No strong preference, but Ville's argument sounds reasonable.
On Thu, May 15, 2025 at 12:25 PM Ville Voutilainen <
ville.voutilai...@gmail.com> wrote:
> Mild preference against; use the names from the standard, not the
> implementation, in such diagnostics.
>
> to 15. toukok. 2025 klo 13.20 Jonathan Wakely <jwak...@redhat.com>
> kirjoitti:
>
>> On Thu, 15 May 2025 at 11:14, Jonathan Wakely <jwak...@redhat.com> wrote:
>> >
>> > On Wed, 14 May 2025 at 20:18, Luc Grosheintz <luc.groshei...@gmail.com>
>> wrote:
>> > >
>> > > The standard states that the IndexType must be a signed or unsigned
>> > > integer. This mandate was implemented using `std::is_integral_v`.
>> Which
>> > > also includes (among others) char and bool, which neither signed nor
>> > > unsigned integers.
>> > >
>> > > libstdc++-v3/ChangeLog:
>> > >
>> > > * include/std/mdspan: Implement the mandate for extents as
>> > > signed or unsigned integer and not any interal type.
>> > > *
>> testsuite/23_containers/mdspan/extents/class_mandates_neg.cc: Check
>> > > that extents<char,...> and extents<bool,...> are invalid.
>> > > * testsuite/23_containers/mdspan/extents/misc.cc: Update
>> > > tests to avoid `char` and `bool` as IndexType.
>> > > ---
>> > > libstdc++-v3/include/std/mdspan | 3 ++-
>> > > .../23_containers/mdspan/extents/class_mandates_neg.cc | 10
>> +++++++---
>> > > .../testsuite/23_containers/mdspan/extents/misc.cc | 8 ++++----
>> > > 3 files changed, 13 insertions(+), 8 deletions(-)
>> > >
>> > > diff --git a/libstdc++-v3/include/std/mdspan
>> b/libstdc++-v3/include/std/mdspan
>> > > index aee96dda7cd..22509d9c8f4 100644
>> > > --- a/libstdc++-v3/include/std/mdspan
>> > > +++ b/libstdc++-v3/include/std/mdspan
>> > > @@ -163,7 +163,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>> > > template<typename _IndexType, size_t... _Extents>
>> > > class extents
>> > > {
>> > > - static_assert(is_integral_v<_IndexType>, "_IndexType must be
>> integral.");
>> > > + static_assert(__is_standard_integer<_IndexType>::value,
>> > > + "_IndexType must be a signed or unsigned
>> integer.");
>> >
>> > GCC's diagnostics never end with a full stop (aka period), and we
>> > follow that convention for our static assertions.
>> >
>> > So I'll remove the '.' at the end of the string literal, and then push
>> > this to trunk.
>> >
>> >
>> > > static_assert(
>> > > (__mdspan::__valid_static_extent<_Extents, _IndexType> &&
>> ...),
>> > > "Extents must either be dynamic or representable as
>> _IndexType");
>>
>> I've just noticed that this static_assert refers to "Extents" without
>> the leading underscore, but "_IndexType" with a leading underscore.
>>
>> I think it's OK to omit the leading underscore, it might be a bit more
>> user-friendly and I don't think anybody will be confused by the fact
>> it's not identical to the real template parameter. But we should
>> either do it consistently for _Extents and _IndexType or for neither
>> of them.
>>
>> Anybody want to argue for or against underscores?
>>
>>
