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[libc++] Mark more types as trivially relocatable (#89724)
Co-authored-by: Louis Dionne <[email protected]>
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‎libcxx/docs/ReleaseNotes/19.rst

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@@ -58,6 +58,7 @@ Improvements and New Features
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-----------------------------
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- The performance of growing ``std::vector`` has been improved for trivially relocatable types.
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- A lot of types are considered trivially relocatable now, including ``vector`` and ``string``.
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- The performance of ``ranges::fill`` and ``ranges::fill_n`` has been improved for ``vector<bool>::iterator``\s,
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resulting in a performance increase of up to 1400x.
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- The ``std::mismatch`` algorithm has been optimized for integral types, which can lead up to 40x performance

‎libcxx/include/__exception/exception_ptr.h

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@@ -66,6 +66,9 @@ class _LIBCPP_EXPORTED_FROM_ABI exception_ptr {
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friend _LIBCPP_HIDE_FROM_ABI exception_ptr make_exception_ptr(_Ep) _NOEXCEPT;
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public:
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// exception_ptr is basically a COW string.
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using __trivially_relocatable = exception_ptr;
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_LIBCPP_HIDE_FROM_ABI exception_ptr() _NOEXCEPT : __ptr_() {}
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_LIBCPP_HIDE_FROM_ABI exception_ptr(nullptr_t) _NOEXCEPT : __ptr_() {}
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‎libcxx/include/__expected/expected.h

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@@ -31,6 +31,7 @@
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#include <__type_traits/is_swappable.h>
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#include <__type_traits/is_trivially_constructible.h>
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#include <__type_traits/is_trivially_destructible.h>
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#include <__type_traits/is_trivially_relocatable.h>
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#include <__type_traits/is_void.h>
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#include <__type_traits/lazy.h>
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#include <__type_traits/negation.h>
@@ -463,6 +464,11 @@ class expected : private __expected_base<_Tp, _Err> {
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using error_type = _Err;
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using unexpected_type = unexpected<_Err>;
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using __trivially_relocatable =
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__conditional_t<__libcpp_is_trivially_relocatable<_Tp>::value && __libcpp_is_trivially_relocatable<_Err>::value,
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expected,
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void>;
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template <class _Up>
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using rebind = expected<_Up, error_type>;
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‎libcxx/include/__locale

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@@ -49,6 +49,9 @@ _LIBCPP_HIDE_FROM_ABI const _Facet& use_facet(const locale&);
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class _LIBCPP_EXPORTED_FROM_ABI locale {
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public:
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// locale is essentially a shared_ptr that doesn't support weak_ptrs and never got a move constructor.
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using __trivially_relocatable = locale;
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// types:
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class _LIBCPP_EXPORTED_FROM_ABI facet;
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class _LIBCPP_EXPORTED_FROM_ABI id;

‎libcxx/include/__memory/shared_ptr.h

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@@ -419,6 +419,10 @@ class _LIBCPP_SHARED_PTR_TRIVIAL_ABI _LIBCPP_TEMPLATE_VIS shared_ptr {
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typedef _Tp element_type;
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#endif
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// A shared_ptr contains only two raw pointers which point to the heap and move constructing already doesn't require
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// any bookkeeping, so it's always trivially relocatable.
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using __trivially_relocatable = shared_ptr;
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private:
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element_type* __ptr_;
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__shared_weak_count* __cntrl_;
@@ -1301,6 +1305,10 @@ class _LIBCPP_SHARED_PTR_TRIVIAL_ABI _LIBCPP_TEMPLATE_VIS weak_ptr {
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typedef _Tp element_type;
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#endif
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// A weak_ptr contains only two raw pointers which point to the heap and move constructing already doesn't require
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// any bookkeeping, so it's always trivially relocatable.
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using __trivially_relocatable = weak_ptr;
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private:
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element_type* __ptr_;
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__shared_weak_count* __cntrl_;

‎libcxx/include/__split_buffer

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@@ -24,12 +24,14 @@
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#include <__memory/pointer_traits.h>
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#include <__memory/swap_allocator.h>
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#include <__type_traits/add_lvalue_reference.h>
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#include <__type_traits/conditional.h>
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#include <__type_traits/enable_if.h>
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#include <__type_traits/integral_constant.h>
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#include <__type_traits/is_nothrow_assignable.h>
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#include <__type_traits/is_nothrow_constructible.h>
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#include <__type_traits/is_swappable.h>
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#include <__type_traits/is_trivially_destructible.h>
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#include <__type_traits/is_trivially_relocatable.h>
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#include <__type_traits/remove_reference.h>
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#include <__utility/forward.h>
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#include <__utility/move.h>
@@ -64,6 +66,15 @@ public:
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using iterator = pointer;
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using const_iterator = const_pointer;
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// A __split_buffer contains the following members which may be trivially relocatable:
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// - pointer: may be trivially relocatable, so it's checked
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// - allocator_type: may be trivially relocatable, so it's checked
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// __split_buffer doesn't have any self-references, so it's trivially relocatable if its members are.
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using __trivially_relocatable = __conditional_t<
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__libcpp_is_trivially_relocatable<pointer>::value && __libcpp_is_trivially_relocatable<allocator_type>::value,
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__split_buffer,
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void>;
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pointer __first_;
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pointer __begin_;
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pointer __end_;

