Arthur O'Dwyer c9af0e61fa [libc++] counting_semaphore should not be default-constructible.
Neither the current C++2b draft, nor any revision of [p1135],
nor libstdc++, claims that `counting_semaphore` should be
default-constructible. I think this was just a copy-paste issue
somehow.

Also, `explicit` was missing from the constructor.

Also, `constexpr` remains missing; but that's probably more of a
technical limitation, since apparently there are some platforms
where we don't (can't??) use the atomic implementation and
have to rely on pthreads, which obviously isn't constexpr.

Differential Revision: https://reviews.llvm.org/D110042
2021-09-21 16:19:31 -04:00

27 lines
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//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// UNSUPPORTED: libcpp-has-no-threads
// UNSUPPORTED: c++03, c++11
// <semaphore>
#include <semaphore>
#include <thread>
#include "test_macros.h"
int main(int, char**)
{
static_assert(std::counting_semaphore<>::max() >= 1, "");
static_assert(std::counting_semaphore<1>::max() >= 1, "");
static_assert(std::counting_semaphore<std::numeric_limits<int>::max()>::max() >= std::numeric_limits<int>::max(), "");
static_assert(std::counting_semaphore<std::numeric_limits<ptrdiff_t>::max()>::max() == std::numeric_limits<ptrdiff_t>::max(), "");
return 0;
}