libstdc++: use __bool_constant instead of integral_constant

  In the type_traits header, both integral_constant<bool> and __bool_constant
are used. This patch unifies those usages into __bool_constant.

libstdc++-v3/ChangeLog:

	* include/std/type_traits: Use __bool_constant instead of
	integral_constant.
---
 libstdc++-v3/include/std/type_traits | 32 ++++++++++++++--------------
 1 file changed, 16 insertions(+), 16 deletions(-)
  

On Thu, 23 Mar 2023 at 02:06, Ken Matsui via Libstdc++ <
libstdc++@gcc.gnu.org> wrote:

> In the type_traits header, both integral_constant<bool> and __bool_constant
> are used.


Yes, this is just because we didn't have __bool_constant originally, and
nobody has needed to touch the traits that still use integral_constant, so
they never got updated.



> This patch unifies those usages into __bool_constant.
>

Thanks, doing this for consistency seems reasonable, and safe to do now
instead of waiting until after the GCC 13 release. I'll test and push the
patch.

Do you have a GCC copyright assignment on file with the FSF?
If not, either you need to complete that paperwork, or add a DCO sign-off
to all your patches:
https://gcc.gnu.org/dco.html


>
> libstdc++-v3/ChangeLog:
>
>         * include/std/type_traits: Use __bool_constant instead of
>         integral_constant.
> ---
>  libstdc++-v3/include/std/type_traits | 32 ++++++++++++++--------------
>  1 file changed, 16 insertions(+), 16 deletions(-)
>
> diff --git a/libstdc++-v3/include/std/type_traits
> b/libstdc++-v3/include/std/type_traits
> index 2bd607a8b8f..bc6982f9e64 100644
> --- a/libstdc++-v3/include/std/type_traits
> +++ b/libstdc++-v3/include/std/type_traits
> @@ -578,19 +578,19 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>    /// is_enum
>    template<typename _Tp>
>      struct is_enum
> -    : public integral_constant<bool, __is_enum(_Tp)>
> +    : public __bool_constant<__is_enum(_Tp)>
>      { };
>
>    /// is_union
>    template<typename _Tp>
>      struct is_union
> -    : public integral_constant<bool, __is_union(_Tp)>
> +    : public __bool_constant<__is_union(_Tp)>
>      { };
>
>    /// is_class
>    template<typename _Tp>
>      struct is_class
> -    : public integral_constant<bool, __is_class(_Tp)>
> +    : public __bool_constant<__is_class(_Tp)>
>      { };
>
>    /// is_function
> @@ -784,7 +784,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>    /// is_trivial
>    template<typename _Tp>
>      struct is_trivial
> -    : public integral_constant<bool, __is_trivial(_Tp)>
> +    : public __bool_constant<__is_trivial(_Tp)>
>      {
>
>  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
>         "template argument must be a complete class or an unbounded
> array");
> @@ -793,7 +793,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>    /// is_trivially_copyable
>    template<typename _Tp>
>      struct is_trivially_copyable
> -    : public integral_constant<bool, __is_trivially_copyable(_Tp)>
> +    : public __bool_constant<__is_trivially_copyable(_Tp)>
>      {
>
>  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
>         "template argument must be a complete class or an unbounded
> array");
> @@ -802,7 +802,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>    /// is_standard_layout
>    template<typename _Tp>
>      struct is_standard_layout
> -    : public integral_constant<bool, __is_standard_layout(_Tp)>
> +    : public __bool_constant<__is_standard_layout(_Tp)>
>      {
>
>  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
>         "template argument must be a complete class or an unbounded
> array");
> @@ -817,7 +817,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>      struct
>      _GLIBCXX20_DEPRECATED_SUGGEST("is_standard_layout && is_trivial")
>      is_pod
> -    : public integral_constant<bool, __is_pod(_Tp)>
> +    : public __bool_constant<__is_pod(_Tp)>
>      {
>
>  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
>         "template argument must be a complete class or an unbounded
> array");
> @@ -831,7 +831,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>      struct
>      _GLIBCXX17_DEPRECATED
>      is_literal_type
> -    : public integral_constant<bool, __is_literal_type(_Tp)>
> +    : public __bool_constant<__is_literal_type(_Tp)>
>      {
>
>  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
>         "template argument must be a complete class or an unbounded
> array");
> @@ -840,13 +840,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>    /// is_empty
>    template<typename _Tp>
>      struct is_empty
> -    : public integral_constant<bool, __is_empty(_Tp)>
> +    : public __bool_constant<__is_empty(_Tp)>
>      { };
>
>    /// is_polymorphic
>    template<typename _Tp>
>      struct is_polymorphic
> -    : public integral_constant<bool, __is_polymorphic(_Tp)>
> +    : public __bool_constant<__is_polymorphic(_Tp)>
>      { };
>
>  #if __cplusplus >= 201402L
> @@ -855,14 +855,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>    /// @since C++14
>    template<typename _Tp>
>      struct is_final
> -    : public integral_constant<bool, __is_final(_Tp)>
> +    : public __bool_constant<__is_final(_Tp)>
>      { };
>  #endif
>
>    /// is_abstract
>    template<typename _Tp>
>      struct is_abstract
> -    : public integral_constant<bool, __is_abstract(_Tp)>
> +    : public __bool_constant<__is_abstract(_Tp)>
>      { };
>
>    /// @cond undocumented
> @@ -873,7 +873,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>
>    template<typename _Tp>
>      struct __is_signed_helper<_Tp, true>
> -    : public integral_constant<bool, _Tp(-1) < _Tp(0)>
> +    : public __bool_constant<_Tp(-1) < _Tp(0)>
>      { };
>    /// @endcond
>
> @@ -1333,7 +1333,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>    /// has_virtual_destructor
>    template<typename _Tp>
>      struct has_virtual_destructor
> -    : public integral_constant<bool, __has_virtual_destructor(_Tp)>
> +    : public __bool_constant<__has_virtual_destructor(_Tp)>
>      {
>
>  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
>         "template argument must be a complete class or an unbounded
> array");
> @@ -1392,7 +1392,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>    template<typename _Tp, typename _Up>
>      struct is_same
>  #ifdef _GLIBCXX_HAVE_BUILTIN_IS_SAME
> -    : public integral_constant<bool, __is_same(_Tp, _Up)>
> +    : public __bool_constant<__is_same(_Tp, _Up)>
>  #else
>      : public false_type
>  #endif
> @@ -1408,7 +1408,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>    /// is_base_of
>    template<typename _Base, typename _Derived>
>      struct is_base_of
> -    : public integral_constant<bool, __is_base_of(_Base, _Derived)>
> +    : public __bool_constant<__is_base_of(_Base, _Derived)>
>      { };
>
>  #if __has_builtin(__is_convertible)
> --
> 2.40.0
>
>
  

