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llvm-project/libcxx/include/__math/traits.h
A. Jiang 3bdfca58a6
[libc++] Workaround for a bug of overloads in MS UCRT's <math.h> (#149234) 
MS UCRT seems confused on the status of LWG1327, and still provides
pre-LWG1327 overload set the related math functions, which can't handle
integer types as required. It is probably that UCRT won't fixed this in
a near future, per
https://developercommunity.visualstudio.com/t/10294165.

Before C++20, libc++ worked around this bug by relying on
`-fdelayed-template-parsing`. However, this non-conforming option is off
by default since C++20. I think we should use `requires` instead.

---------

Co-authored-by: Louis Dionne <ldionne.2@gmail.com>
2025-08-05 17:47:11 +08:00

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//===----------------------------------------------------------------------===//
//
// 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___MATH_TRAITS_H
#define _LIBCPP___MATH_TRAITS_H
#include <__config>
#include <__type_traits/enable_if.h>
#include <__type_traits/is_arithmetic.h>
#include <__type_traits/is_integral.h>
#include <__type_traits/promote.h>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
namespace __math {
// signbit
// TODO(LLVM 22): Remove conditional once support for Clang 19 is dropped.
#if defined(_LIBCPP_COMPILER_GCC) || __has_constexpr_builtin(__builtin_signbit)
# define _LIBCPP_SIGNBIT_CONSTEXPR _LIBCPP_CONSTEXPR_SINCE_CXX23
#else
# define _LIBCPP_SIGNBIT_CONSTEXPR
#endif
// The universal C runtime (UCRT) in the WinSDK provides floating point overloads
// for std::signbit(). By defining our overloads as templates, we can work around
// this issue as templates are less preferred than non-template functions.
template <class = void>
[[__nodiscard__]] inline _LIBCPP_SIGNBIT_CONSTEXPR _LIBCPP_HIDE_FROM_ABI bool signbit(float __x) _NOEXCEPT {
return __builtin_signbit(__x);
}
template <class = void>
[[__nodiscard__]] inline _LIBCPP_SIGNBIT_CONSTEXPR _LIBCPP_HIDE_FROM_ABI bool signbit(double __x) _NOEXCEPT {
return __builtin_signbit(__x);
}
template <class = void>
[[__nodiscard__]] inline _LIBCPP_SIGNBIT_CONSTEXPR _LIBCPP_HIDE_FROM_ABI bool signbit(long double __x) _NOEXCEPT {
return __builtin_signbit(__x);
}
template <class _A1, __enable_if_t<is_integral<_A1>::value, int> = 0>
[[__nodiscard__]] inline _LIBCPP_SIGNBIT_CONSTEXPR _LIBCPP_HIDE_FROM_ABI bool signbit(_A1 __x) _NOEXCEPT {
return __x < 0;
}
// isfinite
template <class _A1, __enable_if_t<is_integral<_A1>::value, int> = 0>
[[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isfinite(_A1) _NOEXCEPT {
return true;
}
[[__nodiscard__]] inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isfinite(float __x) _NOEXCEPT {
return __builtin_isfinite(__x);
}
[[__nodiscard__]] inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isfinite(double __x) _NOEXCEPT {
return __builtin_isfinite(__x);
}
[[__nodiscard__]] inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isfinite(long double __x) _NOEXCEPT {
return __builtin_isfinite(__x);
}
// isinf
template <class _A1, __enable_if_t<is_integral<_A1>::value, int> = 0>
[[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isinf(_A1) _NOEXCEPT {
return false;
}
[[__nodiscard__]] inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isinf(float __x) _NOEXCEPT {
return __builtin_isinf(__x);
}
[[__nodiscard__]] inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI
#ifdef _LIBCPP_PREFERRED_OVERLOAD
_LIBCPP_PREFERRED_OVERLOAD
#endif
bool
isinf(double __x) _NOEXCEPT {
return __builtin_isinf(__x);
}
[[__nodiscard__]] inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isinf(long double __x) _NOEXCEPT {
return __builtin_isinf(__x);
}
// isnan
template <class _A1, __enable_if_t<is_integral<_A1>::value, int> = 0>
[[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isnan(_A1) _NOEXCEPT {
return false;
}
[[__nodiscard__]] inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isnan(float __x) _NOEXCEPT {
return __builtin_isnan(__x);
}
[[__nodiscard__]] inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI
#ifdef _LIBCPP_PREFERRED_OVERLOAD
_LIBCPP_PREFERRED_OVERLOAD
#endif
bool
isnan(double __x) _NOEXCEPT {
return __builtin_isnan(__x);
}
[[__nodiscard__]] inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isnan(long double __x) _NOEXCEPT {
return __builtin_isnan(__x);
}
// isnormal
template <class _A1, __enable_if_t<is_integral<_A1>::value, int> = 0>
[[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isnormal(_A1 __x) _NOEXCEPT {
return __x != 0;
}
[[__nodiscard__]] inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isnormal(float __x) _NOEXCEPT {
return __builtin_isnormal(__x);
}
[[__nodiscard__]] inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isnormal(double __x) _NOEXCEPT {
return __builtin_isnormal(__x);
}
[[__nodiscard__]] inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isnormal(long double __x) _NOEXCEPT {
return __builtin_isnormal(__x);
}
// 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 {
using type = __promote_t<_A1, _A2>;
return __builtin_isgreater((type)__x, (type)__y);
}
// isgreaterequal
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 isgreaterequal(_A1 __x, _A2 __y) _NOEXCEPT {
using type = __promote_t<_A1, _A2>;
return __builtin_isgreaterequal((type)__x, (type)__y);
}
// isless
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 isless(_A1 __x, _A2 __y) _NOEXCEPT {
using type = __promote_t<_A1, _A2>;
return __builtin_isless((type)__x, (type)__y);
}
// islessequal
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 islessequal(_A1 __x, _A2 __y) _NOEXCEPT {
using type = __promote_t<_A1, _A2>;
return __builtin_islessequal((type)__x, (type)__y);
}
// islessgreater
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 islessgreater(_A1 __x, _A2 __y) _NOEXCEPT {
using type = __promote_t<_A1, _A2>;
return __builtin_islessgreater((type)__x, (type)__y);
}
// isunordered
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 isunordered(_A1 __x, _A2 __y) _NOEXCEPT {
using type = __promote_t<_A1, _A2>;
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
#endif // _LIBCPP___MATH_TRAITS_H
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