On Fri, Dec 5, 2025 at 7:01 PM Jonathan Wakely <[email protected]> wrote:
> This allows the [utility.intcmp] functions to be used without including
> all of <utility>.
>
> libstdc++-v3/ChangeLog:
>
> * include/Makefile.am: Add new header.
> * include/Makefile.in: Regenerate.
> * include/std/latch: Include <bits/intcmp.h> instead of
> <utility>.
> * include/std/utility: Include <bits/intcmp.h>.
> (cmp_equal, cmp_not_equal, cmp_less, cmp_greater)
> (cmp_less_equal, cmp_greater_equal, in_range): Move to ...
> * include/bits/intcmp.h: New file.
> ---
>
> I see that <mdspan> uses these functions, but it also uses std::as_const
> so it needs the entire <utility> header. Maybe we should consider moving
> as_const to <bits/move.h>? It's conceptually a cast like std::move and
> std::forward.
>
I think such a change makes sense. I was going to say that submdspan
introduces
dependency on <tuple> from mdpsan, however I do not think that P3663R3:
Future-proof submdspan_mapping
this is still the case, as we use structure binding to decompose strides.
>
> Tested x86_64-linux.
>
> libstdc++-v3/include/Makefile.am | 1 +
> libstdc++-v3/include/Makefile.in | 1 +
> libstdc++-v3/include/bits/intcmp.h | 120 +++++++++++++++++++++++++++++
> libstdc++-v3/include/std/latch | 2 +-
> libstdc++-v3/include/std/utility | 72 +----------------
> 5 files changed, 124 insertions(+), 72 deletions(-)
> create mode 100644 libstdc++-v3/include/bits/intcmp.h
>
> diff --git a/libstdc++-v3/include/Makefile.am
> b/libstdc++-v3/include/Makefile.am
> index 7d65c6f3ab31..847fc13151f5 100644
> --- a/libstdc++-v3/include/Makefile.am
> +++ b/libstdc++-v3/include/Makefile.am
> @@ -134,6 +134,7 @@ bits_freestanding = \
> ${bits_srcdir}/enable_special_members.h \
> ${bits_srcdir}/functexcept.h \
> ${bits_srcdir}/functional_hash.h \
> + ${bits_srcdir}/intcmp.h \
> ${bits_srcdir}/invoke.h \
> ${bits_srcdir}/iterator_concepts.h \
> ${bits_srcdir}/max_size_type.h \
> diff --git a/libstdc++-v3/include/Makefile.in
> b/libstdc++-v3/include/Makefile.in
> index acf8ae9be441..1d6171bac9d1 100644
> --- a/libstdc++-v3/include/Makefile.in
> +++ b/libstdc++-v3/include/Makefile.in
> @@ -492,6 +492,7 @@ bits_freestanding = \
> ${bits_srcdir}/enable_special_members.h \
> ${bits_srcdir}/functexcept.h \
> ${bits_srcdir}/functional_hash.h \
> + ${bits_srcdir}/intcmp.h \
> ${bits_srcdir}/invoke.h \
> ${bits_srcdir}/iterator_concepts.h \
> ${bits_srcdir}/max_size_type.h \
> diff --git a/libstdc++-v3/include/bits/intcmp.h
> b/libstdc++-v3/include/bits/intcmp.h
> new file mode 100644
> index 000000000000..3d3fbc43d2c8
> --- /dev/null
> +++ b/libstdc++-v3/include/bits/intcmp.h
> @@ -0,0 +1,120 @@
> +// Integer comparison functions -*- C++ -*-
> +
> +// Copyright (C) 2020-2025 Free Software Foundation, Inc.
> +//
> +// This file is part of the GNU ISO C++ Library. This library is free
> +// software; you can redistribute it and/or modify it under the
> +// terms of the GNU General Public License as published by the
> +// Free Software Foundation; either version 3, or (at your option)
> +// any later version.
> +
> +// This library is distributed in the hope that it will be useful,
> +// but WITHOUT ANY WARRANTY; without even the implied warranty of
> +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> +// GNU General Public License for more details.
> +
> +// Under Section 7 of GPL version 3, you are granted additional
> +// permissions described in the GCC Runtime Library Exception, version
> +// 3.1, as published by the Free Software Foundation.
