[libc++] Implement P2830R10: Standardized Constexpr Type Ordering by Tsche · Pull Request #216616 · llvm/llvm-project

Tsche · 2026-08-17T00:02:52Z

This patch implements the library side of std::type_order from P2830R10 including the changes from P3778R0, P4140R0 and LWG4305. Since clang's __builtin_type_order's semantics match GCC's, this does not need special casing for GCC.

Resolves #148152
Resolves #171284
Resolves #189595
Resolves #171344

Tsche · 2026-08-17T00:03:48Z

~~Marked as a draft for now since it's still blocked on #216462~~ Merged.

Zingam · 2026-08-17T17:09:56Z

+  using std::type_order;
+  using std::type_order_v;


No change requested: In type_traits.inc it looks like we are exporting the _v-variable but not the struct. I don't know why.

llvmorg-github-actions · 2026-08-20T12:11:14Z

@llvm/pr-subscribers-libcxx

Author: Matthias Wippich (Tsche)

Changes

This patch implements the library side of std::type_order from P2830R10 including the changes from P3778R0, P4140R0 and LWG4305. Since clang's __builtin_type_order's semantics match GCC's, this does not need special casing for GCC.

Resolves #148152
Resolves #171284
Resolves #189595
Resolves #171344

Patch is 24.64 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/216616.diff

16 Files Affected:

(modified) libcxx/docs/FeatureTestMacroTable.rst (+2)
(modified) libcxx/docs/ReleaseNotes/24.rst (+3)
(modified) libcxx/docs/Status/Cxx26Issues.csv (+1-1)
(modified) libcxx/docs/Status/Cxx26Papers.csv (+3-3)
(modified) libcxx/include/CMakeLists.txt (+1)
(added) libcxx/include/__compare/type_order.h (+40)
(modified) libcxx/include/compare (+4)
(modified) libcxx/include/module.modulemap.in (+1)
(modified) libcxx/include/version (+4)
(modified) libcxx/modules/std/compare.inc (+6)
(added) libcxx/test/libcxx/language.support/cmp/cmp.type/nodiscard.verify.cpp (+22)
(added) libcxx/test/std/language.support/cmp/cmp.type/no_specializations.verify.cpp (+30)
(added) libcxx/test/std/language.support/cmp/cmp.type/type_order.compile.pass.cpp (+70)
(modified) libcxx/test/std/language.support/support.limits/support.limits.general/compare.version.compile.pass.cpp (+33)
(modified) libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp (+33)
(modified) libcxx/utils/generate_feature_test_macro_components.py (+7)

diff --git a/libcxx/docs/FeatureTestMacroTable.rst b/libcxx/docs/FeatureTestMacroTable.rst
index b710e3800f70d..44879f08233b3 100644
--- a/libcxx/docs/FeatureTestMacroTable.rst
+++ b/libcxx/docs/FeatureTestMacroTable.rst
@@ -550,6 +550,8 @@ Status
     ---------------------------------------------------------- -----------------
     ``__cpp_lib_tuple_like``                                   *unimplemented*
     ---------------------------------------------------------- -----------------
+    ``__cpp_lib_type_order``                                   ``202506L``
+    ---------------------------------------------------------- -----------------
     ``__cpp_lib_variant``                                      ``202306L``
     ========================================================== =================
 
