[libcxx-commits] [libcxx] [libc++] Decouple `optional<T>` and `optional<T&>` base classes (PR #215012)
William Tran-Viet via libcxx-commits
libcxx-commits at lists.llvm.org
Sun Aug 9 12:29:47 PDT 2026
https://github.com/smallp-o-p updated https://github.com/llvm/llvm-project/pull/215012
>From 76da03f5c3f475c241cb12ed58db39a327a956ec Mon Sep 17 00:00:00 2001
From: William Tran-Viet <wtranviet at proton.me>
Date: Fri, 7 Aug 2026 16:19:10 -0400
Subject: [PATCH 1/9] [libc++] Decouple `optional<T>` and `optional<T&>` base
classes
---
libcxx/include/__optional/common.h | 3 --
libcxx/include/__optional/optional.h | 2 +-
libcxx/include/__optional/optional_ref.h | 49 ++++++++++--------------
3 files changed, 22 insertions(+), 32 deletions(-)
diff --git a/libcxx/include/__optional/common.h b/libcxx/include/__optional/common.h
index 5ddb993f3e376..26031f658a904 100644
--- a/libcxx/include/__optional/common.h
+++ b/libcxx/include/__optional/common.h
@@ -64,9 +64,6 @@ inline constexpr bool __is_std_optional_v = false;
template <class _Tp>
inline constexpr bool __is_std_optional_v<optional<_Tp>> = true;
-template <class _Tp, bool = is_reference<_Tp>::value>
-struct __optional_storage_base;
-
# if _LIBCPP_STD_VER < 26
template <class _Tp>
inline constexpr bool __is_valid_optional_contained_type = is_object_v<_Tp>;
diff --git a/libcxx/include/__optional/optional.h b/libcxx/include/__optional/optional.h
index 8d6a9fbed8599..3cadbae1fcf14 100644
--- a/libcxx/include/__optional/optional.h
+++ b/libcxx/include/__optional/optional.h
@@ -136,7 +136,7 @@ struct __optional_destruct_base<_Tp, true> {
}
};
-template <class _Tp, bool>
+template <class _Tp>
struct __optional_storage_base : __optional_destruct_base<_Tp> {
using __base _LIBCPP_NODEBUG = __optional_destruct_base<_Tp>;
using value_type = _Tp;
diff --git a/libcxx/include/__optional/optional_ref.h b/libcxx/include/__optional/optional_ref.h
index d137b3c40c7e6..e99fc8cf8f143 100644
--- a/libcxx/include/__optional/optional_ref.h
+++ b/libcxx/include/__optional/optional_ref.h
@@ -49,17 +49,17 @@
_LIBCPP_PUSH_MACROS
#include <__undef_macros>
-#if _LIBCPP_STD_VER >= 17
+#if _LIBCPP_STD_VER >= 26
_LIBCPP_BEGIN_NAMESPACE_STD
template <class _Tp>
-struct __optional_storage_base<_Tp, true> {
+struct __optional_ref_base {
using value_type = _Tp;
using __raw_type _LIBCPP_NODEBUG = remove_reference_t<_Tp>;
__raw_type* __value_;
- _LIBCPP_HIDE_FROM_ABI constexpr __optional_storage_base() noexcept : __value_(nullptr) {}
+ _LIBCPP_HIDE_FROM_ABI constexpr __optional_ref_base() noexcept : __value_(nullptr) {}
template <class _Up>
_LIBCPP_HIDE_FROM_ABI constexpr void __convert_init_ref_val(_Up&& __val) {
@@ -68,7 +68,7 @@ struct __optional_storage_base<_Tp, true> {
}
template <class _UArg>
- _LIBCPP_HIDE_FROM_ABI constexpr explicit __optional_storage_base(in_place_t, _UArg&& __uarg) {
+ _LIBCPP_HIDE_FROM_ABI constexpr explicit __optional_ref_base(in_place_t, _UArg&& __uarg) {
static_assert(!__reference_constructs_from_temporary_v<_Tp, _UArg>,
"Attempted to construct a reference element in optional from a "
"possible temporary");
@@ -77,7 +77,7 @@ struct __optional_storage_base<_Tp, true> {
# if _LIBCPP_STD_VER >= 23
template <class _Fp, class... _Args>
- constexpr __optional_storage_base(__optional_construct_from_invoke_tag, _Fp&& __f, _Args&&... __args) {
+ constexpr __optional_ref_base(__optional_construct_from_invoke_tag, _Fp&& __f, _Args&&... __args) {
__convert_init_ref_val(std::forward<invoke_result_t<_Fp, _Args...>>(
std::invoke(std::forward<_Fp>(__f), std::forward<_Args>(__args)...)));
