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libstdc++: Fix redefinition error in std::tuple [PR108822]

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When using a compiler that doesn't define __cpp_conditional_explicit
there's a redefinition error for tuple::__nothrow_assignable. This is
because it's defined in different places for the pre-C++20 and C++20
implementations, which are controled by different preprocessor
conditions. For certain combinations of C++20 feature test macros it's
possible for both __nothrow_assignable definitions to be in scope.

Move the pre-C++20 __assignable and __nothrow_assignable definitions adjacent to
their use, so that only one set of definitions is visible for any given
set of feature test macros.

libstdc++-v3/ChangeLog:

	PR libstdc++/108822
	* include/std/tuple (__assignable, __is_nothrow_assignable):
	Move pre-C++20 definitions adjacent to their use.
This commit is contained in:
Jonathan Wakely 2024-01-15 16:51:39 +00:00
parent 6c703b4eb6
commit 1e88a151f8
1 changed files with 19 additions and 16 deletions
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35
libstdc++-v3/include/std/tuple
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@ -1237,20 +1237,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_TCC<_Cond>::template __is_explicitly_constructible<_Args...>(),
bool>;
template<typename... _UElements>
static constexpr
__enable_if_t<sizeof...(_UElements) == sizeof...(_Elements), bool>
__assignable()
{ return __and_<is_assignable<_Elements&, _UElements>...>::value; }
// Condition for noexcept-specifier of an assignment operator.
template<typename... _UElements>
static constexpr bool __nothrow_assignable()
{
return
__and_<is_nothrow_assignable<_Elements&, _UElements>...>::value;
}
// Condition for noexcept-specifier of a constructor.
template<typename... _UElements>
static constexpr bool __nothrow_constructible()
@ -1685,7 +1671,24 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
operator=(_UTuple&& __u) const;
#endif // C++23
#else // ! concepts
#else // ! (concepts && consteval)
private:
template<typename... _UElements>
static constexpr
__enable_if_t<sizeof...(_UElements) == sizeof...(_Elements), bool>
__assignable()
{ return __and_<is_assignable<_Elements&, _UElements>...>::value; }
// Condition for noexcept-specifier of an assignment operator.
template<typename... _UElements>
static constexpr bool __nothrow_assignable()
{
return
__and_<is_nothrow_assignable<_Elements&, _UElements>...>::value;
}
public:
_GLIBCXX20_CONSTEXPR
tuple&
@ -1728,7 +1731,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
this->_M_assign(std::move(__in));
return *this;
}
#endif // concepts
#endif // concepts && consteval
// tuple swap
_GLIBCXX20_CONSTEXPR