diff --git a/libcxx/docs/ReleaseNotes/24.rst b/libcxx/docs/ReleaseNotes/24.rst
index fc2b95de8a676..895e21c83c1b4 100644
--- a/libcxx/docs/ReleaseNotes/24.rst
+++ b/libcxx/docs/ReleaseNotes/24.rst
@@ -47,6 +47,9 @@ Implemented Papers
 - P3961R1: Less double indirection in ``function_ref`` (RU-220) (`Github <https://llvm.org/PR189606>`__)
 - P1901R2: Enabling the Use of ``weak_ptr`` as Keys in Unordered Associative Containers (`Github <https://llvm.org/PR105372>`__)
 - P0528R3: The Curious Case of Padding Bits, Featuring Atomic Compare-and-Exchange (`Github <https://llvm.org/PR76180>`__)
+- P2830R10: Standardized Constexpr Type Ordering (`Github <https://llvm.org/PR216616>`__)
+- P3778R0: Fix for ``type_order`` template definition (`Github <https://llvm.org/PR216616>`__)
+- P4140R0: Proposed resolution for US70-126: allow incomplete types in type_order (`Github <https://llvm.org/PR216616>`__)
 
 Improvements and New Features
 -----------------------------
diff --git a/libcxx/docs/Status/Cxx26Issues.csv b/libcxx/docs/Status/Cxx26Issues.csv
index 2f22fdb63a815..a8296213a7677 100644
--- a/libcxx/docs/Status/Cxx26Issues.csv
+++ b/libcxx/docs/Status/Cxx26Issues.csv
@@ -183,7 +183,7 @@
 "`LWG4301 <https://wg21.link/LWG4301>`__","``condition_variable{_any}::wait_{for, until}`` should take timeout by value","2025-11 (Kona)","","","`#171341 <https://github.com/llvm/llvm-project/issues/171341>`__",""
 "`LWG4302 <https://wg21.link/LWG4302>`__","Problematic ``vector_sum_of_squares`` wording","2025-11 (Kona)","","","`#171342 <https://github.com/llvm/llvm-project/issues/171342>`__",""
 "`LWG4304 <https://wg21.link/LWG4304>`__","``std::optional<NonReturnable&>`` is ill-formed due to ``value_or``","2025-11 (Kona)","","","`#171343 <https://github.com/llvm/llvm-project/issues/171343>`__",""
-"`LWG4305 <https://wg21.link/LWG4305>`__","Missing user requirements on ``type_order`` template","2025-11 (Kona)","","","`#171344 <https://github.com/llvm/llvm-project/issues/171344>`__",""
+"`LWG4305 <https://wg21.link/LWG4305>`__","Missing user requirements on ``type_order`` template","2025-11 (Kona)","|Complete|","24","`#171344 <https://github.com/llvm/llvm-project/issues/171344>`__",""
 "`LWG4308 <https://wg21.link/LWG4308>`__","``std::optional<T&>::iterator`` can't be a contiguous iterator for some ``T``","2025-11 (Kona)","|Complete|","22","`#171345 <https://github.com/llvm/llvm-project/issues/171345>`__",""
 "`LWG4312 <https://wg21.link/LWG4312>`__","Const and value category mismatch for ``allocator_arg_t``/``allocator_arg`` in the description of uses-allocator construction","2025-11 (Kona)","","","`#171346 <https://github.com/llvm/llvm-project/issues/171346>`__",""
 "`LWG4315 <https://wg21.link/LWG4315>`__","Insufficient specification of ``vector_two_norm`` and ``matrix_frob_norm``","2025-11 (Kona)","","","`#171347 <https://github.com/llvm/llvm-project/issues/171347>`__",""
diff --git a/libcxx/docs/Status/Cxx26Papers.csv b/libcxx/docs/Status/Cxx26Papers.csv
index bbc6310beeb63..fc38b0a47070e 100644
--- a/libcxx/docs/Status/Cxx26Papers.csv
+++ b/libcxx/docs/Status/Cxx26Papers.csv
@@ -137,7 +137,7 @@
 "`P3383R3 <https://wg21.link/P3383R3>`__","``mdspan.at()``","2025-06 (Sofia)","|Complete|","23","`#148149 <https://github.com/llvm/llvm-project/issues/148149>`__",""
