https://github.com/xbmc/xbmc/pull/19904

From 18ff80a9c169fb969b75e2143d9f1f234b71a730 Mon Sep 17 00:00:00 2001
From: Craig Andrews <candrews@integralblue.com>
Date: Thu, 24 Jun 2021 20:41:11 -0400
Subject: [PATCH] [utils] include fmt/xchar.h

fmt 8 moved wchar/custom char overloads to xchar.h, so for fmt 8 compatibility, xchar.h must be included

See https://github.com/fmtlib/fmt/commit/76ee490468212f8705a1421b4c88f8f814b2d351
---
 xbmc/utils/StringUtils.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/xbmc/utils/StringUtils.h b/xbmc/utils/StringUtils.h
index ca6f82953d90a..2dc5c3f03af2f 100644
--- a/xbmc/utils/StringUtils.h
+++ b/xbmc/utils/StringUtils.h
@@ -36,6 +36,9 @@
 #if FMT_VERSION >= 40000
 #include <fmt/printf.h>
 #endif
+#if FMT_VERSION >= 80000
+#include <fmt/xchar.h>
+#endif
 
 #include "XBDateTime.h"
 #include "utils/params_check_macros.h"