Fix realtime_example ffi resolution on Linux

Author: fuzzybinary

examples/realtime_example/CMakeLists.txt

@@ -3,8 +3,6 @@ cmake_minimum_required(VERSION 3.21)
 project(realtime_example)
 set(CMAKE_CXX_STANDARD 17)
 
-set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR})
-
 set(CUTE_FRAMEWORK_STATIC ON)
 set(CF_FRAMEWORK_BUILD_TESTS OFF)
 # Samples Build on Windows Falied
@@ -28,12 +26,17 @@ target_include_directories(realtime_example PRIVATE
     "${DART_DIR}/runtime/include"
 )
 
-add_custom_target(ALWAYS_DO_POST_BUILD
+if(LINUX)
+	# -export-dynamic is required on Linux if your symbols are in your executable,
+	# otherwise dlsym (and therefore Dart FFI) can't find them.
+	set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -export-dynamic")
+endif()
+
+add_custom_command(TARGET realtime_example POST_BUILD
   COMMAND ${CMAKE_COMMAND} -E copy -t $<TARGET_FILE_DIR:realtime_example> $<TARGET_RUNTIME_DLLS:simple_example_ffi>
   COMMAND ${CMAKE_COMMAND} -E copy_directory ${PROJECT_SOURCE_DIR}/dart $<TARGET_FILE_DIR:realtime_example>/dart
   COMMAND_EXPAND_LISTS
 )
-add_dependencies(realtime_example ALWAYS_DO_POST_BUILD)
 
 target_link_libraries(realtime_example PUBLIC dart_dll cute)
 

examples/realtime_example/main.cpp

@@ -37,6 +37,7 @@ bool init_dart() {
   Dart_Handle result =
       Dart_Invoke(root_library, init_function_name, 0, nullptr);
   if (Dart_IsError(result)) {
+    std::cout << Dart_GetError(result);
     Dart_ExitScope();
     return false;
   }
@@ -99,15 +100,9 @@ void render_drawables() {
 // These need to be exposed as "C" functions and be exported
 //
 #if defined(_WIN32)
-#define WORM_EXPORT __declspec(dllexport)
-#elif defined(__GNUC__)
-#define WORM_EXPORT __attribute__((visibility("default")))
+#define WORM_EXPORT exten "C" __declspec(dllexport)
 #else
-#define WORM_EXPORT
-#endif
-
-#ifdef __cplusplus
-extern "C" {
+#define WORM_EXPORT extern "C" __attribute__((visibility("default"))) __attribute((used))
 #endif
 
 WORM_EXPORT unsigned int create_entity(int x, int y, int width, int height) {
@@ -140,10 +135,6 @@ WORM_EXPORT bool get_key_just_pressed(int key_code) {
   return cf_key_just_pressed((CF_KeyButton)key_code);
 }
 
-#ifdef __cplusplus
-}
-#endif
-
 int main(int argc, char* argv[]) {
   // Create a window with a resolution of 640 x 480.
   int options =

examples/simple_example_ffi/hello_world_ffi.dart

@@ -1,7 +1,7 @@
 import 'dart:ffi';
 import 'package:ffi/ffi.dart';
 
-@FfiNative<Void Function(Pointer<Utf8>)>("SimplePrint", isLeaf: true)
+@Native<Void Function(Pointer<Utf8>)>(symbol: "SimplePrint", isLeaf: true)
 external void simplePrint(Pointer<Utf8> string);
 
 void main() {