Thank you so much for your review!

This is my first time contributing to GCC, so I do not have a GCC
copyright assignment. I googled those two ways, but I am still
confused... Is it correct that the DCO sign-off has been getting more
common recently? If so, I will put the sign-off into all my patches. I
would prefer to choose the more common and lightweight way.

Sincerely,
Ken Matsui

On Thu, Mar 23, 2023 at 2:28 AM Jonathan Wakely <jwakely@redhat.com> wrote:
>
>
>
> On Thu, 23 Mar 2023 at 02:06, Ken Matsui via Libstdc++ <libstdc++@gcc.gnu.org> wrote:
>>
>> In the type_traits header, both integral_constant<bool> and __bool_constant
>> are used.
>
>
> Yes, this is just because we didn't have __bool_constant originally, and nobody has needed to touch the traits that still use integral_constant, so they never got updated.
>
>
>>
>> This patch unifies those usages into __bool_constant.
>
>
> Thanks, doing this for consistency seems reasonable, and safe to do now instead of waiting until after the GCC 13 release. I'll test and push the patch.
>
> Do you have a GCC copyright assignment on file with the FSF?
> If not, either you need to complete that paperwork, or add a DCO sign-off to all your patches:
> https://gcc.gnu.org/dco.html
>
>>
>>
>> libstdc++-v3/ChangeLog:
>>
>>         * include/std/type_traits: Use __bool_constant instead of
>>         integral_constant.
>> ---
>>  libstdc++-v3/include/std/type_traits | 32 ++++++++++++++--------------
>>  1 file changed, 16 insertions(+), 16 deletions(-)
>>
>> diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
>> index 2bd607a8b8f..bc6982f9e64 100644
>> --- a/libstdc++-v3/include/std/type_traits
>> +++ b/libstdc++-v3/include/std/type_traits
>> @@ -578,19 +578,19 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>>    /// is_enum
>>    template<typename _Tp>
>>      struct is_enum
>> -    : public integral_constant<bool, __is_enum(_Tp)>
>> +    : public __bool_constant<__is_enum(_Tp)>
>>      { };
>>
>>    /// is_union
>>    template<typename _Tp>
>>      struct is_union
>> -    : public integral_constant<bool, __is_union(_Tp)>
>> +    : public __bool_constant<__is_union(_Tp)>
>>      { };
>>
>>    /// is_class
>>    template<typename _Tp>
>>      struct is_class
>> -    : public integral_constant<bool, __is_class(_Tp)>
>> +    : public __bool_constant<__is_class(_Tp)>
>>      { };
>>
>>    /// is_function
>> @@ -784,7 +784,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>>    /// is_trivial
>>    template<typename _Tp>
>>      struct is_trivial
>> -    : public integral_constant<bool, __is_trivial(_Tp)>
>> +    : public __bool_constant<__is_trivial(_Tp)>
>>      {
>>        static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
>>         "template argument must be a complete class or an unbounded array");
>> @@ -793,7 +793,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>>    /// is_trivially_copyable
>>    template<typename _Tp>
>>      struct is_trivially_copyable
>> -    : public integral_constant<bool, __is_trivially_copyable(_Tp)>
>> +    : public __bool_constant<__is_trivially_copyable(_Tp)>
>>      {
>>        static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
>>         "template argument must be a complete class or an unbounded array");
>> @@ -802,7 +802,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>>    /// is_standard_layout
>>    template<typename _Tp>
>>      struct is_standard_layout
>> -    : public integral_constant<bool, __is_standard_layout(_Tp)>
>> +    : public __bool_constant<__is_standard_layout(_Tp)>