> +
> +// You should have received a copy of the GNU General Public License and
> +// a copy of the GCC Runtime Library Exception along with this program;
> +// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
> +// <http://www.gnu.org/licenses/>.
> +
> +/** @file bits/intcmp.h
> + * This is an internal header file, included by other library headers.
> + * Do not attempt to use it directly. @headername{utility}
> + */
> +
> +#ifndef _GLIBCXX_INTCMP_H
> +#define _GLIBCXX_INTCMP_H 1
> +
> +#ifdef _GLIBCXX_SYSHDR
> +#pragma GCC system_header
> +#endif
> +
> +#include <bits/version.h>
> +
> +#ifdef __glibcxx_integer_comparison_functions // C++ >= 20
> +
> +#include <type_traits>
> +#include <ext/numeric_traits.h> // __int_traits
> +
> +namespace std _GLIBCXX_VISIBILITY(default)
> +{
> +_GLIBCXX_BEGIN_NAMESPACE_VERSION
> +
> + template<typename _Tp, typename _Up>
> + constexpr bool
> + cmp_equal(_Tp __t, _Up __u) noexcept
> + {
> + static_assert(__is_standard_integer<_Tp>::value);
> + static_assert(__is_standard_integer<_Up>::value);
> +
> + if constexpr (is_signed_v<_Tp> == is_signed_v<_Up>)
> + return __t == __u;
> + else if constexpr (is_signed_v<_Tp>)
> + return __t >= 0 && make_unsigned_t<_Tp>(__t) == __u;
> + else
> + return __u >= 0 && __t == make_unsigned_t<_Up>(__u);
> + }
> +
> + template<typename _Tp, typename _Up>
> + constexpr bool
> + cmp_not_equal(_Tp __t, _Up __u) noexcept
> + { return !std::cmp_equal(__t, __u); }
> +
> + template<typename _Tp, typename _Up>
> + constexpr bool
> + cmp_less(_Tp __t, _Up __u) noexcept
> + {
> + static_assert(__is_standard_integer<_Tp>::value);
> + static_assert(__is_standard_integer<_Up>::value);
> +
> + if constexpr (is_signed_v<_Tp> == is_signed_v<_Up>)
> + return __t < __u;
> + else if constexpr (is_signed_v<_Tp>)
> + return __t < 0 || make_unsigned_t<_Tp>(__t) < __u;
> + else
> + return __u >= 0 && __t < make_unsigned_t<_Up>(__u);
> + }
> +
> + template<typename _Tp, typename _Up>
> + constexpr bool
> + cmp_greater(_Tp __t, _Up __u) noexcept
> + { return std::cmp_less(__u, __t); }
> +
> + template<typename _Tp, typename _Up>
> + constexpr bool
> + cmp_less_equal(_Tp __t, _Up __u) noexcept
> + { return !std::cmp_less(__u, __t); }
> +
> + template<typename _Tp, typename _Up>
> + constexpr bool
> + cmp_greater_equal(_Tp __t, _Up __u) noexcept
> + { return !std::cmp_less(__t, __u); }
> +
> + template<typename _Res, typename _Tp>
> + constexpr bool
> + in_range(_Tp __t) noexcept
> + {
> + static_assert(__is_standard_integer<_Res>::value);
> + static_assert(__is_standard_integer<_Tp>::value);
> + using __gnu_cxx::__int_traits;
> +
> + if constexpr (is_signed_v<_Tp> == is_signed_v<_Res>)
> + return __int_traits<_Res>::__min <= __t
> + && __t <= __int_traits<_Res>::__max;
> + else if constexpr (is_signed_v<_Tp>)
> + return __t >= 0
> + && make_unsigned_t<_Tp>(__t) <= __int_traits<_Res>::__max;
> + else
> + return __t <= make_unsigned_t<_Res>(__int_traits<_Res>::__max);
> + }
> +
> +_GLIBCXX_END_NAMESPACE_VERSION
> +} // namespace
> +
> +#endif // __glibcxx_integer_comparison_functions
> +#endif // _GLIBCXX_INTCMP_H
> diff --git a/libstdc++-v3/include/std/latch
> b/libstdc++-v3/include/std/latch
> index 9504df0a7224..df126c6a9ec9 100644
> --- a/libstdc++-v3/include/std/latch
> +++ b/libstdc++-v3/include/std/latch
> @@ -41,7 +41,7 @@
> #ifdef __cpp_lib_latch // C++ >= 20 && atomic_wait
> #include <bits/atomic_base.h>
> #include <ext/numeric_traits.h>
> -#include <utility> // cmp_equal, cmp_less_equal, etc.
