Fix convert_multibyte_charset

src/core/StringBuilder.hpp

@@ -18,7 +18,6 @@
 
 #include "../common.h"
 
-#include "../localisation/localisation.h"
 #include "Math.hpp"
 #include "Memory.hpp"
 #include "String.hpp"
@@ -121,6 +120,22 @@ public:
         }
     }
 
+    /**
+     * Resets the StringBuilder and returns the working buffer (resized to the string size).
+     */
+    utf8 * StealString()
+    {
+        utf8 * result = _buffer;
+        result = Memory::ReallocateArray<utf8>(result, _length + 1);
+        result[_length] = 0;
+
+        _length = 0;
+        _capacity = 0;
+        _buffer = nullptr;
+
+        return result;
+    }
+
     /**
      * Returns the current string buffer as a new fire-and-forget string.
      */

src/localisation/language.cpp

@@ -19,6 +19,7 @@
 #include "../core/Memory.hpp"
 #include "../core/Path.hpp"
 #include "../core/String.hpp"
+#include "../core/StringBuilder.hpp"
 #include "../object/ObjectManager.h"
 #include "LanguagePack.h"
 
@@ -295,31 +296,26 @@ static utf8 * convert_multibyte_charset(const char * src, int languageId)
 {
     constexpr char CODEPOINT_DOUBLEBYTE = (char)0xFF;
 
-    size_t reservedLength = (String::LengthOf(src) * 4) + 1;
-    utf8 * buffer = Memory::Allocate<utf8>(reservedLength);
-    utf8 * dst = buffer;
+    auto sb = StringBuilder(64);
     for (const char * ch = src; *ch != 0;)
     {
         if (*ch == CODEPOINT_DOUBLEBYTE)
         {
             ch++;
-            char a = *ch++;
-            char b = *ch++;
-            uint16 codepoint = (uint16)((a << 8) | b);
+            uint8 a = *ch++;
+            uint8 b = *ch++;
+            wchar_t codepoint16 = (wchar_t)((a << 8) | b);
 
-            codepoint = convert_specific_language_character_to_unicode(languageId, codepoint);
-            dst = String::WriteCodepoint(dst, codepoint);
+            codepoint16 = convert_specific_language_character_to_unicode(languageId, codepoint16);
+            sb.Append(codepoint16);
         }
         else
         {
-            dst = String::WriteCodepoint(dst, *ch++);
+            codepoint_t codepoint = (uint8)*ch++;
+            sb.Append(codepoint);
         }
     }
-    *dst++ = 0;
-    size_t actualLength = (size_t)(dst - buffer);
-    buffer = Memory::Reallocate(buffer, actualLength);
-
-    return buffer;
+    return sb.StealString();
 }
 
 static bool rct2_language_is_multibyte_charset(int languageId)