[libcxx-commits] [PATCH] D149313: [libc++] Use __is_convertible built-in when available

[Roland McGrath via Phabricator via libcxx-commits]

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https://github.com/llvm/llvm-project/issues/62396 reports that
GCC 13 barfs on parsing <type_traits> because of the declarations
of `struct __is_convertible`.  In GCC 13, `__is_convertible` is a
built-in, but `__is_convertible_to` is not.  Clang has both, so
using either should be fine.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D149313

Files:
  libcxx/include/__type_traits/is_convertible.h


Index: libcxx/include/__type_traits/is_convertible.h
===================================================================
--- libcxx/include/__type_traits/is_convertible.h
+++ libcxx/include/__type_traits/is_convertible.h
@@ -24,7 +24,12 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if __has_builtin(__is_convertible_to) && !defined(_LIBCPP_USE_IS_CONVERTIBLE_FALLBACK)
+#if __has_builtin(__is_convertible) && !defined(_LIBCPP_USE_IS_CONVERTIBLE_FALLBACK)
+
+template <class _T1, class _T2>
+struct _LIBCPP_TEMPLATE_VIS is_convertible : public integral_constant<bool, __is_convertible(_T1, _T2)> {};
+
+#elif __has_builtin(__is_convertible_to) && !defined(_LIBCPP_USE_IS_CONVERTIBLE_FALLBACK)
 
 template <class _T1, class _T2> struct _LIBCPP_TEMPLATE_VIS is_convertible
     : public integral_constant<bool, __is_convertible_to(_T1, _T2)> {};


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