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
This commit is contained in:
Dimitry Andric 2015-03-30 19:36:33 +00:00
parent a7dfee7ab1
commit b770021fdb

View File

@ -842,7 +842,16 @@ template <class _T1, class _T2> struct _LIBCPP_TYPE_VIS_ONLY is_convertible
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)