Make CreateFileStream return optional, rather than unique_ptr

Source/mpqapi.cpp

@@ -96,12 +96,12 @@ public:
 
 	void Close()
 	{
-		s_ = nullptr;
+		s_ = std::nullopt;
 	}
 
 	[[nodiscard]] bool IsOpen() const
 	{
-		return s_ != nullptr;
+		return s_ != std::nullopt;
 	}
 
 	bool Seekp(std::streampos pos)
@@ -151,7 +151,7 @@ private:
 		return !s_->fail();
 	}
 
-	std::unique_ptr<std::fstream> s_;
+	std::optional<std::fstream> s_;
 };
 
 constexpr std::size_t BlockEntrySize = INDEX_ENTRIES * sizeof(_BLOCKENTRY);

Source/options.cpp

@@ -69,7 +69,7 @@ CSimpleIni &GetIni()
 		auto path = GetIniPath();
 		auto stream = CreateFileStream(path.c_str(), std::fstream::in | std::fstream::binary);
 		ini.SetSpaces(false);
-		if (stream != nullptr)
+		if (stream)
 			ini.LoadData(*stream);
 		isIniLoaded = true;
 	}

Source/utils/file_util.cpp

@@ -164,17 +164,17 @@ void RemoveFile(const char *lpFileName)
 #endif
 }
 
-std::unique_ptr<std::fstream> CreateFileStream(const char *path, std::ios::openmode mode)
+std::optional<std::fstream> CreateFileStream(const char *path, std::ios::openmode mode)
 {
 #if defined(_WIN64) || defined(_WIN32)
 	const auto pathUtf16 = ToWideChar(path);
 	if (pathUtf16 == nullptr) {
 		LogError("UTF-8 -> UTF-16 conversion error code {}", ::GetLastError());
-		return nullptr;
+		return {};
 	}
-	return std::make_unique<std::fstream>(pathUtf16.get(), mode);
+	return { std::fstream(pathUtf16.get(), mode) };
 #else
-	return std::make_unique<std::fstream>(path, mode);
+	return { std::fstream(path, mode) };
 #endif
 }
 

Source/utils/file_util.h

@@ -6,6 +6,7 @@
 #include <memory>
 
 #include "utils/stdcompat/string_view.hpp"
+#include "utils/stdcompat/optional.hpp"
 
 namespace devilution {
 
@@ -14,7 +15,7 @@ bool FileExistsAndIsWriteable(const char *path);
 bool GetFileSize(const char *path, std::uintmax_t *size);
 bool ResizeFile(const char *path, std::uintmax_t size);
 void RemoveFile(const char *lpFileName);
-std::unique_ptr<std::fstream> CreateFileStream(const char *path, std::ios::openmode mode);
+std::optional<std::fstream> CreateFileStream(const char *path, std::ios::openmode mode);
 FILE *FOpen(const char *path, const char *mode);
 
 #if defined(_WIN64) || defined(_WIN32)