[libcxx-commits] [libcxx] [libc++] Remove `optional::iterator` from experimental mode (PR #203782)
William Tran-Viet via libcxx-commits
libcxx-commits at lists.llvm.org
Sun Jun 14 11:52:55 PDT 2026
https://github.com/smallp-o-p created https://github.com/llvm/llvm-project/pull/203782
We've stabilized on a representation for `optional::iterator` so it should be ready for general release with LLVM 23.
>From 0daa357edac4824cb4d025e7e2a3c780e461080b Mon Sep 17 00:00:00 2001
From: William Tran-Viet <wtranviet at proton.me>
Date: Sun, 14 Jun 2026 14:49:29 -0400
Subject: [PATCH] Remove `optional::iterator` from experimental mode
---
libcxx/docs/ReleaseNotes/23.rst | 1 +
libcxx/include/__configuration/experimental.h | 1 -
libcxx/include/optional | 37 +++++++++----------
libcxx/include/version | 4 +-
libcxx/modules/std/optional.inc | 4 +-
.../fexperimental-library.compile.pass.cpp | 4 --
.../utilities/optional/nodiscard.verify.cpp | 4 +-
.../optional.version.compile.pass.cpp | 16 +++-----
.../version.version.compile.pass.cpp | 16 +++-----
.../generate_feature_test_macro_components.py | 2 -
10 files changed, 32 insertions(+), 57 deletions(-)
diff --git a/libcxx/docs/ReleaseNotes/23.rst b/libcxx/docs/ReleaseNotes/23.rst
index 7823c2db39867..726e576ef4038 100644
--- a/libcxx/docs/ReleaseNotes/23.rst
+++ b/libcxx/docs/ReleaseNotes/23.rst
@@ -65,6 +65,7 @@ Improvements and New Features
``"std::visit: variant is valueless"``, ``"std::get: variant is valueless"``, or
``"std::get: wrong alternative for variant"``. The standard only requires ``what()`` to return an
unspecified non-null string, so user code that does not match on the exact message remains correct.
+- ``optional::iterator`` is no longer experimental.
Deprecations and Removals
-------------------------
diff --git a/libcxx/include/__configuration/experimental.h b/libcxx/include/__configuration/experimental.h
index bb38d8297c63d..d14df3e5175f3 100644
--- a/libcxx/include/__configuration/experimental.h
+++ b/libcxx/include/__configuration/experimental.h
@@ -33,6 +33,5 @@
#define _LIBCPP_HAS_EXPERIMENTAL_TZDB _LIBCPP_HAS_EXPERIMENTAL_LIBRARY
#define _LIBCPP_HAS_EXPERIMENTAL_SYNCSTREAM _LIBCPP_HAS_EXPERIMENTAL_LIBRARY
#define _LIBCPP_HAS_EXPERIMENTAL_HARDENING_OBSERVE_SEMANTIC _LIBCPP_HAS_EXPERIMENTAL_LIBRARY
-#define _LIBCPP_HAS_EXPERIMENTAL_OPTIONAL_ITERATOR _LIBCPP_HAS_EXPERIMENTAL_LIBRARY
#endif // _LIBCPP___CONFIGURATION_EXPERIMENTAL_H
diff --git a/libcxx/include/optional b/libcxx/include/optional
index 66995435b5109..43e8511a95789 100644
--- a/libcxx/include/optional
+++ b/libcxx/include/optional
@@ -737,7 +737,7 @@ using __optional_sfinae_assign_base_t _LIBCPP_NODEBUG =
template <class _Tp>
class optional;
-# if _LIBCPP_STD_VER >= 26 && _LIBCPP_HAS_EXPERIMENTAL_OPTIONAL_ITERATOR
+# if _LIBCPP_STD_VER >= 26
template <class _Tp>
constexpr bool ranges::enable_view<optional<_Tp>> = true;
@@ -780,8 +780,6 @@ struct __optional_iterator_base<_Tp&> : __optional_storage_base<_Tp&> {
using __optional_storage_base<_Tp&>::__optional_storage_base;
};
-# if _LIBCPP_HAS_EXPERIMENTAL_OPTIONAL_ITERATOR
-
template <class _Tp>
requires is_object_v<_Tp>
struct __optional_iterator_base<_Tp> : __optional_move_assign_base<_Tp> {
@@ -792,33 +790,33 @@ private:
public:
using __optional_move_assign_base<_Tp>::__optional_move_assign_base;
-# ifdef _LIBCPP_ABI_BOUNDED_ITERATORS_IN_OPTIONAL
+# ifdef _LIBCPP_ABI_BOUNDED_ITERATORS_IN_OPTIONAL
using iterator = __bounded_iter<__pointer>;
using const_iterator = __bounded_iter<__const_pointer>;
-# else
+# else
