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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug libstdc++/102181] std::advance and
 std::views::iota<std::int64_t> don't work
Date: Thu, 02 Sep 2021 22:13:03 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D102181

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |INVALID
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Raffael Casagrande from comment #3)
> MSVC compiles the snippet without problems...

It looks like they do not correctly implement iota_view. This C++20 proposa=
l,
specifically:
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1522r1.pdf

This program fails with MSVC:

#include <ranges>

int main() {
  using type =3D uint64_t; // using type =3D int works!
  auto v =3D std::views::iota(0ull, ~0ull);
  auto b =3D v.end() - v.begin();
  static_assert(!std::same_as<decltype(b), int64_t>);
}

It is required to compile. You cannot use int64_t to represent the differen=
ce
type of an iota_view with that many elements.

I think GCC is correct according to the standard.=