Fix symbols export/import for shared libs on windows

Author: lapinozz

CMakeLists.txt

@@ -77,8 +77,8 @@ if(WIN32 AND MINGW)
   target_link_libraries(ImGui-SFML PUBLIC imm32)
 endif()
 if(BUILD_SHARED_LIBS)
-  target_compile_definitions(ImGui-SFML PRIVATE IMGUI_SFML_SHARED_LIB)
-  set_target_properties(ImGui-SFML PROPERTIES DEFINE_SYMBOL "IMGUI_SFML_EXPORTS")
+  target_compile_definitions(ImGui-SFML PUBLIC IMGUI_SFML_SHARED_LIB
+                                        PRIVATE IMGUI_SFML_EXPORTS)
   set_target_properties(ImGui-SFML PROPERTIES DEBUG_POSTFIX "_d")
 endif()
 if(IMGUI_SFML_DISABLE_OBSOLETE_FUNCTIONS)

imgui-SFML_export.h

@@ -5,21 +5,17 @@
 #if _WIN32
 #ifdef IMGUI_SFML_EXPORTS
 #define IMGUI_SFML_API __declspec(dllexport)
-#define IMGUI_API      __declspec(dllexport)
 #else
 #define IMGUI_SFML_API __declspec(dllimport)
-#define IMGUI_API      __declspec(dllexport)
 #endif
-#elif __GNUC__ >= 4
+#elif __GNUC__
 #define IMGUI_SFML_API __attribute__((visibility("default")))
-#define IMGUI_API      __attribute__((visibility("default")))
 #else
 #define IMGUI_SFML_API
-#define IMGUI_API
 #endif
 #else
 #define IMGUI_SFML_API
-#define IMGUI_API
 #endif
 
+#define IMGUI_API IMGUI_SFML_API
 #endif