}
@@ -116,7 +116,7 @@ struct __optional_storage_base<_Tp, true> {
}
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __swap(__optional_storage_base& __rhs) noexcept {
+ _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __swap(__optional_ref_base& __rhs) noexcept {
std::swap(__value_, __rhs.__value_);
}
@@ -138,43 +138,38 @@ struct __optional_storage_base<_Tp, true> {
}
};
-# if _LIBCPP_STD_VER >= 26
-
-template <class _Tp>
-struct __optional_iterator_base;
-
template <class _Tp>
-struct __optional_iterator_base<_Tp&> : __optional_storage_base<_Tp&> {
- using __optional_storage_base<_Tp&>::__optional_storage_base;
+struct __optional_ref_iterator_base : __optional_ref_base<_Tp&> {
+ using __optional_ref_base<_Tp&>::__optional_ref_base;
};
-# if _LIBCPP_HAS_EXPERIMENTAL_OPTIONAL_ITERATOR
+# if _LIBCPP_HAS_EXPERIMENTAL_OPTIONAL_ITERATOR
template <class _Tp>
requires(is_object_v<_Tp> && !__is_unbounded_array_v<_Tp>)
-struct __optional_iterator_base<_Tp&> : __optional_storage_base<_Tp&> {
+struct __optional_ref_iterator_base<_Tp&> : __optional_ref_base<_Tp&> {
private:
using __pointer _LIBCPP_NODEBUG = add_pointer_t<_Tp>;
public:
- using __optional_storage_base<_Tp&>::__optional_storage_base;
+ using __optional_ref_base<_Tp&>::__optional_ref_base;
-# ifdef _LIBCPP_ABI_BOUNDED_ITERATORS_IN_OPTIONAL
+# ifdef _LIBCPP_ABI_BOUNDED_ITERATORS_IN_OPTIONAL
using iterator = __bounded_iter<__pointer>;
-# else
+# else
using iterator = __capacity_aware_iterator<__pointer, optional<_Tp&>, 1>;
-# endif
+# endif
// [optional.ref.iterators], iterator support
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto begin() const noexcept {
auto* __ptr = this->has_value() ? std::addressof(this->__get()) : nullptr;
-# ifdef _LIBCPP_ABI_BOUNDED_ITERATORS_IN_OPTIONAL
+# ifdef _LIBCPP_ABI_BOUNDED_ITERATORS_IN_OPTIONAL
return std::__make_bounded_iter(__ptr, __ptr, __ptr + (this->has_value() ? 1 : 0));
-# else
+# else
return std::__make_capacity_aware_iterator<__pointer, optional<_Tp&>, 1>(__ptr);
-# endif
+# endif
}
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto end() const noexcept {
@@ -182,11 +177,11 @@ struct __optional_iterator_base<_Tp&> : __optional_storage_base<_Tp&> {
}
};
-# endif
+# endif
template <class _Tp>
-class optional<_Tp&> : public __optional_iterator_base<_Tp&> {
- using __base _LIBCPP_NODEBUG = __optional_iterator_base<_Tp&>;
+class optional<_Tp&> : public __optional_ref_iterator_base<_Tp&> {
+ using __base _LIBCPP_NODEBUG = __optional_ref_iterator_base<_Tp&>;
template <class _Up, class _QualUp>
static constexpr bool __check_optionalU_ctor =
@@ -346,11 +341,9 @@ class optional<_Tp&> : public __optional_iterator_base<_Tp&> {
using __base::reset;
};
-# endif // _LIBCPP_STD_VER >= 26
-
_LIBCPP_END_NAMESPACE_STD
-#endif // _LIBCPP_STD_VER >= 17
+#endif // _LIBCPP_STD_VER >= 26
_LIBCPP_POP_MACROS
>From 0e679078af8f75b00b5448a3c5c80dbef6605873 Mon Sep 17 00:00:00 2001
From: William Tran-Viet <wtranviet at proton.me>
Date: Sat, 8 Aug 2026 15:37:28 -0400
Subject: [PATCH 2/9] Fix static assert error message
---
libcxx/include/__optional/optional.h | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/libcxx/include/__optional/optional.h b/libcxx/include/__optional/optional.h
index 3cadbae1fcf14..7955ea2812d32 100644
--- a/libcxx/include/__optional/optional.h
+++ b/libcxx/include/__optional/optional.h
@@ -73,6 +73,11 @@ struct __optional_destruct_base;
template <class _Tp>
struct __optional_destruct_base<_Tp, false> {
