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// Copyright (C) 2019-2020 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-options "-std=gnu++2a" }
// { dg-do run { target c++2a } }
#include <ranges>
#include <testsuite_hooks.h>
using std::same_as;
void
test01()
{
int a[2] = {};
static_assert(same_as<decltype(std::ranges::cbegin(a)), const int*>);
static_assert(noexcept(std::ranges::cbegin(a)));
VERIFY( std::ranges::cbegin(a) == (a + 0) );
constexpr long b[2] = {};
static_assert( std::ranges::cbegin(b) == (b + 0) );
}
struct R
{
int a[4] = { 0, 1, 2, 3 };
friend int* begin(R& r) { return r.a + 0; }
friend int* begin(R&&); // this function is not defined
friend const int* begin(const R& r) noexcept { return r.a + 2; }
friend const int* begin(const R&&); // this function is not defined
};
struct RV // view on an R
{
R& r;
friend int* begin(RV&); // this function is not defined
friend const int* begin(const RV& rv) noexcept { return begin(std::as_const(rv.r)); }
};
// Allow ranges::begin to work with RV&&
template<> constexpr bool std::ranges::enable_borrowed_range<RV> = true;
void
test03()
{
R r;
const R& c = r;
VERIFY(std::ranges::cbegin(r) == std::ranges::begin(c));
VERIFY(std::ranges::cbegin(c) == std::ranges::begin(c));
RV v{r};
VERIFY(std::ranges::cbegin(std::move(v)) == std::ranges::begin(c));
const RV cv{r};
VERIFY(std::ranges::cbegin(std::move(cv)) == std::ranges::begin(c));
}
struct RR
{
short s = 0;
long l = 0;
int a[4] = { 0, 1, 2, 3 };
short* begin() noexcept { return &s; }
const long* begin() const { return &l; }
friend int* begin(RR& r) { return r.a + 0; }
friend int* begin(RR&& r) { return r.a + 1; }
friend const int* begin(const RR& r) { return r.a + 2; }
friend const int* begin(const RR&& r) noexcept { return r.a + 3; }
};
// N.B. this is a lie, cbegin on an RR rvalue will return a dangling pointer.
template<> constexpr bool std::ranges::enable_borrowed_range<RR> = true;
void
test04()
{
RR r;
const RR& c = r;
VERIFY(std::ranges::cbegin(r) == std::ranges::begin(c));
VERIFY(std::ranges::cbegin(std::move(r)) == std::ranges::begin(c));
VERIFY(std::ranges::cbegin(c) == std::ranges::begin(c));
VERIFY(std::ranges::cbegin(std::move(c)) == std::ranges::begin(c));
}
int
main()
{
test01();
test03();
test04();
}
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