79 lines
		
	
	
		
			2.0 KiB
		
	
	
	
		
			C++
		
	
	
	
			
		
		
	
	
			79 lines
		
	
	
		
			2.0 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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// <array>
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// reference front();  // constexpr in C++17
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// reference back();   // constexpr in C++17
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#include <array>
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#include <cassert>
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#include "test_macros.h"
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// std::array is explicitly allowed to be initialized with A a = { init-list };.
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// Disable the missing braces warning for this reason.
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#include "disable_missing_braces_warning.h"
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TEST_CONSTEXPR_CXX17 bool tests()
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{
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    {
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        typedef double T;
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        typedef std::array<T, 3> C;
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        C c = {1, 2, 3.5};
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        C::reference r1 = c.front();
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        assert(r1 == 1);
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        r1 = 5.5;
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        assert(c[0] == 5.5);
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        C::reference r2 = c.back();
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        assert(r2 == 3.5);
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        r2 = 7.5;
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        assert(c[2] == 7.5);
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    }
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    {
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        typedef double T;
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        typedef std::array<T, 0> C;
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        C c = {};
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        ASSERT_SAME_TYPE(decltype(c.back()), C::reference);
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        LIBCPP_ASSERT_NOEXCEPT(c.back());
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        ASSERT_SAME_TYPE(decltype(c.front()), C::reference);
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        LIBCPP_ASSERT_NOEXCEPT(c.front());
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        if (c.size() > (0)) { // always false
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            TEST_IGNORE_NODISCARD c.front();
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            TEST_IGNORE_NODISCARD c.back();
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        }
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    }
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    {
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        typedef double T;
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        typedef std::array<const T, 0> C;
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        C c = {};
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        ASSERT_SAME_TYPE(decltype( c.back()), C::reference);
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        LIBCPP_ASSERT_NOEXCEPT(    c.back());
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        ASSERT_SAME_TYPE(decltype( c.front()), C::reference);
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        LIBCPP_ASSERT_NOEXCEPT(    c.front());
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        if (c.size() > (0)) {
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            TEST_IGNORE_NODISCARD c.front();
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            TEST_IGNORE_NODISCARD c.back();
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        }
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    }
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    return true;
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}
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int main(int, char**)
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{
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    tests();
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#if TEST_STD_VER >= 17
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    static_assert(tests(), "");
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#endif
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    return 0;
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}
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