//===----------------------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
// Test all the ways of initializing a std::array.
#include <array>
#include <cassert>
#include <type_traits>
#include "test_macros.h"
struct NoDefault {
TEST_CONSTEXPR NoDefault(int) { }
};
struct test_initialization {
template <typename T>
TEST_CONSTEXPR_CXX14 void operator()() const
{
// Check default initalization
{
std::array<T, 0> a0; (void)a0;
// Before C++20, default initialization doesn't work inside constexpr for
// trivially default constructible types. This only apply to non-empty arrays,
// since empty arrays don't hold an element of type T.
#if TEST_STD_VER < 20
if (!(TEST_IS_CONSTANT_EVALUATED && std::is_trivially_default_constructible<T>::value))
#endif
{
std::array<T, 1> a1;
(void)a1;
std::array<T, 2> a2;
(void)a2;
std::array<T, 3> a3;
(void)a3;
}
std::array<NoDefault, 0> nodefault; (void)nodefault;
}
// A const empty array can also be default-initialized regardless of the type
// it contains. For non-empty arrays, this doesn't work whenever T doesn't
// have a user-provided default constructor.
{
const std::array<T, 0> a0; (void)a0;
const std::array<NoDefault, 0> nodefault; (void)nodefault;
}
// Check direct-list-initialization syntax (introduced in C++11)
#if TEST_STD_VER >= 11
{
{
std::array<T, 0> a0_0{}; (void)a0_0;
}
{
std::array<T, 1> a1_0{}; (void)a1_0;
std::array<T, 1> a1_1{T()}; (void)a1_1;
}
{
std::array<T, 2> a2_0{}; (void)a2_0;
std::array<T, 2> a2_1{T()}; (void)a2_1;
std::array<T, 2> a2_2{T(), T()}; (void)a2_2;
}
{
std::array<T, 3> a3_0{}; (void)a3_0;
std::array<T, 3> a3_1{T()}; (void)a3_1;
std::array<T, 3> a3_2{T(), T()}; (void)a3_2;
std::array<T, 3> a3_3{T(), T(), T()}; (void)a3_3;
}
std::array<NoDefault, 0> nodefault{}; (void)nodefault;
}
#endif
// Check copy-list-initialization syntax
{
{
std::array<T, 0> a0_0 = {}; (void)a0_0;
}
{
std::array<T, 1> a1_0 = {}; (void)a1_0;
std::array<T, 1> a1_1 = {T()}; (void)a1_1;
}
{
std::array<T, 2> a2_0 = {}; (void)a2_0;
std::array<T, 2> a2_1 = {T()}; (void)a2_1;
std::array<T, 2> a2_2 = {T(), T()}; (void)a2_2;
}
{
std::array<T, 3> a3_0 = {}; (void)a3_0;
std::array<T, 3> a3_1 = {T()}; (void)a3_1;
std::array<T, 3> a3_2 = {T(), T()}; (void)a3_2;
std::array<T, 3> a3_3 = {T(), T(), T()}; (void)a3_3;
}
std::array<NoDefault, 0> nodefault = {}; (void)nodefault;
}
// Test aggregate initialization
{
{
std::array<T, 0> a0_0 = {{}}; (void)a0_0;
}
{
std::array<T, 1> a1_0 = {{}}; (void)a1_0;
std::array<T, 1> a1_1 = {{T()}}; (void)a1_1;
}
{
std::array<T, 2> a2_0 = {{}}; (void)a2_0;
std::array<T, 2> a2_1 = {{T()}}; (void)a2_1;
std::array<T, 2> a2_2 = {{T(), T()}}; (void)a2_2;
}
{
std::array<T, 3> a3_0 = {{}}; (void)a3_0;
std::array<T, 3> a3_1 = {{T()}}; (void)a3_1;
std::array<T, 3> a3_2 = {{T(), T()}}; (void)a3_2;
std::array<T, 3> a3_3 = {{T(), T(), T()}}; (void)a3_3;
}
// See http://wg21.link/LWG2157
std::array<NoDefault, 0> nodefault = {{}}; (void)nodefault;
}
}
};
// Test construction from an initializer-list
TEST_CONSTEXPR_CXX14 bool test_initializer_list()
{
{
std::array<double, 3> const a3_0 = {};
assert(a3_0[0] == double());
assert(a3_0[1] == double());
assert(a3_0[2] == double());
}
{
std::array<double, 3> const a3_1 = {1};
assert(a3_1[0] == double(1));
assert(a3_1[1] == double());
assert(a3_1[2] == double());
}
{
std::array<double, 3> const a3_2 = {1, 2.2};
assert(a3_2[0] == double(1));
assert(a3_2[1] == 2.2);
assert(a3_2[2] == double());
}
{
std::array<double, 3> const a3_3 = {1, 2, 3.5};
assert(a3_3[0] == double(1));
assert(a3_3[1] == double(2));
assert(a3_3[2] == 3.5);
}
return true;
}
struct Empty { };
struct Trivial { int i; int j; };
struct NonTrivial {
TEST_CONSTEXPR NonTrivial() { }
TEST_CONSTEXPR NonTrivial(NonTrivial const&) { }
};
struct NonEmptyNonTrivial {
int i; int j;
TEST_CONSTEXPR NonEmptyNonTrivial() : i(22), j(33) { }
TEST_CONSTEXPR NonEmptyNonTrivial(NonEmptyNonTrivial const&) : i(22), j(33) { }
};
template <typename F>
TEST_CONSTEXPR_CXX14 bool with_all_types()
{
F().template operator()<char>();
F().template operator()<int>();
F().template operator()<long>();
F().template operator()<float>();
F().template operator()<double>();
F().template operator()<long double>();
F().template operator()<Empty>();
F().template operator()<Trivial>();
F().template operator()<NonTrivial>();
F().template operator()<NonEmptyNonTrivial>();
return true;
}
// This is a regression test -- previously, libc++ would implement empty arrays by
// storing an array of characters, which means that the array would be initializable
// from nonsense like an integer (or anything else that can be narrowed to char).
#if TEST_STD_VER >= 20
template <class T>
concept is_list_initializable_int = requires {
{ T{123} };
};
struct Foo { };
static_assert(!is_list_initializable_int<std::array<Foo, 0>>);
static_assert(!is_list_initializable_int<std::array<Foo, 1>>);
#endif
int main(int, char**)
{
with_all_types<test_initialization>();
test_initializer_list();
#if TEST_STD_VER >= 14
static_assert(with_all_types<test_initialization>(), "");
static_assert(test_initializer_list(), "");
#endif
return 0;
}
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