Re: [PATCH v2 2/2] libstdc++: use new built-in trait __is_scalar for std::is_scalar

[Ken Matsui <kmatsui@cs.washington.edu>]

On Wed, Jul 12, 2023 at 12:23 PM Jonathan Wakely <jwakely.gcc@gmail.com> wrote:
>
>
>
> On Wed, 12 Jul 2023, 19:33 Ken Matsui via Libstdc++, <libstdc++@gcc.gnu.org> wrote:
>>
>> On Wed, Jul 12, 2023 at 2:50 AM Jonathan Wakely <jwakely@redhat.com> wrote:
>> >
>> > On Sat, 8 Jul 2023 at 05:47, Ken Matsui via Libstdc++
>> > <libstdc++@gcc.gnu.org> wrote:
>> > >
>> > > This patch gets std::is_scalar to dispatch to new built-in trait
>> > > __is_scalar.
>> > >
>> > > libstdc++-v3/ChangeLog:
>> > >
>> > >         * include/std/type_traits (is_scalar): Use __is_scalar built-in
>> > >         trait.
>> > >         (is_scalar_v): Likewise.
>> >
>> > OK for trunk (conditional on the front-end change being committed
>> > first of course).
>> >
>>
>> Thank you for your review!
>>
>> Just to confirm, this approval does not include the [1/2] patch, does
>> it? Or, did you approve this entire patch series?
>
>
> Only this patch. I cannot approve compiler changes, I'm only a reviewer for libstdc++.
>
>
>>
>> > conditional on the front-end change being committed first of course
>>
>> Does this mean we want to commit this [2/2] patch before committing
>> the [1/2] patch in this case?
>
>
> The other way around, as Xi Ruoyao said.
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>
>>
>> Also, can I tweak the commit message without being approved again,
>> such as attaching the benchmark result?
>
>
> Yes, that's fine.

Thank you!

>>
>> > >
>> > > Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
>> > > ---
>> > >  libstdc++-v3/include/std/type_traits | 14 ++++++++++++++
>> > >  1 file changed, 14 insertions(+)
>> > >
>> > > diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
>> > > index 0e7a9c9c7f3..bc90b2c61ca 100644
>> > > --- a/libstdc++-v3/include/std/type_traits
>> > > +++ b/libstdc++-v3/include/std/type_traits
>> > > @@ -678,11 +678,18 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>> > >      struct is_member_pointer;
>> > >
>> > >    /// is_scalar
>> > > +#if __has_builtin(__is_scalar)
>> > > +  template<typename _Tp>
>> > > +    struct is_scalar
>> > > +    : public __bool_constant<__is_scalar(_Tp)>
>> > > +    { };
>> > > +#else
>> > >    template<typename _Tp>
>> > >      struct is_scalar
>> > >      : public __or_<is_arithmetic<_Tp>, is_enum<_Tp>, is_pointer<_Tp>,
>> > >                     is_member_pointer<_Tp>, is_null_pointer<_Tp>>::type
>> > >      { };
>> > > +#endif
>> > >
>> > >    /// is_compound
>> > >    template<typename _Tp>
>> > > @@ -3204,8 +3211,15 @@ template <typename _Tp>
>> > >    inline constexpr bool is_fundamental_v = is_fundamental<_Tp>::value;
>> > >  template <typename _Tp>
>> > >    inline constexpr bool is_object_v = is_object<_Tp>::value;
>> > > +
>> > > +#if __has_builtin(__is_scalar)
>> > > +template <typename _Tp>
>> > > +  inline constexpr bool is_scalar_v = __is_scalar(_Tp);
>> > > +#else
>> > >  template <typename _Tp>
>> > >    inline constexpr bool is_scalar_v = is_scalar<_Tp>::value;
>> > > +#endif
>> > > +
>> > >  template <typename _Tp>
>> > >    inline constexpr bool is_compound_v = is_compound<_Tp>::value;
>> > >  template <typename _Tp>
>> > > --
>> > > 2.41.0
>> > >
>> >