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Overhaul constexpr <cstdlib> and <cinttypes> #6438

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517cdeb
Apply the `extern "C++"` `inline namespace` technique to `__msvc_intt…
StephanTLavavej Sep 5, 2026
96023a3
Avoid unnecessary function calls in `abs()` and `div()` overloads.
StephanTLavavej Sep 5, 2026
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22 changes: 13 additions & 9 deletions stl/inc/__msvc_inttypes.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -51,15 +51,19 @@ typedef _Lldiv_t imaxdiv_t;
#define _CONSTEXPR_CINTTYPES23 inline
#endif // ^^^ inline when /Zc:cmath- opts out of constexpr, and in C++20 and earlier ^^^

[[nodiscard]] _Check_return_ _CONSTEXPR_CINTTYPES23 intmax_t __cdecl imaxabs(_In_ intmax_t _Number) noexcept
/* strengthened */ {
return _Number >= 0 ? _Number : -_Number;
}

[[nodiscard]] _Check_return_ _CONSTEXPR_CINTTYPES23 imaxdiv_t __cdecl imaxdiv(
_In_ intmax_t _Numerator, _In_ intmax_t _Denominator) noexcept /* strengthened */ {
return {_Numerator / _Denominator, _Numerator % _Denominator};
}
extern "C++" {
inline namespace _Msvc_inttypes {
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StephanTLavavej marked this conversation as resolved.
[[nodiscard]] _Check_return_ _CONSTEXPR_CINTTYPES23 intmax_t __cdecl imaxabs(_In_ intmax_t _Number) noexcept
/* strengthened */ {
return _Number >= 0 ? _Number : -_Number;
}

[[nodiscard]] _Check_return_ _CONSTEXPR_CINTTYPES23 imaxdiv_t __cdecl imaxdiv(
_In_ intmax_t _Numerator, _In_ intmax_t _Denominator) noexcept /* strengthened */ {
return {_Numerator / _Denominator, _Numerator % _Denominator};
}
} // namespace _Msvc_inttypes
} // extern "C++"

#undef _CONSTEXPR_CINTTYPES23

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107 changes: 50 additions & 57 deletions stl/inc/__msvc_stdlib.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -222,46 +222,37 @@ typedef struct _lldiv_t {
#define _CONSTEXPR_CSTDLIB23 inline
#endif // ^^^ inline when /Zc:cmath- opts out of constexpr, and in C++20 and earlier ^^^

_Check_return_ _CONSTEXPR_CSTDLIB23 int __cdecl abs(_In_ int) noexcept;
_Check_return_ _CONSTEXPR_CSTDLIB23 long __cdecl labs(_In_ long) noexcept;
_Check_return_ _CONSTEXPR_CSTDLIB23 long long __cdecl llabs(_In_ long long) noexcept;
_Check_return_ _CONSTEXPR_CSTDLIB23 div_t __cdecl div(_In_ int, _In_ int) noexcept;
_Check_return_ _CONSTEXPR_CSTDLIB23 ldiv_t __cdecl ldiv(_In_ long, _In_ long) noexcept;
_Check_return_ _CONSTEXPR_CSTDLIB23 lldiv_t __cdecl lldiv(_In_ long long, _In_ long long) noexcept;

#pragma warning(push)
#pragma warning(disable : 4163) // 'meow' not available as an intrinsic function
#pragma function(abs, labs, llabs)
#pragma function(div, ldiv, lldiv)
#pragma warning(pop)

[[nodiscard]] _Check_return_ _CONSTEXPR_CSTDLIB23 int __cdecl abs(_In_ int _Xx) noexcept /* strengthened */ {
return _Xx >= 0 ? _Xx : -_Xx;
}

[[nodiscard]] _Check_return_ _CONSTEXPR_CSTDLIB23 long __cdecl labs(_In_ long _Xx) noexcept /* strengthened */ {
return _Xx >= 0 ? _Xx : -_Xx;
}

[[nodiscard]] _Check_return_ _CONSTEXPR_CSTDLIB23 long long __cdecl llabs(_In_ long long _Xx) noexcept
/* strengthened */ {
return _Xx >= 0 ? _Xx : -_Xx;
}

[[nodiscard]] _Check_return_ _CONSTEXPR_CSTDLIB23 div_t __cdecl div(_In_ int _Numerator, _In_ int _Denominator) noexcept
/* strengthened */ {
return {_Numerator / _Denominator, _Numerator % _Denominator};
}

