do not make unnecessary exports on nix platforms

CMakeLists.txt

@@ -9,6 +9,8 @@ if(POLICY CMP0069)
 	cmake_policy(SET CMP0069 NEW)
 endif()
 
+include(CheckCXXSymbolExists)
+
 set(CMAKE_FIND_PACKAGE_PREFER_CONFIG TRUE)
 set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_SOURCE_DIR}/CMake_modules/")
 
@@ -329,6 +331,11 @@ set_target_properties( ${PROJECT_NAME}
 	DEBUG_POSTFIX "_d"
 )
 
+check_cxx_symbol_exists(__GNUC__ "" COMPILER_HAVE_GNUC)
+if (COMPILER_HAVE_GNUC)
+	set_target_properties(${PROJECT_NAME} PROPERTIES COMPILE_FLAGS "-fvisibility=hidden")
+endif()
+
 if(NOT ${CMAKE_VERSION} VERSION_LESS "3.16.0")
 	option(USE_PCH "Use precompiled header" ON)
 

lua.cpp

@@ -62,10 +62,16 @@ int lua::openffi(lua_State *s)
     return 1;
 }
 
-#ifdef _WIN32
-#define EXPORT __declspec(dllexport)
+#if defined _WIN32
+#   if defined __GNUC__
+#      define EXPORT __attribute__ ((dllexport))
+#   else
+#      define EXPORT __declspec(dllexport)
+#   endif
+#elif defined __GNUC__
+#   define EXPORT __attribute__ ((visibility ("default")))
 #else
-#define EXPORT
+#   define EXPORT
 #endif
 
 extern "C"

network/backend/asio.h

@@ -2,6 +2,7 @@
 #undef new
 #endif
 
+#define ASIO_DISABLE_VISIBILITY
 #include <asio.hpp>
 
 #include "network/network.h"