typedef _Tp value_type;
+# if _LIBCPP_STD_VER >= 26
+ static_assert(!is_rvalue_reference_v<_Tp>, "instantiation of optional with an rvalue reference type is ill-formed");
+# else
+ static_assert(!is_reference_v<_Tp>, "instantiation of optional with a reference type is ill-formed");
+# endif
static_assert(is_object_v<value_type>, "instantiation of optional with a non-object type is undefined behavior");
union {
char __null_state_;
@@ -109,6 +114,11 @@ struct __optional_destruct_base<_Tp, false> {
template <class _Tp>
struct __optional_destruct_base<_Tp, true> {
typedef _Tp value_type;
+# if _LIBCPP_STD_VER >= 26
+ static_assert(!is_rvalue_reference_v<_Tp>, "instantiation of optional with an rvalue reference type is ill-formed");
+# else
+ static_assert(!is_reference_v<_Tp>, "instantiation of optional with a reference type is ill-formed");
+# endif
static_assert(is_object_v<value_type>, "instantiation of optional with a non-object type is undefined behavior");
union {
char __null_state_;
@@ -419,11 +429,6 @@ class _LIBCPP_DECLSPEC_EMPTY_BASES optional
private:
static_assert(!is_same_v<remove_cv_t<_Tp>, in_place_t>, "instantiation of optional with in_place_t is ill-formed");
static_assert(!is_same_v<remove_cv_t<_Tp>, nullopt_t>, "instantiation of optional with nullopt_t is ill-formed");
-# if _LIBCPP_STD_VER >= 26
- static_assert(!is_rvalue_reference_v<_Tp>, "instantiation of optional with an rvalue reference type is ill-formed");
-# else
- static_assert(!is_reference_v<_Tp>, "instantiation of optional with a reference type is ill-formed");
-# endif
static_assert(is_destructible_v<_Tp>, "instantiation of optional with a non-destructible type is ill-formed");
static_assert(!is_array_v<_Tp>, "instantiation of optional with an array type is ill-formed");
>From e90f5cc1012eed7bbae0e1dd09dfe303296a42c4 Mon Sep 17 00:00:00 2001
From: William Tran-Viet <wtranviet at proton.me>
Date: Sun, 9 Aug 2026 15:02:54 -0400
Subject: [PATCH 3/9] Inline optional<T> iterator base
---
libcxx/include/__optional/optional.h | 107 ++++++++++++---------------
1 file changed, 49 insertions(+), 58 deletions(-)
diff --git a/libcxx/include/__optional/optional.h b/libcxx/include/__optional/optional.h
index 7955ea2812d32..f864f5eddb90b 100644
--- a/libcxx/include/__optional/optional.h
+++ b/libcxx/include/__optional/optional.h
@@ -358,68 +358,12 @@ using __optional_sfinae_assign_base_t _LIBCPP_NODEBUG =
__sfinae_assign_base< (is_copy_constructible_v<_Tp> && is_copy_assignable_v<_Tp>),
(is_move_constructible_v<_Tp> && is_move_assignable_v<_Tp>)>;
-template <class _Tp>
-struct __optional_iterator_base : __optional_move_assign_base<_Tp> {
- using __optional_move_assign_base<_Tp>::__optional_move_assign_base;
-};
-
-# if _LIBCPP_STD_VER >= 26 && _LIBCPP_HAS_EXPERIMENTAL_OPTIONAL_ITERATOR
-
-template <class _Tp>
- requires is_object_v<_Tp>
-struct __optional_iterator_base<_Tp> : __optional_move_assign_base<_Tp> {
-private:
- using __pointer _LIBCPP_NODEBUG = add_pointer_t<_Tp>;
- using __const_pointer _LIBCPP_NODEBUG = add_pointer_t<const _Tp>;
-
-public:
- using __optional_move_assign_base<_Tp>::__optional_move_assign_base;
-
-# ifdef _LIBCPP_ABI_BOUNDED_ITERATORS_IN_OPTIONAL
- using iterator = __bounded_iter<__pointer>;
- using const_iterator = __bounded_iter<__const_pointer>;
-# else
- using iterator = __capacity_aware_iterator<__pointer, optional<_Tp>, 1>;
- using const_iterator = __capacity_aware_iterator<__const_pointer, optional<_Tp>, 1>;
-# endif
-
- // [optional.iterators], iterator support
