From e26ac99551a6ebb358396f2261233a1037619ece Mon Sep 17 00:00:00 2001
From: momo5502 <mauriceheumann@gmail.com>
Date: Sat, 7 Jun 2025 11:25:51 +0200
Subject: [PATCH] Fix char16_t tolower conversion

---
 src/common/utils/string.hpp | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/src/common/utils/string.hpp b/src/common/utils/string.hpp
index de59dfdd..53e416fd 100644
--- a/src/common/utils/string.hpp
+++ b/src/common/utils/string.hpp
@@ -3,6 +3,7 @@
 #include <string>
 #include <vector>
 #include <cstddef>
+#include <cstdint>
 #include <cwctype>
 #include <algorithm>
 #include <string_view>
@@ -43,21 +44,18 @@ namespace utils::string
         return static_cast<char>(std::tolower(static_cast<unsigned char>(val)));
     }
 
-    inline char16_t char_to_lower(const char16_t val)
-    {
-        if (val >= u'A' && val <= u'Z')
-        {
-            return val + 32;
-        }
-
-        return val;
-    }
-
     inline wchar_t char_to_lower(const wchar_t val)
     {
         return static_cast<wchar_t>(std::towlower(val));
     }
 
+    inline char16_t char_to_lower(const char16_t val)
+    {
+        static_assert(sizeof(char16_t) <= sizeof(wchar_t));
+        static_assert(sizeof(char16_t) == sizeof(uint16_t));
+        return static_cast<char16_t>(char_to_lower(static_cast<wchar_t>(static_cast<uint16_t>(val))));
+    }
+
     template <class Elem, class Traits, class Alloc>
     void to_lower_inplace(std::basic_string<Elem, Traits, Alloc>& str)
     {