 "`P2927R3 <https://wg21.link/P2927R3>`__","Inspecting ``exception_ptr``","2025-06 (Sofia)","","","`#148150 <https://github.com/llvm/llvm-project/issues/148150>`__",""
 "`P3748R0 <https://wg21.link/P3748R0>`__","Inspecting ``exception_ptr`` should be constexpr","2025-06 (Sofia)","","","`#148151 <https://github.com/llvm/llvm-project/issues/148151>`__",""
-"`P2830R10 <https://wg21.link/P2830R10>`__","Standardized Constexpr Type Ordering","2025-06 (Sofia)","","","`#148152 <https://github.com/llvm/llvm-project/issues/148152>`__",""
+"`P2830R10 <https://wg21.link/P2830R10>`__","Standardized Constexpr Type Ordering","2025-06 (Sofia)","|Complete|","24","`#148152 <https://github.com/llvm/llvm-project/issues/148152>`__",""
 "`P3570R2 <https://wg21.link/P3570R2>`__","optional variants in sender/receiver","2025-06 (Sofia)","","","`#148153 <https://github.com/llvm/llvm-project/issues/148153>`__",""
 "`P3481R5 <https://wg21.link/P3481R5>`__","``std::execution::bulk()`` issues","2025-06 (Sofia)","","","`#148155 <https://github.com/llvm/llvm-project/issues/148155>`__",""
 "`P3433R1 <https://wg21.link/P3433R1>`__","Allocator Support for Operation States","2025-06 (Sofia)","","","`#148157 <https://github.com/llvm/llvm-project/issues/148157>`__",""
@@ -168,7 +168,7 @@
 "`P3774R1 <https://wg21.link/P3774R1>`__","Rename ``std::nontype``, and make it broadly useful","2025-11 (Kona)","","","`#171279 <https://github.com/llvm/llvm-project/issues/171279>`__",""
 "`P3819R0 <https://wg21.link/P3819R0>`__","Remove ``evaluation_exception()`` from contract-violation handling for C++26","2025-11 (Kona)","","","`#171280 <https://github.com/llvm/llvm-project/issues/171280>`__",""
 "`P3612R1 <https://wg21.link/P3612R1>`__","Harmonize proxy-reference operations (LWG 3638 and 4187)","2025-11 (Kona)","","","`#171281 <https://github.com/llvm/llvm-project/issues/171281>`__",""
-"`P3778R0 <https://wg21.link/P3778R0>`__","Fix for ``type_order`` template definition","2025-11 (Kona)","","","`#171284 <https://github.com/llvm/llvm-project/issues/171284>`__",""
+"`P3778R0 <https://wg21.link/P3778R0>`__","Fix for ``type_order`` template definition","2025-11 (Kona)","|Complete|","24","`#171284 <https://github.com/llvm/llvm-project/issues/171284>`__",""
 "`P1789R3 <https://wg21.link/P1789R3>`__","Library Support for Expansion Statements","2025-11 (Kona)","|Complete|","22","`#167268 <https://github.com/llvm/llvm-project/issues/167268>`__",""
 "`P3922R1 <https://wg21.link/P3922R1>`__","Missing deduction guide from ``simd::mask`` to ``simd::vec``","2025-11 (Kona)","","","`#171285 <https://github.com/llvm/llvm-project/issues/171285>`__",""
 "`P3878R1 <https://wg21.link/P3878R1>`__","Standard library hardening should not use the 'observe' semantic","2025-11 (Kona)","","","`#171286 <https://github.com/llvm/llvm-project/issues/171286>`__",""
@@ -185,7 +185,7 @@
 "`P4012R1 <https://wg21.link/P4012R1>`__","Value-preserving consteval broadcast to ``simd::vec``","2026-03 (Croydon)","","","`#189592 <https://github.com/llvm/llvm-project/issues/189592>`__",""
 "`P3886R0 <https://wg21.link/P3886R0>`__","Wording for AT1-057","2026-03 (Croydon)","","","`#189593 <https://github.com/llvm/llvm-project/issues/189593>`__",""
