17,7 @@
 
 #include <Cocoa/Cocoa.h>
 
-std::string getSavePath(const char* filename) {
+std::string GetSavePath(const char* filename) {
   NSSavePanel* panel = [NSSavePanel savePanel];
   NSURL* userDocumentsDir = [NSFileManager.defaultManager URLsForDirectory:NSDocumentDirectory
                                                           inDomains:NSUserDomainMask].firstObject;
@@ -31,3 +31,14 @@ std::string getSavePath(const char* filename) {
     return "";
   }
 }
+
+#ifdef __AVX__
+void DisplayErrorDialogBox(const char* title, const char* msg) {
+  NSAlert *alert = [[[NSAlert alloc] init] autorelease];
+  [alert setMessageText:[NSString stringWithUTF8String:title]];
+  [alert setInformativeText:[NSString stringWithUTF8String:msg]];
+  [alert setAlertStyle:NSAlertStyleCritical];
+  [alert addButtonWithTitle:@"Exit"];
+  [alert runModal];
+}
+#endif

simulate/main.cc

@@ -437,8 +437,25 @@ void PhysicsThread(mj::Simulate* sim, const char* filename) {
 
 //------------------------------------------ main --------------------------------------------------
 
+// machinery for replacing command line error by a macOS dialog box when running under Rosetta
+#if defined(__APPLE__) && defined(__AVX__)
+extern void DisplayErrorDialogBox(const char* title, const char* msg);
+static const char* rosetta_error_msg = nullptr;
+__attribute__((used, visibility("default"))) extern "C" void _mj_rosettaError(const char* msg) {
+  rosetta_error_msg = msg;
+}
+#endif
+
 // run event loop
 int main(int argc, const char** argv) {
+  // display an error if running on macOS under Rosetta 2
+#if defined(__APPLE__) && defined(__AVX__)
+  if (rosetta_error_msg) {
+    DisplayErrorDialogBox("Rosetta 2 is not supported", rosetta_error_msg);
+    std::exit(1);
+  }
+#endif
+
   // print version, check compatibility
   std::printf("MuJoCo version %s\n", mj_versionString());
   if (mjVERSION_HEADER!=mj_version()) {

simulate/simulate.cc

@@ -40,9 +40,9 @@
 // Since the dialog box logic needs to be written in Objective-C, we separate it into a different
 // source file.
 #ifdef __APPLE__
-std::string getSavePath(const char* filename);
+std::string GetSavePath(const char* filename);
 #else
-static std::string getSavePath(const char* filename) {
+static std::string GetSavePath(const char* filename) {
   return filename;
 }
 #endif
@@ -1077,7 +1077,7 @@ void uiEvent(mjuiState* state) {
       switch (it->itemid) {
       case 0:             // Save xml
         {
-          const std::string path = getSavePath("mjmodel.xml");
+          const std::string path = GetSavePath("mjmodel.xml");
           if (!path.empty() && !mj_saveLastXML(path.c_str(), m, err, 200)) {
             std::printf("Save XML error: %s", err);
           }
@@ -1086,7 +1086,7 @@ void uiEvent(mjuiState* state) {
 
       case 1:             // Save mjb
         {
-          const std::string path = getSavePath("mjmodel.mjb");
+          const std::string path = GetSavePath("mjmodel.mjb");
           if (!path.empty()) {
             mj_saveModel(m, path.c_str(), nullptr, 0);
           }
@@ -1850,7 +1850,7 @@ void Simulate::render() {
     // Unfortunately, if we just yank ".xml"/".mjb" from the filename and append .PNG, the macOS
     // file dialog does not automatically open that location. Thus, we defer to a default
     // "screenshot.png" for now.
-    const std::string path = getSavePath("screenshot.png");
+    const std::string path = GetSavePath("screenshot.png");
     if (!path.empty()) {
       if (lodepng::encode(path, rgb.get(), w, h, LCT_RGB)) {
         mju_error("could not save screenshot");