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Use BOOST_MAY_ALIAS from Boost.Config #36

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Merged
merged 2 commits into from
Aug 8, 2017
Merged

Use BOOST_MAY_ALIAS from Boost.Config #36

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Use BOOST_MAY_ALIAS from Boost.Config.
Lastique Jul 29, 2017
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Lastique Jul 29, 2017
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16 changes: 8 additions & 8 deletions include/boost/optional/detail/old_optional_implementation.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -746,12 +746,12 @@ class optional : public optional_detail::optional_base<T>
optional ( optional const& rhs ) : base( static_cast<base const&>(rhs) ) {}

#ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES
// Creates a deep move of another optional<T>
// Can throw if T::T(T&&) does
optional ( optional && rhs )
BOOST_NOEXCEPT_IF(::boost::is_nothrow_move_constructible<T>::value)
: base( boost::move(rhs) )
{}
// Creates a deep move of another optional<T>
// Can throw if T::T(T&&) does
optional ( optional && rhs )
BOOST_NOEXCEPT_IF(::boost::is_nothrow_move_constructible<T>::value)
: base( boost::move(rhs) )
{}

#endif
// No-throw (assuming T::~T() doesn't)
Expand Down Expand Up @@ -819,7 +819,7 @@ class optional : public optional_detail::optional_base<T>
#ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES
// Assigns from another optional<T> (deep-moves the rhs value)
optional& operator= ( optional && rhs )
BOOST_NOEXCEPT_IF(::boost::is_nothrow_move_constructible<T>::value && ::boost::is_nothrow_move_assignable<T>::value)
BOOST_NOEXCEPT_IF(::boost::is_nothrow_move_constructible<T>::value && ::boost::is_nothrow_move_assignable<T>::value)
{
this->assign( static_cast<base &&>(rhs) ) ;
return *this ;
Expand Down Expand Up @@ -892,7 +892,7 @@ class optional : public optional_detail::optional_base<T>
#endif

void swap( optional & arg )
BOOST_NOEXCEPT_IF(::boost::is_nothrow_move_constructible<T>::value && ::boost::is_nothrow_move_assignable<T>::value)
BOOST_NOEXCEPT_IF(::boost::is_nothrow_move_constructible<T>::value && ::boost::is_nothrow_move_assignable<T>::value)
{
// allow for Koenig lookup
boost::swap(*this, arg);
Expand Down
38 changes: 17 additions & 21 deletions include/boost/optional/detail/optional_aligned_storage.hpp
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Expand Up @@ -25,12 +25,8 @@ template <class T>
class aligned_storage
{
// Borland ICEs if unnamed unions are used for this!
union
// This works around GCC warnings about breaking strict aliasing rules when casting storage address to T*
#if defined(BOOST_OPTIONAL_DETAIL_USE_ATTRIBUTE_MAY_ALIAS)
__attribute__((__may_alias__))
#endif
dummy_u
// BOOST_MAY_ALIAS works around GCC warnings about breaking strict aliasing rules when casting storage address to T*
union BOOST_MAY_ALIAS dummy_u
{
char data[ sizeof(T) ];
BOOST_DEDUCED_TYPENAME type_with_alignment<
Expand All @@ -48,24 +44,24 @@ class aligned_storage
#endif

#if defined(BOOST_OPTIONAL_DETAIL_USE_ATTRIBUTE_MAY_ALIAS)
// This workaround is supposed to silence GCC warnings about broken strict aliasing rules
T const* ptr_ref() const
{
union { void const* ap_pvoid; T const* as_ptype; } caster = { address() };
return caster.as_ptype;
}
T * ptr_ref()
{
union { void* ap_pvoid; T* as_ptype; } caster = { address() };
return caster.as_ptype;
}
// This workaround is supposed to silence GCC warnings about broken strict aliasing rules
T const* ptr_ref() const
{
union { void const* ap_pvoid; T const* as_ptype; } caster = { address() };
return caster.as_ptype;
}
T * ptr_ref()
{
union { void* ap_pvoid; T* as_ptype; } caster = { address() };
return caster.as_ptype;
}
#else
T const* ptr_ref() const { return static_cast<T const*>(address()); }
T * ptr_ref() { return static_cast<T *> (address()); }
T const* ptr_ref() const { return static_cast<T const*>(address()); }
T * ptr_ref() { return static_cast<T *> (address()); }
#endif