‎libcxx/include/__utility/pair.h

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@@ -34,6 +34,7 @@
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#include <__type_traits/is_nothrow_constructible.h>
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#include <__type_traits/is_same.h>
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#include <__type_traits/is_swappable.h>
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#include <__type_traits/is_trivially_relocatable.h>
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#include <__type_traits/nat.h>
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#include <__type_traits/remove_cvref.h>
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#include <__type_traits/unwrap_ref.h>
@@ -71,6 +72,11 @@ struct _LIBCPP_TEMPLATE_VIS pair
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_T1 first;
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_T2 second;
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using __trivially_relocatable =
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__conditional_t<__libcpp_is_trivially_relocatable<_T1>::value && __libcpp_is_trivially_relocatable<_T2>::value,
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pair,
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void>;
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_LIBCPP_HIDE_FROM_ABI pair(pair const&) = default;
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_LIBCPP_HIDE_FROM_ABI pair(pair&&) = default;
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‎libcxx/include/array

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@@ -130,6 +130,7 @@ template <size_t I, class T, size_t N> const T&& get(const array<T, N>&&) noexce
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#include <__type_traits/is_nothrow_constructible.h>
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#include <__type_traits/is_same.h>
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#include <__type_traits/is_swappable.h>
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#include <__type_traits/is_trivially_relocatable.h>
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#include <__type_traits/remove_cv.h>
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#include <__utility/empty.h>
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#include <__utility/integer_sequence.h>
@@ -166,6 +167,8 @@ _LIBCPP_BEGIN_NAMESPACE_STD
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template <class _Tp, size_t _Size>
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struct _LIBCPP_TEMPLATE_VIS array {
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using __trivially_relocatable = __conditional_t<__libcpp_is_trivially_relocatable<_Tp>::value, array, void>;
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// types:
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using __self = array;
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using value_type = _Tp;

‎libcxx/include/deque

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@@ -477,6 +477,16 @@ public:
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using reverse_iterator = std::reverse_iterator<iterator>;
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using const_reverse_iterator = std::reverse_iterator<const_iterator>;
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// A deque contains the following members which may be trivially relocatable:
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// - __map: is a `__split_buffer`, see `__split_buffer` for more information on when it is trivially relocatable
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// - size_type: is always trivially relocatable, since it is required to be an integral type
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// - allocator_type: may not be trivially relocatable, so it's checked
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// None of these are referencing the `deque` itself, so if all of them are trivially relocatable, `deque` is too.
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using __trivially_relocatable = __conditional_t<
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__libcpp_is_trivially_relocatable<__map>::value && __libcpp_is_trivially_relocatable<allocator_type>::value,
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deque,
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void>;
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static_assert(is_same<allocator_type, __rebind_alloc<__alloc_traits, value_type> >::value,
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"[allocator.requirements] states that rebinding an allocator to the same type should result in the "
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"original allocator");

‎libcxx/include/optional

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@@ -209,6 +209,7 @@ namespace std {
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#include <__type_traits/is_trivially_assignable.h>
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#include <__type_traits/is_trivially_constructible.h>
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#include <__type_traits/is_trivially_destructible.h>
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#include <__type_traits/is_trivially_relocatable.h>
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#include <__type_traits/negation.h>
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#include <__type_traits/remove_const.h>
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#include <__type_traits/remove_cvref.h>
@@ -580,6 +581,8 @@ class _LIBCPP_DECLSPEC_EMPTY_BASES optional
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public:
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using value_type = _Tp;
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using __trivially_relocatable = conditional_t<__libcpp_is_trivially_relocatable<_Tp>::value, optional, void>;
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private:
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// Disable the reference extension using this static assert.
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static_assert(!is_same_v<__remove_cvref_t<value_type>, in_place_t>,

‎libcxx/include/tuple

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@@ -240,6 +240,7 @@ template <class... Types>
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#include <__type_traits/is_reference.h>
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#include <__type_traits/is_same.h>
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#include <__type_traits/is_swappable.h>
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#include <__type_traits/is_trivially_relocatable.h>
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#include <__type_traits/lazy.h>
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#include <__type_traits/maybe_const.h>
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#include <__type_traits/nat.h>
@@ -537,6 +538,8 @@ class _LIBCPP_TEMPLATE_VIS tuple {
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get(const tuple<_Up...>&&) _NOEXCEPT;
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public:
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using __trivially_relocatable = __conditional_t<_And<__libcpp_is_trivially_relocatable<_Tp>...>::value, tuple, void>;
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// [tuple.cnstr]
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// tuple() constructors (including allocator_arg_t variants)

