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//===----------------------------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
// <optional>
// UNSUPPORTED: c++98, c++03, c++11, c++14
// UNSUPPORTED: clang-5, apple-clang-9
// UNSUPPORTED: libcpp-no-deduction-guides
// Clang 5 will generate bad implicit deduction guides
// Specifically, for the copy constructor.
// template<class T>
// optional(T) -> optional<T>;
#include <optional>
#include <cassert>
struct A {};
int main()
{
// Test the explicit deduction guides
{
// optional(T)
std::optional opt(5);
static_assert(std::is_same_v<decltype(opt), std::optional<int>>, "");
assert(static_cast<bool>(opt));
assert(*opt == 5);
}
{
// optional(T)
std::optional opt(A{});
static_assert(std::is_same_v<decltype(opt), std::optional<A>>, "");
assert(static_cast<bool>(opt));
}
// Test the implicit deduction guides
{
// optional(optional);
std::optional<char> source('A');
std::optional opt(source);
static_assert(std::is_same_v<decltype(opt), std::optional<char>>, "");
assert(static_cast<bool>(opt) == static_cast<bool>(source));
assert(*opt == *source);
}
}
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