 "`P3936R1 <https://wg21.link/P3936R1>`__","Safer ``atomic_ref::address`` (FR-030-310)","2026-03 (Croydon)","|Complete|","23","`#189594 <https://github.com/llvm/llvm-project/issues/189594>`__",""
-"`P4140R0 <https://wg21.link/P4140R0>`__","Proposed resolution for US70-126: allow incomplete types in type_order","2026-03 (Croydon)","","","`#189595 <https://github.com/llvm/llvm-project/issues/189595>`__",""
+"`P4140R0 <https://wg21.link/P4140R0>`__","Proposed resolution for US70-126: allow incomplete types in type_order","2026-03 (Croydon)","|Complete|","24","`#189595 <https://github.com/llvm/llvm-project/issues/189595>`__",""
 "`P3373R4 <https://wg21.link/P3373R4>`__","Of Operation States and Their Lifetimes","2026-03 (Croydon)","","","`#189597 <https://github.com/llvm/llvm-project/issues/189597>`__",""
 "`P3986R1 <https://wg21.link/P3986R1>`__","A Wording Strategy for Inlinable Receivers","2026-03 (Croydon)","","","`#189598 <https://github.com/llvm/llvm-project/issues/189598>`__",""
 "`P3059R2 <https://wg21.link/P3059R2>`__","Making user-defined constructors of view iterators/sentinels private","2026-03 (Croydon)","|Complete|","24","`#189599 <https://github.com/llvm/llvm-project/issues/189599>`__",""
diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
index a1d6a09aa6b20..88dfda8dec31c 100644
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -308,6 +308,7 @@ set(files
   __compare/strong_order.h
   __compare/synth_three_way.h
   __compare/three_way_comparable.h
+  __compare/type_order.h
   __compare/weak_order.h
   __concepts/arithmetic.h
   __concepts/assignable.h
diff --git a/libcxx/include/__compare/type_order.h b/libcxx/include/__compare/type_order.h
new file mode 100644
index 0000000000000..11f936dfd1547
--- /dev/null
+++ b/libcxx/include/__compare/type_order.h
@@ -0,0 +1,40 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___COMPARE_TYPE_ORDER
+#define _LIBCPP___COMPARE_TYPE_ORDER
+
+#include <__compare/ordering.h>
+#include <__config>
+
+#ifndef _LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER
+#  pragma GCC system_header
+#endif
+
+#if _LIBCPP_STD_VER >= 26 && __has_builtin(__builtin_type_order)
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// [compare.type], type ordering
+template <class _Tp, class _Up>
+struct _LIBCPP_NO_SPECIALIZATIONS type_order {
+  static constexpr strong_ordering value = __builtin_type_order(_Tp, _Up);
+  using value_type                       = strong_ordering;
+
+  _LIBCPP_HIDE_FROM_ABI constexpr operator value_type() const noexcept { return value; }
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr value_type operator()() const noexcept { return value; }
+};
+
+template <class _Tp, class _Up>
+inline constexpr strong_ordering type_order_v = __builtin_type_order(_Tp, _Up);
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_STD_VER >= 26 && __has_builtin(__builtin_type_order)
+
+#endif // _LIBCPP___COMPARE_TYPE_ORDER
diff --git a/libcxx/include/compare b/libcxx/include/compare
index de1f845271a48..7fa8f76713495 100644
--- a/libcxx/include/compare
+++ b/libcxx/include/compare
@@ -161,6 +161,10 @@ namespace std {
 #    include <__compare/weak_order.h>
 #  endif // _LIBCPP_STD_VER >= 20
 
