From 732a7e5e2c725616332f1b06e35afd955a03d5b2 Mon Sep 17 00:00:00 2001
From: Florian Kargl <f.kargl@posteo.de>
Date: Sun, 26 Mar 2023 00:45:18 +0100
Subject: [PATCH] Use __is_convertible builtin in ustl when available

Fix compilation on GCC 13

https://github.com/IAIK/sweb/issues/292
---
 common/include/ustl/uttraits.h | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/common/include/ustl/uttraits.h b/common/include/ustl/uttraits.h
index e0e251a9b..4cafccb3a 100644
--- a/common/include/ustl/uttraits.h
+++ b/common/include/ustl/uttraits.h
@@ -428,7 +428,16 @@ UNARY_TRAIT_DEFB (has_trivial_copy_assign,	__has_trivial_assign(T));
 template <typename T, typename U> struct is_same : public false_type {};
 template <typename T> struct is_same<T,T> : public true_type {};
 
-#if __clang__	// clang has __is_convertible builtin
+#if defined __has_builtin
+  #if __has_builtin (__is_convertible)
+    #define USTL_BUILTIN__is_convertible 1
+  #endif
+#endif
+#ifndef USTL_BUILTIN__is_convertible
+  #define USTL_BUILTIN__is_convertible 0
+#endif
+
+#if __clang__ || USTL_BUILTIN__is_convertible == 1	// clang, gcc >= 13 have __is_convertible builtin
 
 template <typename F, typename T>
 struct is_convertible : public integral_constant<bool, __is_convertible(F, T)> {};