- [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr iterator begin() noexcept {
- auto* __ptr = std::addressof(this->__get());
-
-# ifdef _LIBCPP_ABI_BOUNDED_ITERATORS_IN_OPTIONAL
- return std::__make_bounded_iter(__ptr, __ptr, __ptr + (this->has_value() ? 1 : 0));
-# else
- return std::__make_capacity_aware_iterator<__pointer, optional<_Tp>, 1>(__ptr);
-# endif
- }
-
- [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr const_iterator begin() const noexcept {
- auto* __ptr = std::addressof(this->__get());
-
-# ifdef _LIBCPP_ABI_BOUNDED_ITERATORS_IN_OPTIONAL
- return std::__make_bounded_iter(__ptr, __ptr, __ptr + (this->has_value() ? 1 : 0));
-# else
- return std::__make_capacity_aware_iterator<__const_pointer, optional<_Tp>, 1>(__ptr);
-# endif
- }
-
- [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr iterator end() noexcept {
- return begin() + (this->has_value() ? 1 : 0);
- }
- [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr const_iterator end() const noexcept {
- return begin() + (this->has_value() ? 1 : 0);
- }
-};
-
-# endif // _LIBCPP_STD_VER >= 26 && _LIBCPP_HAS_EXPERIMENTAL_OPTIONAL_ITERATOR
-
template <class _Tp>
class _LIBCPP_DECLSPEC_EMPTY_BASES optional
- : public __optional_iterator_base<_Tp>,
+ : public __optional_move_assign_base<_Tp>,
private __optional_sfinae_ctor_base_t<_Tp>,
private __optional_sfinae_assign_base_t<_Tp> {
- using __base _LIBCPP_NODEBUG = __optional_iterator_base<_Tp>;
+ using __base _LIBCPP_NODEBUG = __optional_move_assign_base<_Tp>;
public:
using value_type = __libcpp_remove_reference_t<_Tp>;
@@ -750,6 +694,53 @@ class _LIBCPP_DECLSPEC_EMPTY_BASES optional
# endif // _LIBCPP_STD_VER >= 23
using __base::reset;
+
+# if _LIBCPP_STD_VER >= 26 && _LIBCPP_HAS_EXPERIMENTAL_OPTIONAL_ITERATOR
+
+private:
+ using __pointer _LIBCPP_NODEBUG = add_pointer_t<_Tp>;
+ using __const_pointer _LIBCPP_NODEBUG = add_pointer_t<const _Tp>;
+
+public:
+ using __optional_move_assign_base<_Tp>::__optional_move_assign_base;
+
+# ifdef _LIBCPP_ABI_BOUNDED_ITERATORS_IN_OPTIONAL
+ using iterator = __bounded_iter<__pointer>;
+ using const_iterator = __bounded_iter<__const_pointer>;
+# else
+ using iterator = __capacity_aware_iterator<__pointer, optional<_Tp>, 1>;
+ using const_iterator = __capacity_aware_iterator<__const_pointer, optional<_Tp>, 1>;
+# endif
+
+ // [optional.iterators], iterator support
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr iterator begin() noexcept {
+ auto* __ptr = std::addressof(this->__get());
+
+# ifdef _LIBCPP_ABI_BOUNDED_ITERATORS_IN_OPTIONAL
+ return std::__make_bounded_iter(__ptr, __ptr, __ptr + (this->has_value() ? 1 : 0));
+# else
+ return std::__make_capacity_aware_iterator<__pointer, optional<_Tp>, 1>(__ptr);
+# endif
+ }
+
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr const_iterator begin() const noexcept {
+ auto* __ptr = std::addressof(this->__get());
+
+# ifdef _LIBCPP_ABI_BOUNDED_ITERATORS_IN_OPTIONAL
+ return std::__make_bounded_iter(__ptr, __ptr, __ptr + (this->has_value() ? 1 : 0));
+# else
+ return std::__make_capacity_aware_iterator<__const_pointer, optional<_Tp>, 1>(__ptr);
+# endif
+ }
+
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr iterator end() noexcept {
+ return begin() + (this->has_value() ? 1 : 0);
+ }
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr const_iterator end() const noexcept {
+ return begin() + (this->has_value() ? 1 : 0);
+ }
+
+# endif // _LIBCPP_STD_VER >= 26 && _LIBCPP_HAS_EXPERIMENTAL_OPTIONAL_ITERATOR
};
_LIBCPP_END_NAMESPACE_STD