using iterator = __capacity_aware_iterator<__pointer, optional<_Tp>, 1>;
using const_iterator = __capacity_aware_iterator<__const_pointer, optional<_Tp>, 1>;
-# endif
+# 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
+# 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 const_iterator begin() const noexcept {
auto* __ptr = std::addressof(this->__get());
-# 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<__const_pointer, optional<_Tp>, 1>(__ptr);
-# endif
+# endif
}
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr iterator end() noexcept {
@@ -838,22 +836,22 @@ private:
public:
using __optional_storage_base<_Tp&>::__optional_storage_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 {
@@ -861,8 +859,7 @@ public:
}
};
-# endif // _LIBCPP_HAS_EXPERIMENTAL_OPTIONAL_ITERATOR
-# endif // _LIBCPP_STD_VER >= 26
+# endif // _LIBCPP_STD_VER >= 26
template <class _Tp>
class _LIBCPP_DECLSPEC_EMPTY_BASES optional
diff --git a/libcxx/include/version b/libcxx/include/version
index 7f2dc9e4b72ab..9d3d7395f98e5 100644
--- a/libcxx/include/version
+++ b/libcxx/include/version
@@ -611,9 +611,7 @@ __cpp_lib_void_t 201411L <type_traits>
# define __cpp_lib_not_fn 202306L
# undef __cpp_lib_optional
# define __cpp_lib_optional 202506L
-# if _LIBCPP_HAS_EXPERIMENTAL_OPTIONAL_ITERATOR
-# define __cpp_lib_optional_range_support 202406L
-# endif
+# define __cpp_lib_optional_range_support 202406L
# undef __cpp_lib_out_ptr
# define __cpp_lib_out_ptr 202311L
// # define __cpp_lib_philox_engine 202406L
diff --git a/libcxx/modules/std/optional.inc b/libcxx/modules/std/optional.inc
index 8196a8dde577c..88de0bb4db12b 100644
--- a/libcxx/modules/std/optional.inc
+++ b/libcxx/modules/std/optional.inc
@@ -10,7 +10,7 @@
export namespace std {
// [optional.optional], class template optional
using std::optional;
-#if _LIBCPP_STD_VER >= 26 && _LIBCPP_HAS_EXPERIMENTAL_OPTIONAL_ITERATOR
+#if _LIBCPP_STD_VER >= 26
// [optional.iterators], iterator support
namespace ranges {
using std::ranges::enable_borrowed_range;
@@ -24,7 +24,7 @@ export namespace std {
// [optional.bad.access], class bad_optional_access
using std::bad_optional_access;
-#if _LIBCPP_STD_VER >= 26 && _LIBCPP_HAS_EXPERIMENTAL_OPTIONAL_ITERATOR
+#if _LIBCPP_STD_VER >= 26
using std::format_kind;
#endif
diff --git a/libcxx/test/libcxx/experimental/fexperimental-library.compile.pass.cpp b/libcxx/test/libcxx/experimental/fexperimental-library.compile.pass.cpp
index 82fd1ad4d9a16..479b46a39e963 100644
--- a/libcxx/test/libcxx/experimental/fexperimental-library.compile.pass.cpp
+++ b/libcxx/test/libcxx/experimental/fexperimental-library.compile.pass.cpp
@@ -16,10 +16,6 @@
#include <version>
-#if !_LIBCPP_HAS_EXPERIMENTAL_OPTIONAL_ITERATOR
-# error "-fexperimental-library should enable optional::iterator"
-#endif
-
#if !_LIBCPP_HAS_EXPERIMENTAL_PSTL
# error "-fexperimental-library should enable the PSTL"
#endif
diff --git a/libcxx/test/libcxx/utilities/optional/nodiscard.verify.cpp b/libcxx/test/libcxx/utilities/optional/nodiscard.verify.cpp
index 0ae368b4f87ce..c49546cfdf4ad 100644
--- a/libcxx/test/libcxx/utilities/optional/nodiscard.verify.cpp
+++ b/libcxx/test/libcxx/utilities/optional/nodiscard.verify.cpp
@@ -32,7 +32,7 @@ void test() {
opt.has_value(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
-#if TEST_STD_VER >= 26 && _LIBCPP_HAS_EXPERIMENTAL_OPTIONAL_ITERATOR
+#if TEST_STD_VER >= 26
opt.begin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
cOpt.begin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
opt.end(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
