| 1 | //===----------------------------------------------------------------------===// |
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| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | |
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| 9 | // <functional> |
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| 10 | |
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| 11 | // namespace placeholders { |
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| 12 | // // M is the implementation-defined number of placeholders |
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| 13 | // extern unspecified _1; |
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| 14 | // extern unspecified _2; |
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| 15 | // . |
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| 16 | // . |
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| 17 | // . |
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| 18 | // extern unspecified _Mp; |
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| 19 | // } |
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| 20 | |
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| 21 | // The Standard recommends implementing them as `inline constexpr` in C++17. |
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| 22 | // |
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| 23 | // Libc++ implements the placeholders as `extern const` in all standard modes |
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| 24 | // to avoid an ABI break in C++03: making them `inline constexpr` requires removing |
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| 25 | // their definition in the shared library to avoid ODR violations, which is an |
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| 26 | // ABI break. |
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| 27 | // |
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| 28 | // Concretely, `extern const` is almost indistinguishable from constexpr for the |
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| 29 | // placeholders since they are empty types. |
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| 30 | |
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| 31 | #include <functional> |
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| 32 | #include <type_traits> |
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| 33 | |
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| 34 | #include "test_macros.h" |
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| 35 | |
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| 36 | template <class T> |
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| 37 | TEST_CONSTEXPR_CXX17 void test(const T& t) { |
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| 38 | // Test default constructible. |
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| 39 | { |
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| 40 | T x; (void)x; |
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| 41 | } |
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| 42 | |
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| 43 | // Test copy constructible. |
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| 44 | { |
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| 45 | T x = t; (void)x; |
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| 46 | static_assert(std::is_nothrow_copy_constructible<T>::value, "" ); |
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| 47 | static_assert(std::is_nothrow_move_constructible<T>::value, "" ); |
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| 48 | } |
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| 49 | |
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| 50 | // It is implementation-defined whether placeholder types are CopyAssignable. |
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| 51 | // CopyAssignable placeholders' copy assignment operators shall not throw exceptions. |
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| 52 | #ifdef _LIBCPP_VERSION |
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| 53 | { |
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| 54 | T x; |
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| 55 | x = t; |
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| 56 | static_assert(std::is_nothrow_copy_assignable<T>::value, "" ); |
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| 57 | static_assert(std::is_nothrow_move_assignable<T>::value, "" ); |
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| 58 | } |
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| 59 | #endif |
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| 60 | } |
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| 61 | |
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| 62 | TEST_CONSTEXPR_CXX17 bool test_all() { |
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| 63 | test(std::placeholders::_1); |
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| 64 | test(std::placeholders::_2); |
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| 65 | test(std::placeholders::_3); |
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| 66 | test(std::placeholders::_4); |
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| 67 | test(std::placeholders::_5); |
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| 68 | test(std::placeholders::_6); |
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| 69 | test(std::placeholders::_7); |
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| 70 | test(std::placeholders::_8); |
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| 71 | test(std::placeholders::_9); |
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| 72 | test(std::placeholders::_10); |
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| 73 | return true; |
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| 74 | } |
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| 75 | |
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| 76 | int main(int, char**) { |
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| 77 | test_all(); |
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| 78 | #if TEST_STD_VER >= 17 |
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| 79 | static_assert(test_all(), "" ); |
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| 80 | #endif |
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| 81 | |
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| 82 | return 0; |
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| 83 | } |
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| 84 | |
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