‎libcxx/include/variant

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@@ -241,6 +241,7 @@ namespace std {
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#include <__type_traits/is_trivially_assignable.h>
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#include <__type_traits/is_trivially_constructible.h>
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#include <__type_traits/is_trivially_destructible.h>
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#include <__type_traits/is_trivially_relocatable.h>
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#include <__type_traits/is_void.h>
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#include <__type_traits/remove_const.h>
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#include <__type_traits/remove_cvref.h>
@@ -1180,6 +1181,9 @@ class _LIBCPP_TEMPLATE_VIS _LIBCPP_DECLSPEC_EMPTY_BASES variant
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using __first_type = variant_alternative_t<0, variant>;
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public:
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using __trivially_relocatable =
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conditional_t<_And<__libcpp_is_trivially_relocatable<_Types>...>::value, variant, void>;
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template <bool _Dummy = true,
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enable_if_t<__dependent_type<is_default_constructible<__first_type>, _Dummy>::value, int> = 0>
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_LIBCPP_HIDE_FROM_ABI constexpr variant() noexcept(is_nothrow_default_constructible_v<__first_type>)

‎libcxx/include/vector

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@@ -406,6 +406,15 @@ public:
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typedef std::reverse_iterator<iterator> reverse_iterator;
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typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
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// A vector containers the following members which may be trivially relocatable:
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// - pointer: may be trivially relocatable, so it's checked
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// - allocator_type: may be trivially relocatable, so it's checked
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// vector doesn't contain any self-references, so it's trivially relocatable if its members are.
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using __trivially_relocatable = __conditional_t<
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__libcpp_is_trivially_relocatable<pointer>::value && __libcpp_is_trivially_relocatable<allocator_type>::value,
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vector,
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void>;
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static_assert((is_same<typename allocator_type::value_type, value_type>::value),
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"Allocator::value_type must be same type as value_type");
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‎libcxx/test/libcxx/transitive_includes/cxx03.csv

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@@ -903,6 +903,7 @@ thread type_traits
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thread version
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tuple compare
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tuple cstddef
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tuple cstdint
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tuple exception
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tuple iosfwd
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tuple new

‎libcxx/test/libcxx/transitive_includes/cxx11.csv

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thread version
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tuple compare
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tuple cstddef
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tuple cstdint
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tuple exception
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tuple iosfwd
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tuple new

‎libcxx/test/libcxx/transitive_includes/cxx14.csv

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thread version
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tuple compare
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tuple cstddef
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tuple cstdint
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tuple exception
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tuple iosfwd
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tuple new

‎libcxx/test/libcxx/transitive_includes/cxx17.csv

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thread version
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tuple compare
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tuple cstddef
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tuple cstdint
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tuple exception
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tuple iosfwd
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tuple new

‎libcxx/test/libcxx/transitive_includes/cxx20.csv

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thread version
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tuple compare
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tuple cstddef
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tuple cstdint
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tuple exception
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tuple iosfwd
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tuple new

‎libcxx/test/libcxx/transitive_includes/cxx23.csv

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@@ -151,6 +151,7 @@ exception typeinfo
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exception version
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execution version
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expected cstddef
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expected cstdint
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expected initializer_list
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expected new
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expected version
@@ -484,6 +485,7 @@ regex typeinfo
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regex vector
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regex version
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scoped_allocator cstddef
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scoped_allocator cstdint
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scoped_allocator limits
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scoped_allocator new
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scoped_allocator tuple
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thread version
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tuple compare
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tuple cstddef
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tuple cstdint
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tuple version
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type_traits cstddef
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type_traits cstdint
@@ -674,6 +677,7 @@ unordered_set tuple
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unordered_set version
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utility compare
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utility cstddef
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utility cstdint
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utility initializer_list
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utility limits
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utility version

‎libcxx/test/libcxx/transitive_includes/cxx26.csv

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exception version
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execution version
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expected cstddef
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expected cstdint
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expected initializer_list
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expected new
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expected version
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regex vector
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regex version
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scoped_allocator cstddef
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scoped_allocator cstdint
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scoped_allocator limits
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scoped_allocator new
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scoped_allocator tuple
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thread version
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tuple compare
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tuple cstddef
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tuple cstdint
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tuple version
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type_traits cstddef
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type_traits cstdint
@@ -674,6 +677,7 @@ unordered_set tuple
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unordered_set version
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utility compare
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utility cstddef
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utility cstdint
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utility initializer_list
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utility limits
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utility version

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