@@ -92,10 +92,8 @@ void test() {
optRef.has_value(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
-# if _LIBCPP_HAS_EXPERIMENTAL_OPTIONAL_ITERATOR
optRef.begin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
optRef.end(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
-# endif
*optRef; // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
*cOptRef; // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/optional.version.compile.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/optional.version.compile.pass.cpp
index 9850c20afec87..c4e652979a4e6 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/optional.version.compile.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/optional.version.compile.pass.cpp
@@ -146,17 +146,11 @@
# error "__cpp_lib_optional should have the value 202506L in c++26"
# endif
-# if !defined(_LIBCPP_VERSION) || _LIBCPP_HAS_EXPERIMENTAL_OPTIONAL_ITERATOR
-# ifndef __cpp_lib_optional_range_support
-# error "__cpp_lib_optional_range_support should be defined in c++26"
-# endif
-# if __cpp_lib_optional_range_support != 202406L
-# error "__cpp_lib_optional_range_support should have the value 202406L in c++26"
-# endif
-# else
-# ifdef __cpp_lib_optional_range_support
-# error "__cpp_lib_optional_range_support should not be defined when the requirement '!defined(_LIBCPP_VERSION) || _LIBCPP_HAS_EXPERIMENTAL_OPTIONAL_ITERATOR' is not met!"
-# endif
+# ifndef __cpp_lib_optional_range_support
+# error "__cpp_lib_optional_range_support should be defined in c++26"
+# endif
+# if __cpp_lib_optional_range_support != 202406L
+# error "__cpp_lib_optional_range_support should have the value 202406L in c++26"
# endif
#endif // TEST_STD_VER > 23
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
index d9c78b73f7e23..ac4e0003347a6 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
@@ -7586,17 +7586,11 @@
# error "__cpp_lib_optional should have the value 202506L in c++26"
# endif
-# if !defined(_LIBCPP_VERSION) || _LIBCPP_HAS_EXPERIMENTAL_OPTIONAL_ITERATOR
-# ifndef __cpp_lib_optional_range_support
-# error "__cpp_lib_optional_range_support should be defined in c++26"
-# endif
-# if __cpp_lib_optional_range_support != 202406L
-# error "__cpp_lib_optional_range_support should have the value 202406L in c++26"
-# endif
-# else
-# ifdef __cpp_lib_optional_range_support
-# error "__cpp_lib_optional_range_support should not be defined when the requirement '!defined(_LIBCPP_VERSION) || _LIBCPP_HAS_EXPERIMENTAL_OPTIONAL_ITERATOR' is not met!"
-# endif
+# ifndef __cpp_lib_optional_range_support
+# error "__cpp_lib_optional_range_support should be defined in c++26"
+# endif
+# if __cpp_lib_optional_range_support != 202406L
+# error "__cpp_lib_optional_range_support should have the value 202406L in c++26"
# endif
# ifndef __cpp_lib_out_ptr
diff --git a/libcxx/utils/generate_feature_test_macro_components.py b/libcxx/utils/generate_feature_test_macro_components.py
index d764a1f677ba6..02e79ad7ca38f 100644
--- a/libcxx/utils/generate_feature_test_macro_components.py
+++ b/libcxx/utils/generate_feature_test_macro_components.py
@@ -1039,8 +1039,6 @@ def add_version_header(tc):
"name": "__cpp_lib_optional_range_support",
"values": {"c++26": 202406}, # P3168R2 Give std::optional Range Support
"headers": ["optional"],
- "test_suite_guard": "!defined(_LIBCPP_VERSION) || _LIBCPP_HAS_EXPERIMENTAL_OPTIONAL_ITERATOR",
- "libcxx_guard": "_LIBCPP_HAS_EXPERIMENTAL_OPTIONAL_ITERATOR",
},
{
"name": "__cpp_lib_out_ptr",
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