>>      {
>>        static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
>>         "template argument must be a complete class or an unbounded array");
>> @@ -817,7 +817,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>>      struct
>>      _GLIBCXX20_DEPRECATED_SUGGEST("is_standard_layout && is_trivial")
>>      is_pod
>> -    : public integral_constant<bool, __is_pod(_Tp)>
>> +    : public __bool_constant<__is_pod(_Tp)>
>>      {
>>        static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
>>         "template argument must be a complete class or an unbounded array");
>> @@ -831,7 +831,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>>      struct
>>      _GLIBCXX17_DEPRECATED
>>      is_literal_type
>> -    : public integral_constant<bool, __is_literal_type(_Tp)>
>> +    : public __bool_constant<__is_literal_type(_Tp)>
>>      {
>>        static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
>>         "template argument must be a complete class or an unbounded array");
>> @@ -840,13 +840,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>>    /// is_empty
>>    template<typename _Tp>
>>      struct is_empty
>> -    : public integral_constant<bool, __is_empty(_Tp)>
>> +    : public __bool_constant<__is_empty(_Tp)>
>>      { };
>>
>>    /// is_polymorphic
>>    template<typename _Tp>
>>      struct is_polymorphic
>> -    : public integral_constant<bool, __is_polymorphic(_Tp)>
>> +    : public __bool_constant<__is_polymorphic(_Tp)>
>>      { };
>>
>>  #if __cplusplus >= 201402L
>> @@ -855,14 +855,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>>    /// @since C++14
>>    template<typename _Tp>
>>      struct is_final
>> -    : public integral_constant<bool, __is_final(_Tp)>
>> +    : public __bool_constant<__is_final(_Tp)>
>>      { };
>>  #endif
>>
>>    /// is_abstract
>>    template<typename _Tp>
>>      struct is_abstract
>> -    : public integral_constant<bool, __is_abstract(_Tp)>
>> +    : public __bool_constant<__is_abstract(_Tp)>
>>      { };
>>
>>    /// @cond undocumented
>> @@ -873,7 +873,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>>
>>    template<typename _Tp>
>>      struct __is_signed_helper<_Tp, true>
>> -    : public integral_constant<bool, _Tp(-1) < _Tp(0)>
>> +    : public __bool_constant<_Tp(-1) < _Tp(0)>
>>      { };
>>    /// @endcond
>>
>> @@ -1333,7 +1333,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>>    /// has_virtual_destructor
>>    template<typename _Tp>
>>      struct has_virtual_destructor
>> -    : public integral_constant<bool, __has_virtual_destructor(_Tp)>
>> +    : public __bool_constant<__has_virtual_destructor(_Tp)>
>>      {
>>        static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
>>         "template argument must be a complete class or an unbounded array");
>> @@ -1392,7 +1392,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>>    template<typename _Tp, typename _Up>
>>      struct is_same
>>  #ifdef _GLIBCXX_HAVE_BUILTIN_IS_SAME
>> -    : public integral_constant<bool, __is_same(_Tp, _Up)>
>> +    : public __bool_constant<__is_same(_Tp, _Up)>
>>  #else
>>      : public false_type
>>  #endif
>> @@ -1408,7 +1408,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>>    /// is_base_of
>>    template<typename _Base, typename _Derived>
>>      struct is_base_of
>> -    : public integral_constant<bool, __is_base_of(_Base, _Derived)>
>> +    : public __bool_constant<__is_base_of(_Base, _Derived)>
>>      { };
>>
>>  #if __has_builtin(__is_convertible)
>> --
>> 2.40.0
>>
  

