Replace boost::optional with std::optional where possible

src/core/loader/loader.h

@@ -7,10 +7,10 @@
 #include <algorithm>
 #include <initializer_list>
 #include <memory>
+#include <optional>
 #include <string>
 #include <utility>
 #include <vector>
-#include <boost/optional.hpp>
 #include "common/common_types.h"
 #include "common/file_util.h"
 #include "core/file_sys/romfs_reader.h"
@@ -107,7 +107,7 @@ public:
      * information.
      * @returns A pair with the optional system mode, and and the status.
      */
-    virtual std::pair<boost::optional<u32>, ResultStatus> LoadKernelSystemMode() {
+    virtual std::pair<std::optional<u32>, ResultStatus> LoadKernelSystemMode() {
         // 96MB allocated to the application.
         return std::make_pair(2, ResultStatus::Success);
     }

src/core/loader/ncch.cpp

@@ -49,11 +49,11 @@ FileType AppLoader_NCCH::IdentifyType(FileUtil::IOFile& file) {
     return FileType::Error;
 }
 
-std::pair<boost::optional<u32>, ResultStatus> AppLoader_NCCH::LoadKernelSystemMode() {
+std::pair<std::optional<u32>, ResultStatus> AppLoader_NCCH::LoadKernelSystemMode() {
     if (!is_loaded) {
         ResultStatus res = base_ncch.Load();
         if (res != ResultStatus::Success) {
-            return std::make_pair(boost::none, res);
+            return std::make_pair(std::optional<u32>{}, res);
         }
     }
 

src/core/loader/ncch.h

@@ -39,7 +39,7 @@ public:
      * Loads the Exheader and returns the system mode for this application.
      * @returns A pair with the optional system mode, and and the status.
      */
-    std::pair<boost::optional<u32>, ResultStatus> LoadKernelSystemMode() override;
+    std::pair<std::optional<u32>, ResultStatus> LoadKernelSystemMode() override;
 
     ResultStatus ReadCode(std::vector<u8>& buffer) override;