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optional (_Has_addressof): Check for non-member operator&.

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* include/experimental/optional (_Has_addressof): Check for non-member
	operator&.
	* testsuite/experimental/optional/observers/2.cc: Add operator&.
	* testsuite/experimental/optional/constexpr/observers/2.cc: Likewise.

From-SVN: r217397
This commit is contained in:
Jonathan Wakely 2014-11-12 00:16:19 +00:00 committed by Jonathan Wakely
parent 847e9cf81e
commit 72e58f18ae
4 changed files with 29 additions and 6 deletions
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7
libstdc++-v3/ChangeLog
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@ -1,3 +1,10 @@
2014-11-12 Jonathan Wakely <jwakely@redhat.com>
* include/experimental/optional (_Has_addressof): Check for non-member
operator&.
* testsuite/experimental/optional/observers/2.cc: Add operator&.
* testsuite/experimental/optional/constexpr/observers/2.cc: Likewise.
2014-11-11 Jonathan Wakely <jwakely@redhat.com>
* include/std/type_traits (__void_t): Define new alias template.

24
libstdc++-v3/include/experimental/optional
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@ -127,13 +127,23 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__throw_bad_optional_access(const char* __s)
{ _GLIBCXX_THROW_OR_ABORT(bad_optional_access(__s)); }
template<typename _Tp, typename _Sfinae = void>
struct _Has_addressof_impl : std::false_type { };
template<typename _Tp, typename = void>
struct _Has_addressof_mem : std::false_type { };
template<typename _Tp>
struct _Has_addressof_impl<_Tp,
decltype( std::declval<const _Tp&>().operator&(), void() )>
: std::true_type { };
struct _Has_addressof_mem<_Tp,
__void_t<decltype( std::declval<const _Tp&>().operator&() )>
>
: std::true_type { };
template<typename _Tp, typename = void>
struct _Has_addressof_free : std::false_type { };
template<typename _Tp>
struct _Has_addressof_free<_Tp,
__void_t<decltype( operator&(std::declval<const _Tp&>()) )>
>
: std::true_type { };
/**
* @brief Trait that detects the presence of an overloaded unary operator&.
@ -143,7 +153,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
* declval<_Tp * const&>().operator&()).
*/
template<typename _Tp>
struct _Has_addressof : _Has_addressof_impl<_Tp>::type { };
struct _Has_addressof
: std::__or_<_Has_addressof_mem<_Tp>, _Has_addressof_free<_Tp>>::type
{ };
/**
* @brief An overload that attempts to take the address of an lvalue as a

2
libstdc++-v3/testsuite/experimental/optional/constexpr/observers/2.cc
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@ -26,6 +26,8 @@
struct value_type
{
int i;
void* operator&() { return nullptr; } // N.B. non-const
};
int main()

2
libstdc++-v3/testsuite/experimental/optional/observers/2.cc
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@ -26,6 +26,8 @@ struct value_type
int i;
};
void* operator&(const value_type&) = delete;
int main()
{
std::experimental::optional<value_type> o { value_type { 51 } };