svn commit: r280864 - head/contrib/libc++/include

[Dimitry Andric]

Author: dim
Date: Mon Mar 30 19:36:33 2015
New Revision: 280864
URL: https://svnweb.freebsd.org/changeset/base/280864

Log:
  Pull in r233552 from upstream libc++ trunk (by Eric Fiselier):
  
    [libcxx] Fix PR22771 - Support access control SFINAE in the library
    version of is_convertible.
  
    Summary:
    Currently the conversion check does not take place in a context where
    access control SFINAE is applied. This patch changes the context of
    the test expression so that SFINAE occurs if access control does not
    permit the conversion.
  
    Related bug: https://llvm.org/bugs/show_bug.cgi?id=22771
  
    Reviewers: mclow.lists, rsmith, dim
  
    Reviewed By: dim
  
    Subscribers: dim, rodrigc, emaste, cfe-commits
  
    Differential Revision: http://reviews.llvm.org/D8461
  
  This fixes building clang, and other programs using libc++, with newer
  versions of gcc (specifically, gcc 4.8 and higher).
  
  Reported by:	rodrigc
  MFC after:	1 week

Modified:
  head/contrib/libc++/include/type_traits

Modified: head/contrib/libc++/include/type_traits
==============================================================================
--- head/contrib/libc++/include/type_traits	Mon Mar 30 19:15:43 2015	(r280863)
+++ head/contrib/libc++/include/type_traits	Mon Mar 30 19:36:33 2015	(r280864)
@@ -842,7 +842,16 @@ template <class _T1, class _T2> struct _
 
 namespace __is_convertible_imp
 {
-template <class _Tp> char  __test(_Tp);
+template <class _Tp> void  __test_convert(_Tp);
+
+template <class _From, class _To, class = void>
+struct __is_convertible_test : public false_type {};
+
+template <class _From, class _To>
+struct __is_convertible_test<_From, _To,
+    decltype(__test_convert<_To>(_VSTD::declval<_From>()))> : public true_type
+{};
+
 template <class _Tp> __two __test(...);
 #ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
 template <class _Tp> _Tp&& __source();
@@ -877,10 +886,8 @@ template <class _T1, class _T2,
     unsigned _T2_is_array_function_or_void = __is_convertible_imp::__is_array_function_or_void<_T2>::value>
 struct __is_convertible
     : public integral_constant<bool,
-#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
-        sizeof(__is_convertible_imp::__test<_T2>(__is_convertible_imp::__source<_T1>())) == 1
-#else
-        sizeof(__is_convertible_imp::__test<_T2>(__is_convertible_imp::__source<_T1>())) == 1
+        __is_convertible_imp::__is_convertible_test<_T1, _T2>::value
+#if defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES)
          && !(!is_function<_T1>::value && !is_reference<_T1>::value && is_reference<_T2>::value
               && (!is_const<typename remove_reference<_T2>::type>::value
                   || is_volatile<typename remove_reference<_T2>::type>::value)