> +#include <bits/intcmp.h> // cmp_equal, cmp_less_equal, etc.
>
> namespace std _GLIBCXX_VISIBILITY(default)
> {
> diff --git a/libstdc++-v3/include/std/utility
> b/libstdc++-v3/include/std/utility
> index 3ae1852426e8..0f6dd82b1a78 100644
> --- a/libstdc++-v3/include/std/utility
> +++ b/libstdc++-v3/include/std/utility
> @@ -78,7 +78,7 @@
> #include <bits/utility.h>
>
> #if __cplusplus >= 202002L
> -#include <ext/numeric_traits.h> // __is_standard_integer, __int_traits
> +#include <bits/intcmp.h>
> #endif
>
> #if __cplusplus > 202302L
> @@ -129,76 +129,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> void as_const(const _Tp&&) = delete;
> #endif
>
> -#ifdef __cpp_lib_integer_comparison_functions // C++ >= 20
> - template<typename _Tp, typename _Up>
> - constexpr bool
> - cmp_equal(_Tp __t, _Up __u) noexcept
> - {
> - static_assert(__is_standard_integer<_Tp>::value);
> - static_assert(__is_standard_integer<_Up>::value);
> -
> - if constexpr (is_signed_v<_Tp> == is_signed_v<_Up>)
> - return __t == __u;
> - else if constexpr (is_signed_v<_Tp>)
> - return __t >= 0 && make_unsigned_t<_Tp>(__t) == __u;
> - else
> - return __u >= 0 && __t == make_unsigned_t<_Up>(__u);
> - }
> -
> - template<typename _Tp, typename _Up>
> - constexpr bool
> - cmp_not_equal(_Tp __t, _Up __u) noexcept
> - { return !std::cmp_equal(__t, __u); }
> -
> - template<typename _Tp, typename _Up>
> - constexpr bool
> - cmp_less(_Tp __t, _Up __u) noexcept
> - {
> - static_assert(__is_standard_integer<_Tp>::value);
> - static_assert(__is_standard_integer<_Up>::value);
> -
> - if constexpr (is_signed_v<_Tp> == is_signed_v<_Up>)
> - return __t < __u;
> - else if constexpr (is_signed_v<_Tp>)
> - return __t < 0 || make_unsigned_t<_Tp>(__t) < __u;
> - else
> - return __u >= 0 && __t < make_unsigned_t<_Up>(__u);
> - }
> -
> - template<typename _Tp, typename _Up>
> - constexpr bool
> - cmp_greater(_Tp __t, _Up __u) noexcept
> - { return std::cmp_less(__u, __t); }
> -
> - template<typename _Tp, typename _Up>
> - constexpr bool
> - cmp_less_equal(_Tp __t, _Up __u) noexcept
> - { return !std::cmp_less(__u, __t); }
> -
> - template<typename _Tp, typename _Up>
> - constexpr bool
> - cmp_greater_equal(_Tp __t, _Up __u) noexcept
> - { return !std::cmp_less(__t, __u); }
> -
> - template<typename _Res, typename _Tp>
> - constexpr bool
> - in_range(_Tp __t) noexcept
> - {
> - static_assert(__is_standard_integer<_Res>::value);
> - static_assert(__is_standard_integer<_Tp>::value);
> - using __gnu_cxx::__int_traits;
> -
> - if constexpr (is_signed_v<_Tp> == is_signed_v<_Res>)
> - return __int_traits<_Res>::__min <= __t
> - && __t <= __int_traits<_Res>::__max;
> - else if constexpr (is_signed_v<_Tp>)
> - return __t >= 0
> - && make_unsigned_t<_Tp>(__t) <= __int_traits<_Res>::__max;
> - else
> - return __t <= make_unsigned_t<_Res>(__int_traits<_Res>::__max);
> - }
> -#endif // __cpp_lib_integer_comparison_functions
> -
> #ifdef __cpp_lib_to_underlying // C++ >= 23
> /// Convert an object of enumeration type to its underlying type.
> template<typename _Tp>
> --
> 2.52.0
>
>
