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[libc++] Move std::abs into __math/abs.h (#139586)

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`template <class = int>` is also added to our implementations to avoid
an ambiguity between the libc's version and our version when both are
visible.

This avoids including `<stdlib.h>` in `<math.h>`.
This commit is contained in:
Nikolas Klauser
2025-06-19 10:37:18 +02:00
committed by GitHub
parent 681db064d2
commit 584cc37687
4 changed files with 29 additions and 29 deletions
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24
libcxx/include/__math/abs.h
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@@ -39,6 +39,30 @@ template <class _A1, __enable_if_t<is_integral<_A1>::value, int> = 0>
return __builtin_fabs((double)__x);
}
// abs
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI inline float abs(float __x) _NOEXCEPT { return __builtin_fabsf(__x); }
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI inline double abs(double __x) _NOEXCEPT { return __builtin_fabs(__x); }
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI inline long double abs(long double __x) _NOEXCEPT {
return __builtin_fabsl(__x);
}
template <class = int>
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI inline int abs(int __x) _NOEXCEPT {
return __builtin_abs(__x);
}
template <class = int>
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI inline long abs(long __x) _NOEXCEPT {
return __builtin_labs(__x);
}
template <class = int>
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI inline long long abs(long long __x) _NOEXCEPT {
return __builtin_llabs(__x);
}
} // namespace __math
_LIBCPP_END_NAMESPACE_STD

11
libcxx/include/math.h
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@@ -378,9 +378,7 @@ extern "C++" {
# include <__math/traits.h>
# include <__math/trigonometric_functions.h>
# include <__type_traits/enable_if.h>
# include <__type_traits/is_floating_point.h>
# include <__type_traits/is_integral.h>
# include <stdlib.h>
// fpclassify relies on implementation-defined constants, so we can't move it to a detail header
_LIBCPP_BEGIN_NAMESPACE_STD
@@ -431,19 +429,12 @@ using std::__math::isnormal;
using std::__math::isunordered;
# endif // _LIBCPP_MSVCRT
// abs
//
// handled in stdlib.h
// div
//
// handled in stdlib.h
// We have to provide double overloads for <math.h> to work on platforms that don't provide the full set of math
// functions. To make the overload set work with multiple functions that take the same arguments, we make our overloads
// templates. Functions are preferred over function templates during overload resolution, which means that our overload
// will only be selected when the C library doesn't provide one.
using std::__math::abs;
using std::__math::acos;
using std::__math::acosh;
using std::__math::asin;

19
libcxx/include/stdlib.h
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@@ -106,23 +106,8 @@ extern "C++" {
# undef llabs
# endif
// MSVCRT already has the correct prototype in <stdlib.h> if __cplusplus is defined
# if !defined(_LIBCPP_MSVCRT)
[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI long abs(long __x) _NOEXCEPT { return __builtin_labs(__x); }
[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI long long abs(long long __x) _NOEXCEPT { return __builtin_llabs(__x); }
# endif // !defined(_LIBCPP_MSVCRT)
[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI float abs(float __lcpp_x) _NOEXCEPT {
return __builtin_fabsf(__lcpp_x); // Use builtins to prevent needing math.h
}
[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI double abs(double __lcpp_x) _NOEXCEPT {
return __builtin_fabs(__lcpp_x);
}
[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI long double abs(long double __lcpp_x) _NOEXCEPT {
return __builtin_fabsl(__lcpp_x);
}
# include <__math/abs.h>
using std::__math::abs;
// div

4
libcxx/test/std/numerics/c.math/abs.verify.cpp
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@@ -13,10 +13,10 @@ void f() {
(void)std::abs(ui); // expected-error {{call to 'abs' is ambiguous}}
unsigned char uc = -5;
(void)std::abs(uc); // expected-warning {{taking the absolute value of unsigned type 'unsigned char' has no effect}}
(void)std::abs(uc); // expected-warning 0-1 {{taking the absolute value of unsigned type 'unsigned char' has no effect}}
unsigned short us = -5;
(void)std::abs(us); // expected-warning {{taking the absolute value of unsigned type 'unsigned short' has no effect}}
(void)std::abs(us); // expected-warning 0-1 {{taking the absolute value of unsigned type 'unsigned short' has no effect}}
unsigned long ul = -5;
(void)std::abs(ul); // expected-error {{call to 'abs' is ambiguous}}