Fix ustring type relying on non-standard C++ behavior

Author: sfan5

src/types.h

@@ -1,5 +1,40 @@
+#pragma once
+
 #include <string>
 
-typedef std::basic_string<unsigned char> ustring;
+// Define custom char traits since std::char_traits<unsigend char> is not part of C++ standard
+struct uchar_traits : std::char_traits<char>
+{
+	using super = std::char_traits<char>;
+	using char_type = unsigned char;
+
+	static void assign(char_type& c1, const char_type& c2) noexcept {
+		c1 = c2;
+	}
+	static char_type* assign(char_type* ptr, std::size_t count, char_type c2) {
+		return reinterpret_cast<char_type*>(
+			super::assign(reinterpret_cast<char*>(ptr), count, static_cast<char>(c2)));
+	}
+
+	static char_type* move(char_type* dest, const char_type* src, std::size_t count) {
+		return reinterpret_cast<char_type*>(
+			super::move(reinterpret_cast<char*>(dest), reinterpret_cast<const char*>(src), count));
+	}
+
+	static char_type* copy(char_type* dest, const char_type* src, std::size_t count) {
+		return reinterpret_cast<char_type*>(
+			super::copy(reinterpret_cast<char*>(dest), reinterpret_cast<const char*>(src), count));
+	}
+
+	static int compare(const char_type* s1, const char_type* s2, std::size_t count) {
+		return super::compare(reinterpret_cast<const char*>(s1), reinterpret_cast<const char*>(s2), count);
+	}
+
+	static char_type to_char_type(int_type c) noexcept {
+		return static_cast<char_type>(c);
+	}
+};
+
+typedef std::basic_string<unsigned char, uchar_traits> ustring;
 typedef unsigned int uint;
 typedef unsigned char u8;