>From a34f19711cf9924d2802d1cfd3755d634633b3db Mon Sep 17 00:00:00 2001
From: William Tran-Viet <wtranviet at proton.me>
Date: Sun, 9 Aug 2026 15:20:03 -0400
Subject: [PATCH 4/9] Inline optional<T> optional.observe
---
libcxx/include/__optional/optional.h | 111 +++++++++++++--------------
1 file changed, 53 insertions(+), 58 deletions(-)
diff --git a/libcxx/include/__optional/optional.h b/libcxx/include/__optional/optional.h
index f864f5eddb90b..99ee2578d4ff8 100644
--- a/libcxx/include/__optional/optional.h
+++ b/libcxx/include/__optional/optional.h
@@ -201,61 +201,6 @@ struct __optional_storage_base : __optional_destruct_base<_Tp> {
}
}
}
-
- // [optional.observe]
- _LIBCPP_HIDE_FROM_ABI constexpr add_pointer_t<_Tp const> operator->() const noexcept {
- _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(this->has_value(), "optional operator-> called on a disengaged value");
- return std::addressof(this->__get());
- }
-
- _LIBCPP_HIDE_FROM_ABI constexpr add_pointer_t<_Tp> operator->() noexcept {
- _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(this->has_value(), "optional operator-> called on a disengaged value");
- return std::addressof(this->__get());
- }
-
- [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr const _Tp& operator*() const& noexcept {
- _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(this->has_value(), "optional operator* called on a disengaged value");
- return this->__get();
- }
-
- [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp& operator*() & noexcept {
- _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(this->has_value(), "optional operator* called on a disengaged value");
- return this->__get();
- }
-
- [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp&& operator*() && noexcept {
- _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(this->has_value(), "optional operator* called on a disengaged value");
- return std::move(this->__get());
- }
-
- [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr const _Tp&& operator*() const&& noexcept {
- _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(this->has_value(), "optional operator* called on a disengaged value");
- return std::move(this->__get());
- }
-
- [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp const& value() const& {
- if (!this->has_value())
- std::__throw_bad_optional_access();
- return this->__get();
- }
-
- [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp& value() & {
- if (!this->has_value())
- std::__throw_bad_optional_access();
- return this->__get();
- }
-
- [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp&& value() && {
- if (!this->has_value())
- std::__throw_bad_optional_access();
- return std::move(this->__get());
- }
-
- [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp const&& value() const&& {
- if (!this->has_value())
- std::__throw_bad_optional_access();
- return std::move(this->__get());
- }
};
template <class _Tp, bool = is_trivially_copy_constructible_v<_Tp>>
@@ -554,14 +499,64 @@ class _LIBCPP_DECLSPEC_EMPTY_BASES optional
this->__swap(__opt);
}
- using __base::operator*;
- using __base::operator->;
+ // [optional.observe]
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr const _Tp& operator*() const& noexcept {
+ _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(this->has_value(), "optional operator* called on a disengaged value");
+ return this->__get();
+ }
+
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp& operator*() & noexcept {
