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[libc++] Make <set> std::set constexpr as part of P3372R3 #167241

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[libc++] Make <set> std::set constexpr as part of P3372R3 #167241

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c7046ab
Initial patch from PR#134330
vinay-deshmukh Nov 9, 2025
49d74e1
Add test boilerplate for constexpr testing
vinay-deshmukh Nov 9, 2025
594dff9
Get ready for set.cons
vinay-deshmukh Nov 9, 2025
f29268a
Test set.cons
vinay-deshmukh Nov 9, 2025
b2e088a
Test set.erasure
vinay-deshmukh Nov 9, 2025
42f2950
Test set.observers
vinay-deshmukh Nov 9, 2025
b30297e
hash correct version from main
vinay-deshmukh Nov 9, 2025
df77e29
saturation correct version from main
vinay-deshmukh Nov 9, 2025
7ce7dcd
Fix set/ final tests
vinay-deshmukh Nov 10, 2025
5764d91
restore libcxx/test/std/containers/associative/iterator_types.pass.cpp
vinay-deshmukh Nov 10, 2025
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3 changes: 2 additions & 1 deletion libcxx/include/__iterator/erase_if_container.h
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Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,8 @@ _LIBCPP_PUSH_MACROS
_LIBCPP_BEGIN_NAMESPACE_STD

template <class _Container, class _Predicate>
_LIBCPP_HIDE_FROM_ABI typename _Container::size_type __libcpp_erase_if_container(_Container& __c, _Predicate& __pred) {
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 typename _Container::size_type
__libcpp_erase_if_container(_Container& __c, _Predicate& __pred) {
typename _Container::size_type __old_size = __c.size();

const typename _Container::iterator __last = __c.end();
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56 changes: 30 additions & 26 deletions libcxx/include/__node_handle
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Original file line number Diff line number Diff line change
Expand Up @@ -31,29 +31,29 @@ private:
public:
// [container.node.cons], constructors, copy, and assignment
constexpr node-handle() noexcept : ptr_(), alloc_() {}
node-handle(node-handle&&) noexcept;
node-handle& operator=(node-handle&&);
constexpr node-handle(node-handle&&) noexcept; // constexpr since C++26
constexpr node-handle& operator=(node-handle&&); // constexpr since C++26

// [container.node.dtor], destructor
~node-handle();
constexpr ~node-handle(); // constexpr since C++26

// [container.node.observers], observers
value_type& value() const; // not present for map containers
key_type& key() const; // not present for set containers
mapped_type& mapped() const; // not present for set containers
value_type& value() const; // not present for map containers
key_type& key() const; // not present for set containers
constexpr mapped_type& mapped() const; // not present for set containers, constexpr since C++26

allocator_type get_allocator() const;
explicit operator bool() const noexcept;
[[nodiscard]] bool empty() const noexcept; // nodiscard since C++20
constexpr allocator_type get_allocator() const; // constexpr since C++26
constexpr explicit operator bool() const noexcept; // constexpr since C++26
[[nodiscard]] constexpr bool empty() const noexcept; // nodiscard since C++20, constexpr since C++26

// [container.node.modifiers], modifiers
void swap(node-handle&)
constexpr void swap(node-handle&)
noexcept(ator_traits::propagate_on_container_swap::value ||
ator_traits::is_always_equal::value);
ator_traits::is_always_equal::value); // constexpr since C++26

friend void swap(node-handle& x, node-handle& y) noexcept(noexcept(x.swap(y))) {
constexpr friend void swap(node-handle& x, node-handle& y) noexcept(noexcept(x.swap(y))) {
x.swap(y);
}
} // constexpr since C++26
};

*/
Expand Down Expand Up @@ -99,12 +99,12 @@ private:
__node_pointer_type __ptr_ = nullptr;
optional<allocator_type> __alloc_;

_LIBCPP_HIDE_FROM_ABI void __release_ptr() {
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void __release_ptr() {
__ptr_ = nullptr;
__alloc_ = std::nullopt;
}