T const& ref() const { return *ptr_ref(); }
T & ref() { return *ptr_ref(); }
T const& ref() const { return *ptr_ref(); }
T & ref() { return *ptr_ref(); }

} ;

Expand Down
10 changes: 5 additions & 5 deletions include/boost/optional/detail/optional_config.hpp
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Expand Up @@ -44,11 +44,11 @@
# define BOOST_OPTIONAL_WEAK_OVERLOAD_RESOLUTION
#endif

#if defined(__GNUC__) && !defined(__INTEL_COMPILER)
// GCC since 3.3 has may_alias attribute that helps to alleviate optimizer issues with
// regard to violation of the strict aliasing rules. The optional< T > storage type is marked
// with this attribute in order to let the compiler know that it will alias objects of type T
// and silence compilation warnings.
#if !defined(BOOST_NO_MAY_ALIAS)
// GCC since 3.3 and some other compilers have may_alias attribute that helps to alleviate
// optimizer issues with regard to violation of the strict aliasing rules. The optional< T >
// storage type is marked with this attribute in order to let the compiler know that it will
// alias objects of type T and silence compilation warnings.
# define BOOST_OPTIONAL_DETAIL_USE_ATTRIBUTE_MAY_ALIAS
#endif

Expand Down
20 changes: 10 additions & 10 deletions include/boost/optional/optional.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -67,7 +67,7 @@ struct in_place_init_t
};
const in_place_init_t in_place_init ((in_place_init_t::init_tag()));

// a tag for conditional in-place initialization of contained value
// a tag for conditional in-place initialization of contained value
struct in_place_init_if_t
{
struct init_tag{};
Expand Down Expand Up @@ -896,12 +896,12 @@ class optional : public optional_detail::optional_base<T>
optional ( optional const& rhs ) : base( static_cast<base const&>(rhs) ) {}

#ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES
// Creates a deep move of another optional<T>
// Can throw if T::T(T&&) does
optional ( optional && rhs )
BOOST_NOEXCEPT_IF(::boost::is_nothrow_move_constructible<T>::value)
: base( boost::move(rhs) )
{}
// Creates a deep move of another optional<T>
// Can throw if T::T(T&&) does
optional ( optional && rhs )
BOOST_NOEXCEPT_IF(::boost::is_nothrow_move_constructible<T>::value)
: base( boost::move(rhs) )
{}

#endif

Expand All @@ -910,7 +910,7 @@ class optional : public optional_detail::optional_base<T>
~optional() {}
#endif


#if !defined(BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT) && !defined(BOOST_OPTIONAL_WEAK_OVERLOAD_RESOLUTION)
// Assigns from an expression. See corresponding constructor.
// Basic Guarantee: If the resolved T ctor throws, this is left UNINITIALIZED
Expand Down Expand Up @@ -968,7 +968,7 @@ class optional : public optional_detail::optional_base<T>
#ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES
// Assigns from another optional<T> (deep-moves the rhs value)
optional& operator= ( optional && rhs )
BOOST_NOEXCEPT_IF(::boost::is_nothrow_move_constructible<T>::value && ::boost::is_nothrow_move_assignable<T>::value)
BOOST_NOEXCEPT_IF(::boost::is_nothrow_move_constructible<T>::value && ::boost::is_nothrow_move_assignable<T>::value)
{
this->assign( static_cast<base &&>(rhs) ) ;
return *this ;
Expand Down Expand Up @@ -1112,7 +1112,7 @@ class optional : public optional_detail::optional_base<T>
#endif

void swap( optional & arg )
BOOST_NOEXCEPT_IF(::boost::is_nothrow_move_constructible<T>::value && ::boost::is_nothrow_move_assignable<T>::value)
BOOST_NOEXCEPT_IF(::boost::is_nothrow_move_constructible<T>::value && ::boost::is_nothrow_move_assignable<T>::value)
{
// allow for Koenig lookup
boost::swap(*this, arg);
Expand Down