+ _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(this->has_value(), "optional operator* called on a disengaged value");
+ return this->__get();
+ }
+
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp&& operator*() && noexcept {
+ _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(this->has_value(), "optional operator* called on a disengaged value");
+ return std::move(this->__get());
+ }
+
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr const _Tp&& operator*() const&& noexcept {
+ _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(this->has_value(), "optional operator* called on a disengaged value");
+ return std::move(this->__get());
+ }
+ _LIBCPP_HIDE_FROM_ABI constexpr add_pointer_t<_Tp const> operator->() const noexcept {
+ _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(this->has_value(), "optional operator-> called on a disengaged value");
+ return std::addressof(this->__get());
+ }
+
+ _LIBCPP_HIDE_FROM_ABI constexpr add_pointer_t<_Tp> operator->() noexcept {
+ _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(this->has_value(), "optional operator-> called on a disengaged value");
+ return std::addressof(this->__get());
+ }
+
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp const& value() const& {
+ if (!this->has_value())
+ std::__throw_bad_optional_access();
+ return this->__get();
+ }
+
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp& value() & {
+ if (!this->has_value())
+ std::__throw_bad_optional_access();
+ return this->__get();
+ }
+
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp&& value() && {
+ if (!this->has_value())
+ std::__throw_bad_optional_access();
+ return std::move(this->__get());
+ }
+
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp const&& value() const&& {
+ if (!this->has_value())
+ std::__throw_bad_optional_access();
+ return std::move(this->__get());
+ }
_LIBCPP_HIDE_FROM_ABI constexpr explicit operator bool() const noexcept { return has_value(); }
using __base::__get;
using __base::has_value;
- using __base::value;
template <class _Up = remove_cv_t<_Tp>>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp value_or(_Up&& __v) const& {
>From a8c64b867945fd9addda6fcafc6613ad2d1a67b3 Mon Sep 17 00:00:00 2001
From: William Tran-Viet <wtranviet at proton.me>
Date: Sun, 9 Aug 2026 15:21:12 -0400
Subject: [PATCH 5/9] Inline optional<T> swap
---
libcxx/include/__optional/optional.h | 31 ++++++++++++----------------
1 file changed, 13 insertions(+), 18 deletions(-)
diff --git a/libcxx/include/__optional/optional.h b/libcxx/include/__optional/optional.h
index 99ee2578d4ff8..5aa3c936760b7 100644
--- a/libcxx/include/__optional/optional.h
+++ b/libcxx/include/__optional/optional.h
@@ -184,23 +184,6 @@ struct __optional_storage_base : __optional_destruct_base<_Tp> {
__construct(std::forward<_That>(__opt).__get());
}
}
-
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void
- __swap(__optional_storage_base& __rhs) noexcept(is_nothrow_move_constructible_v<_Tp> && is_nothrow_swappable_v<_Tp>) {
- using std::swap;
- if (this->has_value() == __rhs.has_value()) {
- if (this->has_value())
- swap(this->__get(), __rhs.__get());
- } else {
- if (this->has_value()) {
- __rhs.__construct(std::move(this->__get()));
- this->reset();
- } else {
- this->__construct(std::move(__rhs.__get()));
- __rhs.reset();
- }
- }
- }
};
template <class _Tp, bool = is_trivially_copy_constructible_v<_Tp>>
@@ -496,7 +479,19 @@ class _LIBCPP_DECLSPEC_EMPTY_BASES optional
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void