_LIBCPP_HIDE_FROM_ABI void __destroy_node_pointer() {
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void __destroy_node_pointer() {
if (__ptr_ != nullptr) {
typedef typename __allocator_traits_rebind< allocator_type, _NodeType>::type __node_alloc_type;
__node_alloc_type __alloc(*__alloc_);
Expand All @@ -113,19 +113,20 @@ private:
}
}

_LIBCPP_HIDE_FROM_ABI __basic_node_handle(__node_pointer_type __ptr, allocator_type const& __alloc)
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26
__basic_node_handle(__node_pointer_type __ptr, allocator_type const& __alloc)
: __ptr_(__ptr), __alloc_(__alloc) {}

public:
_LIBCPP_HIDE_FROM_ABI __basic_node_handle() = default;
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 __basic_node_handle() = default;

_LIBCPP_HIDE_FROM_ABI __basic_node_handle(__basic_node_handle&& __other) noexcept
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 __basic_node_handle(__basic_node_handle&& __other) noexcept
: __ptr_(__other.__ptr_), __alloc_(std::move(__other.__alloc_)) {
__other.__ptr_ = nullptr;
__other.__alloc_ = std::nullopt;
}

_LIBCPP_HIDE_FROM_ABI __basic_node_handle& operator=(__basic_node_handle&& __other) {
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 __basic_node_handle& operator=(__basic_node_handle&& __other) {
_LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(
__alloc_ == std::nullopt || __alloc_traits::propagate_on_container_move_assignment::value ||
__alloc_ == __other.__alloc_,
Expand All @@ -144,13 +145,13 @@ public:
return *this;
}

_LIBCPP_HIDE_FROM_ABI allocator_type get_allocator() const { return *__alloc_; }
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 allocator_type get_allocator() const { return *__alloc_; }

_LIBCPP_HIDE_FROM_ABI explicit operator bool() const { return __ptr_ != nullptr; }
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 explicit operator bool() const { return __ptr_ != nullptr; }

[[nodiscard]] _LIBCPP_HIDE_FROM_ABI bool empty() const { return __ptr_ == nullptr; }
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 bool empty() const { return __ptr_ == nullptr; }

_LIBCPP_HIDE_FROM_ABI void swap(__basic_node_handle& __other) noexcept(
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void swap(__basic_node_handle& __other) noexcept(
__alloc_traits::propagate_on_container_swap::value || __alloc_traits::is_always_equal::value) {
using std::swap;
swap(__ptr_, __other.__ptr_);
Expand All @@ -159,26 +160,29 @@ public:
swap(__alloc_, __other.__alloc_);
}

_LIBCPP_HIDE_FROM_ABI friend void
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 friend void
swap(__basic_node_handle& __a, __basic_node_handle& __b) noexcept(noexcept(__a.swap(__b))) {
__a.swap(__b);
}

_LIBCPP_HIDE_FROM_ABI ~__basic_node_handle() { __destroy_node_pointer(); }
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 ~__basic_node_handle() { __destroy_node_pointer(); }
};

template <class _NodeType, class _Derived>
struct __set_node_handle_specifics {
typedef typename _NodeType::__node_value_type value_type;

_LIBCPP_HIDE_FROM_ABI value_type& value() const { return static_cast<_Derived const*>(this)->__ptr_->__get_value(); }
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 value_type& value() const {
return static_cast<_Derived const*>(this)->__ptr_->__get_value();
}
};

template <class _NodeType, class _Derived>
struct __map_node_handle_specifics {
using key_type = __remove_const_t<typename _NodeType::__node_value_type::first_type>;
using mapped_type = typename _NodeType::__node_value_type::second_type;

// This method is not constexpr as per the standard.
_LIBCPP_HIDE_FROM_ABI key_type& key() const {
return const_cast<key_type&>(static_cast<_Derived const*>(this)->__ptr_->__get_value().first);
}
Expand Down
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