[GSoC] Conflicted Built-in Trait Name

[Ken Matsui]

Hi François,

I tried to use `make check-debug`, but my Makefile does not include
the target. Could you please tell me how you generated your Makefile?

FYI, I did this command: `../configure --enable-languages=c++
--disable-error --disable-bootstrap`.

Sincerely,
Ken Matsui

On Mon, Mar 27, 2023 at 10:33 AM François Dumont <frs.dumont@gmail.com> wrote:
>
>
> On 26/03/2023 04:01, Ken Matsui via Libstdc++ wrote:
> > On Sat, Mar 25, 2023 at 5:38 AM Marc Glisse <marc.glisse@inria.fr> wrote:
> >> On Sat, 25 Mar 2023, Ken Matsui via Gcc wrote:
> >>
> >>> Built-in trait naming simply adds two underscores (__) to the original
> >>> trait name. However, the same names are already in use for some
> >>> built-in traits, such as is_void, is_pointer, and is_signed.
> >>>
> >>> For example, __is_void is used in the following files:
> >>>
> >>> * gcc/testsuite/g++.dg/tm/pr46567.C
> >> This is a testcase, you can rename __is_void to whatever in there, it
> >> doesn't matter.
> >>
> >>> * libstdc++-v3/include/bits/cpp_type_traits.h
> >> This __is_void seems to be used in a single place in
> >> include/debug/helper_functions.h, couldn't we tweak that code so __is_void
> >> becomes unused and can be removed?
> > That worked. Thank you!
> What worked ?
> >
> > So, we can remove a code in a header as long as it is not standard and
> > is not used elsewhere, can't we?
>
> You can do anything you like as long as you run the testsuite before
> presenting your patch. Here note that you'll need to run:
>
> make check-debug
>
> to run tests in _GLIBCXX_DEBUG mode which is making use of the code in
> helper_functions.h.
>
> Clearly this usage of std::__is_void could be replaced with your builtin
> by reimplementing _Distance_traits like this:
>
>    template<typename _Iterator,
>         typename = typename std::__is_integer<_Iterator>::__type>
>      struct _Distance_traits
>      {
>      private:
>        typedef
>      typename std::iterator_traits<_Iterator>::difference_type _ItDiffType;
>
>        typedef
>      typename std::conditional<__is_void<_ItDiffType>,
>                    std::ptrdiff_t, _ItDiffType>::type _DiffType;
>
>      public:
>        typedef std::pair<_DiffType, _Distance_precision> __type;
>      };
>
> this is untested, just to give you an idea of what your patch could be.
>
> François
>
>