swap(optional& __opt) noexcept((is_nothrow_move_constructible_v<_Tp> && is_nothrow_swappable_v<_Tp>)) {
- this->__swap(__opt);
+ using std::swap;
+ if (this->has_value() == __opt.has_value()) {
+ if (this->has_value())
+ swap(this->__get(), __opt.__get());
+ } else {
+ if (this->has_value()) {
+ __opt.__construct(std::move(this->__get()));
+ this->reset();
+ } else {
+ this->__construct(std::move(__opt.__get()));
+ __opt.reset();
+ }
+ }
}
// [optional.observe]
>From 6cc48cf353c116af85969cfba240f2f675d5ee7e Mon Sep 17 00:00:00 2001
From: William Tran-Viet <wtranviet at proton.me>
Date: Sun, 9 Aug 2026 15:23:09 -0400
Subject: [PATCH 6/9] Inline optional.ref.observer
---
libcxx/include/__optional/optional_ref.h | 36 +++++++++++-------------
1 file changed, 16 insertions(+), 20 deletions(-)
diff --git a/libcxx/include/__optional/optional_ref.h b/libcxx/include/__optional/optional_ref.h
index e99fc8cf8f143..37a9d91b961b5 100644
--- a/libcxx/include/__optional/optional_ref.h
+++ b/libcxx/include/__optional/optional_ref.h
@@ -119,23 +119,6 @@ struct __optional_ref_base {
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __swap(__optional_ref_base& __rhs) noexcept {
std::swap(__value_, __rhs.__value_);
}
-
- // [optional.ref.observe]
- _LIBCPP_HIDE_FROM_ABI constexpr add_pointer_t<_Tp> operator->() const noexcept {
- _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(this->has_value(), "optional operator-> called on a disengaged value");
- return std::addressof(this->__get());
- }
-
- [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp& operator*() const noexcept {
- _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(this->has_value(), "optional operator* called on a disengaged value");
- return this->__get();
- }
-
- [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp& value() const {
- if (!this->has_value())
- std::__throw_bad_optional_access();
- return this->__get();
- }
};
template <class _Tp>
@@ -288,13 +271,26 @@ class optional<_Tp&> : public __optional_ref_iterator_base<_Tp&> {
constexpr void swap(optional& __rhs) noexcept { this->__swap(__rhs); }
- using __base::operator->;
- using __base::operator*;
+ // [optional.ref.observe]
+ _LIBCPP_HIDE_FROM_ABI constexpr add_pointer_t<_Tp> operator->() const noexcept {
+ _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(this->has_value(), "optional operator-> called on a disengaged value");
+ return std::addressof(this->__get());
+ }
+
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp& operator*() const noexcept {
+ _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(this->has_value(), "optional operator* called on a disengaged value");
+ return this->__get();
+ }
constexpr explicit operator bool() const noexcept { return has_value(); }
using __base::has_value;
- using __base::value;
+
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp& value() const {
+ if (!this->has_value())
+ std::__throw_bad_optional_access();
+ return this->__get();
+ }
template <class _Up = remove_cv_t<_Tp>>
requires(!is_array_v<_Tp> && is_object_v<_Tp>)
>From 2cc421cee195a42940dc5a729cb2d0f38ea21131 Mon Sep 17 00:00:00 2001
From: William Tran-Viet <wtranviet at proton.me>
Date: Sun, 9 Aug 2026 15:23:21 -0400
Subject: [PATCH 7/9] Delete redundant __assign_from
---
libcxx/include/__optional/optional_ref.h | 13 -------------
1 file changed, 13 deletions(-)
diff --git a/libcxx/include/__optional/optional_ref.h b/libcxx/include/__optional/optional_ref.h
index 37a9d91b961b5..b280b8cff40e7 100644
--- a/libcxx/include/__optional/optional_ref.h
