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libstdc++: Simplify std::any to fix -Wdeprecated-declarations warning

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We don't need to use std::aligned_storage in std::any. We just need a
POD type of the right size. The void* union member already ensures the
alignment will be correct. Avoiding std::aligned_storage means we don't
need to suppress a -Wdeprecated-declarations warning.

libstdc++-v3/ChangeLog:

	* include/experimental/any (experimental::any::_Storage): Use
	array of unsigned char instead of deprecated
	std::aligned_storage.
	* include/std/any (any::_Storage): Likewise.
	* testsuite/20_util/any/layout.cc: New test.
This commit is contained in:
Jonathan Wakely 2024-08-28 13:07:47 +01:00 • committed by Jonathan Wakely
parent efe6efb6f3
commit dee3c5c6ff
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3 changed files with 24 additions and 2 deletions
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2
libstdc++-v3/include/experimental/any
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@ -102,7 +102,7 @@ inline namespace fundamentals_v1
_Storage& operator=(const _Storage&) = delete;
void* _M_ptr;
aligned_storage<sizeof(_M_ptr), alignof(void*)>::type _M_buffer;
unsigned char _M_buffer[sizeof(_M_ptr)];
};
template<typename _Tp, typename _Safe = is_nothrow_move_constructible<_Tp>,

2
libstdc++-v3/include/std/any
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@ -90,7 +90,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_Storage& operator=(const _Storage&) = delete;
void* _M_ptr;
aligned_storage<sizeof(_M_ptr), alignof(void*)>::type _M_buffer;
unsigned char _M_buffer[sizeof(_M_ptr)];
};
template<typename _Tp, typename _Safe = is_nothrow_move_constructible<_Tp>,

22
libstdc++-v3/testsuite/20_util/any/layout.cc Normal file
View file

@ -0,0 +1,22 @@
// { dg-options "-Wno-deprecated-declarations" }
// { dg-do compile { target c++17 } }
// Verify that r15-3419 did not change the layout of std::any
#include <any>
namespace test {
class any {
union Storage {
constexpr Storage() : ptr(nullptr) { }
void* ptr;
std::aligned_storage<sizeof(ptr), alignof(void*)>::type buffer;
};
void (*manager)(int, const any*, void*);
Storage storage;
};
}
static_assert( sizeof(std::any) == sizeof(test::any) );
static_assert( alignof(std::any) == alignof(test::any) );