only export interface symbols from shared libraries on non-Windows

CMakeLists.txt

@@ -1,5 +1,9 @@
 cmake_minimum_required(VERSION 3.13...3.19)
 
+set(CMAKE_C_VISIBILITY_PRESET hidden)
+set(CMAKE_CXX_VISIBILITY_PRESET hidden)
+set(CMAKE_VISIBILITY_INLINES_HIDDEN ON)
+
 if (VCPKG_LIBSNDFILE)
 	list(APPEND VCPKG_MANIFEST_FEATURES "vcpkg-libsndfile")
 endif()

source/CMakeLists.txt

@@ -2,6 +2,7 @@
 # added as interface sources.  Thus whatever links to zmusic-obj will be in
 # charge of compiling.  As a result any properties set on zmusic-obj should be
 # interface.
+
 add_library(zmusic-obj INTERFACE)
 target_sources(zmusic-obj
 INTERFACE

source/zmusic/zmusic_internal.h

@@ -1,12 +1,17 @@
 #pragma once
 #define ZMUSIC_INTERNAL
 
-#if defined(_MSC_VER) && !defined(ZMUSIC_STATIC)
-#define DLL_EXPORT __declspec(dllexport)
-#define DLL_IMPORT __declspec(dllexport)	// without this the compiler complains.
+#if !defined(ZMUSIC_STATIC)
+    #if defined(_MSC_VER)
+        #define DLL_EXPORT __declspec(dllexport)
+        #define DLL_IMPORT __declspec(dllexport)	// without this the compiler complains.
+    #else
+        #define DLL_EXPORT __attribute__((visibility("default")))
+        #define DLL_IMPORT
+    #endif
 #else
-#define DLL_EXPORT
-#define DLL_IMPORT
+    #define DLL_EXPORT
+    #define DLL_IMPORT
 #endif
 
 typedef class MIDISource *ZMusic_MidiSource;

thirdparty/game-music-emu/CMakeLists.txt

@@ -84,8 +84,9 @@ if (COMPILER_IS_GNUCXX_COMPATIBLE)
     set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -W -Wextra")
     set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
 
-    # Assume we have visibility support on any compiler that supports C++11
-    add_definitions (-DLIBGME_VISIBILITY)
+    # Assume we have visibility support on any compiler that supports C++11 
+    # [ZMusic] we do not want to export this interface, so do not unhide the API functions.
+    #add_definitions (-DLIBGME_VISIBILITY)
     set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fvisibility=hidden -fvisibility-inlines-hidden")
 
     # Try to protect against undefined behavior from signed integer overflow

thirdparty/game-music-emu/gme/CMakeLists.txt

@@ -8,6 +8,7 @@ set(libgme_SRCS Blip_Buffer.cpp
                 Effects_Buffer.cpp
                 Fir_Resampler.cpp
                 gme.cpp
+                gme.h
                 Gme_File.cpp
                 M3u_Playlist.cpp
                 Multi_Buffer.cpp