+#  if _LIBCPP_STD_VER >= 26
+#    include <__compare/type_order.h>
+#  endif
+
 #  include <version>
 
 #  if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
diff --git a/libcxx/include/module.modulemap.in b/libcxx/include/module.modulemap.in
index 4512cc71153ca..570ea706458e1 100644
--- a/libcxx/include/module.modulemap.in
+++ b/libcxx/include/module.modulemap.in
@@ -1064,6 +1064,7 @@ module std {
     module strong_order                     { header "__compare/strong_order.h" }
     module synth_three_way                  { header "__compare/synth_three_way.h" }
     module three_way_comparable             { header "__compare/three_way_comparable.h" }
+    module type_order                       { header "__compare/type_order.h" }
     module weak_order                       { header "__compare/weak_order.h" }
 
     header "compare"
diff --git a/libcxx/include/version b/libcxx/include/version
index 9a151910ae590..c96942a5b6c74 100644
--- a/libcxx/include/version
+++ b/libcxx/include/version
@@ -283,6 +283,7 @@ __cpp_lib_tuple_like                                    202311L <map> <tuple> <u
                                                         202207L // C++23
 __cpp_lib_tuples_by_type                                201304L <tuple> <utility>
 __cpp_lib_type_identity                                 201806L <type_traits>
+__cpp_lib_type_order                                    202506L <compare>
 __cpp_lib_type_trait_variable_templates                 201510L <type_traits>
 __cpp_lib_uncaught_exceptions                           201411L <exception>
 __cpp_lib_unordered_map_try_emplace                     201411L <unordered_map>
@@ -645,6 +646,9 @@ __cpp_lib_void_t                                        201411L <type_traits>
 // # define __cpp_lib_to_string                            202306L
 # undef  __cpp_lib_tuple_like
 // # define __cpp_lib_tuple_like                           202311L
+# if __has_builtin(__builtin_type_order)
+#   define __cpp_lib_type_order                         202506L
+# endif
 # undef  __cpp_lib_variant
 # define __cpp_lib_variant                              202306L
 #endif
diff --git a/libcxx/modules/std/compare.inc b/libcxx/modules/std/compare.inc
index 9d002d301efc3..fcd12fddabd52 100644
--- a/libcxx/modules/std/compare.inc
+++ b/libcxx/modules/std/compare.inc
@@ -48,4 +48,10 @@ export namespace std {
     using std::__cpo::weak_order;
   } // namespace __cpo
 