[[nodiscard]] _Check_return_ _CONSTEXPR_CSTDLIB23 ldiv_t __cdecl ldiv(
_In_ long _Numerator, _In_ long _Denominator) noexcept /* strengthened */ {
return {_Numerator / _Denominator, _Numerator % _Denominator};
}

[[nodiscard]] _Check_return_ _CONSTEXPR_CSTDLIB23 lldiv_t __cdecl lldiv(
_In_ long long _Numerator, _In_ long long _Denominator) noexcept /* strengthened */ {
return {_Numerator / _Denominator, _Numerator % _Denominator};
}
extern "C++" {
inline namespace _Msvc_stdlib {
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StephanTLavavej marked this conversation as resolved.
[[nodiscard]] _Check_return_ _CONSTEXPR_CSTDLIB23 int __cdecl abs(_In_ int _Xx) noexcept /* strengthened */ {
return _Xx >= 0 ? _Xx : -_Xx;
}

[[nodiscard]] _Check_return_ _CONSTEXPR_CSTDLIB23 long __cdecl labs(_In_ long _Xx) noexcept /* strengthened */ {
return _Xx >= 0 ? _Xx : -_Xx;
}

[[nodiscard]] _Check_return_ _CONSTEXPR_CSTDLIB23 long long __cdecl llabs(_In_ long long _Xx) noexcept
/* strengthened */ {
return _Xx >= 0 ? _Xx : -_Xx;
}

[[nodiscard]] _Check_return_ _CONSTEXPR_CSTDLIB23 div_t __cdecl div(
_In_ int _Numerator, _In_ int _Denominator) noexcept /* strengthened */ {
return {_Numerator / _Denominator, _Numerator % _Denominator};
}

[[nodiscard]] _Check_return_ _CONSTEXPR_CSTDLIB23 ldiv_t __cdecl ldiv(
_In_ long _Numerator, _In_ long _Denominator) noexcept /* strengthened */ {
return {_Numerator / _Denominator, _Numerator % _Denominator};
}

[[nodiscard]] _Check_return_ _CONSTEXPR_CSTDLIB23 lldiv_t __cdecl lldiv(
_In_ long long _Numerator, _In_ long long _Denominator) noexcept /* strengthened */ {
return {_Numerator / _Denominator, _Numerator % _Denominator};
}
} // namespace _Msvc_stdlib
} // extern "C++"

_Check_return_ __int64 __cdecl _abs64(_In_ __int64 _Number);

Expand Down Expand Up @@ -302,23 +293,25 @@ _ACRTIMP errno_t __cdecl rand_s(_Out_ unsigned int* _RandomValue);


extern "C++" {
[[nodiscard]] _CONSTEXPR_CSTDLIB23 long abs(long const _Xx) noexcept /* strengthened */ {
return labs(_Xx);
}

[[nodiscard]] _CONSTEXPR_CSTDLIB23 long long abs(long long const _Xx) noexcept /* strengthened */ {
return llabs(_Xx);
}

[[nodiscard]] _CONSTEXPR_CSTDLIB23 ldiv_t div(long const _Numerator, long const _Denominator) noexcept
/* strengthened */ {
return ldiv(_Numerator, _Denominator);
}

[[nodiscard]] _CONSTEXPR_CSTDLIB23 lldiv_t div(long long const _Numerator, long long const _Denominator) noexcept
/* strengthened */ {
return lldiv(_Numerator, _Denominator);
}
inline namespace _Msvc_stdlib {
[[nodiscard]] _CONSTEXPR_CSTDLIB23 long abs(long const _Xx) noexcept /* strengthened */ {
return _Xx >= 0 ? _Xx : -_Xx;
}

[[nodiscard]] _CONSTEXPR_CSTDLIB23 long long abs(long long const _Xx) noexcept /* strengthened */ {
return _Xx >= 0 ? _Xx : -_Xx;
}

[[nodiscard]] _CONSTEXPR_CSTDLIB23 ldiv_t div(long const _Numerator, long const _Denominator) noexcept
/* strengthened */ {
return {_Numerator / _Denominator, _Numerator % _Denominator};
}

[[nodiscard]] _CONSTEXPR_CSTDLIB23 lldiv_t div(long long const _Numerator, long long const _Denominator) noexcept
/* strengthened */ {
return {_Numerator / _Denominator, _Numerator % _Denominator};
}
} // namespace _Msvc_stdlib
} // extern "C++"

#undef _CONSTEXPR_CSTDLIB23
Expand Down