[libcxx-commits] [libcxx] [libc++][math] Add `constexpr` to `std::isgreater()` (PR #210075)

[Lucas Mellone via libcxx-commits]

https://github.com/lknknm created https://github.com/llvm/llvm-project/pull/210075

Implement `constexpr` to `std::isgreater() as defined by [P0533R9](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p0533r9.pdf).

Towards https://github.com/llvm/llvm-project/issues/105174

>From 1fc2d6029a58ceaed872953980ae0f9b2bc9e178 Mon Sep 17 00:00:00 2001
From: Lucas Mellone <github.snugness349 at passinbox.com>
Date: Thu, 16 Jul 2026 16:47:35 +0200
Subject: [PATCH] add: constexpr to isgreater

---
 libcxx/include/__math/traits.h                        | 11 +++++------
 .../numerics/c.math/constexpr-cxx23-clang.pass.cpp    |  6 +++---
 .../numerics/c.math/constexpr-cxx23-gcc.pass.cpp      |  6 +++---
 3 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/libcxx/include/__math/traits.h b/libcxx/include/__math/traits.h
index ff22cee7305d7..28269eef46743 100644
--- a/libcxx/include/__math/traits.h
+++ b/libcxx/include/__math/traits.h
@@ -82,8 +82,7 @@ template <class _A1, __enable_if_t<is_integral<_A1>::value, int> = 0>
 #ifdef _LIBCPP_PREFERRED_OVERLOAD
 _LIBCPP_PREFERRED_OVERLOAD
 #endif
-    bool
-    isinf(double __x) _NOEXCEPT {
+    bool isinf(double __x) _NOEXCEPT {
   return __builtin_isinf(__x);
 }
 
@@ -106,8 +105,7 @@ template <class _A1, __enable_if_t<is_integral<_A1>::value, int> = 0>
 #ifdef _LIBCPP_PREFERRED_OVERLOAD
 _LIBCPP_PREFERRED_OVERLOAD
 #endif
-    bool
-    isnan(double __x) _NOEXCEPT {
+    bool isnan(double __x) _NOEXCEPT {
   return __builtin_isnan(__x);
 }
 
@@ -137,7 +135,8 @@ template <class _A1, __enable_if_t<is_integral<_A1>::value, int> = 0>
 // isgreater
 
 template <class _A1, class _A2, __enable_if_t<is_arithmetic<_A1>::value && is_arithmetic<_A2>::value, int> = 0>
-[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI bool isgreater(_A1 __x, _A2 __y) _NOEXCEPT {
+[[__nodiscard__]] inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool
+isgreater(_A1 __x, _A2 __y) _NOEXCEPT {
   using type = __promote_t<_A1, _A2>;
   return __builtin_isgreater((type)__x, (type)__y);
 }
@@ -216,7 +215,7 @@ template <class _A1>
 
 template <class _A1, class _A2>
   requires is_arithmetic_v<_A1> && is_arithmetic_v<_A2>
-[[nodiscard]] inline _LIBCPP_HIDE_FROM_ABI bool isgreater(_A1 __x, _A2 __y) noexcept {
+[[nodiscard]] inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isgreater(_A1 __x, _A2 __y) noexcept {
   using type = __promote_t<_A1, _A2>;
   return __builtin_isgreater((type)__x, (type)__y);
 }
diff --git a/libcxx/test/libcxx/numerics/c.math/constexpr-cxx23-clang.pass.cpp b/libcxx/test/libcxx/numerics/c.math/constexpr-cxx23-clang.pass.cpp
index 93865afc5e68b..642806ffbd960 100644
--- a/libcxx/test/libcxx/numerics/c.math/constexpr-cxx23-clang.pass.cpp
+++ b/libcxx/test/libcxx/numerics/c.math/constexpr-cxx23-clang.pass.cpp
@@ -227,9 +227,9 @@ int main(int, char**) {
   ASSERT_CONSTEXPR_CXX23(std::signbit(-1.0) == 1);
   ASSERT_CONSTEXPR_CXX23(std::signbit(-1.0L) == 1);
 
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isgreater(-1.0f, 0.0f) == 0);
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isgreater(-1.0, 0.0) == 0);
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isgreater(-1.0L, 0.0L) == 0);
+  ASSERT_CONSTEXPR_CXX23(std::isgreater(-1.0f, 0.0f) == 0);
+  ASSERT_CONSTEXPR_CXX23(std::isgreater(-1.0, 0.0) == 0);
+  ASSERT_CONSTEXPR_CXX23(std::isgreater(-1.0L, 0.0L) == 0);
 
   ASSERT_NOT_CONSTEXPR_CXX23(std::isgreaterequal(-1.0f, 0.0f) == 0);
   ASSERT_NOT_CONSTEXPR_CXX23(std::isgreaterequal(-1.0, 0.0) == 0);
diff --git a/libcxx/test/libcxx/numerics/c.math/constexpr-cxx23-gcc.pass.cpp b/libcxx/test/libcxx/numerics/c.math/constexpr-cxx23-gcc.pass.cpp
index d8779706bcee2..34513b459a056 100644
--- a/libcxx/test/libcxx/numerics/c.math/constexpr-cxx23-gcc.pass.cpp
+++ b/libcxx/test/libcxx/numerics/c.math/constexpr-cxx23-gcc.pass.cpp
@@ -221,9 +221,9 @@ int main(int, char**) {
   ASSERT_CONSTEXPR_CXX23(std::signbit(-1.0) == 1);
   ASSERT_CONSTEXPR_CXX23(std::signbit(-1.0L) == 1);
 
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isgreater(-1.0f, 0.0f) == 0);
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isgreater(-1.0, 0.0) == 0);
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isgreater(-1.0L, 0.0L) == 0);
+  ASSERT_CONSTEXPR_CXX23(std::isgreater(-1.0f, 0.0f) == 0);
+  ASSERT_CONSTEXPR_CXX23(std::isgreater(-1.0, 0.0) == 0);
+  ASSERT_CONSTEXPR_CXX23(std::isgreater(-1.0L, 0.0L) == 0);
 
   ASSERT_NOT_CONSTEXPR_CXX23(std::isgreaterequal(-1.0f, 0.0f) == 0);
   ASSERT_NOT_CONSTEXPR_CXX23(std::isgreaterequal(-1.0, 0.0) == 0);