+#if _LIBCPP_STD_VER >= 26 && __has_builtin(__builtin_type_order)
+  // [compare.type], type ordering
+  using std::type_order;
+  using std::type_order_v;
+#endif
+
 } // namespace std
diff --git a/libcxx/test/libcxx/language.support/cmp/cmp.type/nodiscard.verify.cpp b/libcxx/test/libcxx/language.support/cmp/cmp.type/nodiscard.verify.cpp
new file mode 100644
index 0000000000000..e71cd615786ab
--- /dev/null
+++ b/libcxx/test/libcxx/language.support/cmp/cmp.type/nodiscard.verify.cpp
@@ -0,0 +1,22 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++26
+
+// These compilers do not support __builtin_type_order
+// UNSUPPORTED: clang-21, clang-22, clang-23, apple-clang-21
+// UNSUPPORTED: gcc-15
+
+// Check that type_order::operator() is marked [[nodiscard]]
+
+#include <compare>
+
+void test() {
+  std::type_order<int, char>()();
+  // expected-warning@-1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+}
diff --git a/libcxx/test/std/language.support/cmp/cmp.type/no_specializations.verify.cpp b/libcxx/test/std/language.support/cmp/cmp.type/no_specializations.verify.cpp
new file mode 100644
index 0000000000000..e2f24e6aaa48f
--- /dev/null
+++ b/libcxx/test/std/language.support/cmp/cmp.type/no_specializations.verify.cpp
@@ -0,0 +1,30 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++26
+
+// These compilers do not support __builtin_type_order
+// UNSUPPORTED: clang-21, clang-22, clang-23, apple-clang-21
+// UNSUPPORTED: gcc-15
+
+// <compare>
+
+// template<class T, class U>
+//   struct type_order;
+
+#include <compare>
+
+#if !__has_warning("-Winvalid-specializations")
+// expected-no-diagnostics
+#else
+template <>
+struct std::type_order<int, int>; // expected-error {{cannot be specialized}}
+
+template <class T>
+struct std::type_order<T, int>; // expected-error {{cannot be specialized}}
+#endif
diff --git a/libcxx/test/std/language.support/cmp/cmp.type/type_order.compile.pass.cpp b/libcxx/test/std/language.support/cmp/cmp.type/type_order.compile.pass.cpp
new file mode 100644
index 0000000000000..da3d5f3a256d8
--- /dev/null
+++ b/libcxx/test/std/language.support/cmp/cmp.type/type_order.compile.pass.cpp
@@ -0,0 +1,70 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++26
+
+// These compilers do not support __builtin_type_order
+// UNSUPPORTED: clang-21, clang-22, clang-23, apple-clang-21
+// UNSUPPORTED: gcc-15
+
+// <compare>
+
+// template<class T, class U>
+//   struct type_order;
+// template<class T, class U>
+//   constexpr strong_ordering type_order_v = type_order<T, U>::value;
+
+#include <compare>
+#include <concepts>
+
+template <class T, class U>
+constexpr bool test_order(std::strong_ordering expected) {
+  return std::type_order<T, U>()() == expected && std::type_order<T, U>::value == expected &&
+         std::type_order_v<T, U> == expected && static_cast<std::strong_ordering>(std::type_order<T, U>()) == expected;
+}
+
+template <class T, class U>
+constexpr bool eq = test_order<T, U>(std::strong_ordering::equal);
+template <class T, class U>
+constexpr bool lt = test_order<T, U>(std::strong_ordering::less);
+template <class T, class U>
+constexpr bool gt = test_order<T, U>(std::strong_ordering::greater);
+template <class T, class U>
+constexpr bool ne = lt<T, U> || gt<T, U>;
+
+struct A {};
+struct B {};
+struct C {};
+
+static_assert(std::same_as<std::type_order<A, A>::value_type, std::strong_ordering>);
+static_assert(std::same_as<decltype(std::type_order<A, A>::value), const std::strong_ordering>);
+static_assert(std::same_as<decltype(std::type_order_v<A, A>), const std::strong_ordering>);
+
+static_assert(noexcept(std::type_order<int, int>()()));
+static_assert(noexcept(static_cast<std::strong_ordering>(std::type_order<int, int>())));
+
+static_assert(ne<int, const int>);
+static_assert(ne<int, int&>);
+static_assert(ne<int&, int&&>);
+
+static_assert(eq<A, A>);
+static_assert(ne<A, B> && ne<B, A>);
+
+// Since we do lexicographical compare of the mangled names and both A and B
+// are class types, A must compare less than B regardless of ABI
+static_assert(lt<A, B>);
+static_assert(gt<B, A>);
+static_assert(!(lt<A, B> && lt<B, C>) || lt<A, C>);
+
+struct incomplete;
+static_assert(eq<incomplete, incomplete>);
+static_assert(ne<incomplete, A>);
+
+template <auto>
+constexpr bool test_template_arg = true;
+static_assert(test_template_arg<std::type_order<A, incomplete>{}>);
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/compare.version.compile.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/compare.version.compile.pass.cpp
index 907535a087de2..a1c0f478ed623 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/compare.version.compile.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/compare.version.compile.pass.cpp
@@ -24,18 +24,30 @@
 #    error "__cpp_lib_three_way_comparison should not be defined before c++20"
 #  endif
 
+#  ifdef __cpp_lib_type_order
+#    error "__cpp_lib_type_order should not be defined before c++26"
+#  endif
+
 #elif TEST_STD_VER == 14
 
 #  ifdef __cpp_lib_three_way_comparison
 #    error "__cpp_lib_three_way_comparison should not be defined before c++20"
 #  endif
 
