Use 3rd party optional wrapper, always use local verison on Apple

src/3rdparty/optional/optional.hpp

@@ -97,9 +97,8 @@
 #   define OPTIONAL_MUTABLE_CONSTEXPR constexpr
 # endif
 
-namespace std{
-
-namespace experimental{
+namespace ottd_optional{
+using namespace std;
 
 // BEGIN workaround for missing is_trivially_destructible
 # if defined TR2_OPTIONAL_GCC_4_8_AND_HIGHER___
@@ -1032,16 +1031,15 @@ constexpr optional<X&> make_optional(reference_wrapper<X> v)
 }
 
 
-} // namespace experimental
-} // namespace std
+} // namespace ottd_optional
 
 namespace std
 {
   template <typename T>
-  struct hash<std::experimental::optional<T>>
+  struct hash<ottd_optional::optional<T>>
   {
     typedef typename hash<T>::result_type result_type;
-    typedef std::experimental::optional<T> argument_type;
+    typedef ottd_optional::optional<T> argument_type;
 
     constexpr result_type operator()(argument_type const& arg) const {
       return arg ? std::hash<T>{}(*arg) : result_type{};
@@ -1049,10 +1047,10 @@ namespace std
   };
 
   template <typename T>
-  struct hash<std::experimental::optional<T&>>
+  struct hash<ottd_optional::optional<T&>>
   {
     typedef typename hash<T>::result_type result_type;
-    typedef std::experimental::optional<T&> argument_type;
+    typedef ottd_optional::optional<T&> argument_type;
 
     constexpr result_type operator()(argument_type const& arg) const {
       return arg ? std::hash<T>{}(*arg) : result_type{};

src/3rdparty/optional/ottd_optional.h

@@ -16,7 +16,7 @@
 #	endif
 #endif
 
-#if (__cplusplus >= 201703L) || (defined(__cpp_lib_optional) && __cpp_lib_optional >= 201606L)
+#if !defined(__APPLE__) && ((__cplusplus >= 201703L) || (defined(__cpp_lib_optional) && __cpp_lib_optional >= 201606L))
 
 /* Native std::optional. */
 #include <optional>
@@ -26,7 +26,7 @@ namespace opt = std;
 
 /* No std::optional, use local copy instead. */
 #include "optional.hpp"
-namespace opt = std::experimental;
+namespace opt = ottd_optional;
 
 #endif
 

src/fios.cpp

@@ -20,7 +20,7 @@
 #include "tar_type.h"
 #include <sys/stat.h>
 #include <functional>
-#include <optional>
+#include "3rdparty/optional/ottd_optional.h"
 
 #ifndef _WIN32
 # include <unistd.h>
@@ -495,7 +495,7 @@ FiosType FiosGetSavegameListCallback(SaveLoadOperation fop, const std::string &f
  */
 void FiosGetSavegameList(SaveLoadOperation fop, FileList &file_list)
 {
-	static std::optional<std::string> fios_save_path;
+	static opt::optional<std::string> fios_save_path;
 
 	if (!fios_save_path) fios_save_path = FioFindDirectory(SAVE_DIR);
 
@@ -544,7 +544,7 @@ static FiosType FiosGetScenarioListCallback(SaveLoadOperation fop, const std::st
  */
 void FiosGetScenarioList(SaveLoadOperation fop, FileList &file_list)
 {
-	static std::optional<std::string> fios_scn_path;
+	static opt::optional<std::string> fios_scn_path;
 
 	/* Copy the default path on first run or on 'New Game' */
 	if (!fios_scn_path) fios_scn_path = FioFindDirectory(SCENARIO_DIR);
@@ -606,7 +606,7 @@ static FiosType FiosGetHeightmapListCallback(SaveLoadOperation fop, const std::s
  */
 void FiosGetHeightmapList(SaveLoadOperation fop, FileList &file_list)
 {
-	static std::optional<std::string> fios_hmap_path;
+	static opt::optional<std::string> fios_hmap_path;
 
 	if (!fios_hmap_path) fios_hmap_path = FioFindDirectory(HEIGHTMAP_DIR);
 
@@ -623,7 +623,7 @@ void FiosGetHeightmapList(SaveLoadOperation fop, FileList &file_list)
  */
 const char *FiosGetScreenshotDir()
 {
-	static std::optional<std::string> fios_screenshot_path;
+	static opt::optional<std::string> fios_screenshot_path;
 
 	if (!fios_screenshot_path) fios_screenshot_path = FioFindDirectory(SCREENSHOT_DIR);