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// Copyright (C) 2018-2025 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING3. If not see
// <http://www.gnu.org/licenses/>.
// { dg-do compile { target c++17 } }
#include <variant>
#include <utility>
#include <limits>
template<std::size_t I>
struct S {
};
template <std::size_t... Is>
void f_impl(std::index_sequence<Is...>)
{
using V = std::variant<S<Is>...>;
// For a variant of 255 alternatives the valid indices are [0,254]
// and index 255 means valueless-by-exception, so fits in one byte.
if constexpr (std::variant_size_v<V> <=
std::numeric_limits<unsigned char>::max())
static_assert(sizeof(V) == 2);
else
static_assert(sizeof(V) > 2);
}
template <std::size_t I>
void f()
{
f_impl(std::make_index_sequence<I>{});
}
int main()
{
f<std::numeric_limits<unsigned char>::max() - 1>();
f<std::numeric_limits<unsigned char>::max()>();
f<std::numeric_limits<unsigned char>::max() + 1>();
}
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