Remove redundant __constexpr_addressof function

The std::__addressof function is always constexpr, even in C++14, so we
can just use that.

	* include/experimental/bits/lfts_config.h: Improve doc markup.
	* include/experimental/optional: Improve docs.
	(_Has_addressof_mem, _Has_addressof_free, _Has_addressof)
	(__constexpr_addressof): Remove.
	(optional::operator->()): Use std::__addressof().
	* include/std/optional (optional::operator->()): Adjust whitespace.
	* testsuite/experimental/optional/constexpr/observers/2.cc: Check
	that operator-> is still constexpr with overloaded operator&. Change
	to compile-only test.
	* testsuite/experimental/optional/constexpr/observers/3.cc: Change to
	compile-only test.

From-SVN: r270826
This commit is contained in:
Jonathan Wakely 2019-05-02 22:23:35 +01:00 committed by Jonathan Wakely
parent efa9d8eef0
commit b752e2c926
6 changed files with 28 additions and 71 deletions

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@ -1,5 +1,17 @@
2019-05-02 Jonathan Wakely <jwakely@redhat.com>
* include/experimental/bits/lfts_config.h: Improve doc markup.
* include/experimental/optional: Improve docs.
(_Has_addressof_mem, _Has_addressof_free, _Has_addressof)
(__constexpr_addressof): Remove.
(optional::operator->()): Use std::__addressof().
* include/std/optional (optional::operator->()): Adjust whitespace.
* testsuite/experimental/optional/constexpr/observers/2.cc: Check
that operator-> is still constexpr with overloaded operator&. Change
to compile-only test.
* testsuite/experimental/optional/constexpr/observers/3.cc: Change to
compile-only test.
* include/bits/shared_ptr.h: Improve docs.
* include/bits/shared_ptr_atomic.h: Likewise.
* include/bits/unique_ptr.h: Likewise. Adjust whitespace.

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@ -36,9 +36,8 @@
* Components defined by the _C++ Extensions for Library Fundamentals_
* Technical Specification, versions 1 and 2.
*
* ISO/IEC TS 19568:2015 C++ Extensions for Library Fundamentals
*
* ISO/IEC TS 19568:2017 C++ Extensions for Library Fundamentals, Version 2
* - ISO/IEC TS 19568:2015 C++ Extensions for Library Fundamentals
* - ISO/IEC TS 19568:2017 C++ Extensions for Library Fundamentals, Version 2
*/
#if _GLIBCXX_INLINE_VERSION

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@ -112,6 +112,8 @@ inline namespace fundamentals_v1
virtual ~bad_optional_access() noexcept = default;
};
/// @cond undocumented
void
__throw_bad_optional_access(const char*)
__attribute__((__noreturn__));
@ -121,59 +123,6 @@ inline namespace fundamentals_v1
__throw_bad_optional_access(const char* __s)
{ _GLIBCXX_THROW_OR_ABORT(bad_optional_access(__s)); }
#ifndef __cpp_lib_addressof_constexpr
template<typename _Tp, typename = void>
struct _Has_addressof_mem : std::false_type { };
template<typename _Tp>
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&.
*
* Practically speaking this detects the presence of such an operator when
* called on a const-qualified lvalue (e.g.
* declval<const _Tp&>().operator&()).
*/
template<typename _Tp>
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
* constant expression. Falls back to __addressof in the presence of an
* overloaded addressof operator (unary operator&), in which case the call
* will not be a constant expression.
*/
template<typename _Tp>
constexpr
enable_if_t<!_Has_addressof<_Tp>::value, _Tp*>
__constexpr_addressof(_Tp& __t)
{ return &__t; }
/**
* @brief Fallback overload that defers to __addressof.
*/
template<typename _Tp>
inline
enable_if_t<_Has_addressof<_Tp>::value, _Tp*>
__constexpr_addressof(_Tp& __t)
{ return std::__addressof(__t); }
#endif // __cpp_lib_addressof_constexpr
/**
* @brief Class template that holds the necessary state for @ref optional
* and that has the responsibility for construction and the special members.
@ -452,9 +401,6 @@ inline namespace fundamentals_v1
bool _M_engaged = false;
};
template<typename _Tp>
class optional;
template<typename _Tp, typename _Up>
using __converts_from_optional =
__or_<is_constructible<_Tp, const optional<_Up>&>,
@ -473,6 +419,8 @@ inline namespace fundamentals_v1
is_assignable<_Tp&, const optional<_Up>&&>,
is_assignable<_Tp&, optional<_Up>&&>>;
/// @endcond
/**
* @brief Class template for optional values.
*/
@ -698,13 +646,7 @@ inline namespace fundamentals_v1
// [X.Y.4.5] Observers.
constexpr const _Tp*
operator->() const
{
#ifndef __cpp_lib_addressof_constexpr
return __constexpr_addressof(this->_M_get());
#else
return std::__addressof(this->_M_get());
#endif
}
{ return std::__addressof(this->_M_get()); }
_Tp*
operator->()
@ -796,6 +738,8 @@ inline namespace fundamentals_v1
}
};
/// @relates experimental::optional @{
// [X.Y.8] Comparisons between optional values.
template<typename _Tp>
constexpr bool
@ -966,11 +910,14 @@ inline namespace fundamentals_v1
make_optional(_Tp&& __t)
{ return optional<decay_t<_Tp>> { std::forward<_Tp>(__t) }; }
// @} relates experimental::optional
// @} group optional
} // namespace fundamentals_v1
} // namespace experimental
// [X.Y.12]
/// std::hash partial specialization for experimental::optional
/// @relates experimental::optional
template<typename _Tp>
struct hash<experimental::optional<_Tp>>
{

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@ -888,8 +888,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
operator->() const
{ return std::__addressof(this->_M_get()); }
constexpr
_Tp*
constexpr _Tp*
operator->()
{ return std::__addressof(this->_M_get()); }

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@ -1,4 +1,4 @@
// { dg-do run { target c++14 } }
// { dg-do compile { target c++14 } }
// Copyright (C) 2013-2019 Free Software Foundation, Inc.
//
@ -23,7 +23,7 @@ struct value_type
{
int i;
void* operator&() { return nullptr; } // N.B. non-const
void* operator&() const { return nullptr; }
};
int main()

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@ -1,4 +1,4 @@
// { dg-do run { target c++14 } }
// { dg-do compile { target c++14 } }
// Copyright (C) 2013-2019 Free Software Foundation, Inc.
//