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7c3769df62
to reflect the new license. These used slightly different spellings that defeated my regular expressions. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@351648 91177308-0d34-0410-b5e6-96231b3b80d8
102 lines
3.0 KiB
C++
102 lines
3.0 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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// <tuple>
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// template <class... Types> class tuple;
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// UNSUPPORTED: c++98, c++03
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#include <tuple>
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#include <utility>
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#include <cassert>
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template <class ConstructFrom>
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struct ConstructibleFromT {
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ConstructibleFromT() = default;
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ConstructibleFromT(ConstructFrom v) : value(v) {}
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ConstructFrom value;
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};
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template <class AssertOn>
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struct CtorAssertsT {
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bool defaulted;
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CtorAssertsT() : defaulted(true) {}
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template <class T>
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constexpr CtorAssertsT(T) : defaulted(false) {
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static_assert(!std::is_same<T, AssertOn>::value, "");
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}
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};
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template <class AllowT, class AssertT>
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struct AllowAssertT {
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AllowAssertT() = default;
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AllowAssertT(AllowT) {}
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template <class U>
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constexpr AllowAssertT(U) {
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static_assert(!std::is_same<U, AssertT>::value, "");
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}
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};
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// Construct a tuple<T1, T2> from pair<int, int> where T1 and T2
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// are not constructible from ints but T1 is constructible from std::pair.
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// This considers the following constructors:
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// (1) tuple(TupleLike) -> checks is_constructible<Tn, int>
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// (2) tuple(UTypes...) -> checks is_constructible<T1, pair<int, int>>
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// and is_default_constructible<T2>
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// The point of this test is to ensure that the consideration of (1)
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// short circuits before evaluating is_constructible<T2, int>, which
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// will cause a static assertion.
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void test_tuple_like_lazy_sfinae() {
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#if defined(_LIBCPP_VERSION)
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// This test requires libc++'s reduced arity initialization.
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using T1 = ConstructibleFromT<std::pair<int, int>>;
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using T2 = CtorAssertsT<int>;
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std::pair<int, int> p(42, 100);
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std::tuple<T1, T2> t(p);
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assert(std::get<0>(t).value == p);
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assert(std::get<1>(t).defaulted);
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#endif
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}
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struct NonConstCopyable {
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NonConstCopyable() = default;
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explicit NonConstCopyable(int v) : value(v) {}
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NonConstCopyable(NonConstCopyable&) = default;
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NonConstCopyable(NonConstCopyable const&) = delete;
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int value;
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};
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template <class T>
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struct BlowsUpOnConstCopy {
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BlowsUpOnConstCopy() = default;
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constexpr BlowsUpOnConstCopy(BlowsUpOnConstCopy const&) {
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static_assert(!std::is_same<T, T>::value, "");
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}
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BlowsUpOnConstCopy(BlowsUpOnConstCopy&) = default;
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};
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// Test the following constructors:
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// (1) tuple(Types const&...)
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// (2) tuple(UTypes&&...)
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// Test that (1) short circuits before evaluating the copy constructor of the
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// second argument. Constructor (2) should be selected.
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void test_const_Types_lazy_sfinae()
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{
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NonConstCopyable v(42);
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BlowsUpOnConstCopy<int> b;
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std::tuple<NonConstCopyable, BlowsUpOnConstCopy<int>> t(v, b);
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assert(std::get<0>(t).value == 42);
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}
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int main() {
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test_tuple_like_lazy_sfinae();
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test_const_Types_lazy_sfinae();
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}
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