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Use BOOST_MAY_ALIAS from Boost.Config.

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This commit is contained in:
Andrey Semashev
2017-07-29 17:18:27 +03:00
committed by Andrzej Krzemienski
parent 61bf382ffa
commit 7e1beb473c
2 changed files with 7 additions and 11 deletions
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8
include/boost/optional/detail/optional_aligned_storage.hpp
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@ -25,12 +25,8 @@ template <class T>
class aligned_storage class aligned_storage
{ {
// Borland ICEs if unnamed unions are used for this! // Borland ICEs if unnamed unions are used for this!
union // BOOST_MAY_ALIAS works around GCC warnings about breaking strict aliasing rules when casting storage address to T*
// This works around GCC warnings about breaking strict aliasing rules when casting storage address to T* union BOOST_MAY_ALIAS dummy_u
#if defined(BOOST_OPTIONAL_DETAIL_USE_ATTRIBUTE_MAY_ALIAS)
__attribute__((__may_alias__))
#endif
dummy_u
{ {
char data[ sizeof(T) ]; char data[ sizeof(T) ];
BOOST_DEDUCED_TYPENAME type_with_alignment< BOOST_DEDUCED_TYPENAME type_with_alignment<

10
include/boost/optional/detail/optional_config.hpp
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@ -44,11 +44,11 @@
# define BOOST_OPTIONAL_WEAK_OVERLOAD_RESOLUTION # define BOOST_OPTIONAL_WEAK_OVERLOAD_RESOLUTION
#endif #endif
#if defined(__GNUC__) && !defined(__INTEL_COMPILER) #if !defined(BOOST_NO_MAY_ALIAS)
// GCC since 3.3 has may_alias attribute that helps to alleviate optimizer issues with // GCC since 3.3 and some other compilers have may_alias attribute that helps to alleviate
// regard to violation of the strict aliasing rules. The optional< T > storage type is marked // optimizer issues with regard to violation of the strict aliasing rules. The optional< T >
// with this attribute in order to let the compiler know that it will alias objects of type T // storage type is marked with this attribute in order to let the compiler know that it will
// and silence compilation warnings. // alias objects of type T and silence compilation warnings.
# define BOOST_OPTIONAL_DETAIL_USE_ATTRIBUTE_MAY_ALIAS # define BOOST_OPTIONAL_DETAIL_USE_ATTRIBUTE_MAY_ALIAS
#endif #endif