[PATCH v3 4/6] libstdc++: use new built-in trait __is_function for std::is_function

[Ken Matsui]

On Fri, Jun 9, 2023 at 10:54 AM Patrick Palka <ppalka@redhat.com> wrote:
>
> On Sun, 2 Apr 2023, Ken Matsui via Gcc-patches wrote:
>
> > This patch gets std::is_function to dispatch to new built-in trait
> > __is_function.
>
> For std::is_function and other predicate-like type traits, I think we also
> want to make the corresponding variable template is_function_v directly
> use the built-in too.

Oh, thank you! Will implement it!

> >
> > libstdc++-v3/ChangeLog:
> >
> >       * include/std/type_traits (is_function): Use __is_function built-in
> >       trait.
> >
> > Signed-off-by: Ken Matsui <kmatsui@cs.washington.edu>
> > ---
> >  libstdc++-v3/include/std/type_traits | 7 +++++++
> >  1 file changed, 7 insertions(+)
> >
> > diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
> > index 58a732735c8..9eafd6b16f2 100644
> > --- a/libstdc++-v3/include/std/type_traits
> > +++ b/libstdc++-v3/include/std/type_traits
> > @@ -594,6 +594,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> >      { };
> >
> >    /// is_function
> > +#if __has_builtin(__is_function)
> > +  template<typename _Tp>
> > +    struct is_function
> > +    : public __bool_constant<__is_function(_Tp)>
> > +    { };
> > +#else
> >    template<typename _Tp>
> >      struct is_function
> >      : public __bool_constant<!is_const<const _Tp>::value> { };
> > @@ -605,6 +611,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> >    template<typename _Tp>
> >      struct is_function<_Tp&&>
> >      : public false_type { };
> > +#endif
> >
> >  #define __cpp_lib_is_null_pointer 201309L
> >
> > --
> > 2.40.0
> >
> >
>