1 files changed, 76 insertions, 0 deletions
diff --git a/libcxx/include/__math/traits.h b/libcxx/include/__math/traits.h
index 4a6e58c..00db2a8 100644
--- a/libcxx/include/__math/traits.h
+++ b/libcxx/include/__math/traits.h
@@ -189,6 +189,82 @@ template <class _A1, class _A2, __enable_if_t<is_arithmetic<_A1>::value && is_ar
   return __builtin_isunordered((type)__x, (type)__y);
 }
 
+// MS UCRT incorrectly defines some functions in a way not working with integer types. Until C++20, this was worked
+// around by -fdelayed-template-parsing. Since C++20, we can use standard feature "requires" instead.
+
+// TODO: Remove the workaround once UCRT fixes these functions. Note that this doesn't seem planned as of 2025-07 per
+// https://developercommunity.visualstudio.com/t/10294165.
+
+#if defined(_LIBCPP_MSVCRT) && _LIBCPP_STD_VER >= 20
+namespace __ucrt {
+template <class _A1>
+  requires is_integral_v<_A1>
+[[nodiscard]] inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isfinite(_A1) noexcept {
+  return true;
+}
+
+template <class _A1>
+  requires is_integral_v<_A1>
+[[nodiscard]] inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isinf(_A1) noexcept {
+  return false;
+}
+
+template <class _A1>
+  requires is_integral_v<_A1>
+[[nodiscard]] inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isnan(_A1) noexcept {
+  return false;
+}
+
+template <class _A1>
+  requires is_integral_v<_A1>
+[[nodiscard]] inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isnormal(_A1 __x) noexcept {
+  return __x != 0;
+}
+
+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 {
+  using type = __promote_t<_A1, _A2>;
+  return __builtin_isgreater((type)__x, (type)__y);
+}
+
+template <class _A1, class _A2>
+  requires is_arithmetic_v<_A1> && is_arithmetic_v<_A2>
+[[nodiscard]] inline _LIBCPP_HIDE_FROM_ABI bool isgreaterequal(_A1 __x, _A2 __y) noexcept {
+  using type = __promote_t<_A1, _A2>;
+  return __builtin_isgreaterequal((type)__x, (type)__y);
+}
+
+template <class _A1, class _A2>
+  requires is_arithmetic_v<_A1> && is_arithmetic_v<_A2>
+[[nodiscard]] inline _LIBCPP_HIDE_FROM_ABI bool isless(_A1 __x, _A2 __y) noexcept {
+  using type = __promote_t<_A1, _A2>;
+  return __builtin_isless((type)__x, (type)__y);
+}
+
+template <class _A1, class _A2>
+  requires is_arithmetic_v<_A1> && is_arithmetic_v<_A2>
+[[nodiscard]] inline _LIBCPP_HIDE_FROM_ABI bool islessequal(_A1 __x, _A2 __y) noexcept {
+  using type = __promote_t<_A1, _A2>;
+  return __builtin_islessequal((type)__x, (type)__y);
+}
+
+template <class _A1, class _A2>
+  requires is_arithmetic_v<_A1> && is_arithmetic_v<_A2>
+[[nodiscard]] inline _LIBCPP_HIDE_FROM_ABI bool islessgreater(_A1 __x, _A2 __y) noexcept {
+  using type = __promote_t<_A1, _A2>;
+  return __builtin_islessgreater((type)__x, (type)__y);
+}
+
+template <class _A1, class _A2>
+  requires is_arithmetic_v<_A1> && is_arithmetic_v<_A2>
+[[nodiscard]] inline _LIBCPP_HIDE_FROM_ABI bool isunordered(_A1 __x, _A2 __y) noexcept {
+  using type = __promote_t<_A1, _A2>;
+  return __builtin_isunordered((type)__x, (type)__y);
+}
+} // namespace __ucrt
+#endif
+
 } // namespace __math
 
 _LIBCPP_END_NAMESPACE_STD