+++ b/libcxx/include/__optional/optional_ref.h
@@ -103,19 +103,6 @@ struct __optional_ref_base {
__construct(std::forward<_That>(__opt).__get());
}
- template <class _That>
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __assign_from(_That&& __opt) {
- if (has_value() == __opt.has_value()) {
- if (has_value())
- *__value_ = std::forward<_That>(__opt).__get();
- } else {
- if (has_value())
- reset();
- else
- __construct(std::forward<_That>(__opt).__get());
- }
- }
-
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __swap(__optional_ref_base& __rhs) noexcept {
std::swap(__value_, __rhs.__value_);
}
>From f3d29330849d61b7e9f6a16696ba923911b5ab17 Mon Sep 17 00:00:00 2001
From: William Tran-Viet <wtranviet at proton.me>
Date: Sun, 9 Aug 2026 15:25:31 -0400
Subject: [PATCH 8/9] Inline optional<T&> swap
---
libcxx/include/__optional/optional_ref.h | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)
diff --git a/libcxx/include/__optional/optional_ref.h b/libcxx/include/__optional/optional_ref.h
index b280b8cff40e7..29809e2d8c4f3 100644
--- a/libcxx/include/__optional/optional_ref.h
+++ b/libcxx/include/__optional/optional_ref.h
@@ -102,10 +102,6 @@ struct __optional_ref_base {
if (__opt.has_value())
__construct(std::forward<_That>(__opt).__get());
}
-
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __swap(__optional_ref_base& __rhs) noexcept {
- std::swap(__value_, __rhs.__value_);
- }
};
template <class _Tp>
@@ -256,7 +252,7 @@ class optional<_Tp&> : public __optional_ref_iterator_base<_Tp&> {
return this->__get();
}
- constexpr void swap(optional& __rhs) noexcept { this->__swap(__rhs); }
+ constexpr void swap(optional& __rhs) noexcept { std::swap(this->__value_, __rhs.__value_); }
// [optional.ref.observe]
_LIBCPP_HIDE_FROM_ABI constexpr add_pointer_t<_Tp> operator->() const noexcept {
>From 0c02a21769efeaf3bd385a8f7919d60b9b4d470e Mon Sep 17 00:00:00 2001
From: William Tran-Viet <wtranviet at proton.me>
Date: Sun, 9 Aug 2026 15:26:11 -0400
Subject: [PATCH 9/9] Replace redundant _LIBCPP_CONSTEXPR_SINCE_CXX20
---
libcxx/include/__optional/optional_ref.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/libcxx/include/__optional/optional_ref.h b/libcxx/include/__optional/optional_ref.h
index 29809e2d8c4f3..9207d22f8f9b7 100644
--- a/libcxx/include/__optional/optional_ref.h
+++ b/libcxx/include/__optional/optional_ref.h
@@ -83,14 +83,14 @@ struct __optional_ref_base {
}
# endif
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void reset() noexcept { __value_ = nullptr; }
+ _LIBCPP_HIDE_FROM_ABI constexpr void reset() noexcept { __value_ = nullptr; }
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr bool has_value() const noexcept { return __value_ != nullptr; }
_LIBCPP_HIDE_FROM_ABI constexpr value_type& __get() const noexcept { return *__value_; }
template <class _UArg>
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __construct(_UArg&& __val) {
+ _LIBCPP_HIDE_FROM_ABI constexpr void __construct(_UArg&& __val) {
static_assert(!__reference_constructs_from_temporary_v<_Tp, _UArg>,
"Attempted to construct a reference element in tuple from a "
"possible temporary");
@@ -98,7 +98,7 @@ struct __optional_ref_base {
}
template <class _That>
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __construct_from(_That&& __opt) {
+ _LIBCPP_HIDE_FROM_ABI constexpr void __construct_from(_That&& __opt) {
if (__opt.has_value())
__construct(std::forward<_That>(__opt).__get());
}
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