+#  ifdef __cpp_lib_type_order
+#    error "__cpp_lib_type_order should not be defined before c++26"
+#  endif
+
 #elif TEST_STD_VER == 17
 
 #  ifdef __cpp_lib_three_way_comparison
 #    error "__cpp_lib_three_way_comparison should not be defined before c++20"
 #  endif
 
+#  ifdef __cpp_lib_type_order
+#    error "__cpp_lib_type_order should not be defined before c++26"
+#  endif
+
 #elif TEST_STD_VER == 20
 
 #  ifndef __cpp_lib_three_way_comparison
@@ -45,6 +57,10 @@
 #    error "__cpp_lib_three_way_comparison should have the value 201907L in c++20"
 #  endif
 
+#  ifdef __cpp_lib_type_order
+#    error "__cpp_lib_type_order should not be defined before c++26"
+#  endif
+
 #elif TEST_STD_VER == 23
 
 #  ifndef __cpp_lib_three_way_comparison
@@ -54,6 +70,10 @@
 #    error "__cpp_lib_three_way_comparison should have t...
[truncated]

Tsche · 2026-08-28T02:35:31Z

the test failure looks unrelated

philnik777

Basically LGTM, but I'd like to see transitivity tested.

…vm#216616) This patch implements the library side of `std::type_order` from P2830R10 including the changes from P3778R0, P4140R0 and LWG4305. Since clang's `__builtin_type_order`'s semantics match GCC's, this does not need special casing for GCC. Resolves llvm#148152 Resolves llvm#171284 Resolves llvm#189595 Resolves llvm#171344

[libc++] Implement P2830R10: Standardized Constexpr Type Ordering

cccd37d

Tsche added 3 commits August 17, 2026 02:19

rerun generator scripts

4a6268a

add pr number

c2fac1f

define ne in terms of lt/gt

78caa7f

Zingam reviewed Aug 17, 2026

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address review comments

53f05b4

Zingam reviewed Aug 18, 2026

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Comment thread libcxx/include/__compare/type_order.h

Tsche added 2 commits August 19, 2026 04:46

fix build

1c3e4b6

Merge remote-tracking branch 'origin/main' into type_order_lib

209482e

Tsche marked this pull request as ready for review August 20, 2026 12:10

Tsche requested a review from a team as a code owner August 20, 2026 12:10

llvmorg-github-actions Bot added the libc++ libc++ C++ Standard Library. Not GNU libstdc++. Not libc++abi. label Aug 20, 2026

philnik777 requested changes Aug 20, 2026

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reduce test

3598fbe

Zingam reviewed Aug 20, 2026

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Comment thread libcxx/test/libcxx/language.support/cmp/cmp.type/nodiscard.verify.cpp Outdated

philnik777 reviewed Aug 20, 2026

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Tsche added 7 commits August 23, 2026 21:04

address review comments

598fd32

check for the builtin in tests

fdab499

fix test

1b2719d

fix failing test

623d598

fix misattached test assertion

362be98

Merge remote-tracking branch 'origin/main' into type_order_lib

50dc15b

regenerate feature test macros

f219fb4

Tsche requested a review from philnik777 August 28, 2026 02:35

philnik777 reviewed Aug 28, 2026

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Comment thread libcxx/test/std/language.support/cmp/cmp.type/type_order.compile.pass.cpp Outdated

Tsche added 2 commits August 31, 2026 09:12

add transitivity test, address review comments

b0bf686

Merge remote-tracking branch 'origin/main' into type_order_lib

b2bc9ce

philnik777 approved these changes Aug 31, 2026

View reviewed changes

Tsche merged commit 678058a into llvm:main Sep 1, 2026
84 of 85 checks passed

Tsche deleted the type_order_lib branch September 1, 2026 06:38

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Tsche commented Aug 17, 2026

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Tsche commented Aug 28, 2026

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Tsche commented Aug 17, 2026 •

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