On Thu, 23 Mar 2023 at 12:18, Ken Matsui via Libstdc++
<libstdc++@gcc.gnu.org> wrote:
>
> Thank you so much for your review!
>
> This is my first time contributing to GCC, so I do not have a GCC
> copyright assignment. I googled those two ways, but I am still
> confused... Is it correct that the DCO sign-off has been getting more
> common recently? If so, I will put the sign-off into all my patches. I
> would prefer to choose the more common and lightweight way.

DCO sign-off is indeed more light-weight, and sure, it's becoming more common
since it's relatively new as an option.
  

On Thu, Mar 23, 2023 at 3:46 AM Ville Voutilainen
<ville.voutilainen@gmail.com> wrote:
>
> On Thu, 23 Mar 2023 at 12:18, Ken Matsui via Libstdc++
> <libstdc++@gcc.gnu.org> wrote:
> >
> > Thank you so much for your review!
> >
> > This is my first time contributing to GCC, so I do not have a GCC
> > copyright assignment. I googled those two ways, but I am still
> > confused... Is it correct that the DCO sign-off has been getting more
> > common recently? If so, I will put the sign-off into all my patches. I
> > would prefer to choose the more common and lightweight way.
>
> DCO sign-off is indeed more light-weight, and sure, it's becoming more common
> since it's relatively new as an option.

Thank you!

To add a DCO sign-off, do I need to bump up the subject line to [PATCH v2]?
  

On Thu, 23 Mar 2023 at 12:53, Ken Matsui <kmatsui@cs.washington.edu> wrote:

> > DCO sign-off is indeed more light-weight, and sure, it's becoming more common
> > since it's relatively new as an option.
>
> Thank you!
>
> To add a DCO sign-off, do I need to bump up the subject line to [PATCH v2]?

No. The format of the subject for patch submission emails is not that strict. :)
  

On Thu, Mar 23, 2023 at 3:56 AM Ville Voutilainen
<ville.voutilainen@gmail.com> wrote:
>
> On Thu, 23 Mar 2023 at 12:53, Ken Matsui <kmatsui@cs.washington.edu> wrote:
>
> > > DCO sign-off is indeed more light-weight, and sure, it's becoming more common
> > > since it's relatively new as an option.
> >
> > Thank you!
> >
> > To add a DCO sign-off, do I need to bump up the subject line to [PATCH v2]?
>
> No. The format of the subject for patch submission emails is not that strict. :)

I see. I will update this patch. Thank you so much for your support!

Sincerely,
Ken Matsui